bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increasing stereotypy in adult zebra finch song correlates with a declining rate of adult neurogenesis
Authors: Pytte Carolyn L. , Gerson Miles , Miller Janet , Kirn John R. 
Published: June 2007

AbstractAdult neurogenesis is often correlated with learning new tasks, suggesting that a function of incorporating new neurons is to permit new memory formation. However, in the zebra finch, neurons are added to the song motor pathway throughout life, long after the initial song motor pattern is acquired by about 3 months of age. To explore this paradox, we examined the relationship between adult song structure and neuron addition using sensitive measures of song acoustic structure. We report that between 4 and 15 months of age there was an increase in the stereotypy of fine‐grained spectral and temporal features of syllable acoustic structure. These results indicate that the zebra finch continues to refine motor output, perhaps by practice, over a protracted period beyond the time when song is first learned. Over the same age range, there was a decrease in the addition of new neurons to HVC, a region necessary for song production, but not to Area X or the hippocampus, regions not essential for singing. We propose that age‐related changes in the stereotypy of syllable acoustic structure and HVC neuron addition are functionally related. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
A Novel Functionalized Single‐Wall Carbon Nanotube Modified Electrode and Its Application in Determination of Dopamine and Uric Acid in the Presence of High Concentrations of Ascorbic Acid
Authors: Zhang Yuzhong , Pan Yan , Su Shao , Zhang Liping , Li Shuping , Shao Mingwang 
Published: June 2007

AbstractMultilayer films of negatively charged single‐wall carbon nanotubes (SWCNTs) and positively charged cetylpyridinium bromide (CPB) have been deposited on a glassy carbon electrode (GCE) using layer‐by‐layer (LBL) technique. The assembled multilayer films have been investigated by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and quartz crystal microbalance (QCM) measurements. The voltammetric signal of dopamine (DA), uric acid (UA), and ascorbic acid (AA) could be observed well‐separated with the assembled SWCNTs/CPB multilayer films in pH 7.0 PBS. The oxidation peak potentials of DA, UA, and AA are centered at about 169 mV, 292 mV and −10 mV on differential pulse voltammograms (DPVs), respectively. The peak‐to‐peak potential separation was 123 mV, 179 mV, and 302 mV for DA‐UA, DA‐AA, and UA‐AA in DPVs, respectively. This permits the simultaneous detection of DA and UA in the presence of AA.
Properties of Dendrimer‐Encapsulated Pt Nanoparticles Doped Polypyrrole Composite Films and Their Electrocatalytic Activity for Glucose Oxidation
Authors: Tang Longhua , Zhu Yihua , Xu Lihuan , Yang Xiaoling , Li Chunzhong 
Published: June 2007

AbstractA type of novel electroanalytical sensing nanobiocomposite material was prepared by electropolymerization of pyrrole containing poly(amidoamine) dendrimers‐encapsulated platinum nanoparticles (Pt‐PAMAM), and glucose oxidase (GOx). The Pt nanoparticles encapsulated in PAMAM are nearly monodisperse with an average diameter of 3 nm, and they provide electrical conductivity. Polypyrrole acts as a polymer backbone to give stable and homogeneous cast thin films, and it also defines the electrical conductivity. Both Polypyrrole and PAMAM can provide a favorable microenvironment to keep the bioactivity of enzymes such as glucose oxidase. The homogeneity of GOx/Pt‐PAMAM‐PPy nanobiocomposite films was characterized by atomic force microscopy (AFM). Amperometric biosensors fabricated with these materials were characterized electrochemically using cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and amperometric measurements in the presence of hydrogen peroxide or glucose. All those show the resultant biosensor sensitivity was strongly enhanced within the nanobiocomposite film. The optimized glucose biosensor displayed a sensitivity of 164 μA mM−1 cm−1, a linear range of 0.2 to 600 μM, a detection limit of 10 nM, and a response time of <3 s.
Gene expression analysis of multiple gastrointestinal regions reveals activation of common cell regulatory pathways following cytotoxic chemotherapy
Authors: Bowen Joanne M. , Gibson Rachel J. , Tsykin Anna , Stringer Andrea M. , Logan Richard M. , Keefe Dorothy M.K. 
Published: June 2007

AbstractGastrointestinal mucositis involves many changes at the gene level, affecting epithelial/subepithelial interactions and leading to overt damage. The regional specificity and time course of these changes, and how they relate to subsequent mucositis development however remain unknown. The aim of this study was to determine the early time course of gene expression changes along the gastrointestinal tract of the DA rat following chemotherapy. Female DA rats were treated with a single dose of 200 mg/kg irinotecan to induce mucositis, and were killed at short intervals following treatment. Small sections of stomach, jejunum and colon were harvested for analysis of genetic profiles. RNA was hybridised to high density Affymetrix oligonucleotide microarrays. Data analysis was carried out with software package, TimeCourse, freely available through Bioconductor. As early as 1 hr following chemotherapy, expression of hundreds of genes was altered, including those for transcription factors, stress response proteins and protein turnover. These genes are involved in cell proliferation, differentiation and apoptosis along with other cellular processes. At early time points, there was a significant response involving the mitogen‐activated protein kinase pathway, cell cycle regulation and cytokine receptor signalling. At later time points, changes to the complement cascade became prominent. We have shown that changes in gene expression following chemotherapy occur by 1 hr, and persist for at least 72 hr after treatment. Many of these changes are highly likely to be specifically related to the subsequent development of gastrointestinal mucositis. © 2007 Wiley‐Liss, Inc.
Identification of Fn14/TWEAK receptor as a potential therapeutic target in esophageal adenocarcinoma
Authors: Watts George S. , Tran Nhan L. , Berens Michael E. , Bhattacharyya Achyut K. , Nelson Mark A. , Montgomery Elizabeth A. , Sampliner Richard E. 
Published: June 2007

AbstractGiven the poor survival rate and efficacy of current therapy for esophageal adenocarcinoma (EAC), there is a need to identify and develop new therapeutic targets for treatment. Microarray analysis (Affymetrix U133A GeneChips, Robust Multi‐Chip Analysis) was used to expression profile 11 normal squamous and 18 Barrett's esophagus biopsies, 7 surgically resected EACs and 3 EAC cell lines. Two hundred transcripts representing potential therapeutic targets were identified using the following criteria: significant overexpression in EAC by analysis of variance (p = 0.05, Benjamini Hochberg false discovery rate); 3‐fold increase in EAC relative to normal and Barrett's esophagus and expression in at least 2 of the 3 EAC cell lines. From the list of potential targets we selected TNFRSF12A/Fn14/TWEAK receptor, a tumor necrosis factor super‐family receptor, for further validation based on its reported role in tumor cell survival and potential as a target for therapy. Fn14 protein expression was confirmed in SEG‐1 and BIC‐1 cell lines, but Fn14 was not found to affect tumor cell survival after exposure to chemotherapeutics as expected. Instead, a novel role in EAC was discovered in transwell assays, in which modulating Fn14 expression affected tumor cell invasion. Fn14's potential as a therapeutic target was further supported by immunohistochemistry on a tissue microarray of patient samples that showed that Fn14 protein expression increased with disease progression in EAC. © 2007 Wiley‐Liss, Inc.
Patients with previous cancer should not be excluded in international comparative cancer survival studies
Authors: Brenner Hermann , Hakulinen Timo 
Published: June 2007

AbstractIn international comparisons or time trend analyses of cancer survival, it is common practice to restrict analyses to patients with a first cancer, i.e., to exclude patients with previous cancer diagnoses. However, the proportion of cancer patients with known previous cancer depends on the time cancer registries have been running, which results in varying proportions of excluded patients across registries. If prognosis of patients with second cancers differs from prognosis of patients with first cancers, varying exclusions may bias survival comparisons. We empirically evaluate the dependence of proportions of patients recorded as having a first cancer on time since initiation of cancer registration and the impact of excluding patients with known previous cancer on cancer survival estimates using the data of the nationwide Finnish Cancer Registry. Among 20 common cancer sites investigated, the proportion of “first cancers” varied between 97.4 and 99.7% in 1953–1957, the first 5‐years of cancer registration, and decreased continuously to levels between 83.9 and 92.7% in 1993–1997. Excluding patients with a previous cancer diagnosis had little impact on estimates of survival of cancer patients diagnosed in 1953–1957, but increased 5‐year relative survival estimates among patients diagnosed in 1993–1997 for each of the 20 cancers. The extent of the increase varied by cancer site and age. The increase ranged up to 2.9% points for crude and up to 1.7% points for age adjusted 5‐year relative survival. These results caution against exclusion of patients with previous cancer diagnosis in comparative analyses of cancer survival. © 2007 Wiley‐Liss, Inc.
Comparative in vitro study of the cell proliferation of ovine and human osteoblast‐like cells on conventionally and rapid prototyping produced scaffolds tailored for application as potential bone replacement material
Authors: Wagner M. , Kiapur N. , Wiedmann‐Al‐Ahmad M. , Hübner U. , Al‐Ahmad A. , Schön R. , Schmelzeisen R. , Mülhaupt R. , Gellrich N.‐C. 
Published: June 2007

AbstractReconstruction of bone defects in the field of craniomaxillofacial surgery is a relevant problem. In regenerative medicine, autologous bone is not available sufficiently. The full replacement of autologous bone grafts is required. A promising research field is the bone engineering. Especially the application of rapid prototyping (RP) enables new perspectives concerning the scaffold design. The aim of the study was to compare scaffolds produced by RP‐technology (native and plasma‐coated PLGA‐scaffolds) with conventionally produced scaffolds (agar plates with hydroxyapatite and hyaluronic acid coated agar plates with hydroxyapatite) relating to proliferation, adhesion, and morphology of osteoblasts to get knowledge about the application potential of such 3D‐manufactured matrices for bone engineering. TissueFoil E served as reference. To compare the scaffolds, 12 ovine and 12 human osteoblast‐like cell cultures of the skull were used. Results were obtained by EZ4U, scanning electron microscopy, and light microscopy. The highest cell proliferation rate of human osteoblast‐like cells was measured on TissueFoil E followed by plasma‐coated PLGA‐scaffolds and uncoated PLGA‐scaffolds, whereas of ovine osteoblast‐like cells on plasma‐coated PLGA‐scaffolds followed by TissueFoil E and uncoated PLGA‐scaffolds. Human and ovine osteoblast‐like cells on coated and uncoated agar plates had significant lower proliferation rates compared with TissueFoil E and PLGA‐scaffolds. These results showed the potential of RP in the field of bone engineering. Mechanical properties of such scaffolds and in vivo studies should be investigated to examine if the scaffolds hold up the pressure it will undergo long enough to allow regrowth of bone and to examine the revascularization. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Study on the heat resistant property of Ag/4A antibacterial agent
Authors: Bingshe Xu , Wensheng Hou , Shuhua Wang , Liqiao Wei , Husheng Jia , Xuguang Liu 
Published: June 2007

AbstractThe heat resistant property of silver‐loading zeolite 4A antibacterial agent (SLZ) was investigated by heat treatment methodology. The morphological and structural changes of the specimens were characterized by using differential thermal analyzer (TG‐DTA), scanning electron microscopy, and X‐ray diffraction techniques. The particle size of the specimens was measured by Malvern instruments zetasizer systems, and silver content of specimens was determined by inductively coupled plasma spectrometer. Escherichia coli (E. coli) was chosen as indicators of fecal contamination to evaluate the antibacterial effect of the specimens by minimum inhibitory concentration method. The service life of the specimens was also tested. The experimental results indicated that as heat‐treatment temperature increases, the particle size increases, more aggregating occurs, silver content decreases, the color of SLZ gradually changes from white to brown, and the antibacterial ability falls. The release rate of Ag+ cation from SLZ became slow after heat treatment at 400, 450, and 500°C, thus resulting in prolonged service life of SLZ. When the heat‐treatment temperature approached 800°C, the collapse of SLZ structure occurred, and the crystals of SiO2 and Al2O3 were formed after recrystallization. Consequently, the heat resistant temperature of SLZ can be as high as 500°C. SLZ could be used in antibacterial plastics, antibacterial fibers, or biomedical materials. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Bone response to endosseous titanium implants surface‐modified by blasting and chemical treatment: A histomorphometric study in the rabbit femur
Authors: Park Jin‐Woo , Jang Il‐Sung , Suh Jo‐Young 
Published: June 2007

AbstractThis study evaluated the effects of the addition of oxide structure with submicron‐scale porous morphology on the periimplant bone response around titanium (Ti) implants with microroughened surfaces. Hydroxyapatite‐blasted Ti implants with (experimental) and without (control) a porous oxide structure produced by chemical treatment were investigated in a rabbit femur model. Surface characterizations and in vivo bone response at 4 and 8 weeks after implantation were compared. The experimental implants had submicron‐scale porous surface structure consisted of anatase and rutile phase, and the original Ra values produced by blasting were preserved. The histomorphometric evaluation demonstrated statistically significantly increased bone‐to‐implant contact (BIC) for experimental implants, both in the three best consecutive threads (p < 0.01) and all threads (p < 0.05) at 4 weeks. There was no remarkable difference in the BIC% or bone area percentage between the two groups at 8 weeks. The porous Ti oxide surface enhanced periimplant bone formation around the Ti implants with microroughened surfaces at the early healing stage. Based on the results of this study, the addition of crystalline Ti oxide surface with submicron‐sized porous morphology produced by chemical treatment may be an effective approach for enhancing the osseointegration of Ti implants with microroughened surfaces by increasing early bone‐implant contact. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Mesoporous silica from rice hull ash
Authors: Sánchez‐Flores Norma A , Pacheco‐Malagón Graciela , Pérez‐Romo Patricia , Armendariz Héctor , de L Guzmán‐Castillo María , Saniger José M , Fripiat Jose J 
Published: June 2007

AbstractIn the synthesis of mesoporous materials, the use of a template with an adequate porosity is normally favoured. As far as silica is concerned, many sophisticated procedures directed towards this goal have been published. It is already well documented that rice hull contains relatively pure silica after combustion of the residual organic matter. The authors of this contribution have recently demonstrated that large surface area silicates react with glycerol around 200 °C to give depolymerized silica with a chemical composition similar to that of poly‐alkoxides. The interest in this so‐called depolymerization is to allow easy formation of reactive gels which retain the memory of the porous structure of the original starting material. Rice hull ash (RHA), obtained after combustion of the organic residues at 500 °C, gives a silica characterized by mesopores with an average diameter about 3.5 nm. It is shown that RHA reacts with glycerol at 200 °C to form gels which, after hydrolysis and calcination, retain the mesoporous character. The hydrolysis procedure and especially, the pH is important for the distribution of the mesoporosity. The very simple reaction of a by‐product of the food industry with glycerol, a “green reagent”, gives a mesoporous solid silica in the form of a reactive gel, with many potential uses. Its use in a new procedure for the synthesis of a supported ZSM‐5 zeolite has been demonstrated. Copyright © 2007 Society of Chemical Industry
Optimization of nitrilase production from a new thermophilic isolate
Authors: Khandelwal Amit Kumar , Nigam Vinod Kumar , Choudhury Bijan , Mohan Medicherla Krishna , Ghosh Purnendu 
Published: June 2007

AbstractA new thermostable nitrilase‐producing isolate identified as Streptomyces sp. MTCC 7546 has been studied extensively for the optimization of enzyme production operating in batch mode. The benzonitrile was observed as inducer of nitrilase production. The isolate showed maximum nitrilase production after 24 h of incubation at optimal conditions. The strain grows well on a variety of carbon sources and produces the nitrilase that catalyses the hydrolysis of nitriles to acids without formation of amides. The enzyme is mostly active against mono‐ and di‐aliphatic nitriles (10 mmol L−1) at pH of 7.4 and at a temperature of 50 °C. Copyright © 2007 Society of Chemical Industry
The synthesis of three isotopomers of 2‐methyl‐2‐(4‐[3‐[1‐(4‐methylbenzyl)‐5‐oxo‐4,5‐dihydro‐1H‐[1,2,4]triazol‐3‐yl]propyl]phenoxy)propionic acid, a potent and selective peroxisome proliferator‐activated receptor alpha agonist
Authors: Kuo Fengjiun , Clodfelter Dean K. , Farid Nagy A. , Wheeler William J. , McKendry Lennon H. 
Published: June 2007

AbstractAlthough fenofibrate (1a) is commercially available and clinically effective in lowering serum triglycerides, its activity and sub‐type selectivity at the PPARα receptors are only moderate; therefore, there exists a need for more potent and sub‐type selective PPARα agonists. To that end, discovery efforts have identified 2‐methyl‐2‐(4‐[3‐[1‐(4‐methylbenzyl)‐5‐oxo‐4,5‐dihydro‐1H‐[1,2,4]triazol‐3‐yl]propyl]phenoxy)propionic acid (2), a potent and selective human PPARα receptor agonist. In support of pre‐clinical ADME studies and bioanalysis, three isotopomers of 2 have been synthesized. The results of these efforts are described below. Copyright © 2007 John Wiley & Sons, Ltd.
Raman scattering studies on nanocrystalline BaTiO3 Part II—consolidated polycrystalline ceramics
Authors: Shiratori Y. , Pithan C. , Dornseiffer J. , Waser R. 
Published: June 2007

AbstractBaTiO3 dense ceramics with different grain sizes from 5.6 µm down to 35 nm were thoroughly studied by Raman spectroscopy. The temperature characteristics of optical phonons were compared with those obtained for powders. The micrograined ceramic revealed the well‐known spectrum profiles and transitions, typical for bulk BaTiO3. On the other hand, the Raman spectra obtained for a nanograined ceramic with an average grain size of 35 nm revealed a tetragonally distorted pure BaTiO3 phase showing a diffused phase transition behaviour with respect to temperature. Abnormality of phonon damping characteristics for the nanograined ceramic was demonstrated through comparison with powders with various crystallite sizes and the micrograined ceramic. The Curie temperature of the nanograined ceramic was estimated to be 105 °C from the temperature characteristic of a sharp peak at 307 cm−1, which is one of the most specific tetragonal features for bulk BaTiO3. In the present study, local stabilization of the tetragonal phase in ultra‐fine grains was experimentally demonstrated from comparison between the Raman spectroscopic results for powders and ceramics prepared through microemulsion‐mediated synthesis. Rather long phonon mean free paths can exist even in such ultra‐fine grains, but the phonon characteristics originating from various grains are diffused mainly because of the effect of internal stress. Copyright © 2007 John Wiley & Sons, Ltd.
Macroporous gels prepared at subzero temperatures as novel materials for chromatography of particulate‐containing fluids and cell culture applications
Authors: Plieva Fatima M. , Galaev Igor Yu. , Mattiasson Bo 
Published: June 2007

AbstractMacroporous gels (MGs) with a broad variety of morphologies are prepared using the cryotropic gelation technique, i. e. gelation at subzero temperatures. These highly elastic hydrophilic materials can be produced from practically any gel‐forming system with a broad range of porosity extending from elastic and porous gels with pore sizes up to 1.0 μm to elastic and sponge‐like gels with pore sizes up to 100 μm. The versatility of the cryogelation technique is demonstrated by use of different chemical reactions (hydrogen bond formation, chemical cross‐linking of polymers, free radical polymerization) mainly in an aqueous medium. Appropriate control over solvent crystallization (formation of solvent crystals) and rate of chemical reaction during the cryogelation allows the reproducible preparation of cryogels with tailored properties. Different approaches, such as chemical modification of reactive groups, grafting of the pore surface with an appropriate polymer, or direct copolymerization with functional monomers are used for control of the surface chemistry of MGs. Typically, MGs with pore sizes up to 1.0 μm are produced in the shape of beads and MGs with pore size up to 100 μm are prepared as monoliths, discs, and sheets. The difference in porous structure of MGs defines the main applications of these porous materials. Elastic beaded MGs are mostly used as carriers for cell and enzyme immobilization or for capture of low‐molecular weight targets from particulate‐containing fluids in expanded‐bed mode. However, the elastic and sponge‐like MG monoliths with interconnected pores measuring hundreds of μm have been successfully used as monolithic columns for chromatography of particulate‐containing fluids (crude cell homogenates, viruses, whole cells, wastewater effluents) and as three‐dimensional scaffolds for mammalian cell culture applications.
Opposite effects of internal globus pallidus stimulation on pallidal neurones activity
Authors: Pralong Etienne , Pollo Claudio , Villemure Jean‐Guy , Debatisse Damien 
Published: June 2007

AbstractBesides clinical efficacy, the mechanisms of action of deep brain stimulation (DBS) are still debated. To shed light on this complex issue, we have taken the opportunity to record the response of globus pallidus internus (GPi) neurones to 100 Hz stimulations in a case of Lesch–Nyhan syndrome (LNS) where four pallidal electrodes were implanted. Three types of response were observed, 2/19 neurones were unaffected by DBS. About 7/19 neurones were inhibited during DBS stimulation and 10/19 neurones were excited during DBS stimulation. Both effects ceased when DBS was turned off. Inhibited neurones were situated lower that exited ones on the trajectory (1.25 and 4.65 mm above the center of GPi respectively). These observations suggest that locally DBS induces a reversible inhibition of neurone firing rate while at the same time distantly exciting the main afferents to and/or efferents from the GPi. Both actions would result in a strong GPi inhibition that does not preclude increased outflow from the GPi. © 2007 Movement Disorder Society