bluuebunny/crossref_metadata_2025_split huggingface dataset:
Friction, lubrication, and polymer transfer between UHMWPE and CoCrMo hip‐implant materials: A fluorescence microscopy study
Authors: Crockett Rowena , Roba Marcella , Naka Marco , Gasser Beat , Delfosse Daniel , Frauchiger Vinzenz , Spencer Nicholas D. 
Published: May 2008

AbstractThe friction coefficients of CoCrMo sliding against UHMWPE and CoCrMo were measured in solutions of albumin and synovial fluid containing fluorescently labeled albumin. No fluorescence could be observed on the CoCrMo disc following incubation in labeled albumin or after sliding against CoCrMo. This was due to quenching of the fluorophore by the metal and indicated that a protein film thicker than 10 nm was not formed on the surface. A more complicated behavior was observed for UHMWPE sliding against CoCrMo. For each lubricating solution and at each load, a bimodal distribution of steady‐state friction values was observed, the friction coefficient either remaining constant or decreasing during the early stages of the measurement. As no quenching of the fluorophores occurred on the UHMWPE surface, the fluorescence labeling method could be used to reveal polyethylene (PE) transfer and to show that it correlates with the friction coefficient: Low friction coefficients corresponded to a low density of PE spots on the CoCrMo surface. In addition, it was found that the friction coefficients for UHMWPE sliding against CoCrMo in synovial fluid were not significantly different from those in phosphate‐buffered saline (PBS), but that the addition of albumin to PBS did cause a significant increase in the friction coefficient. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Enhancement of biocompatibility of 316LVM stainless steel by cyclic potentiodynamic passivation
Authors: Shahryari Arash , Omanovic Sasha , Szpunar Jerzy A. 
Published: May 2008

AbstractPassivation of stainless steel implants is a common procedure used to increase their biocompatibility. The results presented in this work demonstrate that the electrochemical cyclic potentiodynamic polarization (CPP) of a biomedical grade 316LVM stainless steel surface is a very efficient passivation method that can be used to significantly improve the material's general corrosion resistance and thus its biocompatibility. The influence of a range of experimental parameters on the passivation/corrosion protection efficiency is discussed. The passive film formed on a 316LVM surface by using the CPP method offers a significantly higher general corrosion resistance than the naturally grown passive film. The corresponding relative corrosion protection efficiency measured in saline during a 2‐month period was 97% ± 1%, which demonstrates a very high stability of the CPP‐formed passive film. Its high corrosion protection efficiency was confirmed also at temperatures and chloride concentrations well above normal physiological levels. It was also shown that the CPP is a significantly more effective passivation method than some other surface‐treatment methods commonly used to passivate biomedical grade stainless steels. In addition, the CPP‐passivated 316LVM surface showed an enhanced biocompatibility in terms of preosteoblast (MC3T3) cells attachment. An increased thickness of the CPP‐formed passive film and its enrichment with Cr(VI) and oxygen was determined to be the origin of the material's increased general corrosion resistance, whereas the increased surface roughness and surface (Volta) potential were suggested to be the origin of the enhanced preosteoblast cells attachment. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Preparation and evaluation of chitosan‐ethylenediaminetetraacetic acid hydrogel films for the mucoadhesive transbuccal delivery of insulin
Authors: Cui Fuying , He Chunbai , He Miao , Tang Cui , Yin Lichen , Qian Feng , Yin Chunhua 
Published: May 2008

AbstractThis manuscript describes the development of a new porous, flexible bilaminated film for buccal protein administration by a simple and mild casting procedure. It consists of a mucoadhesive layer (chitosan‐ethylenediaminetetraacetic acid hydrogel film) containing protein drugs and an impermeable protective layer made of ethylcellose. The obtained mucoadhesive layer was characterized in terms of Fourier transform infrared spectroscopy, rheology, swelling, and mucoadhesion. Rheology results showed that chitosan‐ethylenediaminetetraacetic acid hydrogel (10:2) possessed the greatest degree of viscoelasticity and was well‐structured compared with other hydrogels. The in vitro mucoadhesion studies also showed that the mucoadhesive force of the hydrogel remained over 17,000 N/m2 during 4 h in the simulated oral cavity. The insulin loaded bilaminated film showed a pronounced hypoglycemic effect following buccal administration to healthy rats, achieving a 17% pharmacological availability compared with subcutaneous insulin injection. According to these results, the bilaminated film would be a promising delivery carrier for protein drugs via the buccal route. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
In vivo human electrochemical properties of a NiTi‐based alloy (Nitinol) used for minimally invasive implants
Authors: Pértile Luana B. , Silva Patrícia M. S. , Peccin Vinícius B. , Peres Ricardo , Silveira Pierre G. , Giacomelli Cristiano , Giacomelli Fernando C. , Fredel Márcio C. , Spinelli Almir 
Published: May 2008

AbstractThe development of a homemade device for in vivo human determination of the open circuit potential (OCP) of Nitinol is described. Pseudo‐reference electrodes (316L stainless steel and Pt) were initially tested and validated in vitro using simulated body fluids. As judged from the excellent electrochemical responses in terms of both accuracy and precision, the most ideal system comprised the combination of sterilized Pt (pseudo‐reference) and Nitinol (working) needle‐shaped electrodes. The average in vivo human OCP determined from independent measurements on six human patients with indication of direct arterial surgery was −0.334 ± 0.030 V/SCE. This value was in good agreement with data recorded in vitro using simulated body fluids (−0.313 ± 0.003 V/SCE in AFNOR S90‐701 artificial saliva; −0.334 ± 0.001 V/SCE in artificial urine; −0.239 ± 0.007 V/SCE in Ringer's solution). The thin surface film protecting the bulk NiTi alloy is therefore not susceptible to active dissolution at rest as long as the break down potentials (≫0.0 V/SCE) so far reported are well above OCP measured in this study. These results highlight the importance of evaluating the corrosion resistance of Nitinol under realistic conditions (mechanical loads, wear and fatigue) in order to establish multifaceted mechanisms that might lead to accelerated dissolution and failure of implanted stents. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Development of salmon collagen vascular graft: Mechanical and biological properties and preliminary implantation study
Authors: Nagai Nobuhiro , Nakayama Yasuhide , Zhou Yue‐Min , Takamizawa Keiichi , Mori Kazuo , Munekata Masanobu 
Published: May 2008

AbstractElastic salmon collagen (SC) vascular grafts were prepared by incubating a mixture of acidic SC solution and a fibrillogenesis‐inducing buffer containing a crosslinking agent [water‐soluble carbodiimide (WSC)] in a tubular mold at 4°C for 24 h and then at 60°C for 5 min. Subsequently, re‐crosslinking in ethanol solution containing WSC was performed. The dimension of the SC grafts was easily controlled by changing the size of the mold used. The compliance (stiffness parameter: β) and burst strength of the SC grafts (internal diameter, 2 mm; length, 20 mm; and wall thickness, 0.75 mm) that were prepared for implantation were 18.2 and 1434 mmHg, respectively; both these values were comparable with those of native vessels. Upon placement in rat subcutaneous pouches, the SC grafts were gradually biodegraded with little inflammatory reaction. The SC grafts were preliminarily implanted in rat abdominal aortas by using specially designed vascular connecting system. This system was used because the graft exhibited easy tearing and thus inadequate suturability. There was neither aneurysm formation nor graft rupture, but mild thrombus formation was seen within the 4‐week observation period. These grafts may be ideal for use in regenerative medicine because we believe that SC would be completely replaced with native vascular tissues after implantation, although further improvement in the mechanical properties of the graft is needed for anastomosis. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
QSAR model for alignment‐free prediction of human breast cancer biomarkers based on electrostatic potentials of protein pseudofolding HP‐lattice networks
Authors: Vilar Santiago , González‐Díaz Humberto , Santana Lourdes , Uriarte Eugenio 
Published: May 2008

AbstractNetwork theory allows relationships to be established between numerical parameters that describe the molecular structure of genes and proteins and their biological properties. These models can be considered as quantitative structure–activity relationships (QSAR) for biopolymers. The work described here concerns the first QSAR model for 122 proteins that are associated with human breast cancer (HBC), as identified experimentally by Sjöblom et al. (Science 2006, 314, 268) from over 10,000 human proteins. In this study, the 122 proteins related to HBC (HBCp) and a control group of 200 proteins that are not related to HBC (non‐HBCp) were forced to fold in an HP lattice network. From these networks a series of electrostatic potential parameters (ξk) was calculated to describe each protein numerically. The use of ξk as an entry point to linear discriminant analysis led to a QSAR model to discriminate between HBCp and non‐HBCp, and this model could help to predict the involvement of a certain gene and/or protein in HBC. In addition, validation procedures were carried out on the model and these included an external prediction series and evaluation of an additional series of 1000 non‐HBCp. In all cases good levels of classification were obtained with values above 80%. This study represents the first example of a QSAR model for the computational chemistry inspired search of potential HBC protein biomarkers. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
Structures, stabilities, electronic, and optical properties of C64 fullerene isomers, anions (C and C644−), metallofullerene Sc2@C64, and Sc2C2@C64
Authors: Cui Yan‐Hong , Tian Wei Quan , Feng Ji‐Kang , Chen De‐Li 
Published: May 2008

AbstractThe 3465 classical isomers of C64 fullerene have been investigated by quantum chemical methods PM3, and the most stable isomers have been refined with HCTH/3‐21G//SVWN/STO‐3G, B3LYP/6‐31G(d)//HCTH/3‐21G, and B3LYP/6‐311G(d)//B3LYP/6‐31G(d) level. C64(D2:0003) with the lowest e55 (e55 = 2), the number of pentagon‐pentagon fusions, is predicted to be the most stable isomer and it is followed by the C64(Cs:0077) and C64(C2:0103) isomers within relative energy of 20.0 kcal/mol. C64(D2:0003) prevails in a wide temperature range according to energy analysis with entropy contribution at B3LYP/6‐31G(d) level. The simulated IR spectra and electronic spectra help to identify different fullerene isomers. All the hexagons in the isomers with e55 = 2 display local aromaticity. The relative stabilities of C64 isomers change with charging in ionic states. Doping also affects the relative stabilities of fullerene isomers as demonstrated by Sc2@C64(D2:0003) and Sc2@C64(Cs:0077). The bonding of Sc atoms with C64 elongates the CC bond of two adjacent pentagons and enhances the local aromaticity of the fullerene cages. Charging, doping, and derativization can be utilized to isolate C64 isomers through differentiating the electronic and steric effects. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
Catecholaminergic responses to environmental stress in the hemolymph of zhikong scallop Chlamys farreri
Authors: Chen Muyan , Yang Hongsheng , Xu Biao , Wang Fangyu , Liu Baozhong 
Published: May 2008

AbstractCatecholamines have long been known to play essential roles in several physiological processes in invertebrates. In this study, enzyme immunoassays were used to examine the levels of catecholamines (including adrenaline (AD), noradrenaline (NA) and dopamine (DA)) in the hemolymph of the scallop, Chlamys farreri, in responses to selected environmental stress. These stressors include high temperature (acute transfer from 17 to 28°C), low salinity (acute transfer from salinity 31 to 20 psu) and air exposure, which are commonly encountered in aquaculture practices or in their natural habitat. The results showed that both AD and NA concentrations increased significantly in response to all the stressors. The levels of these catecholamines peaked 72 hr after acute temperature or salinity stresses, and then decreased gradually. For scallops subjected to air exposure, the duration of AD concentration elevation depended on the exposure temperature with a higher air temperature resulting in a shorter time to return to control level. In contrast, the NA responses were long lasting and no obvious decreases were observed after reaching the peak value. Interestingly, the DA concentration showed an inverse trend in response to stresses compared with AD or NA. These results suggested that the catecholaminergic responses in bivalve hemolymph will provide useful references in predicting the success of aquaculture practices and monitoring the environmental stresses. J. Exp. Zool. 309A:289–296, 2008. © 2008 Wiley‐Liss, Inc.
Novel regimen through combination of memantine and tea polyphenol for neuroprotection against brain excitotoxicity
Authors: Chen Chang‐Mu , Lin Jen‐Kun , Liu Shing‐Hwa , Lin‐Shiau Shoei‐Yn 
Published: May 2008

AbstractNMDA receptors are abundant, ubiquitously distributed throughout the brain, fundamental to excitatory neurotransmission, and critical for normal CNS function. However, excessive glutamate overstimulates NMDA receptors, leading to increased intracellular calcium and excitotoxicity. Mitochondrial dysfunction associated with loss of Ca2+homeostasis and enhanced cellular oxidative stress has long been recognized to play a major role in cell damage associated with excitotoxicity. In this experiment, we attempted to explore whether treatment with memantine (an NMDA receptor antagonist) and tea polyphenol (an antioxidant and anti‐inflammatory agent), either alone or in combination, is effective in neuroprotection in a mouse excitotoxic injury model. Memantine (10 mg/kg/day), tea polyphenol (60 mg/kg/day), or a combination (memantine 5 mg/kg/day plus tea polyphenol 30 mg/kg/day) was administered by oral gavage for 2 consecutive days before causing excitotoxic injury. Mice received a 0.3‐μL NMDA [335 mM (pH 7.2)] injection into the left striatum. Locomotor activity was assessed 24 hr before and after excitotoxic injury. Brain synaptosomes were harvested 24 hr after excitotoxic injury for assessment of Na+, K+‐ATPase and Mg2+‐ATPase activity, reactive oxygen species production, mitochondrial membrane potential (ΔΨm), mitochondrial reductase activity (MTT test), and Ca2+concentration. The results showed that treatment with memantine could significantly rescue mitochondrial function by attenuating the decreased mitochondrial membrane potential (ΔΨm) and mitochondrial reductase activity in mouse excitotoxic injury. Treatment with tea polyphenol could significantly decrease the increased production of synaptosomal reactive oxygen species (ROS) and thus reduced the deteriorative ROS‐sensitive Na+, K+‐ATPase and Mg2+‐ATPase activity. However, neither memantine nor tea polyphenol alone could significantly improve the impaired locomotor activity unless treatment was combined. Combined treatment with memantine and tea polyphenol could significantly protect mice against excitotoxic injury by reducing the increased synaptosomal ROS production, attenuating the decreased Na+, K+‐ATPase and Mg2+‐ATPase activity, the mitochondrial membrane potential (ΔΨm), the mitochondrial reductase activity, and the increased synaptosomal Ca2+concentration. In addition, the impairment in locomotor activity was also significantly improved. Therefore, the combined treatment of memantine and tea polyphenol is more effective in neuroprotection than either memantine or tea polyphenol alone in mouse excitotoxic injury. These findings provide useful information about the potential application of memantine and tea polyphenols in preventing clinical excitotoxic injury such as brain trauma, brain ischemia, epilepsy, and Alzheimer's disease. © 2008 Wiley‐Liss, Inc.
Up‐regulation of ciliary neurotrophic factor receptor expression by GABAA receptors in undifferentiated neural progenitors of fetal mouse brain
Authors: Fukui Masaki , Nakamichi Noritaka , Yoneyama Masanori , Yoshida Kohei , Ozawa Shusuke , Kitayama Tomoya , Nakamura Nobuhiro , Taniura Hideo , Yoneda Yukio 
Published: May 2008

AbstractIn this study, we evaluated the role of the GABAA receptor (GABAAR), expressed by undifferentiated neural progenitors isolated from fetal mouse neocortex, in the mechanisms relevant to self‐replication and differentiation toward neuronal and astroglial lineages. Round spheres were formed with clusters of proliferating cells within 2–4 days during culture with epidermal growth factor (EGF), whereas the size of these clusters was drastically increased in proportion to increasing durations up to 10 days. Sustained exposure to the GABAAR agonist muscimol at 100 μM led to significant increases in the size of neurospheres cultured for 6–10days, with increased proliferative activity and unchanged lactate dehydrogenase release in a manner sensitive to the GABAAR antagonist bicuculline. Muscimol also significantly increased the incorporation of 5‐bromo‐2′‐deoxyuridine in neurospheres in a bicuculline‐sensitive manner, whereas both high potassium and nifedipine significantly decreased the neurosphere area with increased numbers of apoptotic cells. Prior activation of GABAAR significantly promoted the subsequent expression of an astroglial marker protein in cells differentiated by ciliary neurotrophic factor (CNTF) toward an astroglial lineage after the removal of EGF, with a concomitant decrease in neuronal marker protein expression. In neurospheres with GABAAR activation, a significant and predominant increase was seen in mRNA expression of CNTF receptors. These results suggest that prior tonic activation of GABAAR may preferentially promote the differentiation by CNTF of neural progenitor cells toward an astroglial lineage through selective up‐regulation of CNTF receptor expression in the developing mouse brain. © 2008 Wiley‐Liss, Inc.
Protein phosphatase 2A–negative regulation of the protective signaling pathway of Ca2+/CaM‐dependent ERK activation in cerebral ischemia
Authors: Zhao Jie , Wu Hui‐wen , Chen Yun‐jiao , Tian He‐ping , Li Li‐xin , Han Xiao , Guo Jun 
Published: May 2008

AbstractExtracellular‐signal‐regulated kinase (ERK) undergoes rapid inactivation following the intense activation evoked by cerebral ischemia and reperfusion. However, the precise mechanism of this inactivation has not been elucidated. To investigate how phosphatases regulate the ERK cascade following ischemia, the PP2A inhibitors cantharidin and okadaic acid were administrated to the CA1 subregion of the rat hippocampus. The resulting sustained ERK activity implies that PP2A is a major phosphatase contributing to the rapid inactivation, but not activation, of ERK following cerebral ischemia. The increase in PP2A activity induced by ceramide has a weak effect on the activation of Raf via dephosphorylation of Ser259 in response to ischemia. In contrast, ketamine (Keta) and cyclosporine A (CsA), two chemicals that block calcium signal in ischemia, decrease ERK activity by blocking Raf dephosphorylation of Ser259. We also observed that activation of an upstream protein, Ras‐GRF, leads to calcium/calmodulin‐dependent activation of the ERK signaling cascade in response to ischemic stimuli. In addition, the activity of cyclic AMP response element‐binding protein (CREB) and estrogen receptor α (ERα), target proteins of ERK and protective elements against ischemic lesion, parallels the activity of ERK. These data indicate that PP2A plays a significant role in blocking the protective effect induced by the ERK kinase pathway and that fast inactivation of ERK is the result of cross talk between calcium/calmodulin‐dependent, positively regulated signal cascades and a ceramide‐dependent negative signaling pathway. © 2008 Wiley‐Liss, Inc.
The growth‐inhibitory protein Nogo is involved in midline routing of axons in the mouse optic chiasm
Authors: Wang Jun , Chan Chung‐Kit , Taylor Jeremy S.H. , Chan Sun‐On 
Published: May 2008

AbstractWe have investigated the role of Nogo, a protein that inhibits regenerating axons in the adult central nervous system, on axon guidance in the developing optic chiasm of mouse embryos. Nogo protein is expressed by radial glia in the midline within the optic chiasm where uncrossed axons turn, and the Nogo receptor (NgR) is expressed on retinal neurites and growth cones. In vitro neurite outgrowth from both dorsonasal and ventrotemporal retina was inhibited by Nogo protein, and this inhibition was abolished by blocking NgR activity. In slice cultures of the optic pathway, blocking NgR with a peptide antagonist produced significant reduction in the uncrossed projection but had no effect on the crossing axons. This result was confirmed by treating cultures with an anti‐Nogo functional blocking antibody. In vitro coculture assays of retina and optic chiasm showed that NgR was selectively reduced on neurites and growth cones from dorsonasal retina when they contacted chiasm cells, but not on those from ventrotemporal retina. These findings provide evidence that Nogo signaling is involved in directing the growth of axons in the mouse optic chiasm and that this process relies on a differential regulation of NgR on axons from the dorsonasal and ventrotemporal retina. © 2008 Wiley‐Liss, Inc.
Virus‐induced alterations of membrane lipids affect the incorporation of PrPSc into cells
Authors: Avrahami Dana , Dayan‐Amouyal Yael , Tal Saar , Mincberg Michal , Davis Claytus , Abramsky Oded , Gabizon Ruth 
Published: May 2008

AbstractPrion diseases are fatal neurodegenerative disorders characterized by long incubation periods. To investigate whether concurrent diseases can modify the clinical outcome of prion‐affected subjects, we tested the effect of viral infection on the binding and internalization of PrPSc, essential steps of prion propagation. To this effect, we added scrapie brain homogenate or purified PrPSc to fibroblasts previously infected with minute virus of mice (MVM), a mouse parvovirus. We show here that the rate of incorporation of PrPSc into MVM‐infected cells was significantly higher than that observed for naïve cells. Immunostaining of cells and immunoblotting of subcellular fractions using antibodies recognizing PrP and LysoTracker, a lysosomal marker, revealed that in both control and MVM‐infected cells the incorporated PrPSc was associated mostly with lysosomes. Interestingly, floatation gradient analysis revealed that the majority of the PrPSc internalized into MVM‐infected cells shifted toward raft‐containing low‐density fractions. Concomitantly, the MVM‐infected cells demonstrated increased levels of the glycosphingolipid GM1 (an essential raft lipid component) throughout the gradient and a shift in caveolin 1 (a raft protein marker) toward lighter membrane fractions compared with noninfected cells. Our results suggest that the effect of viral infection on membrane lipid composition may promote the incorporation of exogenous PrPSc into rafts. Importantly, membrane rafts are believed to be the conversion site of PrPC to PrPSc; therefore, the association of exogenous PrPSc with such membrane microdomains may facilitate prion infection. © 2008 Wiley‐Liss, Inc.