bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of rigid strip foundations embedded in orthotropic elastic soils
Authors: Wang Y. , Rajapakse R. K. N. D.
Published: April 2007

This study is concerned with the dynamic response of an arbitrary shaped rigid strip foundation embedded in an orthotropic elastic soil. The foundation is subjected to time‐harmonic vertical, horizontal and moment loadings. The boundary‐value problem related to an embedded foundation is analysed by using the indirect boundary integral equation method. The kernel functions of the integral equations are displacement and traction Green's functions of an anisotropic elastic half plane. Exact analytical solutions are used for the Green's functions. The boundary integral equation is solved by using numerical techniques. Selected numerical results are presented for the impedances of rectangular and semi‐circular rigid strip foundations embedded in four types of anisotropic soils. A discussion on the influence of soil anisotropy and frequency of excitation on the impedances is presented. The versatility of the analysis is demonstrated by considering the through soil interaction between two semi‐circular strip foundations.
Response variability in structural dynamics
Authors: Jensen H. , Iwan W. D.
Published: April 2007

This paper presents a technique for treating uncertainties in the dynamic models of a structural system. The formulation of the method is presented for a simple case of a single‐degree‐of‐freedom linear oscillator. The uncertainties are modelled as random variables and are assumed to be time‐independent. The solution is expanded as a series involving the random terms, and a system of linear ordinary differential equations for the unknowns of the problem is derived using the weighted residual method. The system of equations is then integrated in time and the response variability is computed. Validation calculations show that the results from the method agree well with those obtained by other solution techniques. Finally, some possible applications and extensions of the present work are discussed.
Spatially coupled vibrations of a suspension bridge under random highway traffic
Authors: Bryja D. , Śrniady P.
Published: April 2007

The problem of spatial dynamic response of a suspension bridge to the passage of trains of concentrated forces with random values is considered. The arrival of forces at the bridge is assumed to constitute a Poisson process of events. Such an excitation process is an appropriate model of vehicular traffic loads acting on the bridge. The bridge is idealized by a single‐span thin‐walled beam underslung to two cables. The response of the bridge in the space‐time domain is described by a coupled system of non‐linear, integro‐differential equations. The dynamic influence functions of vertical and horizontal deflections at each cross‐section point are obtained for the linear case. Cumulants and probability density functions of response are determined. Numerical methods have been used to develop a computer‐oriented algorithm aimed at the numerical solution of the problem. As examples, numerical results for a particular bridge with some practical load cases are presented and illustrated by graphs.
Impedance functions for three‐dimensional foundations supported on an infinitely‐long canyon of uniform cross‐section in a homogeneous half‐space
Authors: Zhang Liping , Chopra Anil K.
Published: April 2007

A direct boundary element procedure is presented to determine the impedance matrix for a three‐dimensional foundation supported on an infinitely‐long canyon of uniform cross‐section cut in a homogeneous half‐space. The uniform cross‐section of the canyon permits analytical integration along the canyon axis leading to a series of two‐dimensional boundary problems involving Fourier transforms of the full‐space Green's functions. Solution of these two‐dimensional boundary problems leads to a dynamic flexibility influence matrix which is inverted to determine the impedance matrix. The accuracy of the procedure is demonstrated by comparison with previous solutions for a surface‐supported, square foundation and results obtained by a three‐dimensional boundary element method (BEM) for a foundation of finite‐width supported on an infinitely‐long canyon. Compared with the three‐dimensional BEM, the present method requires less computer storage and is more accurate and efficient. The foundation impedance matrix determined by this procedure can be incorporated in a substructure method for earthquake analysis of arch dams.
A case study of mimo system identification applied to building seismic records
Authors: Li Yi , Mau S. T.
Published: April 2007

A large number of high quality strong‐motion records of building response are obtained from recent earthquake events in California. The accelerometers are typically deployed at several levels from the basement up. In order to learn as much as possible about the building behaviour from these records, a multiple input‐multiple output (MIMO) system identification procedure is implemented to analyse these records in a systematic way. The procedure is an extension of the least‐square‐output‐error method applied to a classically damped linear second order system. The time varying behaviour is modelled through a time window approach. The procedure includes (i) preliminary record analysis, (ii) input and model selection, (iii) parameter identification and (iv) drift analysis.

The records of a 15‐storey reinforced concrete building obtained during the Whittier earthquake are analysed. It is found that the fundamental period is much longer than that of a regular building. The torsional response is significant and is caused by both the translational and the torsional motions at the ground level. The maximum drift occurs at the ground storey. The second and the third translational modes in each direction are as important as the first modes in making up the ground storey drift. When the maximum drift occurs in one direction the corresponding drift in the orthogonal direction can be as high as 30 per cent of the maximum drift.
Vibration of three‐dimensional rigid raft foundation on viscoelastic medium
Authors: Zhao Chongbin , Valliappan S.
Published: April 2007

Using the coupled model of finite and infinite elements, the compliance of a rigid raft (plate) on a viscoelastic medium is calculated in this paper. Further, the effects of different proportions of radiation damping and material damping in the total damping and the distribution of wave motion in the near field are also investigated. From the numerical results, it can be concluded that: (1) the radiation damping plays an important role in the total damping, compared to the material damping; (2) the material damping has some effect on the compliance of the raft; (3) under the action of harmonic concentrated loads, the displacement amplitudes in the near field gradually decrease with the increase in the distance from the raft and the material damping; (4) the strata characteristics of the soil medium have considerable influence on the compliance of the raft and the distribution of wave motion in the near field.
Ambient vibration survey of the fatih sultan mehmet (second Bosporus) suspension bridge
Authors: Brownjohn J. M. W. , Dumanoglu A. A. , Severn R. T.
Published: April 2007

Ambient accelerations due to dynamic excitation by wind and traffic were measured on the deck, towers, cables and hangers of the Fatih suspension bridge. From these measurements it was possible to obtain natural frequencies, mode shapes and damping ratios for vertical, lateral, torsional and associated modes in the deck and tower up to a maximum of 2 Hz.

The objective of the test was to validate the mathematical modelling used in seismic analyses of the bridge. The agreement between the experimental and theoretical modes was acceptable for vertical modes below 1 Hz, and for torsional modes, but it was difficult to identify the lateral modes due to low levels of response.

The dynamic behaviour of this bridge and two other major European suspension bridges is discussed in relation to the differences in loading and structural design.
The Effect of the Anode Loading and Method of MEA Fabrication on DMFC Performance
Authors: Reshetenko T. V. , Kim H.‐T. , Krewer U. , Kweon H.‐J.
Published: April 2007

The influence of the Pt‐Ru anode loading and MEA preparation techniques on direct methanol fuel cell (DMFC) performance is studied. Two different anode catalyst layer preparation techniques are employed. One is the direct coating of anode catalyst ink on a membrane to form a catalyst coated membrane, CCManode, and the other is the coating of the ink on the diffusion layers, which generates a catalyst coated substrate, CCSanode. The power density of a combined CCManode/CCScathodeMEA is higher than for a CCSanode/CCScathodeMEA. The main difference in the performance is observed in the high current density region, where two‐phase flow is present and mass transfer processes govern the performance. The CCManodeand CCSanodehave different macroscopic structures, while showing the same microscopic morphology. Based on their morphological differences, it is expected that the combination of the CCManodeand carbon paper provides the more homogeneous removal of CO2at high currents. The authors suggest that the application of the CCManodewith an optimal anode loading improves anode mass transfer, reduces methanol crossover, and enhances the electrochemical reactions.
Graphite Electrodes Modified with Platinum‐Nickel Nano‐Particles for Methanol Oxidation
Authors: Abdel Rahim M. A. , Hassan H. B. , Abdel Hameed R. M.
Published: April 2007

Methanol electro‐oxidation is investigated at graphite electrodes modified with various platinum and nickel nano‐particle deposits using cyclic voltammetry. The modified electrodes are prepared by the simultaneous electrodeposition of metals from their salt solutions using potentiostatic and galvanostatic techniques. They show enhanced catalytic activity towards methanol oxidation in KOH solution. The catalytic activity of platinum nano‐particles is found to be significantly affected by the presence of relatively small amounts of nickel deposits. A comparison is made between the electrocatalytic activity of Pt/C and (Pt‐Ni)/C electrodes. The results show that the methanol electro‐oxidation current increases with an increase in the nickel content. In particular, the highest catalytic activity is achieved for platinum to nickel deposits of 95%:5% (wt.‐%), in other cases the catalytic activity decreases. It is found that Ni enhances the catalytic activity of Pt by increasing the number of active sites, as well as through an electron donation process from Ni to Pt. This process takes place once the nickel hydroxide (Ni(OH)2)/nickel oxy‐hydroxide (NiOOH) transformation begins. The effect of the methanol concentration on the methanol oxidation reaction is investigated. The order of reaction, with respect to methanol, at the modified (Pt‐Ni)/C electrode is found to be 0.5.
Expression of a functional metabotropic glutamate receptor 5 on enteric glia is altered in states of inflammation
Authors: Nasser Yasmin , Keenan Catherine M. , Ma Adrienne C. , McCafferty Donna‐Marie , Sharkey Keith A.
Published: April 2007

The metabotropic glutamate receptor 5 (mGluR5) is expressed by astrocytes and its expression is modulated by inflammation. Enteric glia have many similarities to astrocytes and are the most numerous cell in the enteric nervous system (ENS). We investigated whether enteric glia express a functional mGluR5 and whether expression of this receptor was altered in colitis. In both enteric plexuses of the ileum and colon of guinea pigs and mice, we observed widespread glial mGluR5 expression. Incubation of isolated segments of the guinea pig ileum with the mGluR5 specific agonist RS‐2‐chloro‐5‐hydroxyphenylglycine (CHPG) caused a dose‐dependent increase in the glial expression of c‐Fos and the phosphorylated form of the extracellular signal‐regulated kinase 1/2. Preincubation of tissues with the group I metabotropic glutamate receptor antagonist, S‐4‐carboxyphenylglycine, abolished the effects of CHPG. We examined mGluR5 expression in the guinea pig trinitrobenzene sulfonic acid and the IL‐10 gene‐deficient (IL‐10−/−) mouse models of colitis. In guinea pigs, mGluR5 immunoreactivity became diffusely localized over the colonic myenteric ganglia, suggesting a change in receptor distribution. In contrast, glial mGluR5 expression was significantly reduced in the colonic myenteric plexus of IL‐10−/− mice, as assessed with both real‐time quantitative RT‐PCR as well as immunohistochemistry and image analysis. These changes occurred without concomitant changes to enteric ganglia or glial fibrillary acidic protein expression in the IL‐10−/− mouse. Our data suggest that enteric glia are a functional target of the glutamatergic neurotransmitter system in the ENS and that changes in mGluR5 expression may be of physiological significance during colitis. © 2007 Wiley‐Liss, Inc.
Purines induce directed migration and rapid homing of microglia to injured pyramidal neurons in developing hippocampus
Authors: Kurpius Dana , Nolley Eric P. , Dailey Michael E.
Published: April 2007

Traumatic CNS injury activates and mobilizes resident parenchymal microglia (MG), which rapidly accumulate near injured neurons where they transform into phagocytes. The mechanisms underlying this rapid ‘homing’in situare unknown. Using time‐lapse confocal imaging in acutely excised neonatal hippocampal slices, we show that rapid accumulation of MG near somata of injured pyramidal neurons in the stratum pyramidale (SP) results from directed migration from tissue regions immediately adjacent to (<200 μm from) the SP. Time‐lapse sequences also reveal a ‘spreading activation wave’ wherein MG situated progressively farther from the SP begin to migrate later and exhibit less directional migration toward the SP. Because purines have been implicated in MG activation and chemotaxis, we tested whether ATP/ADP released from injured pyramidal neurons might account for these patterns of MG behavior. Indeed, application of apyrase, which degrades extracellular ATP/ADP, inhibits MG motility and homing to injured neurons in the SP. Moreover, bath application of exogenous ATP/ADP disrupts MG homing by inducing directional migration toward the slice exterior and away from injured neurons. These results indicate that extracellular ATP/ADP is both necessary and sufficient to induce directional migration and rapid homing of neonatal MG to injured neuronsin situ. Rapid, ATP/ADP‐dependent MG homing may promote clearance of dead and dying cells and help limit secondary damage during the critical first few hours after neuronal injury. © 2007 Wiley‐Liss, Inc.
Olfactory ensheathing cells promote migration of Schwann cells by secreted nerve growth factor
Authors: Cao Li , Zhu Yan‐Ling , Su Zhida , Lv Baolai , Huang Zhihui , Mu Lifang , He Cheng
Published: April 2007

Transplantation of Schwann cells (SCs) and olfactory ensheathing cells (OECs) have emerged as very promising therapies for spinal cord repair. The important features of interaction between SCs and OECs are beginning to be appreciated, although the underlying mechanism remains unclear. In the present study, we tested the effects of OECs on SCs migration using a range of in vitro migration assays. We found that SCs migrated abundantly upon OECs monolayer, and the migration‐promoting effects were identified to be due to the secreted diffusible factors in OEC‐derived conditioned medium (OEC‐CM). Furthermore, neutralizing nerve growth factor (NGF) in OEC‐CM with NGF antibody could block this effect. Moreover, we found that NGF promotes SCs migration even on astrocyte monolayer. Taken together, these findings provide the first evidence that OECs can promote SCs migration in astrocytic environment by secreted NGF. © 2007 Wiley‐Liss, Inc.
Cardiovascular effects of high dose venlafaxine XL in patients with major depressive disorder
Authors: Mbaya Patrick , Alam Faouzi , Ashim Sindhu , Bennett David
Published: April 2007

Objective

To assess cardiovascular safety profile of high dose Venlafaxine XL in patients with major depression.

Method

Effects of high dose venlafaxine (mean 346.15 mg;) on the cardiovascular system in 37 patients with major depressive disorder were evaluated: BP, ECG (PR, QT, QRSD and QTc intervals) and heart rate.

Results

12.5% of patients developed hypertension after starting treatment with venlafaxine. There was an association between heart rate and the dose of venlafaxine although not statistically significant. There was no association between dose of venlafaxine and PR, QT, QRSD and QTc intervals. One patient on 300 mg who was hypertensive and on other medications that may prolong QTc, had mildly prolonged QTc. However this was not clinically significant.

Conclusion

This study of subjects on high dose venlafaxine (mean 346.15 mg; range 225–525 mg) did not demonstrate any clinical or statistically significant effects on electrocardiogram (ECG) parameters including PR, QT, QRSD and QTc interval. Copyright © 2007 John Wiley & Sons, Ltd.
Human papillomavirus type distribution in invasive cervical cancer and high‐grade cervical lesions: A meta‐analysis update
Authors: Smith Jennifer S. , Lindsay Lisa , Hoots Brooke , Keys Jessica , Franceschi Silvia , Winer Rachel , Clifford Gary M.
Published: April 2007

Data on human papillomavirus (HPV) type distribution in invasive and pre‐invasive cervical cancer is essential to predict the future impact of HPV16/18 vaccines and HPV‐based screening tests. A meta‐analyses of HPV type distribution in invasive cervical cancer (ICC) and high‐grade squamous intraepithelial lesions (HSIL) identified a total of 14,595 and 7,094 cases, respectively. In ICC, HPV16 was the most common, and HPV18 the second most common, type in all continents. Combined HPV16/18 prevalence among ICC cases was slightly higher in Europe, North America and Australia (74–77%) than in Africa, Asia and South/Central America (65–70%). The next most common HPV types were the same in each continent, namely HPV31, 33, 35, 45, 52 and 58, although their relative importance differed somewhat by region. HPV18 was significantly more prevalent in adeno/adenosquamous carcinoma than in squamous cell carcinoma, with the reverse being true for HPV16, 31, 33, 52 and 58. Among HSIL cases, HPV16/18 prevalence was 52%. However, HPV 16, 18 and 45 were significantly under‐represented, and other high‐risk HPV types significantly over‐represented in HSIL compared to ICC, suggesting differences in type‐specific risks for progression. Data on HPV‐typed ICC and HSIL cases were particularly scarce from large regions of Africa and Central Asia. © 2007 Wiley‐Liss, Inc.
Serial transplantation of NMU‐induced rat mammary tumors: A model of human breast cancer progression
Authors: Chan Maren M. , Lu Xin , Merchant Faisal M. , Dirk Iglehart James , Miron Penelope L.
Published: April 2007

Human breast cancer is a heterogeneous disease that appears to progress from an in situ tumor to invasive cancer. Little is known about the molecular events driving this progression. Although microarray technology has helped us understand the genetic heterogeneity of breast cancer, its application to studying the transition from in situ to invasive disease is limited by the inability to follow the progression of a single patient's tumor. We previously used rat specific microarrays to show that N‐methyl‐N‐nitrosourea induced tumors are similar to low‐grade estrogen‐receptor positive human breast cancer. Here, we transplanted these tumors through 5 generations of syngeneic hosts, and studied 65 resulting tumors. Most transplanted tumors gradually progressed from a noninvasive, low‐grade cancer to a higher‐grade invasive disease, losing p63 localization and basement membrane integrity. Invasive cancers frequently demonstrated a more mesenchymal phenotype with increased vimentin expression. Additionally, a unique transplant series is described with a phenotype similar to human basal‐like breast cancer. Rat‐specific Affymetrix gene arrays containing 15,866 gene probes identified genes that differentiated highly invasive tumors from those of low invasive potential. A linear regression analysis was used to find genes whose change in expression paralleled increasing invasive features independent of the transplant lineage of origin. Genes identified were assigned membership in cell adhesion, signal transduction, cell cycle and extracellular matrix groups, among others. This animal model overcomes the difficulty in studying human breast cancer progression. Our data support a gradual and continuous alteration in programs of gene expression during breast cancer invasion. © 2007 Wiley‐Liss, Inc.
Structure and properties of methacrylate‐endcapped caprolactone networks with modulated water uptake for biomedical applications
Authors: Ivirico J. L. Escobar , Martínez E. Costa , Sánchez M. Salmerón , Criado I. Muñoz , Ribelles J. L. Gómez , Pradas M. Monleón
Published: April 2007

Methacrylate‐endcapped caprolactone (CLMA) networks were synthesized and copolymerized with 2‐hydroxyethyl acrylate (HEA) seeking to tailor the hydrophilicity of the system. The resulting structure of the copolymer network is investigated by differential scanning calorimetry, thermogravimetry, and Fourier transform infrared spectroscopy. The dynamic swelling behavior and the equilibrium water sorption is measured and correlated with the microstructure. The experimental results allow one to conclude that the new material is a random copolymer of both components, HEA and CLMA. The effect of cell attachment and proliferation on the new copolymer networks was observed by in vitro culture of human chondrocytes up to 8 days. Enhanced cellular adhesion, similar to that obtained with tissue culture polystyrene (TCPS), was obtained in the hydrophilized systems. The new copolymers are appropriate for the fabrication of scaffolds with controlled porosity for tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Equivalent potential of water molecules for electronic structure of glutamic acid
Authors: Zhang Tian , Zheng Haoping , Yan Shu
Published: April 2007

The fundamental importance of the electronic structure of molecules is widely recognized. To get reliable electronic structure of protein in aqueous solution, it is necessary to construct a simple, easy‐use equivalent potential of water molecules for protein's electronic structure calculation. Here, the first‐principles, all‐electron, ab initio calculations have been performed to construct the equivalent potential of water molecules for the electronic structure of glutamic acid, which is a hydrophilic amino acid and is negatively charged (Glu−) in neutral water solution. The main process of calculation consists of three steps. Firstly, the geometric structure of the cluster containing Glu− and water molecules is calculated by free cluster calculation. Then, based on the geometric structure, the electronic structure of Glu− with the potential of water molecules is calculated using the self‐consistent cluster‐embedding method. Finally, the electronic structure of Glu− with the potential of dipoles is calculated. Our calculations show that the major effect of water molecules on Glu−'s electronic structure is lowering the occupied electronic states by about 0.017 Ry, and broadening energy gap by 12%. The effect of water molecules on the electronic structure of Glu− can be well simulated by dipoles potential. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu3Au3 homotops
Authors: Tsipis Constantinos A. , Depastas Ioannis G. , Kefalidis Christos E.
Published: April 2007

Bimetallic Cu3Au3 clusters have been investigated using electronic structure calculation techniques (DFT) to understand their electronic, magnetic, and optical properties as well as the geometrical structures. The most stable homotop is the planar cyclo‐[Cu3(μ‐Au)3] form consisting of a triangular positively charged Cu3 structural core with negatively charged Au atoms occupying exposed positions. This structure is characterized by the maximum number of heterobonds and peripheral positions of Au atoms. Possible growth formats of the cyclo‐[Cu3(μ‐Au)3] homotops have been explored following both the edge‐capping and the stepwise metal atom substitution mechanism. The bonding pattern along with the density of states (DOS) plots of the cyclo‐[Cu3(μ‐Au)3] homotop are thoroughly analyzed and compared with those of the pure cyclo‐[Cu3(μ‐Cu)3] and cyclo‐[Au3(μ‐Au)3] clusters. Particular attention was paid on the stability of these bimetallic clusters in relation with the ring‐shaped electron density distribution (aromaticity). It was found that all 3‐membered metal rings exhibit significant aromatic character, which was verified by a number of established criteria of aromaticity, such as structural, energetic, magnetic (NICS profiles), and out‐of‐plane ring deformability criteria. The NICS (1) values correlate well with the out‐of‐plane ring deformation energy. Finally, a comprehensive analysis of the optical spectra of the CuAu, Cu2, and Au2 diatomics and the cyclo‐[Cu3(μ‐Au)3], cyclo‐[Cu3(μ‐Cu)3], and cyclo‐[Au3(μ‐Au)3] clusters placed the electronic assignments of the optical transitions on a firm footing. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Recombinant fusion proteins TAT‐Mu, Mu and Mu‐Mu mediate efficient non‐viral gene delivery
Authors: Rajagopalan Rukkumani , Xavier Jennifer , Rangaraj Nandini , Rao Nalam Madhusudhana , Gopal Vijaya
Published: April 2007

Background

The inherent ability of certain peptides or proteins of viral, prokaryotic and eukaryotic origin to bind DNA was used to generate novel peptide‐based DNA delivery protocols. We have developed a recombinant approach to make fusion proteins with motifs for DNA‐binding ability, Mu and membrane transduction domains, TAT, and tested them for their DNA‐binding, uptake and transfection efficiencies. In one of the constructs, the recombinant plasmid was designed to encode the Mu moiety of sequence MRRAHHRRRRASHRRMRGG in‐frame with TAT of sequence YGRKKRRQRRR to generate TAT‐Mu, while the other two constructs, Mu and Mu‐Mu, harbor a single copy or two copies of the Mu moiety.

Methods

Recombinant his‐tag fusion proteins TAT‐Mu, Mu and Mu‐Mu were purified by overexpression of plasmid constructs using cobalt‐based affinity resins. The peptides were characterized for their size and interaction with DNA, complexed with plasmid pCMVβ‐gal, and shown to transfect MCF‐7, COS and CHOK‐1 cells efficiently.

Results

Recombinant fusion proteins TAT‐Mu, Mu and Mu‐Mu were cloned and overexpressed in BL21(DE3)pLysS with greater than 95% purity. The molecular weight of TAT‐Mu was determined by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) to be 11.34 kDa while those of Mu and Mu‐Mu were 7.78 and 9.83 kDa, respectively. Live uptake analysis of TAT‐Mu, Mu and Mu‐Mu as DP (DNA + peptide) or DPL (DNA + peptide + lipid) complexes into MCF‐7 cells, followed by immunostaining and laser scanning confocal microscopy, demonstrated that the complexes are internalized very efficiently and localized in the nucleus. DNA : peptide complexes (DP) transfect MCF‐7, COS and CHOK‐1 cells. The addition of cationic liposomes enhances the uptake of the ternary complexes (DPL) further and also brings about 3–7‐fold enhancement in reporter gene expression compared to DP alone.

Conclusions

Recombinant proteins that are heterologous fusions, having DNA‐binding domains and nuclear localization epitopes, generated in this study have considerable potential to facilitate DNA delivery and enhance transfection. The domains in these fusion proteins would be promising in the development of non‐viral gene delivery vectors particularly in cells that do not divide. Copyright © 2007 John Wiley & Sons, Ltd.
Hypoxia‐targeted over‐expression of carboxylesterase as a means of increasing tumour sensitivity to irinotecan (CPT‐11)
Authors: Matzow Torkjel , Cowen Rachel L. , Williams Kaye J. , Telfer Brian A. , Flint Pamela J. , Southgate Thomas D. , Saunders Mark P.
Published: April 2007

The induced expression of carboxylesterase (CE) enzymes, which convert the prodrug irinotecan (CPT‐11) into its active cytotoxic metabolite SN‐38, constitutes a promising strategy for cancer gene therapy. By incorporating hypoxia‐responsive elements (HREs) in conjunction with the transgene, expression can be targeted specifically to hypoxic tissues (such as solid tumours), expressing the hypoxia‐inducible factor 1 (HIF‐1). We have constructed a recombinant adenoviral vector, AdHRE‐rCE, encoding the cDNA for the highly efficient rabbit liver CE (rCE), under the control of a HRE derived from the human phosphoglycerate kinase 1 (PGK‐1) gene in conjunction with a minimal SV40 promoter. In vitro, HT1080 fibrosarcoma and SW480 colon carcinoma cells demonstrated an approximately 10‐fold hypoxia‐dependent induction in CE expression following pre‐infection with AdHRE‐rCE, which led to a15–30‐fold increased sensitivity to CPT‐11. Furthermore, in vivo, SW480 tumour xenografts infected with AdHRE‐rCE demonstrated a 2‐fold decrease in tumour doubling time, when combined with 7 days of CPT‐11 treatment, in comparison to mock‐infected controls, with rCE expression shown to be limited to hypoxic regions only. As the cytotoxicity of CPT‐11 is reduced under hypoxic conditions, over‐expression of a highly efficient CE such as rCE under hypoxia control within these hypoxic cells could reverse this effect and, therefore, form the basis for future clinical treatment strategies. Copyright © 2007 John Wiley & Sons, Ltd.
Novel chitosan derivative nanoparticles enhance the immunogenicity of a DNA vaccine encoding hepatitis B virus core antigen in mice
Authors: Jiang Lei , Qian Feng , He Xiaowen , Wang Fang , Ren Ding , He Ying , Li Ka , Sun Shuhan , Yin Chunhua
Published: April 2007

Background

Chitosan has been shown to possess useful properties such as non‐toxicity, high biocompatibility and non‐antigenicity that offer advantages for vaccine delivery systems. In this study, we prepared novel chitosan derivative nanoparticles as DNA vaccine carriers and the potential and mechanism of the DNA‐nanoparticle complexes in inducing augmented immune responses were explored.

Methods

The pVAX(HBc)DNA‐nanoparticle complexes as vaccine delivery systems were studied in several aspects: the protection against DNase I degradation was measured by an in vitro inhibition assay; the sustained expression of the plasmid in vivo was determined by RT‐PCR; the elevated uptake efficiency by phagocytes was observed with confocal microscopy; the biocompatibility was evaluated by cytotoxicity and histology assay; the complexes were administrated to C57BL/6 mice and the humoral and cellular immune responses were evaluated by ELISA, IFN‐γ production and cytolytic T lymphocyte (CTL)‐specific lysis assay.

Results

The remaining relative activity of DNase I after inhibition varied from 32.3% to 77.6%. The complexes were observed with higher uptake efficiency by phagocytes than naked DNA. Three types of nanoparticles did not induce significant cytotoxicity at concentrations ⩽400 µg/ml. No specific histological alteration related to the injection of the complexes was observed. The formulations of DNA‐nanoparticle complexes significantly enhanced the immunogenicity in several parameters: elevated antibody production, higher level of IFN‐γ secretion, and augmented specific cell lysis.

Conclusions

This study demonstrated the potential of the novel chitosan derivative nanoparticles for safe and effective DNA vaccine delivery. Copyright © 2007 John Wiley & Sons, Ltd.
Long‐term follow‐up of metal‐on‐metal total hip replacement
Authors: Grübl Alexander , Marker Martina , Brodner Wolfram , Giurea Alexander , Heinze Georg , Meisinger Vanee , Zehetgruber Harald , Kotz Rainer
Published: April 2007

Metal‐on‐metal articulations were reintroduced to reduce polyethylene particle‐induced osteolysis. Elevated serum metal levels have been detected at short‐ and intermediate‐term follow‐up. There is little knowledge about long‐term effects of increased ionic metal generation. Our study was undertaken to provide information about long‐term survival, clinical outcome, radiographic appearance, and serum metal concentrations after a minimum 10 years follow‐up with a metal‐on‐metal hip prosthesis: 105 cementless primary total hip prostheses with metal‐on‐metal articulating surfaces were implanted in 98 patients with a mean age of 56 years. Clinical data, radiographs, and blood samples were obtained at a follow‐up visit 10 years after implantation. Serum cobalt and chromium levels were determined with use of atomic absorption spectrometry. General laboratory analyses included a full blood count and kidney function parameters. The Harris score was 92 points and the UCLA score 6 points after 10 years. Small osteolytic lesions and radiolucent lines were found in Gruen's zones 1, 7, 8, and 14. The probability of survival was 98.6%. The median serum cobalt concentration of the 22 patients with their hip replacement as the only source of cobalt was 0.75 µg/L (range, 0.3–50.1 µg/L). No patient was diagnosed with renal insufficiency during the study period. Five patients were diagnosed with a malignancy between surgery and the follow‐up. We do not have evidence of an increased rate of primary malignancies nor could we detect renal failure in our study group. Serum metal levels did not differ from short‐ and intermediate term follow‐up values. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:841–848, 2007
Enhanced early chondrogenesis in articular defects following arthroscopic mesenchymal stem cell implantation in an equine model
Authors: Wilke Markus M. , Nydam Daryl V. , Nixon Alan J.
Published: April 2007

Mesenchymal stem cells (MSCs) provide an important source of pluripotent cells for musculoskeletal tissue repair. This study examined the impact of MSC implantation on cartilage healing characteristics in a large animal model. Twelve full‐thickness 15‐mm cartilage lesions in the femoropatellar articulations of six young mature horses were repaired by injection of a self‐polymerizing autogenous fibrin vehicle containing mesenchymal stem cells, or autogenous fibrin alone in control joints. Arthroscopic second look and defect biopsy was obtained at 30 days, and all animals were euthanized 8 months after repair. Cartilage repair tissue and surrounding cartilage were assessed by histology, histochemistry, collagen type I and type II immunohistochemistry, collagen type II in situ hybridization, and matrix biochemical assays. Arthroscopic scores for MSC‐implanted defects were significantly improved at the 30‐day arthroscopic assessment. Biopsy showed MSC‐implanted defects contained increased fibrous tissue with several defects containing predominantly type II collagen. Long‐term assessment revealed repair tissue filled grafted and control lesions at 8 months, with no significant difference between stem cell‐treated and control defects. Collagen type II and proteoglycan content in MSC‐implanted and control defects were similar. Mesenchymal stem cell grafts improved the early healing response, but did not significantly enhance the long‐term histologic appearance or biochemical composition of full‐thickness cartilage lesions. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:913–925, 2007
Lattice dynamics of tetragonal R2BaCuO5 (R = La, Nd) oxides in the P4/mbm structure
Authors: Gupta H. C. , Sharma V.
Published: April 2007

A short‐range force constant model (SRFCM) has been applied to investigate the Raman and the infrared wavenumbers in R2BaCuO5 (R = La, Nd) in their tetragonal phase of space group P4/mbm. Calculations of zone‐center phonons are made with six stretching and five bending force constants. All the Raman and infrared values are then assigned to their corresponding modes. The force constants were evaluated by fitting ten Raman and eight infrared modes. The calculated Raman and infrared modes show good agreement with the observed values. Copyright © 2007 John Wiley & Sons, Ltd.
pH‐dependent surface‐enhanced Raman scattering studies of N‐acetylalanine monolayers self‐assembled on a silver surface
Authors: Yang Haifeng , Zhu Jun , Sheng Chun , Sun Xiaojing , Ji Jiahua , Ma Xiaoling
Published: April 2007

Monolayers of N‐acetylalanine on a metallic surface can serve as a biocompatible functional interface to construct biosensors. In the present paper, the surface‐enhanced Raman scattering (SERS) spectra of N‐acetylalanine monolayers self‐assembled on a silver surface under different pH were recorded. Assignments of the obtained spectra were carried out by density functional theory (DFT) calculations (BLYP/6‐311G). On the basis of the SERS effect, the nature of adsorption of N‐acetylalanine on a silver surface was deduced. It can be concluded that the fully protonated N‐acetylalanine is adsorbed on the silver surface via the imine group together with the carboxylate group, while it anchored onto the surface not only through both the imine and the carboxylate groups but also through the amide group after being completely deprotonated in the basic solution. Copyright © 2007 John Wiley & Sons, Ltd.
The linkage between cell wall metabolism and fruit softening: looking to the future
Authors: Vicente Ariel R , Saladié Montserrat , Rose Jocelyn KC , Labavitch John M
Published: April 2007

The softening that accompanies ripening of commercially important fruits exacerbates damage incurred during shipping and handling and increases pathogen susceptibility. Thus, postharvest biologists have studied fruit softening to identify ways to manage ripening and optimise fruit quality. Studies, generally based on the premise that cell wall polysaccharide breakdown causes ripening‐associated softening, have not provided the insights needed to genetically engineer, or selectively breed for, fruits whose softening can be adequately controlled. Herein it is argued that a more holistic view of fruit softening is required. Polysaccharide metabolism is undoubtedly important, but understanding this requires a full appreciation of wall structure and how wall components interact to provide strength. Consideration must be given to wall assembly as well as to wall disassembly. Furthermore, the apoplast must be considered as a developmentally and biochemically distinct, dynamic ‘compartment’, not just the location of the cell wall structural matrix. New analytical approaches for enhancing the ability to understand wall structure and metabolism are discussed. Fruit cells regulate their turgor pressure as well as cell wall integrity as they ripen, and it is proposed that future studies of fruit softening should include attempts to understand the bases of cell‐ and tissue‐level turgor regulation if the goal of optimising softening control is to be reached. Finally, recent studies show that cell wall breakdown provides sugar substrates that fuel other important cellular pathways and processes. These connections must be explored so that optimisation of softening does not lead to decreases in other aspects of fruit quality. Copyright © 2007 Society of Chemical Industry
In vitro gas production profile and the formation of end products from non‐ washable, insoluble washable and soluble washable fractions in some concentrate ingredients
Authors: Azarfar Arash , Williams Barbara A , Boer Huug , Tamminga Seerp
Published: April 2007

A procedure that mimics washing in the in situ incubation technique, combined with an in vitro gas and volatile fatty acids (VFAs) production technique, was used to verify the assumption that rumen degradation behaviour of material washed out of nylon bags is instantaneous and complete. In a 6 × 4 factorial arrangement of treatments with three replicates, fractions of maize, barley, milo, yellow peas, lupins (a mixture of white and spotted lupins) and round‐seeded brown faba beans were subjected to an in vitro incubation technique. Fractions were whole (WHO), non‐washable (NWF), insoluble washable (ISWF) and soluble washable (SWF). In a manually operated in vitro fermentation system, another 24 samples of the same substrates were fermented for VFA and ammonia analysis. Except in lupins, ISWF in the concentrate ingredients was very rich in starch. SWF was relatively rich in ash, crude protein, soluble sugars, and a residual unknown fraction but contained only a negligible quantity of starch. Thus, the fermentation characteristics of ISWF were more like WHO and NWF than SWF. Total gas production of SWF was considerably lower than the other fractions. A very rapidly degradable fraction was seen in the first phase of degradation of SWF. The pattern of fermentation end‐product formation for SWF differed from that of the other fractions. Copyright © 2007 Society of Chemical Industry
Uncooked Taiwanese yam (Dioscorea alata L. cv. Tainung No. 2) beneficially modulated the large bowel function and faecal microflora in BALB/c mice
Authors: Wang Cheng‐Hsin , Tsai Chung‐Hung , Lin Hui‐Ju , Wang Tse‐Cheng , Chen Hsiao‐Ling
Published: April 2007

This study investigated the effects of an uncooked Taiwanese yam, Dioscorea alata L. cv. Tainung No. 2, on faecal characteristics, faecal microflora, short‐chain fatty acid (SCFA) levels in the caecal content and faeces, and morphological and proliferation indices of the caecal and colonic crypts in BALB/c mice. Mice were randomly allocated to consume a control diet or a 25 or 50% (w/w) yam diet for 21 days. Faecal wet and dry masses increased with increasing proportions of dietary yam. Both yam diets similarly increased faecal moisture content and decreased faecal pH as compared with the control diet. The yam diets increased total bacteria and bifidobacteria counts and decreased Clostridium perfringens counts in faeces. The 50% yam diet, but not the 25% yam diet, increased total SCFA concentration in the caecal content. However, both yam diets increased total SCFA output in faeces. Both yam diets also promoted crypt depth, width and proliferation indices in the caecum; in contrast, they only promoted crypt width in the distal colon. In conclusion, the 25 and 50% yam diets increased the faecal mass and SCFA output, modulated the faecal microflora and thickened the mucosa lining of the caecum in BALB/c mice. Copyright © 2007 Society of Chemical Industry
The yield and quality of fresh and ensiled plant material from intercropped maize (Zea mays) and beans (Phaseolus vulgaris)
Authors: Dawo Mohamed I , Wilkinson J Michael , Sanders Francis ET , Pilbeam David J
Published: April 2007

An investigation was carried out in the UK to determine whether intercropping with Phaseolus vulgaris beans increases the yield and nutritional quality of maize forage. Fresh and dry yields arising from different sowing dates and different densities of the two species were evaluated, with total nitrogen concentration (TNC) of the plants, and crude protein concentration (CPC), dry matter, metabolizable energy (ME), pH and starch, lactic acid and ash contents of ensiled material. Highest biomass yields of intercrops were obtained when the two species were planted simultaneously. There was a higher TNC in intercropped maize plants than in maize plants grown without beans (P < 0.05). Biomass yields were not significantly higher with a higher density of maize in the intercrop than with a lower density, nor were they higher with monocrop maize than with intercropping. However, the biomass had higher CPC at 75 000 maize plus 50 000 beans ha−1 and 50 000 maize plus 50 000 beans ha−1 than monocrop maize. Other nutritional characteristics of the silage made from the intercrop treatments were not significantly different from those of the silage made from monocrop maize. As the silage from intercrops of 75 000 maize plus 50 000 beans ha−1 and 50 000 maize plus 50 000 beans ha−1 gave more CP per land area than monocrop silage, and gave biomass yields that were not significantly different from monocrop maize, it was concluded that such intercropping is suitable for producing high‐quality silage under similar agro‐climatic conditions. Copyright © 2007 Society of Chemical Industry
Quality changes in fresh‐cut celery as affected by heat treatment and storage
Authors: Viña Sonia Z , Osornio María M López , Chaves Alicia R
Published: April 2007

This work was intended to investigate the effect of thermal treatment (by immersion or heated air) on quality attributes of pre‐cut celery stored at 0 °C for 21 days. The evolution of organoleptic characteristics, weight loss, surface color, chlorophyll content, texture and microbiological counts were determined. Quality of cut celery mostly maintained its initial level up to 14 days at 0 °C, regardless of the treatment applied. The control and heated‐air‐treated samples experienced a similar evolution of surface color, chlorophyll content, texture and microbial counts. There was a slight advantage of the heated air treatment compared to the control, as measured by sensory parameters. The immersion treatment allowed a better retention of the original color and the total chlorophyll content of pieces. However, after 14 days at 0 °C, a more noticeable tissue softening along with rapid microbial development was observed. Copyright © 2007 Society of Chemical Industry
Mass spectrometry‐based “omics” technologies in cancer diagnostics
Authors: Zhang Xuewu , Wei Dong , Yap Yeeleng , Li Lin , Guo Siyuan , Chen Feng
Published: April 2007

Many “omics” techniques have been developed for one goal: biomarker discovery and early diagnosis of human cancers. A comprehensive review of mass spectrometry‐based “omics” approaches performed on various biological samples for molecular diagnosis of human cancers is presented in this article. Furthermore, the existing and potential problems/solutions (both de facto experimental and bioinformatic challenges), and future prospects have been extensively discussed. Although the use of present omic methods as diagnostic tools are still in their infant stage and consequently not ready for immediate clinical use, it can be envisaged that the “omics”‐based cancer diagnostics will gradually enter into the clinic in next 10 years as an important supplement to current clinical diagnostics. © 2007 Wiley Periodicals, Inc., Mass Spec Rev
Myelinated nerve endings in human skin
Authors: Provitera Vincenzo , Nolano Maria , Pagano Angela , Caporaso Giuseppe , Stancanelli Annamaria , Santoro Lucio
Published: April 2007

We used immunohistochemical techniques and confocal microscopy to study the morphometry of myelinated nerve endings in glabrous and hairy skin. A total of 30 healthy volunteers took part in this study designed to assess the possibility of obtaining reliable information on myelinated fibers using samples of hairy skin and to determine whether differences exist between myelinated terminations from different sites. We obtained consistent information on cutaneous myelinated terminations using hairy as well as glabrous skin samples. Myelinated endings from hairy and glabrous skin differ in density and distribution. However, from a comparison of our findings with data from nerve biopsy studies, we conclude that all cutaneous myelinated terminations are thinner terminal branches of large myelinated Aβ fibers, whereas cutaneous terminations of small myelinated Aδ fibers lose their myelin before entering the dermis and become indistinguishable from C‐fiber terminations. The classic criteria, based on fiber size, used to distinguish myelinated fiber subgroups in sensory nerves are therefore not suitable for identifying myelinated terminations in the skin. Muscle Nerve, 2007