bluuebunny/crossref_metadata_2025_split huggingface dataset:
Susceptibility of nitinol to localized corrosion
Authors: Pound Bruce G. 
Published: January 2006

AbstractThe effect of different conditions on the susceptibility of nitinol to localized corrosion was examined using the cyclic potentiodynamic polarization technique. Tests were performed on mechanically polished (MP) and electropolished (EP) nitinol wire in 0.9 wt % NaCl and phosphate‐buffered saline (PBS). A polarization curve was also obtained for an EP stent in the NaCl. Differences between the breakdown potential and the corrosion potential (Ecorr) and between the protection potential and Ecorr were used to evaluate the susceptibility to pitting corrosion and crevice corrosion, respectively. The type of solution and, particularly, the surface condition affected the resistance of nitinol to pitting corrosion. Both EP and MP nitinol were more susceptible to breakdown in the NaCl than in PBS, indicating that the NaCl provides a more severe test environment than does PBS. Electropolishing increased the breakdown resistance of nitinol in PBS and the NaCl, as found in previous studies with Hank's solution. Surface condition, however, did not have a significant effect on the repassivation behavior of nitinol, as is also the case with titanium. The EP wire and stent showed similar breakdown and repassivation behavior in the NaCl, suggesting that the nature of the EP surface was similar in both cases. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Concentration‐dependent effects of titanium and aluminium ions released from thermally oxidized Ti6Al4V alloy on human osteoblasts
Authors: Saldaña L. , Barranco V. , García‐Alonso M.C. , Vallés G. , Escudero M.L. , Munuera L. , Vilaboa N. 
Published: January 2006

AbstractThermal oxidation treatments of Ti6Al4V, at 500 and 700°C, for 1 h result in the formation of an outer “ceramic” layer of rutile, which enhances osteoblast response. In the present study, we have measured in vitro Ti and Al ion release from Ti64 alloy in the as‐received state and after thermal oxidation treatments at 500 or 700°C, to culture medium under standard cell‐culture conditions. Concentrations of both Ti and Al released from both thermal oxidation treatments were lower than from polished alloy. Al was released from the treated or untreated surfaces in substantially lower extent than Ti. Titanium and aluminium ions affected primary human osteoblast proliferation, metabolic activity, and differentiation in a dose‐dependent manner. Treatments with individual Ti or Al metal ions in similar concentration ranges than released from the surfaces did not alter osteoblast response, which also remained unaffected after treatments with combinations of Ti plus Al applied in the proportional relations than detected in ion‐release experiments. We then selected higher concentrations of Ti that impaired osteoblast proliferation and differentiation, while the proportional lower concentrations of Al did not alter osteoblast behavior. In spite of its inert character, it was found that Al significantly enhanced the deleterious effect of Ti on osteoblast differentiation. Therefore, thermal oxidation treatments of Ti6Al4V alloy may improve the biocompatibility of the alloy by reducing both Ti and Al release, and thus attenuating ion‐mediated interference with osteoblast differentiation. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Alginate hydrogel and matrigel as potential cell carriers for neurotransplantation
Authors: Novikova Liudmila N. , Mosahebi Afshin , Wiberg Mikael , Terenghi Giorgio , Kellerth Jan‐Olof , Novikov Lev N. 
Published: January 2006

AbstractDevelopment of biosynthetic conduits carrying extracellular matrix molecules and cell lines expressing neurotrophic growth factors represents a novel and promising strategy for spinal cord and peripheral nerve repair. In the present in vitro study, the compatibility and growth‐promoting effects of (i) alginate hydrogel, (ii) alginate hydrogel complemented with fibronectin, and (iii) matrigel were compared between olfactory ensheathing cells (OECs), Schwann cells (SCs), and bone marrow stromal cells (BMSCs). Neurite outgrowth from embryonic dorsal root ganglia (DRG) neurons was used to assess the efficacy of the hydrogels alone or in combination with cultured cells to promote axonal regeneration. The result showed that alginate hydrogel transformed OECs, SCs, and BMSCs into atypical cells with spherical shape and inhibited their metabolic activity. Combination of alginate hydrogel with fibronectin promoted only OECs proliferation. Alginate hydrogel also inhibited outgrowth of DRG neurites, although this effect was attenuated by addition of fibronectin, SCs, or BMSCs. In contrast, matrigel stimulated cell proliferation, preserved the typical morphological features of the cultured cells and induced massive sprouting of DRG neurites. Addition of cultured cells to matrigel did not further improve DRG neurite outgrowth. The present findings suggest that addition of extracellular matrix should be considered when engineering biosynthetic scaffolds on the basis of alginate hydrogels. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Hydration and dynamic fatigue of dentin
Authors: Arola D. , Zheng W. 
Published: January 2006

AbstractAn experimental investigation on the dynamic fatigue response of dentin was conducted to examine the influence of stress rate on the strength and energy to fracture. Rectangular beams were prepared from the coronal dentin of bovine maxiallary molars and subjected to four‐point flexure to failure. The dentin beams were examined in the fully hydrated and dehydrated condition at stress rates () ranging from 0.01 to 100 MPa/s. Results for the hydrated dentin showed that the flexure strength, energy to fracture, and flexure modulus all increased with increasing stress rate; the flexure strength increased from 100 MPa (() = 0.01 MPa/s) to 250 MPa (() = 100 MPa/s). In contrast, the elastic modulus and strength of the dehydrated dentin decreased with increasing stress rate; the flexural strength of the dehydrated dentin deceased from 170 MPa (() = 0.01 MPa/s) to 100 MPa (() = 100 MPa/s). While the hydrated dentin behaved more like a brittle material at low stress rates, the strain to fracture was found to be nearly independent of (). According to the experimental results, restorative conditions that cause development of static stresses within the tooth could promote a decrease in the damage tolerance of dentin. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Augmentation of acrylic bone cement with multiwall carbon nanotubes
Authors: Marrs Brock , Andrews Rodney , Rantell Terry , Pienkowski David 
Published: January 2006

AbstractAcrylic bone cement, based on polymethylmethacrylate (PMMA), is a proven polymer having important applications in medicine and dentistry, but this polymer continues to have less than ideal resistance to mechanical fatigue and impact. A variety of materials have been added to bone cement to augment its mechanical strength, but none of these augmentative materials has proven successful. Carbon nanotubes, a new hollow multiwalled tubular material 10–40 nm in diameter, 10–100 μm long, and 50–100 times the strength of steel at 1/6 the weight, have emerged as a viable augmentation candidate because of their large surface area to volume ratio. The objective of this study was to determine if the addition of multiwall carbon nanotubes to bone cement can alter its static or dynamic mechanical properties. Bar‐shaped specimens made from six different (0–10% by weight) concentrations of multiwall carbon nanotubes were tested to failure in quasi‐static 3‐point bending and in 4‐point bending fatigue (5 Hz). Analyses of variance and the 3‐Parameter Weibull model were used to analyze the material performance data. The 2 wt % MWNT concentration enhanced flexural strength by 12.8% (p = 0.003) and produced a 13.1% enhancement in yield stress (p = 0.002). Bending modulus increased slightly with the smaller (<5 wt % MWNT) concentrations, but increased 24.1% (p < 0.001) in response to the 10 wt % loading. While the 2 wt % loading produced slightly improved quasi‐static test results, it was associated with clearly superior fatigue performance (3.3× increase in the Weibull mean fatigue life). Weibull minimum fatigue life (No), Weibull modulus (α), and characteristic fatigue life (β) for bone cement augmented with carbon nanotubes were enhanced versus that observed in the control group. These data unambiguously showed that the bone cement–MWNT polymer system has an enhanced fatigue life compared to “control” bone cement (no added nanotubes). It is concluded that specific multiwall carbon nanotube loadings can favorably improve the mechanical performance of bone cement. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Porcine bladder acellular matrix porosity: Impact of hyaluronic acid and lyophilization
Authors: Cartwright Lisa M. , Shou Zhiping , Yeger Herman , Farhat Walid A. 
Published: January 2006

AbstractBladder acellular matrix (ACM) is being investigated as a urinary bladder replacement scaffold. We have demonstrated that ACM is porous and theorized that this contributes to ACM fibrosis and contracture over time in vivo and may preclude uptake and retention of molecules, which may aid cellular repopulation. We sought to determine if hyaluronic acid (HA) would decrease ACM porosity. Porcine ACM was lyophilized and rehydrated in HA (SIGMA) to form the hybrid HA‐ACM construct. Three groups (n = 15/group: HA‐ACM, ACM, and lyophilized/rehydrated ACM) were tested for porosity to a 10 cm column of distilled water, measuring the effluent hourly for 3 h. A porosity index was determined as the total effluent divided by time and area (cc/cm2 hr). Alcian blue staining and fluorophore‐assisted carbohydrate electrophoresis qualitatively and quantitatively confirmed the uptake of HA. HA‐ACM and lyophilized/rehydrated ACM were significantly less porous to water than untreated ACM [mean (±SE): 0.09 (±0.02), 0.74 (±0.4), and 9.8 (±1.6) cc/cm2 hr, respectively; Mann Whitney p < 0.0001 (HA) and p < 0.0001 (lyo)]. The difference between HA‐ACM and lyophilized ACM was also statistically significant (p = 0.014). ACM hybridization with HA decreases ACM porosity, in part because of ACM lyophilization during the hybridization process. In future applications, HA may function as a carrier for smaller molecules such as growth factors, and as a bioactive molecule to improve wound healing and decrease fibrosis in tissue‐engineered bladder constructs. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Differential effect of in vitro degradation on resin–dentin bonds produced by self‐etch versus total‐etch adhesives
Authors: Toledano Manuel , Osorio Raquel , Albaladejo Alberto , Aguilera Fatima S. , Osorio Estrella 
Published: January 2006

AbstractObjective: To evaluate the effect of an in vitro challenge (NaOCl immersion) on microtensile bond strength (MTBS) of five adhesive systems to dentin. Methods: Flat dentin surfaces from 40 molars were bonded with three total‐etch adhesives (Single Bond, Prime&Bond NT and the experimental Prime&Bond XP), and two self‐etching agents (Clearfil SE Bond and Etch&Prime 3.0). Composite build‐ups were constructed with Tetric Ceram. Teeth were then sectioned into beams of 1.0 mm2 cross‐sectional area. Half of the beams were immersed in 10% NaOCl aqueous solution for 5 h. Each beam was tested in tension in an Instron machine at 0.5 mm/min. Data were analyzed by 2‐way ANOVA and multiple comparisons tests (p < 0.05). Results: Clearfil SE Bond and Single Bond attained higher MTBS than the other three adhesives. Prime&Bond NT and Prime&Bond XP performed equally, and Etch&Prime resulted in the lowest MTBS. After NaOCl immersion, MTBS decreased in all groups. The highest MTBS values were obtained for Clearfil SE Bond and Prime&Bond XP. Scaning electron mycroscopy observation of debonded sticks evidenced dissolution and microstructural alterations of intertubular dentin, except when Clearfil SE Bond was used. Conclusions: Resin–dentin bonds are prone to chemical degradation. The extent of the resin degradation is adhesive system specific. Chemical degradation of the nonresin infiltrated collagen fibers does also exist in total‐etch adhesives. Both processes may reduce long‐term resin–dentin bond strength. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Electroporation‐mediated interleukin‐10 overexpression in skeletal muscle reduces acute rejection in rat cardiac allografts
Authors: Tavakoli Reza , Gazdhar Amiq , Pierog Jaroslaw , Bogdanova Anna , Gugger Mathias , Pringle Ian A , Gill Deborah R. , Hyde Stephen C. , Genoni Michele , Schmid Ralph A. 
Published: January 2006

AbstractObjectivesHuman interleukin 10 (hIL‐10) may reduce acute rejection after organ transplantation. Our previous data shows that electroporation‐mediated transfer of plasmid DNA to peripheral muscle enhances gene transduction dramatically. This study was designed to investigate the effect of electroporation‐mediated overexpression of hIL‐10 on acute rejection of cardiac allografts in the rat.MethodsThe study was designed to evaluate the effect of hIL‐10 gene transfer on (a) early rejection pattern and (b) graft survival. Gene transfer was achieved by intramuscular (i.m.) injection into the tibialis anterior muscle of Fischer (F344) male recipients followed by electroporation 24 h prior to transplantation. Heterotopic cardiac transplantation was performed from male Brown Norway rat to F344. Four groups were studied (n = 6). Treated animals in groups B1 and B2 received 2.5 µg of pCIK hIL‐10 and control animals in groups A1 and A2 distilled water. Graft function was assessed by daily palpation. Animals from group A1 were sacrificed at the cessation of the heart beat of the graft and those in group B1 were sacrificed at day 7; blood was taken for ELISA measurement of hIL‐10 and tissue for myeloperoxidase (MPO) measurement and histological assessment. To evaluate graft survival, groups A2 and B2 were sacrificed at cessation of the heart beat of the graft.ResultsHistological examination revealed severe rejection (IIIB‐IV) in group A1 in contrast to low to moderate rejection (IA‐IIIA) in group B1 (p = 0.02). MPO activity was significantly lower in group B1 compared to group A1 (18 ± 7 vs. 32 ± 14 mU/mg protein, p = 0.05). Serum hIL‐10 levels were 46 ± 13 pg/ml in group B1 vs. 0 pg/ml in group A1. At day 7 all heart allografts in the treated groups B1 and B2 were beating, whereas they stopped beating at 5 ± 2 days in groups A1 and A2 vs. 14 ± 2 days in group B2 (p = 0.0012).ConclusionsElectroporation‐mediated intramuscular overexpression of hIL‐10 reduces acute rejection and improves survival of heterotopic heart allografts in rats. This study demonstrates that peripheral overexpression of specific genes in skeletal muscle may reduce acute rejection after whole organ transplantation. Copyright © 2006 John Wiley & Sons, Ltd.
Stable RNA interference: comparison of U6 and H1 promoters in endothelial cells and in mouse brain
Authors: Mäkinen Petri I. , Koponen Jonna K. , Kärkkäinen Anna‐Mari , Malm Tarja M. , Pulkkinen Kati H. , Koistinaho Jari , Turunen Mikko P. , Ylä‐Herttuala Seppo 
Published: January 2006

AbstractBackgroundRNA interference (RNAi) is a post‐transcriptional RNA degradation process, which has become a very useful tool in gene function studies and gene therapy applications. Long‐term cellular expression of small interfering RNA (siRNA) molecules required for many gene therapy applications can be achieved by lentiviral vectors (LVs). The two most commonly used promoters to drive the short hairpin RNA (shRNA) expression are the human U6 small nuclear promoter (U6) and the human H1 promoter (H1).MethodsWe investigated whether there is any significant difference between the efficiencies of U6 and H1 in LV‐mediated RNAi using green fluorescent protein (GFP) as a target gene by flow cytometry and real‐time reverse‐transcription polymerase chain reaction (RT‐PCR) in endothelial cells. Also, we compared the efficiencies of U6 and H1 in the GFP transgenic mouse brain after stereotactic LV injection.ResultsWe show that the U6 promoter is more efficient than H1 in GFP silencing in vitro, leading to 80% GFP knockdown at an average of one integrated vector genome per target cell genome. The silencing is persistent for several months. In addition, the U6 promoter is superior to H1 in vivo and leads to stable GFP knockdown in mouse brain for at least 9 months.ConclusionsThese results show that LV‐mediated RNAi is a powerful gene‐silencing method for the long‐term inhibition of gene expression in vitro and in vivo. Copyright © 2006 John Wiley & Sons, Ltd.
Lentiviral gene delivery to CNS by spinal intrathecal administration to neonatal mice
Authors: Fedorova Elena , Battini Lorenzo , Prakash‐Cheng Ainu , Marras Daniele , Gusella G. Luca 
Published: January 2006

AbstractBackgroundDirect injection of lentivectors into the central nervous system (CNS) mostly results in localized parenchymal transgene expression. Intrathecal gene delivery into the spinal canal may produce a wider dissemination of the transgene and allow diffusion of secreted transgenic proteins throughout the cerebrospinal fluid (CSF). Herein, we analyze the distribution and expression of LacZ and SEAP transgenes following the intrathecal delivery of lentivectors into the spinal canal.MethodsFour weeks after intrathecal injection into the spinal canal of newborn mice, the expression of the LacZ gene was assessed by histochemical staining and by in situ polymer chain reaction (PCR). Following the spinal infusion of a lentivector carrying the SEAP gene, levels of enzymatically active SEAP were measured in the CSF, blood serum, and in brain extracts.ResultsIntrathecal spinal canal delivery of lentivectors to newborn mice resulted in patchy, widely scattered areas of β‐gal expression mostly in the meninges. The transduction of the meningeal cells was confirmed by in situ PCR. Following the spinal infusion of a lentivector carrying the SEAP gene, sustained presence of the reporter protein was detected in the CSF, as well as in blood serum, and brain extracts.ConclusionsThese findings indicate that intrathecal injections of lentivectors can provide significant levels of transgene expression in the meninges. Unlike intracerebral injections of lentivectors, intrathecal gene delivery through the spinal canal appears to produce a wider diffusion of the transgene. This approach is less invasive and may be useful to address those neurological diseases that benefit from the ectopic expression of soluble factors impermeable to the blood‐brain barrier. Copyright © 2006 John Wiley & Sons, Ltd.
Protection against influenza infection by cytokine‐enhanced aerosol genetic immunization
Authors: Orson Frank M. , Kinsey Berma M. , Densmore Charles L. , Nguyen Tina , Wu Yan , Mbawuike Innocent N. , Wyde Philip R. 
Published: January 2006

AbstractBackgroundConventional vaccine development for newly emerging pandemic influenza virus strains would likely take too long to prevent devastating global morbidity and mortality. If DNA vaccines can be distributed and delivered efficiently, genetic immunization could be an attractive solution to this problem, since plasmid DNA is stable, easily engineered to encode new protein antigens, and able to be quickly produced in large quantities.MethodsWe compared two novel genetic immunization methods in a mouse model of influenza to evaluate protective effects: aerosol delivery of polyethylenimine (PEI)‐complexed hemagglutinin (HA)‐expressing plasmid and intravenous (IV) delivery of the plasmid complexed with macroaggregated albumin/PEI. Serial serum samples were obtained for assay of neutralizing antibodies against HA. Mice were then challenged in the airway with influenza virus, and production of infectious virus in the lungs was titered.ResultsMost mice immunized with HA plasmid alone by aerosol and all mice immunized IV developed protective immune responses, whereas none administered control plasmid were protected. Aerosol co‐administration of HA plasmid with plasmids encoding the cytokines interleukin 12 (IL12) and granulocyte‐macrophage colony stimulating factor (GM‐CSF) markedly increased neutralizing antibody responses, so that all aerosol immunized mice were protected from high level virus proliferation.ConclusionsCytokine‐enhanced aerosol delivery of plasmid vaccines can elicit robust protective immune responses against influenza. Thus, aerosol delivery has the potential to address the need for rapid widespread immunization against new influenza virus strains, and may have applications for other infectious and toxic disease processes. Copyright © 2006 John Wiley & Sons, Ltd.
Adrenomedullin gene transfer induces neointimal apoptosis and inhibits neointimal hyperplasia in injured rat artery
Authors: Rauma‐Pinola Tanja , Pääkkö Paavo , Ilves Mika , Serpi Raisa , Romppanen Hannu , Vuolteenaho Olli , Ruskoaho Heikki , Hautala Timo 
Published: January 2006

AbstractArterial wall injury leads to inflammatory reaction and release of growth factors that may mediate intimal regrowth. It is hypothesized that the neointimal cells may originate from adventitial myofibroblasts, medial smooth muscle cells, or differentiated bone marrow derived cells. Adrenomedullin (AM), an auto/paracrine cardiovascular peptide that is secreted from fibroblasts, endothelial cells, and vascular smooth muscle cells, may have a regulatory role in the intimal regeneration. In order to investigate the role of AM in neointimal growth, stimulation of stem cell migration, and apoptosis, we overexpressed AM with recombinant adenovirus in a rat arterial injury model. The intimae were significantly thinner in the arteries treated with AM adenovirus compared to the control group. Intima/media ratios were 0.48 ± 0.18 and 1.01 ± 0.20 (P < 0.05) in the AM group and the control group, respectively. In addition, a significantly higher apoptotic index of neointimal cells was seen in the AM gene transfer group compared to the control (2.78 ± 0.5 vs. 0.57 ± 0.20, P < 0.01). The neointimal cells stained positive for α‐smooth muscle actin and negative for desmin suggesting possible myofibroblast origin. Very few c‐Kit+ or MDR1+ cells were detected 2 weeks after the injury. We conclude that AM overexpression inhibits neointimal growth. The inhibition is associated with enhanced apoptosis of the neointimal cells which may be of myofibroblast origin. Copyright © 2006 John Wiley & Sons, Ltd.