bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oligodendrocyte precursor cells generate pituicytes in vivo during neurohypophysis development
Authors: Virard Isabelle , Coquillat Delphine , Bancila Mircea , Kaing Sovann , Durbec Pascale 
Published: November 2005

AbstractIn the vertebrate brain, much remains to be understood concerning the origin of glial cell diversity and the potential lineage relationships between the various types of glia. Besides astrocytes and myelin‐forming oligodendrocytes, other macroglial cell populations are found in discrete areas of the central nervous system (CNS). They share functional features with astrocytes and oligodendrocytes but also display specific characteristics. Such specialized cells, called pituicytes, are located in the neurohypophysis (NH). Our work focuses on the lineage of the pituicytes during rodent development. First, we show that cells identified with a combination of oligodendrocyte precursor cell (OPC) markers are present in the developing rat NH. In culture, neonatal NH progenitors also share major functional characteristics with OPCs, being both migratory and bipotential, i.e. able to give rise to type 2 astrocytes and oligodendrocytes. We then observe that, either in vitro or after transplantation into myelin‐deficient Shiverer brain, pieces of NH generate myelinating oligodendrocytes, confirming the oligodendrogenic potentiality of NH cells. However, no mature oligodendrocyte can be found in the NH. This led us to hypothesize that the OPCs present in the developing NH might be generating other glial cells, especially the pituicytes. Consistent with this hypothesis, the OPCs appear during NH development before pituicytes differentiate. Finally, we establish a lineage relationship between olig1+ cells, most likely OPCs, and the pituicytes by fate‐mapping experiments using genetically engineered mice. This constitutes the first demonstration that OPCs generate glial cells other than oligodendrocytes in vivo. © 2005 Wiley‐Liss, Inc.
Role of intracellular S100A4 for migration of rat astrocytes
Authors: Takenaga Keizo , Kozlova Elena N. 
Published: November 2005

AbstractS100A4 is a member of the EF‐hand family of calcium‐binding proteins, first identified in tumor cells, and implicated in tumor invasion and metastasis. Intracellular upregulation of S100A4 is associated with increased motility of tumor cells. Extracellular application of S100A4 increases the motility of glioma cells in vitro. We showed previously that astrocytes in spinal cord and brain white matter also express S100A4. This expression is markedly increased in reactive white matter astrocytes after injury. Here, we have explored how changes in intracellular S100A4 affect migration of astrocytes. We produced cultures of white matter, S100A4 expressing astrocytes, and developed a small interfering (si) RNA approach to specifically eliminate S100A4 expression in these cells, and compared the migration of astrocytes expressing S100A4 with astrocytes transfected with S100A4 siRNA. As a “positive control” we used S100A4 expressing C6 glioma cells. In contrast to malignant cells, S100A4 expressing astrocytes increased their migration capacity after S100A4 siRNA treatment. At the same time, and in parallel with increased migration, white matter astrocytes increased their expression of metalloproteinases MMP‐9 and MT1‐MMP. The addition of MMP‐2/MMP‐9 inhibitor resulted in a significant inhibition of migration in S100A4 siRNA‐treated astrocytes. These findings indicate that S100A4 has a stabilizing function in reactive white matter astrocytes, a function that may contribute to the development of a rigid, growth‐inhibitory glial scar. © 2005 Wiley‐Liss, Inc.
Functional expression of NOD2, a novel pattern recognition receptor for bacterial motifs, in primary murine astrocytes
Authors: Sterka David , Rati Dana M. , Marriott Ian 
Published: November 2005

AbstractThere is growing appreciation that resident brain cells can initiate and/or regulate inflammation after trauma or infection in the central nervous system (CNS). Recent studies from our laboratory have begun to shed light on the mechanisms by which astrocytes perceive bacterial challenges by demonstrating the functional expression of Toll‐like receptors (TLR) in this cell type. In the present study, we demonstrate that astrocytes also express members of the novel nucleotide‐binding oligomerization domain (NOD) family of proteins that can serve as cytosolic pattern recognition receptors. We show that isolated cultures of murine astrocytes constitutively express robust levels of NOD2, a molecule that can recognize a minimal peptidoglycan motif. Expression of NOD2 is significantly upregulated after exposure to two disparate and clinically relevant bacterial pathogens of the CNS, Borrelia burgdorferi and Neisseria meningitidis. Similarly, NOD2 protein expression is elevated after exposure to specific bacterial ligands for TLRs. Importantly, we show that astrocytes express Rip2 kinase, an essential downstream effector molecule for NOD‐mediated cell responses, and demonstrate that this expression is upregulated after bacterial challenge. Furthermore, we confirm the functional nature of NOD2 in astrocytes by demonstrating that a specific ligand for this receptor induces significant inflammatory cytokine production and augments immune responses induced by TLR ligation. Taken together, the present demonstration that astrocytes express functional NOD2 proteins may represent a potentially important mechanism by which this glial cell type initiates either protective host responses within the brain or the progression of damaging CNS inflammation. © 2005 Wiley‐Liss, Inc.
Local release of dexamethasone from polymer millirods effectively prevents fibrosis after radiofrequency ablation
Authors: Blanco Elvin , Weinberg Brent D. , Stowe Nicholas T. , Anderson James M. , Gao Jinming 
Published: November 2005

AbstractRecent studies show that after radiofrequency (RF) ablation, fibrosis occurs at the ablation boundary, hindering anticancer drug transport from a locally implanted polymer depot to the ablation margin, where tumors recur. The purpose of this study is to investigate strategies that can effectively deliver dexamethasone (DEX), an anti‐inflammatory agent, to prevent fibrosis. Polymer millirods consisting of poly(D,L‐lactide‐co‐glycolide) (PLGA) were loaded with either DEX complexed with hydroxypropyl β‐cyclodextrin (HPβ‐CD), or an NaCl and DEX mixture. In vitro release studies show that DEX complexed with HPβ‐CD released 95% of the drug after 4 days, compared to 14% from millirods containing NaCl and DEX. Rat livers underwent RF ablation and received either DEX‐HPβ‐CD‐loaded millirods, PLGA millirods with an intraperitoneal (i.p.) DEX injection, or control PLGA millirods alone. After 8 days in vivo, heightened inflammation and the appearance of a well‐defined fibrous capsule can be observed in both the control experiments and those receiving a DEX injection (0.29 ± 0.08 and 0.26 ± 0.07 mm in thickness, respectively), with minimal inflammation and fibrosis present in livers receiving DEX millirods (0.04 ± 0.01 mm). Results from this study show that local release of DEX prevents fibrosis more effectively than a systemic i.p. injection. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
A novel bioactive porous CaSiO3 scaffold for bone tissue engineering
Authors: Ni Siyu , Chang Jiang , Chou Lee 
Published: November 2005

AbstractThe aim of this study was to fabricate bioactive porous CaSiO3 scaffolds and examine their effects on proliferation and differentiation of osteoblast‐like cells. In this study, porous CaSiO3 scaffolds were obtained by sintering a ceramic slip‐coated polymer foam at 1350°C. X‐ray diffraction (XRD) of the scaffolds indicated that the products were essentially pure α‐CaSiO3. The obtained scaffolds had a well‐interconnected porous structure with pore sizes ranging from several micrometers to more than 100 μm and porosities of 88.5 ± 2.8%. The in vitro bioactivity of the scaffolds was investigated by soaking them in simulated body fluid (SBF) for 7 days and then characterizing them by scanning electron microscopy (SEM) and energy‐dispersive spectroscopy (EDS) analysis. The results indicated that hydroxyapatite (HAp) was formed on the surface of the scaffolds. In addition, the scaffolds were incubated in Ringer's solution at 37°C to study the in vitro degradation by measurement of weight loss after incubation, which showed that the CaSiO3 scaffolds were degradable. The cellular responses to the scaffolds were assessed in terms of cell proliferation and differentiation. Osteoblast‐like cells were seeded into the CaSiO3 scaffolds. SEM observations showed that there was significant cell adhesion, as the cells spread and grew in the scaffolds. In addition, the proliferation rate and alkaline phosphatase (ALP) activity of the cells in the scaffolds were improved as compared to the controls. These studies demonstrate initial in vitro cell compatibility and their potential application to bone tissue engineering. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Enhancement of in vivo endothelialization of tissue‐engineered vascular grafts by granulocyte colony‐stimulating factor
Authors: Cho Seung‐Woo , Lim Joung Eun , Chu Hun Su , Hyun Hye‐Jin , Choi Cha Yong , Hwang Ki‐Chul , Yoo Kyung Jong , Kim Dong‐Ik , Kim Byung‐Soo 
Published: November 2005

AbstractSuccessful reconstruction of large‐diameter blood vessel in humans has been demonstrated using the tissue engineering technique, but improvement in patency of small‐diameter bioartificial vascular graft remains a great challenge. This study reports that granulocyte colony‐stimulating factor (G‐CSF) can enhance in vivo endothelialization of tissue‐engineered vascular grafts, which could be used to improve patency of small‐diameter vascular graft. Vascular grafts were tissue engineered with decellularized canine abdominal aortas and canine autologous bone marrow–derived cells. Prior to cell seeding onto decellularized graft matrices, bone marrow–derived cells were induced to differentiate into endothelial cells and smooth muscle cells. The cell‐seeded vascular grafts were implanted into the abdominal aortas of bone marrow donor dogs. Before and after graft implantation, G‐CSF was administered subcutaneously to the dogs (n = 3). The grafts implanted into the dogs not receiving G‐CSF were used as controls (n = 3). Eight weeks after implantation, grafts in both groups showed regeneration of vascular tissues including endothelium and smooth muscle. Importantly, endothelium formation was more extensive in the G‐CSF–treated grafts than in the control grafts, as assessed with reverse transcription polymerase chain reaction, western blot, and immunohistochemistry. In addition, intimal hyperplasia was significantly reduced in the G‐CSF–treated grafts compared to the control grafts. This study suggests that G‐CSF administration could be applied to improve patency of small‐diameter tissue‐engineered vascular grafts. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Morphological features of ovine embryonic lung fibroblasts cultured on different bioactive scaffolds
Authors: Moscato S. , Cascone M. G. , Lazzeri L. , Danti S. , Mattii L. , Dolfi A. , Bernardini N. 
Published: November 2005

AbstractTissue regeneration with autologous cell transplantation is one of the most important goals in clinical research. In this field, the development of bioactive materials that provide microenvironments for cell–matrix interactions mimicking biological conditions is required. In recent years, many synthetic materials have been developed as scaffolds and many procedures for the surface modification of these materials have been applied using biological molecules. In this study, we analyzed the morphology and the molecule production by ovine embryonic lung fibroblasts cultured on three different sponge‐like matrices based on poly(L‐lactic acid) (PLLA): agarose/PLLA, crosslinked and uncrosslinked gelatin/PLLA. The matrices were produced by using an emulsion freeze‐drying method leading to the formation of sponge‐like materials with high porosity and with interconnection between the pores. In vitro MTT test demonstrated that transplanted cells were viable and metabolically active. Morphological analysis revealed that fibroblasts adhered to and penetrated the polymeric structures. Moreover, all the different matrices supported fibroblast production of proteoglycans, glycoproteins, and matrix molecules such as elastin, collagen I, and fibronectin. These data suggest that the tested bioactive scaffolds may support the growth and extracellular matrix molecule production of fibroblasts allowing in vitro connective tissue regeneration. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Sensitivity to implant materials in patients undergoing total hip replacement
Authors: Granchi Donatella , Cenni Elisabetta , Trisolino Giovanni , Giunti Armando , Baldini Nicola 
Published: November 2005

AbstractSensitivity to implant materials is an unpredictable event, which may contribute to the process leading to the failure of the total hip replacement (THR). The aim of the current study was to investigate the informative power of skin testing in detecting the sensitization to the implant components in patients undergoing THR. A consecutive series of 223 patients was enrolled in the study, including 66 candidates to THR, 53 with stable implant, and 104 with THR loosening. The patch testing was performed by using the most relevant components of cobalt‐based alloys (CoCrMo), Ti‐based alloys (TiAlV), and bone cements. The frequency of positive patch testing in preimplant patients did not differ from that observed after THR. Patients with CoCrMo‐failed implant showed a significant low frequency of nickel‐positive skin reaction, while patients with TiAlV‐THR had a high incidence of vanadium‐positive patch testing. The panel of haptens showed a good performance in the identification of patients known to have a contact dermatitis. With regard to the THR outcome, patch testing was not able to discriminate between stable and failed implant. Sensitivity to at least one hapten, namely bone cement, as well as the positive medical history of hypersensitivity, influenced negatively the THR survival. Our results show the reliability of patch testing for investigating the sensitivity to implant components. The cause–effect relationship between sensitization and negative outcome cannot be established, but the shorter lifespan of THR in patients who have a positive patch testing supports the significant role of this event in contributing to the implant failure. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Aid and growth in Sub‐Saharan Africa: accounting for transmission mechanisms
Authors: Gomanee Karuna , Girma Sourafel , Morrissey Oliver 
Published: November 2005

AbstractThis paper is a contribution to the literature on aid and growth. Despite an extensive empirical literature in this area, existing studies have not addressed directly the mechanisms via which aid should affect growth. We identify investment as the most significant transmission mechanism, and also consider effects through financing imports and government consumption spending. With the use of residual generated regressors, we achieve a measure of the total effect of aid on growth, accounting for the effect via investment. Pooled panel results for a sample of 25 Sub‐Saharan African countries over the period 1970 to 1997 point to a significant positive effect of foreign aid on growth, ceteris paribus. On average, each one percentage point increase in the aid/GNP ratio contributes one‐quarter of one percentage point to the growth rate. Africa's poor growth record should not therefore be attributed to aid ineffectiveness. Copyright © 2005 John Wiley & Sons, Ltd.
Palaeoenvironmental evolution and sea‐level fluctuations along the southeastern Pampa grasslands coast of Argentina during the Holocene
Authors: Vilanova Isabel , Prieto Aldo R. , Espinosa Marcela 
Published: November 2005

AbstractHolocene pollen and diatom analyses and complementary data from δ18O and δ13C, malacology and sedimentology have provided a detailed record of vegetation history and palaeoenvironmental change at arroyo Las Brusquitas, on the southeastern coast of the pampas of Argentina especially in relation to past sea levels. Holocene palaeosalinity trends were estimated by Detrended Correspondence Analysis and by salinity indexes based on pollen and diatom data. As a consequence of sea‐level rise from the postglacial an extensive wave‐cut platform formed over which Holocene infilling sequences were deposited unconformably. In these sequences, variation in pollen and diatom assemblages occurred in agreement with changes in mollusc diversity and abundance, isotope values, and sediment deposits. Between ca. 6700 and 6190 14C yr BP (6279–6998 cal. yr BP) saline conditions predominated in an environment highly influenced by tides and salt water during the Holocene sea‐level highstand. Between ca. 6200 and 3900 14C yr BP (4235–4608 cal. yr BP) shallow brackish water bodies formed surrounded by saltmarsh vegetation that became more widespread from 5180 14C yr BP (5830–6173 cal. yr BP) to 3900 14C yr BP in relation to a sea‐level stabilisation period within the regression phase. Less saline conditions marked by frequent variations in salinity predominated between ca. 3900 and 2040 yr 14C BP (1830–2160 cal. yr BP). The intertidal saltmarsh environment changed into a brackish marsh dominated by freshwater conditions and sporadic tidal influence. Halophytic vegetation increased towards ca. 200014C yr BP indicating that saline conditions may be due to either desiccation or an unusually high tide range with rare frequency. After ca. 2000 14C yr BP the sedimentary sequences were buried by aeolian sand dunes. Changes in Holocene vegetation and environments in Las Brusquitas area are in agreement with data obtained from various southeastern coastal sites of the Pampa grasslands. Copyright © 2005 John Wiley & Sons, Ltd.
Singularity functions at axisymmetric edges and their representation by Fourier series
Authors: Heinrich Bernd 
Published: November 2005

AbstractThe regularity of solutions of the Dirichlet problem for the Poisson equation in three‐dimensional axisymmetric domains with reentrant edges is studied by means of Fourier series. The decomposition of the 3D problem into variational equations in 2D, a priori estimates of their solutions, a theorem of Riesz–Fischer type and two singularity functions (of tensor and non‐tensor product type) are given.
Local existence of solutions of impedance initial‐boundary value problem for non‐linear Maxwell equations
Authors: Picard R. H. , Zajaczkowski W. M. 
Published: November 2005

AbstractLocal existence of solutions of a mixed problem for non‐linear Maxwell equations is proved. The solution is so regular that its third derivatives are from L2. However, the considered problem is characteristic we were able to obtain necessary estimate because compatibility conditions were used.
Existence of a solution for a lubrication problem in elastic journal‐bearing devices with thin bearing
Authors: Bayada G. , Durany J. , Vázquez C. 
Published: November 2005

AbstractA particular elastohydrodynamic lubrication problem is modelled in this work. The presence of elasticity, lubrication and cavitation calls for a non‐linear coupled system of variational equations. The existence of a solution is deduced by means of a constructive algorithm that decouples biharmonic equation of the elastic hinged plate and the lubrication‐cavitation Elrod‐Adams free boundary problem.
Boundary layer resolution in hierarchical plate modelling
Authors: Schwab C. 
Published: November 2005

AbstractThe dimensional reduction of an elliptic model boundary value problem on a thin, plate‐like domain of thickness 2d is analysed. A class of lower‐dimensional models with variable model orders in the interior and near the boundary of the plate is investigated and it is shown that for a sufficiently large model order in a O(d∣ln d∣)‐neighbourhood of the edge the hierarchical models compensate for the boundary layers of the exact solution—in the sense that their asymptotic rate of convergence as d → 0 is the same as the optimal one for compatible, layer‐free solutions.
Uniqueness theorems for a nonlinear Tricomi problem and the related evolution problem
Authors: Lar'kin N. A. , Schneider M. 
Published: November 2005

AbstractWe consider an initial‐boundary value problem for the non‐linear evolution equation

equation image

in a cylinder Qt = Ω × (0, t), where T[u] = yuxx + uyy is the Tricomi operator and l(u) a special differential operator of first order. In [10] we proved the existence of a generalized solution of problem (1) and the existence of a generalized solution of the corresponding stationary boundary value problem (non‐linear Tricomi problem)

equation image
In this paper we give sufficient conditions for the uniqueness of these solutions.
Assessment of glutamate and glutamine contribution to in vivo N‐acetylaspartate quantification in human brain by 1H‐magnetic resonance spectroscopy
Authors: Clementi Valeria , Tonon Caterina , Lodi Raffaele , Malucelli Emil , Barbiroli Bruno , Iotti Stefano 
Published: November 2005

AbstractN‐Acetylaspartate (NAA) is one of the most important metabolites detectable by brain 1H‐MRS being considered an index of neuronal integrity. At the low magnetic field used in most clinical settings β,γ‐glutamate/glutamine (Glx) resonances are very close and partially overlap the methyl‐NAA resonance interfering with NAA quantification especially at low TE and in the presence of increased Glx signals. NAA overestimation due to Glx on a set of model solutions containing NAA, glutamate, and glutamine in variable amounts was evaluated and the result tested in vivo in six healthy controls and five age‐ and sex‐matched patients with hepatic encephalopathy (HE), the latter having an increased Glx content. A method to assess in vivo the NAA overestimation caused by Glx is proposed. A perfect match was obtained between the assessment of Glx contamination on the NAA of healthy controls and that obtained on the model solutions. However, a substantial difference in NAA overestimation was found between controls and HE patients that cannot be explained by our model. An interpretative hypothesis is provided. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
T2† measurement during acute cerebral ischemia by Carr‐Purcell MRI at 4T
Authors: Nikolova Simona , Hughes Sarah , Bartha Robert 
Published: November 2005

AbstractMetabolic and structural changes occur in brain tissue within minutes of ischemia. The adiabatic multi‐echo (Carr‐Purcell) localization pulse sequence LASER has shown promise in detecting tissue contrast changes within the first hour of ischemia. The purpose of this initial study was to combine the LASER localization sequence with fast 3D echo‐planar imaging (EPI) to quantify the regional apparent transverse relaxation (T2†) in a rabbit model of acute embolic ischemia at 4 Tesla. Carr‐Purcell T2†‐weighted images were acquired at 7 different echo‐times and used to estimate T2† in both cortex and striatum. In ischemic tissue identified by 2,3,5 ‐ triphenyltetrazolium chloride (TTC) staining, the T2† increased by approximately 31% after 1 hour of ischemia and remained elevated until study completion at 4 h of ischemia. Lesion volume, defined as the number of pixels with T2† greater than 90 ms, increased by 40% between 1 and 4 h after induction of ischemia. Carr‐Purcell LASER‐EPI T2†‐weighted images show promise in detecting early tissue changes in focal cerebral ischemia. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.