bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antiviral drug-resistant HBV
Authors: Lok Anna S. , Zoulim Fabien , Locarnini Stephen , Bartholomeusz Angeline , Ghany Marc G. , Pawlotsky Jean-Michel , Liaw Yun-Fan , Mizokami Masashi , Kuiken Carla 
Published: June 2007

Abstract

Substantial advances have been made in the treatment of chronic hepatitis B in the past decade. Approved treatments for chronic hepatitis B include 2 formulations of interferon and 4 nucleos(t)ide analogues (NAs). Sustained viral suppression is rarely achieved after withdrawal of a 48-week course of NA therapy, necessitating long, and in many cases, indefinite treatment with increasing risk of development of drug resistance. Antiviral resistance and poor adherence are the most important factors in treatment failure of hepatitis B. Thus, there is a need to standardize nomenclature relating to hepatitis B antiviral resistance, and to define genotypic, phenotypic, and clinical resistance to NA therapy. (HEPATOLOGY 2007;46:254–265.)
Adipose tissue-derived mesenchymal stem cells as a source of human hepatocytes
Authors: Banas Agnieszka , Teratani Takumi , Yamamoto Yusuke , Tokuhara Makoto , Takeshita Fumitaka , Quinn Gary , Okochi Hitoshi , Ochiya Takahiro 
Published: June 2007

Abstract

Recent observations indicate that several stem cells can differentiate into hepatocytes; thus, cell-based therapy is a potential alternative to liver transplantation. The goal of the present study was to examine the

in vitro

hepatic differentiation potential of adipose tissue-derived mesenchymal stem cells (AT-MSCs). We used AT-MSCs from different age patients and found that, after incubation with specific growth factors (hepatocyte growth factor [HGF], fibroblast growth factor [FGF1], FGF4) the CD105+ fraction of AT-MSCs exhibited high hepatic differentiation ability in an adherent monoculture condition. CD105+ AT-MSC-derived hepatocyte-like cells revealed several liver-specific markers and functions, such as albumin production, low-density lipoprotein uptake, and ammonia detoxification. More importantly, CD105+ AT-MSC-derived hepatocyte-like cells, after transplantation into mice incorporated into the parenchyma of the liver.

Conclusion:

Adipose tissue is a source of multipotent stem cells that can be easily isolated, selected, and induced into mature, transplantable hepatocytes. The fact that they are easy to procure

ex vivo

in large numbers makes them an attractive tool for clinical studies in the context of establishing an alternative therapy for liver dysfunction. (HEPATOLOGY 2007;46:219–228.)
Learning in a geometric model of place cell firing
Authors: Barry Caswell , Burgess Neil 
Published: June 2007

AbstractFollowing Hartley et al. (Hartley et al. (2000) Hippocampus 10:369–379), we present a simple feed‐forward model of place cell (PC) firing predicated on neocortical information regarding the environmental geometry surrounding the animal. Incorporating the idea of boundaries with distinct sensory qualities, we show that synaptic plasticity mediated by a BCM‐like rule (Bienenstock et al. (1982) J Neurosci 2:32–48) produces PCs that encode position relative to specific extended landmarks. In an unchanging environment the model is shown to undergo an initial phase of learning, resulting in the formation of stable place fields. In familiar environments, perturbation of environmental cues produces graded changes in the firing rate and position of place fields. Model simulations are compared favorably with three sets of experimental data: (1) Results published by Barry et al. (Barry et al. (2006) Rev Neurosci 17:71–97) showing the slow disappearance of duplicate place fields produced when a barrier is placed into a familiar environment. (2) Rivard et al.'s (Rivard et al. (2004) J Gen Physiol 124:9–25) study showing a graded response in PC firing such that fields near to a centrally placed object encode space relative to the object, whereas more distant fields respond to the surrounding environment. (3) Fenton et al.'s (Fenton et al. (2000a) J Gen Physiol 116:191–209) observation that inconsistent rotation of cue cards produces parametric changes in place field positions. The merits of the model are discussed in terms of its extensibility and biological plausibility. © 2007 Wiley‐Liss, Inc.
An investigation on stream temperature analysis based on evolutionary computing
Authors: Doglioni A. , Giustolisi O. , Savic D. A. , Webb B. W. 
Published: June 2007

AbstractThe data‐driven technique, evolutionary polynomial regression, has been tested and used for the study of water temperature behaviour in the River Barle (south‐west England). The study aimed to produce multiple models for forecasting water temperature, using air temperature as input. In addition, river discharge data were used to describe the hydrological regime of the study stream, even if they are not involved in the modelling phase. The availability of data sampled at hourly intervals allowed behaviour to be studied at several time scales, including short‐term lags between air temperature and water temperature. The approach to model building differs from previous studies in that the relationship between air temperature and water temperature is not evaluated on the basis of a multi‐parameter regression, nor does it identify particular structures; rather the evolutionary technique identifies the model by itself. In fact, the non‐linear relationship between air temperature and water temperature is investigated by an evolutionary search in the space of particular pseudo‐polynomials structures. Copyright © 2007 John Wiley & Sons, Ltd.
In vivo stability and biocompatibility of implanted calcium alginate disks
Authors: Nunamaker Elizabeth A. , Purcell Erin K. , Kipke Daryl R. 
Published: June 2007

AbstractAlginate is a commonly used biomedical hydrogel whose in vivo degradation behavior is only beginning to be understood. The use of alginate in the central nervous system is gaining popularity as an electrode coating, cell encapsulation matrix, and for duraplasty. However, it is necessary to understand how the hydrogel will behave in vivo to aid in the development of alginate for use as a neural interface material. The goal of the current study was to compare the rheological behavior of explanted alginate disks and the inflammatory response to subcutaneously implanted alginate hydrogels over a 3‐month period. Specifically, the effects due to (1) in situ gelling, (2) diffusion gelling, and (3) use of a poly‐l‐lysine (PLL) coating were investigated. While all samples' complex moduli decreased 80% in the first day, in situ gelled alginate was more stable for the first week of implantation. The PLL coating offered some stability increases for diffusion gelled alginate, but the stability in both conditions remained significantly lower than that in in situ gelled alginate. There were no differences in biocompatibility that clearly suggested one gelation method over another. These results indicate that in situ gelation is the preferred method in neural interface applications where stability is the primary concern. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Pasty injectable biodegradable polymers derived from natural acids
Authors: Krasko Michal Y. , Domb Abraham J. 
Published: June 2007

AbstractPasty biodegradable polymers that can be mixed with drugs at room temperature and injected to tissue as neat composition are advantageous as they allow simple preparation and delivery of drugs, particularly for heat sensitive drugs. A series of biodegradable pasty poly (ester‐anhydride)s were prepared from alkanedicarboxylic acids and ricinoleic acid and its oligomers by transesterification‐repolymerization method. The polymers were characterized by common spectroscopic, chromatography, and thermal methods. Polymers containing 70% ricinoleic acid and 30% linear dicarboxylic acids with 4‐10 methylene groups were synthesized. The melting point of these poly (ester‐anhydride)s increased as the number of methylenes in the alkanedicarboxylic acid increased. Use of short oligomers of ricinoleic acid instead of ricinoleic acid itself increased the melting point and decreased the softness of the resulting polymers. The polymers released model drugs for a few weeks while being degraded to their fatty acid counterparts. Copolymerization of alkanedicarboxylic acids with ricinoleic acid resulted in pasty biodegradable polymers useful as injectable carriers for drugs. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Bisphosphonates incorporated in a poly(D,L‐lactide) implant coating inhibit osteoclast like cells in vitro
Authors: Greiner Stefan , Kadow‐Romacker Anke , Wildemann Britt , Schwabe Philipp , Schmidmaier Gerhard 
Published: June 2007

AbstractNitrogen containing bisphosphonates such as zoledronic acid (ZOL) are clinically used to prevent osteoclast induced bone loss. Previous studies indicated that bisphosphonates prevent osteoclast formation, decreases their resorption activity and lead to osteoclast apoptosis. Aim of the study was to investigate the effect of ZOL on fusion and resorption activity of osteoclast like cells (OLC) derived from human peripheral blood mononuclear cells (PBMNC) in vitro. For application of ZOL a local drug delivery system based on a coating for medical devices was used. ZOL was incorporated in the coating based on Poly(D,L‐Lactide) (PDLLA) in different concentrations (10–50 μM). Control groups were treated without ZOL or ZOL pure substance in corresponding concentrations. Human PBMNCs were isolated and stimulated to form OLCs. After an experimental period of 144 h, TRAP staining of polynucleated cells was performed and TRAP positive cells were counted. A pit formation assay was performed and resorption lacunas on dentin chips were counted. Results showed a significant dose dependent decrease in the number of TRAP positive cells after exposure to ZOL incorporated in the drug delivery system or applied as pure substance. The amount of resorption lacunas was also dose dependent decreased using both application methods. In conclusion, exposure to specific concentrations of ZOL incorporated in a drug delivery system showed a significant decrease in OLC formation and activity comparable to the effect of pure substance. The effect on osteoclasts might be of clinical benefit to reduce orthopedic implant loosening and to support fracture healing. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Validation and quantification of an in vitro model of continuous infusion of submicron‐sized particles
Authors: Ortiz Steven G. , Ma Ting , Epstein Noah J. , Smith R. Lane , Goodman Stuart B. 
Published: June 2007

AbstractWear particles produced from total joint replacements have been shown to stimulate a foreign body and chronic inflammatory reaction that results in periprosthetic osteolysis. Most animal models that simulate these events have used a single injection of particles, which is not representative of the clinical scenario, in which particles are continuously generated. The goal of this study was to evaluate the feasibility of an osmotic pump for the continuous delivery of clinically relevant submicron‐sized particles over an extended period of time. Blue‐dyed polystyrene particles and retrieved ultra‐high molecular weight polyethylene (UHMWPE) particles, both suspended in mouse serum, were loaded into an Alzet mini‐osmotic pump. Pumps were attached to vinyl tubing that ended with hollow titanium rods, simulating a metal implant, which was suspended in a collection vessel. The number of particles collected was evaluated over 2‐ and 4‐week time periods. Delivery of both the polystyrene and UHMWPE particles was feasible over pump concentrations of 109 to 1011 particles per pump. Furthermore, delivery efficiency of polystyrene particles decreased with increasing initial particle concentration, whereas delivery efficiency of UHMWPE particles increased slightly with increasing initial particle concentration. For UHMWPE, approximately one‐third of the particles in the pump were collected at 4 weeks. This in vitro study has quantified the efficiency of a unique particle pumping system that may be used in future in vivo investigations to develop a murine model of continuous particle infusion. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Phase conversion of tricalcium phosphate into Ca‐deficient apatite during sintering of hydroxyapatite–tricalcium phosphate biphasic ceramics
Authors: Kong Young‐Min , Kim Hyoun‐Ee , Kim Hae‐Won 
Published: June 2007

AbstractIn this study, we report a new observation on the phase conversion that occurs during the sintering of hydroxyapatite (HA)–tricalcium phosphate (TCP) biphasic ceramics. During the sintering of the HA‐TCP mixture powders, a large amount of TCP was converted into HA, as detected by X‐ray diffraction. The amount of TCP transformed into HA was ∼10–90% of that initially added. From the electron probe microscopy analysis, the HA transformed from TCP was found to be Ca‐deficient with Ca/P ratios of 1.62–1.64. The dissolution behavior and osteoblastic responses in a series of HA‐TCP biphasic ceramics (10–90% TCP) were assessed. The solubility of the HA‐TCP biphasic ceramics was intermediate between that of the HA and TCP pure ceramics. However, in the case of the HA‐90% TCP biphasic ceramic, the solubility was even higher than that of pure TCP. The cell proliferation and alkaline phosphatase activity of the cells on the biphasic ceramics were lower than those on pure HA, but higher than those on pure TCP. However, particularly in the HA‐50% TCP biphasic composition, the cellular responses were significantly higher than those on pure HA. It is considered that the Ca‐deficient apatite newly formed from the TCP may affect in some way the solubility and biological properties of the HA‐TCP biphasic ceramics. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Effects of anodic oxidation parameters on a modified titanium surface
Authors: Park Il Song , Lee Min Ho , Bae Tae Sung , Seol Kyeong Won 
Published: June 2007

AbstractAnodic oxidation is an electrochemical treatment that can be used to control the thickness of an oxide layer formed on a titanium surface. This procedure has the advantage of allowing the ions contained in an electrolyte to deposit onto the oxide layer. The characteristics of a layer treated with anodic oxidation can vary according to the type and concentration of the electrolytes as well as the processing variables used during anodic oxidation. In this study, the constant electrolyte for anodic oxidation was a mixed solution containing 0.02M DL‐α‐glycerophosphate disodium salt and 0.2M calcium acetate. Anodic oxidation was carried out at different voltages, current densities, and duration of anodic oxidation. The results showed that the current density and variation in the duration of anodic oxidation did not have a large effect on the change in the characteristics of the layer. On the other hand, the size of the micropores was increased with increasing voltage of anodic oxidation, and anatase and rutile phases were found to co‐exist in the porous titanium dioxide layer. In addition, the thickness of the oxide layer on titanium and the characteristic of corrosion resistance increased with increasing voltage. The MTT test showed that the cell viability was increased considerably as a result of anodic oxidation. The anodizing voltage is an important parameter that determines the characteristics of the anodic oxide layer of titanium. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Influence of endodontic sealers on the bond strength of carbon fiber posts
Authors: Teixeira C.S. , Pasternak‐Junior B. , Borges A.H. , Paulino S.M. , Sousa‐Neto M.D. 
Published: June 2007

AbstractObjective:The aim of this study was to verify the influence of endodontic sealers on the bond strength of an adhesive system and a resin cement used for carbon posts cementation.Methods:Thirty extracted human premolars were instrumented and randomly divided into three groups according to the tested sealer: EndoFill, Sealapex, or EndoREZ. Specimens were stored at 37°C. After 48 h, half of specimens were prepared to receive the post and the others after 7 days. The posts were cemented with Adper Single Bond/Rely X ARC and stored in distilled water at 37°C for 7 days. After this period, the specimens were sectioned in three slices (coronal, middle, and apical). The push‐out test was performed in a universal machine and the debonded area was examined in a stereomicroscope.Results:Data were submitted ANOVA and Tukey test (α = 0.05). The EndoFill showed lower bond strength than other sealers (p < 0.01). The EndoREZ sealer was statistically greater than other groups for coronal and middle portions and similar for apical portion (p > 0.05). Coronal and middle portions showed the best results for all groups, mainly when the canal preparation was performed after 48 h (p < 0.01). Mixed failure occurs with more frequency (55.6%) followed by failure in adhesive‐dentin interface (34.4%) and adhesive‐post interface (10.0%).Conclusion:The use of EndoREZ sealer promoted higher bond strength in root coronal and middle portions when carbon post was fixed with a resin cement. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Agitation requirements for complete solid suspension in an unbaffled agitated vessel with an unsteadily forward–reverse rotating impeller
Authors: Tezura Shuichi , Kimura Akihiro , Yoshida Masanori , Yamagiwa Kazuaki , Ohkawa Akira 
Published: June 2007

AbstractBackground: To develop a new type of solid–liquid apparatus, we have proposed the application of an agitation system with an impeller whose rotation alternates direction unsteadily, i.e., a forward–reverse rotating impeller. For an unbaffled agitated vessel fitted with this system, the suspension of solid particles in a liquid was studied using a disk turbine impeller with six flat blades.Results: The effects of the solid–liquid conditions and geometrical conditions of the apparatus on the minimum rotation rate and the corresponding impeller power consumption were evaluated experimentally for a completely suspended solid. The power consumption for a just suspended solid with this type of vessel was comparable with that for a baffled vessel with a unidirectionally rotating impeller, taking the liquid flow along the vessel bottom into consideration.Conclusion: Empirical relationships to predict the parameters of agitation requirements were found. A comparative investigation demonstrated the usefulness of the forward–reverse rotation mode of the impeller for off‐bottom suspension of solid particles. Copyright © 2007 Society of Chemical Industry
Distribution patterns of β‐ and γ‐herpesviruses within Waldeyer's ring organs
Authors: Berger Christoph , Hug Martina , Gysin Claudine , Molinari Luciano , Frei Martina , Bossart Walter , Nadal David 
Published: June 2007

AbstractThe Waldeyer's ring designates a functional unit of lymphoid tissue within the pharynx including the adenoids and tonsils. To gain insight into distribution patterns of β‐ and γ‐human herpesviruses (HHVs) and their potential mutual influences at their natural portal of entry, quantitative polymerase chain reaction (qPCR) assays were applied to adenoids and tonsils obtained from 30 children. DNA of Epstein‐Barr virus (EBV), cytomegalovirus (CMV), HHV‐6, HHV‐7, and HHV‐8 was detected in adenoids, tonsils, or both of 24 (80%), 19 (63%), 23 (77%), 23 (77%), and 0 (0%) children, respectively. EBV, CMV, HHV‐6, and ‐7 localized in both adenoids and tonsils from 92%, 37%, 52%, and 70% of children, respectively, with the virus detectable by qPCR. The amount of EBV was 2–10‐fold higher than of other HHVs and correlated in autologous organs (P = 0.01) as did the amount of HHV‐7 (P = 0.002). The amount of CMV correlated with the HHV‐6 amount in adenoids (P = 0.028) and tonsils (P = 0.007), and with the amount of HHV‐7 in adenoids (P < 0.01). Levels of HHV‐6 DNA were lower in adenoids with detectable CMV DNA than in adenoids without detectable CMV DNA (P = 0.0062). Inversely, CMV and HHV‐7 levels were higher in adenoids with than in adenoids without detectable EBV DNA (P = 0.019 and P = 0.039, respectively).Thus, β‐ and γ‐HHV exhibit distinct distribution behaviors in Waldeyer's ring organs and seem to interact. This may be of medical importance in immunocompromised hosts who are likely to reactivate HHVs causing severe morbidity and death. J. Med. Virol. 79: 1147–1152, 2007. © 2007 Wiley‐Liss, Inc.
Surface‐enhanced Raman scattering study of the red dye laccaic acid
Authors: Cañamares M. V. , Leona M. 
Published: June 2007

AbstractFT‐Raman and surface‐enhanced Raman scattering (SERS) spectroscopy were applied to the study of lac dye, a highly fluorescent anthraquinone red dye. The SERS spectra were obtained at different pH values, on Ag nanoparticles prepared by chemical reduction with citrate and hydroxylamine, and at several excitation wavelengths, in order to find the best experimental conditions for the detection of the lac dye. The lower detection limit was achieved using nanoparticles prepared by reduction with hydroxylamine, excitation at 514.5 nm, and slightly acidic pH conditions, thus exploiting a combination of factors including lower electrostatic repulsion between dye and nanoparticles and resonance Raman enhancement. A comparison between the adsorption of laccaic acid (LA) and carminic acid (CA), another anthraquinone red dye, was also done, based on the SERS spectra of both dyes. Copyright © 2007 John Wiley & Sons, Ltd.
Raman scattering studies on nanocrystalline BaTiO3 Part I—isolated particles and aggregates
Authors: Shiratori Y. , Pithan C. , Dornseiffer J. , Waser R. 
Published: June 2007

AbstractBaTiO3 powders with various crystallite sizes, which were prepared through microemulsion‐mediated synthesis, were thoroughly studied by Raman spectroscopy. Clear evidence for the presence of the tetragonal phase was found for ultrafine powders with an average crystallite size above 30 nm. The lifetime of phonons that are specifically assigned to the tetragonal phase decreased with decreasing crystallite size below a critical size of 100 nm. In particles as fine as 100 nm, the short mean free path of phonons, mainly due to internal pressure, causes decoupling of the coupled A1 (TO) phonons and a diffuse phase transition behaviour (TC = 115 °C). Coupled A1(TO) phonons, which give a spectral dip at around 180 cm−1 and a lesser extent of diffuseness, were revealed for powders consisting of particles as large as 0.17 µm (TC = 123 °C). Further coarsening upon annealing induced the formation of aggregates, resulting in the shift of phase transition points to higher temperatures for the rhombohedral to orthorhombic and the orthorhombic to tetragonal transitions and to lower temperatures for the tetragonal to cubic transition, respectively. Phase stability in powders is discussed by considering possible factors such as internal pressure in isolated particles and internal stress in aggregates. Copyright © 2007 John Wiley & Sons, Ltd.