bluuebunny/crossref_metadata_2025_split huggingface dataset:
PKC alpha protein but not kinase activity is critical for glioma cell proliferation and survival
Authors: Cameron Angus J. , Procyk Katarzyna J. , Leitges Michael , Parker Peter J. 
Published: May 2008

AbstractProtein kinase C alpha (PKCα) has been implicated in tumor development with high levels of PKCα expression being associated with various malignancies including glioblastomas and tumors of the breast and prostate. To account for its upregulation in these cancers, studies have suggested that PKCα plays a role in promoting cell survival. Here we show by siRNA depletion in U87MG glioma cells that a critical threshold level of PKCα protein expression is essential for their growth in the presence of serum and for their survival following serum deprivation. Derivation of PKCα wt and KO mouse embryo fibroblast cell lines confirms a role for PKCα in protecting cells from apoptosis induced by serum deprivation. Notably, PKCα was found to mediate chemo‐protection in these fibroblastic cell lines. In U87MG cells PKCα does not confer chemoprotection though this likely reflects growth arrest associated with its depletion. To determine the requirements for catalytic function, comparison was made between distinct classes of PKC inhibitors. In contrast to loss of PKCα protein, inhibition of PKC kinase activity in glioma cell lines does not significantly inhibit growth or survival. Conversely, inhibition with calphostin C, which targets the regulatory domain of PKC, potently inhibits proliferation and induces apoptosis. Evidence is presented that it is the fully phosphorylated, folded form of PKCα that confers this activity‐independent behaviour. These results indicate an essential pro‐proliferative and pro‐survival role for PKCα in glioma but question the use of ATP competitive inhibitors as therapeutics, either alone, or in combination with chemotoxic agents. © 2008 Wiley‐Liss, Inc.
Enhanced expression of NADPH oxidase Nox4 in human gliomas and its roles in cell proliferation and survival
Authors: Shono Tadahisa , Yokoyama Nobuhiko , Uesaka Toshio , Kuroda Junya , Takeya Ryu , Yamasaki Tomoko , Amano Toshiyuki , Mizoguchi Masahiro , Suzuki Satoshi O. , Niiro Hiroaki , Miyamoto Kyoko , Akashi Koichi , Iwaki Toru , Sumimoto Hideki , Sasaki Tomio 
Published: May 2008

AbstractReactive oxygen species (ROS) have been attracting attention as mediators of various cell‐signaling pathways. Nox‐family NADPH oxidases have proven to be a major source of ROS production in various cell types and have crucial roles in various physiological and pathological processes. In this study, we show that Nox4, a member of Nox family, is prominently expressed in various neuroepithelial tumors by reverse transcription‐polymerase chain reaction (RT‐PCR) and immunohistochemical studies. We quantified Nox4 mRNA expression by real‐time PCR in tumor specimens from 58 patients with astrocytomas and found that the expression levels of Nox4 mRNA in glioblastomas (WHO grade IV) were significantly higher than those in other astrocytomas (WHO grade II and III). In addition, we show that specific knockdown of Nox4 expression by RNA interference results in cell‐growth inhibition and enhances induction of apoptosis by chemotherapeutic agents, such as cisplatin, in cultured glioma cell lines. Based on these observations, enhanced expression of Nox4 appears to be involved in cell proliferation and survival in glioma cells. © 2008 Wiley‐Liss, Inc.
Risk of gastric cancer in asymptomatic, middle‐aged Japanese subjects based on serum pepsinogen and Helicobacter pylori antibody levels
Authors: Yanaoka Kimihiko , Oka Masashi , Yoshimura Noriko , Mukoubayashi Chizu , Enomoto Shotaro , Iguchi Mikitaka , Magari Hirohito , Utsunomiya Hirotoshi , Tamai Hideyuki , Arii Kenji , Yamamichi Nobutake , Fujishiro Mitsuhiro , Takeshita Tatsuya , Mohara Osamu , Ichinose Masao 
Published: May 2008

AbstractA total of 5,209 asymptomatic, middle‐aged subjects, whose serum pepsinogen (PG) and Helicobacter pylori antibody levels had been assessed, were followed for 10 years. Subjects with positive serum H. pylori antibodies (>50 U/mL) had an increased cancer risk (HR = 3.48, 95% CI = 1.26–9.64). Risk of gastric cancer increased as the antibody level increased; the H. pylori‐positive group with antibody levels >500 U/mL had the highest incidence rate (325/100,000 person‐years). Cancer development also increased with a reduced serum PG I level or a reduced PG I/II ratio; the risk was significantly elevated with serum PG I level ≤30 ng/mL (HR = 3.54, 95% CI = 1.95–6.40) or PG I/II ratio ≤3.0 (HR = 4.25, 95% CI = 2.47–7.32). Furthermore, the risk of diffuse‐type cancer increased as PG II level increased; it was significantly elevated with PG II level ≥30 ng/mL (HR = 3.81, 95% CI = 1.10–13.21). Using H. pylori antibody and PG levels, subgroups with an especially high or low cancer incidence rate could be identified. H. pylori‐negative or indeterminate subjects with low PG level (PG I ≤30 ng/mL or PG I/II ratio ≤2.0) or H. pylori‐positive subjects with antibody levels >500 U/mL and a low PG level were among the subgroups with a high cancer incidence rate (over 400/100,000 person‐years). In contrast, H. pylori‐negative subjects with a PG I level >70 ng/mL or a PG I/II ratio >3.0 had the lowest risk; none of these subjects developed cancer. Thus, serum PG levels and/or H. pylori antibody levels can be used to predict the risk of cancer in individuals with H. pylori‐related gastritis from the general population. © 2008 Wiley‐Liss, Inc.
Single‐nucleotide polymorphism‐mass array reveals commonly deleted regions at 3p22 and 3p14.2 associate with poor clinical outcome in esophageal squamous cell carcinoma
Authors: Qin Yan Ru , Fu Li , Sham Pak C. , Kwong Dora L.W. , Zhu Cai Lei , Chu Kevin K.W. , Li Yan , Guan Xin‐Yuan 
Published: May 2008

AbstractEsophageal squamous cell carcinoma (ESCC) is one of the most common solid tumors in the world with poor prognosis. Deletion of chromosome 3p is one of the most frequent chromosomal alterations in ESCC, suggesting the existence of one or more tumor suppressor genes (TSGs) at this region. In the present study, a recently developed high‐throughput and high‐resolution technology, single‐nucleotide polymorphism (SNP)‐mass array, was applied to investigate loss of heterozygosity on 3p in 100 primary ESCC cases with 386 SNP markers. Four commonly deleted regions (CDRs) at 3p26.3, 3p22, 3p21.3 and 3p14.2 were identified. Absent and down‐regulated expression of several candidate TSGs, including CHL1, PCAF, RBMS3, PLCD1 and CACNA2D3, were detected in primary ESCC tumors and ESCC cell lines. Moreover, deletions of CDRs 2 and 4 were correlated with advanced tumor stage and deletion of CDR2 was associated with tumor metastasis in ESCC. Our findings provided evidence that minimal deleted regions at 3p26.3, 3p22, 3p21.3 and 3p14.2 containing potential TSGs may contribute to the pathogenesis of esophageal cancer. © 2008 Wiley‐Liss, Inc.
Novel “anchor modification” of polymeric biomaterial surfaces by the utilization of cyclodextrin inclusion complex supramolecules
Authors: Zhao Xiaobin , Courtney James M. 
Published: May 2008

AbstractIn this article, a novel approach for the surface modification of polymeric biomaterials by the utilization of supramolecules was studied. The supramolecules selected were cyclodextrin inclusion complexes (CICs). The biomaterial selected for surface modification was plasticized poly (vinyl chloride) (PVC‐P). Results indicate that when the CICs were blended into PVC‐P, they tend to migrate and “anchor” on the surface to achieve a remarkable protein‐resistant surface, with improved blood compatibility. In comparison with a physical mixture of cyclodextrins and a “guest” molecule, such as poly(ethylene oxide) (PEO)‐poly(propylene oxide) (PPO)‐PEO and PPO‐PEO‐PPO for PVC‐P modification, CICs modified PVC‐P are more consistent in processing and achieve reproducible surface characteristics. Based on this study, a novel “anchor modification” was proposed regarding CICs modified surface. This “anchor modification” is likely to reduce plasticizer extraction from PVC‐P and also can be utilized for the modification of polymers other than PVC‐P. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
The mechanism of deposition of calcium phosphate coatings from solution onto magnesium alloy AZ31
Authors: Gray‐Munro J. E. , Strong M. 
Published: May 2008

AbstractIn recent years, magnesium alloys have been proposed as a new class of metallic bioabsorbable implant material. Unfortunately, hydrogen gas evolution and an increase in alkalinity are both byproducts of the degradation process. This necessitates the development of magnesium alloys with controlled degradation rates. The development of biocompatible coatings that can delay the onset of corrosion is essential for improving the lifetime and performance of these materials in vivo. Calcium phosphate coatings have been shown to improve the biocompatibility of metallic implants for orthopedic applications. In this article, we report a solution chemistry technique for depositing calcium phosphate coatings on magnesium alloy surfaces. Our kinetic studies indicate that the deposition of the coating is related to the anodic dissolution of the substrate. Characterization of the coating by XPS, SEM/EDS, and XRD reveal that the coating produced is a poorly crystalline calcium magnesium hydroxyapatite material. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Multiaxial analysis of dental composite materials
Authors: Kotche Miiri , Drummond James L. , Sun Kang , Vural Murat , DeCarlo Francesco 
Published: May 2008

AbstractDental composites are subjected to extreme chemical and mechanical conditions in the oral environment, contributing to the degradation and ultimate failure of the material in vivo. The objective of this study is to validate an alternative method of mechanically loading dental composite materials. Confined compression testing more closely represents the complex loading that dental restorations experience in the oral cavity. Dental composites, a nanofilled and a hybrid microfilled, were prepared as cylindrical specimens, light‐cured in ring molds of 6061 aluminum, with the ends polished to ensure parallel surfaces. The samples were subjected to confined compression loading to 3, 6, 9, 12, and 15% axial strain. Upon loading, the ring constrains radial expansion of the specimen, generating confinement stresses. A strain gage placed on the outer wall of the aluminum confining ring records hoop strain. Assuming plane stress conditions, the confining stress (σc) can be calculated at the sample/ring interface. Following mechanical loading, tomographic data was generated using a high‐resolution microtomography system developed at beamline 2‐BM of the Advanced Photon Source at Argonne National Laboratory. Extraction of the crack and void surfaces present in the material bulk is numerically represented as crack edge/volume (CE/V), and calculated as a fraction of total specimen volume. Initial results indicate that as the strain level increases the CE/V increases. Analysis of the composite specimens under different mechanical loads suggests that microtomography is a useful tool for three‐dimensional evaluation of dental composite fracture surfaces. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Effects of geometry on fracture initiation and propagation in all‐ceramic crowns
Authors: Rekow E. Dianne , Zhang Guangming , Thompson Van , Kim Jae‐Won , Coehlo Paulo , Zhang Yu 
Published: May 2008

AbstractThe complex and patient‐unique geometry of posterior all‐ceramic dental crowns represents a particularly interesting set of challenges to understanding stress concentration and fracture evolution in response to loading. A series of numerical and physical experiments, with both single cycle and fatigue loading, show that geometry profoundly influences the stress concentration and fracture initiation and propagation. In stylized crowns with uniform axial wall height, stresses concentrate beneath the indenter. As the height of the axial wall increases, loads to cause failure increase linearly. In crowns with variation in axial wall height around the periphery, stresses concentrate both beneath the indenter and at the margin of the core ceramic. The magnitude of the stress concentration at the margin is directly related to the amount of variation in axial wall height around the periphery of the crown. Anatomically correct veneered zirconia core crowns subjected to single‐cycle loads, fracture in areas of greatest stress concentration identified by finite element models. Fractures and stress concentrations that occur in response to single‐cycle loading are important indicators of initiation sites for fatigue failure. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Analysis of the fracture morphology of polyamide, polyester, polypropylene, and silk sutures before and after implantation in vivo
Authors: Karaca Esra , Hockenberger Asli S. 
Published: May 2008

AbstractThis study has analyzed fracture morphology of four nonabsorbable commercially available sutures before and after implantation in rats. Also, tensile and knot strength retention have been evaluated after 3 and 8 weeks in vivo. Scanning electron and optical light microscopes were used for analysis of fracture morphologies and surface changes of the sutures. A clear effect of in vivo on the tensile and knot strength changes, and the fracture mechanism was seen for braided sutures. The suture size was also important for braided sutures, as fibrous tissue formation plays an important role in terms of the size. The fiber's surface properties were also important for the fracture morphology. A smooth and even surface was not suitable for the fibrous tissue formation as seen in monofilament sutures. Therefore, the polymer type was very important for the monofilament sutures, as it was the most important parameter to determine the fracture morphology and was not affected by the implantation and the implantation time. The size of the suture was also important for the polypropylene in terms of axial splitting before and after implantation. This, however, was not the case for knot strength tests. The knot was undone regardless of the size. Surface characteristics were very important for braided sutures, as they have a rough surface that supports tissue formation on the fracture mechanism, tensile and knot strength. Silk suture has single filaments with no regular diameter and smooth surface. Therefore, silk suture has more tissue formation postimplantation compared to polyester suture. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Effects of environmental calcium and phosphate on wear and strength of glass ionomers exposed to acidic conditions
Authors: Wang X. Y. , Yap Adrian U. J. 
Published: May 2008

AbstractThis study evaluated the effects of environmental calcium and phosphate on wear resistance, strength, and surface morphology of highly viscous glass‐ionomers (HVGICs) (Fuji IX Fast [FN] and KetacMolar [KM]) when exposed to acidic conditions. Fabricated specimens were randomly divided into five groups and kept in acidic solutions (pH 3) with varied levels of calcium and phosphate ranging from 0 to 2.4 mM. After 4 weeks of conditioning, the specimens were subjected to wear testing, shear punch, and surface roughness testing as well as SEM evaluation. Multiple comparisons of wear depth (μm), shear strength (MPa), and surface roughness (Ra) between acidic conditions were performed using ANOVA/post‐hoc Scheffe's test (p < 0.05). Results showed that FN and KM exposed to acidic conditions had varied wear resistance, shear strength, surface roughness, and structure depending on environmental phosphate level. Increased level of environmental phosphate led to rougher surface, greater wear resistance, and strength of FN and KM than the controls (acid of pH 3). Under SEM, the surface of both FN and KM specimens were covered by numerous small particles when environmental phosphate was high. Results suggest that environmental phosphate may improve wear resistance and shear strength of HVGICs when challenged by acids. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
ABSINTH: A new continuum solvation model for simulations of polypeptides in aqueous solutions
Authors: Vitalis Andreas , Pappu Rohit V. 
Published: May 2008

AbstractA new implicit solvation model for use in Monte Carlo simulations of polypeptides is introduced. The model is termed ABSINTH for self‐Assembly of Biomolecules Studied by an Implicit, Novel, and Tunable Hamiltonian. It is designed primarily for simulating conformational equilibria and oligomerization reactions of intrinsically disordered proteins in aqueous solutions. The paradigm for ABSINTH is conceptually similar to the EEF1 model of Lazaridis and Karplus (Proteins 1999, 35, 133). In ABSINTH, the transfer of a polypeptide solute from the gas phase into a continuum solvent is the sum of a direct mean field interaction (DMFI), and a term to model the screening of polar interactions. Polypeptide solutes are decomposed into a set of distinct solvation groups. The DMFI is a sum of contributions from each of the solvation groups, which are analogs of model compounds. Continuum‐mediated screening of electrostatic interactions is achieved using a framework similar to the one used for the DMFI. Promising results are shown for a set of test cases. These include the calculation of NMR coupling constants for short peptides, the assessment of the thermal stability of two small proteins, reversible folding of both an α‐helix and a β‐hairpin forming peptide, and the polymeric properties of intrinsically disordered polyglutamine peptides of varying lengths. The tests reveal that the computational expense for simulations with the ABSINTH implicit solvation model increase by a factor that is in the range of 2.5–5.0 with respect to gas‐phase calculations. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
On relativistic effects in ground state potential curves of Zn2, Cd2, and Hg2 dimers. A CCSD(T) study
Authors: Bučinský Lukáš , Biskupič Stanislav , Ilčin Michal , Lukeš Vladimír , Laurinc Viliam 
Published: May 2008

AbstractThe ground state potential curves of the Zn2, Cd2, and Hg2 dimers calculated at different levels of theory are presented and compared with each other as well as with experimental and other theoretical studies. The calculations at the level of Dirac‐Coulomb Hamiltonian (DCH), 4‐component spin‐free Hamiltonian, nonrelativistic Lévy–Leblond Hamiltonian and at the level of simple Coulombic correction to DCH are presented. The potential curves are calculated in an all‐electron supermolecular approach including the correction to basis set superposition error (BSSE). Electron correlation is treated at the coupled cluster level including single and double excitations and noniterative triple corrections, CCSD(T). In addition, simulations of the temperature dependence of dynamic viscosities in the low‐density limit using the obtained ground state potential curves are presented. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
Regulation of insulin receptor substrate‐1 expression levels by caveolin‐1
Authors: Chen Jia , Capozza Franco , Wu An , deAngelis Tiziana , Sun Hongzhi , Lisanti Michael , Baserga Renato 
Published: May 2008

AbstractThe insulin receptor substrate‐1 (IRS‐1), a docking protein of the type 1 insulin‐like growth factor receptor (IGF‐IR) plays a significant role in cell proliferation and differentiation. The expression of IRS‐1 is down‐regulated in mouse embryo fibroblasts (MEFs) with a deletion of caveolin‐1 (cav1) genes (KO cells). Levels of IRS‐1 mRNA are not affected. Re‐introduction of cav1 into KO cells rescues IRS‐1 expression. Stabilization of protein levels is reciprocal and a strict correlation between IRS‐1 and cav1 levels was confirmed in five cell lines, and in mouse tissues. IRS‐1 binds through its phosphotyrosine binding (PTB) domain to tyrosine 14 (Y14) of cav1, the residue phosphorylated by IGF‐1 stimulation and by v‐src. The down‐regulation of IRS‐1 in cav−/− cells occurs via the proteasome pathway. These results indicate a novel mechanism for the regulation of IRS‐1 expression levels, an important finding in view of IRS‐1 role in cell proliferation and transformation. J. Cell. Physiol. 217: 281–289, 2008. © 2008 Wiley‐Liss, Inc.
Artificial neural networks model for the prediction of steady state phenol biodegradation in a pulsed plate bioreactor
Authors: Shetty K Vidya , Nandennavar Santosh , Srinikethan G 
Published: May 2008

AbstractBACKGROUND: A recent innovation in fixed film bioreactors is the pulsed plate bioreactor (PPBR) with immobilized cells. The successful development of a theoretical model for this reactor relies on the knowledge of several parameters, which may vary with the process conditions. It may also be a time‐consuming and costly task because of their nonlinear nature. Artificial neural networks (ANN) offer the potential of a generic approach to the modeling of nonlinear systems.RESULTS: A feedforward ANN based model for the prediction of steady state percentage degradation of phenol in a PPBR by immobilized cells of Nocardia hydrocarbonoxydans (NCIM 2386) during continuous biodegradation has been developed to correlate the steady state percentage degradation with the flow rate, influent phenol concentration and vibrational velocity (amplitude × frequency). The model used two hidden layers and 53 parameters (weights and biases). The network model was then compared with a Multiple Regression Analysis (MRA) model, derived from the same training data. Further these two models were used to predict the percentage degradation of phenol for blind test data.CONCLUSIONS: The performance of the ANN model was superior to that of the MRA model and was found to be an efficient data‐driven tool to predict the performance of a PPBR for phenol biodegradation. Copyright © 2008 Society of Chemical Industry
A comprehensive study of extraction of hyperoside from Hypericum perforatum L. using CTAB reverse micelles
Authors: Zhou Xiaohua , Dong Lichun , Li Duanhua 
Published: May 2008

AbstractBACKGROUND: Hyperoside is a valuable natural pharmaceutical that has many biomedical functions. By the traditional method of alcohol extraction, only hyperoside solution of very low concentration can be obtained, so a new method is urgently needed to produce pure hyperoside more effectively. Reverse micellar extraction has been widely used in the purification of biological macromolecules. Theoretically, this method could also be used to purify materials with small molecules. Therefore it would seem appropriate to consider the extraction of hyperoside, a material with small molecules, using reverse micelles. In this study the factors affecting hyperoside extraction using cetyl trimethylammonium bromide (CTAB) reverse micelles were comprehensively investigated.RESULTS: The results showed that the partition coefficient increases with an increase in aqueous phase pH or CTAB concentration before reaching a saturated state. The existence of anions in the system can affect the extraction in several ways. For example, SO$_{4}^{2-}$ and PO$_{4}^{3-}$ ions can form hydrogen bonds with hyperoside and thereby improve the extraction significantly.CONCLUSION: This study proved that extraction using CTAB reverse micelles is a very effective method to separate hyperoside from Hypericum perforatum L. Under optimal conditions the extraction efficiency can reach 68.3% and the single‐strip‐extraction efficiency can reach 85.9%. The proportion of hyperoside among the flavonoids left in the strip‐extract can reach 93.3 wt%. This finding is very significant, because it demonstrates that reverse micellar extraction is a promising way to separate and purify materials with small molecules. Copyright © 2008 Society of Chemical Industry