bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mevastatin induces degeneration and decreases viability of cAMP‐induced differentiated neuroblastoma cells in culture by inhibiting proteasome activity, and mevalonic acid lactone prevents these effects
Authors: Kumar Bipin , Andreatta Cynthia , Koustas William T. , Cole William C. , Edwards‐Prasad Judith , Prasad Kedar N. 
Published: August 2002

AbstractStatins with a closed‐ring structure (mevastatin, lovastatin, and simvastatin) and with an open‐ring structure (pravastatin and fluvastatin) are widely used in the human population to manage hypercholesterolemia. These statins may have neuroprotective or neurotoxic effects, but these effects remain controversial. We have utilized adenosine 3',5'‐cyclic monophosphate‐induced terminally differentiated murine neuroblastoma (NB) cells in culture as an experimental model to study the effect of statins. Results showed that mevastatin induced degenerative changes and reduced the viability of differentiated NB cells by inhibiting proteasome activity. Lactacystin, an established inhibitor of proteasome, also produced similar degenerative changes in these cells. In contrast, pravastatin neither affected the degeneration and viability of differentiated NB cells nor the proteasome activity. High‐performance liquid chromatography (HPLC) analysis of the extract obtained from mevastatin‐treated growth medium and differentiated cells revealed that about 50% of mevastatin is converted to an open‐ring structure in the growth medium; however, differentiated cells did not convert any portion of mevastatin into an open‐ring structure and accumulated only mevastatin with a closed‐ring structure. Mevalonic acid lactone by itself did not affect the viability of differentiated NB cells or the proteasome activity, but it completely prevented mevastatin‐induced degeneration and decreased viability by reducing the uptake of mevastatin and by blocking its action on proteasome activity. Mevalonic acid failed to prevent lactacystin‐induced degeneration and inhibition of proteasome activity. Our results suggest that mevastatin could act as a neurotoxic agent or neuroprotective agent, depending upon the extent of its hydrolysis to an open‐ring structure and the level of mevalonic acid. © 2002 Wiley‐Liss, Inc.
Stimulation of myelin gene expression in vitro and of sciatic nerve remyelination by interleukin‐6 receptor–interleukin‐6 chimera
Authors: Haggiag S. , Zhang P.‐L. , Slutzky G. , Shinder V. , Kumar A. , Chebath J. , Revel M. 
Published: August 2002

AbstractInduction of myelin gene expression denotes the last stage of differentiation of myelinating glial cells. Following peripheral nerve transection, Schwann cells (SC) lose myelin gene expression and proliferate, resembling premyelinating embryonic SC (eSC). We show that a fusion protein of the soluble interleukin‐6 receptor to interleukin‐6 (IL6RIL6), a potent activator of the gp130 signaling receptor, is an inducer of MBP and Po gene products in rat E18 embryonic dorsal root ganglia (DRG) 3 day cultures. Cells whose growth is dependent on the IL6RIL6 chimera were isolated from DRG. These cells (designated CH cells) express Krox‐20, as do promyelinating and myelinating SC (mSC). IL6RIL6 induces Po and MBP in CH cells and their cocultures with neurons. In addition, IL6RIL6 leads to a disappearance of Pax‐3, a marker of eSC and nonmyelinating Schwann cells (nmSC). Glial fibrillary acidic protein, present in nmSC, is not significantly induced by IL6RIL6. The CH cells acquire glial morphology when exposed to IL6RIL6 and cover axons in cocultures. In a sciatic nerve‐derived SC line, IL6RIL6 also induces Po and triggers a rapid attachment along axons. In vivo administration of IL6RIL6 intraperitoneally to rats after sciatic nerve transection and resuture increases 4‐fold the number of myelinated nerve fibers (MF) measured on day 12, 2.5–5 mm distal to the suture. The stimulation by IL6RIL6 treatment is highest (7.1‐fold) at the more distant 5 mm site, and the thickness of myelin sheaths is increased. Compared to known SC growth factors, the gp130 activator IL6RIL6 appears to combine both in vitro mitogenic effects and promotion of myelin gene expression. J. Neurosci. Res. 64:564–574, 2001. © 2001 Wiley‐Liss, Inc.
Alterations in ciliary neurotrophic factor signaling in rapsyn deficient mice
Authors: Bartlett Selena E. , Banks Glen B. , Reynolds Anna J. , Waters Mike J. , Hendry Ian A. , Noakes Peter G. 
Published: August 2002

AbstractRapsyn is a key molecule involved in the formation of postsynaptic specializations at the neuromuscular junction, in its absence there are both pre‐ and post‐synaptic deficits including failure to cluster acetylcholine receptors. Recently we have documented increases in both nerve‐muscle branching and numbers of motoneurons, suggesting alterations in skeletal muscle derived trophic support for motoneurons. The aim of the present study was to evaluate the contribution of target derived trophic factors to increases in motoneuron branching and number, in rapsyn deficient mice that had their postsynaptic specializations disrupted. We have used reverse transcription‐polymerase chain reaction and Western blot to document the expression of known trophic factors and their receptors in muscle, during the period of synapse formation in rapsyn deficient mouse embryos. We found that the mRNA levels for ciliary neurotrophic factor (CNTF) was decreased in the rapsyn deficient muscles compared with litter mate controls although those for NGF, BDNF, NT‐3 and TGF‐β2 did not differ. We found that both the mRNA and the protein expression for suppressor of cytokine signaling 3 (SOCS3) decreased although janus kinase 2 (JAK2) did not change in the rapsyn deficient muscles compared with litter mate controls. These results suggest that failure to form postsynaptic specializations in rapsyn deficient mice has altered the CNTF cytokine signaling pathway within skeletal muscle, the target for motoneurons. This alteration may in part, account for the increased muscle nerve branching and motoneuron survival seen in rapsyn deficient mice. J. Neurosci. Res. 64:575–581, 2001. © 2001 Wiley‐Liss, Inc.
Human medulloblastoma cell line DEV is a potent tool to screen for factors influencing differentiation of neural stem cells
Authors: Buzanska L. , Spassky N. , Belin M.F. , Giangrande A. , Guillemot F. , Klämbt C. , Labouesse M. , Thomas J.L. , Domanska‐Janik K. , Zalc B. 
Published: August 2002

AbstractThe aim of our study was to investigate whether a human neural cell line could be used as a reliable screening tool to examine the functional conservation, in humans, of transcription factors involved in neuronal or glial specification in other species. Gain‐of‐function experiments were performed on DEV cells, a cell line derived from a human medulloblastoma. Genes encoding nine different transcription factors were tested for their influence on the process of specification of human DEV cells towards a neuronal or glial fate. In a first series of experiments, DEV cells were transfected with murine genes encoding transcription factors known to be involved in the neuronal differentiation cascade. Neurogenins‐1, ‐2, and ‐3; Mash‐1; and NeuroD increased the differentiation of DEV cells towards a neuronal phenotype by a factor of 2–3.5. In a second series of experiments, we tested transcription factors involved in invertebrate glial specification. In the embryonic Drosophila CNS, the development of most glial cells depends on the master regulatory gene glial cell missing (gcm). Expression of gcm in DEV cells induced a twofold increase of astrocytic and a sixfold increase of oligodendroglial cell types. Interestingly, expression of tramtrack69, which is required in all Drosophila glial cells, resulted in a fourfold increase of only the oligodendrocyte phenotype. Expression of the related tramtrack88 protein, which is not expressed in the fly glia, or the C. elegans lin26 protein showed no effect. These results show that the Drosophila transcription factor genes tested can conserve their function upon transfection into the human DEV cells, qualifying this cell line as a screening tool to analyze the mechanisms of neuronal and glial specification. J. Neurosci. Res. 65:17–23, 2001. © 2001 Wiley‐Liss, Inc.
Macrophage colony‐stimulating factor is expressed in neuron and microglia after focal brain injury
Authors: Takeuchi Akihide , Miyaishi Osamu , Kiuchi Kazutoshi , Isobe Ken‐ichi 
Published: August 2002

AbstractIn a previous study, we have demonstrated that damaged neurons within a boundary area around necrosis fall into delayed neuronal death owing to the cytotoxic effect of microglial nitric oxide (NO), and these neurons are finally eliminated by activated microglia. In this process, microglia are activated to release NO, increase in number, and accumulate toward the damaged area. In this study, we investigated the expression of macrophage colony‐stimulating factor (M‐CSF, also called colony stimulating factor‐1; CSF‐1) and other cytokines, which are reported to relate to activation, proliferation, or migration of microglia. The mRNA of M‐CSF arose biphasically from 30 min to 1 hr and from 6 to 72 hr after the injury, as demonstrated by semiquantitative RT‐PCR. However, another cytokine of granulocyte‐macrophage CSF (GM‐CSF) or interleukin‐3 (IL‐3), which causes proliferation of microglia in vitro, was not detected. From immunohistochemical studies, positive staining of M‐CSF was observed mainly in neuron‐specific enolase (NSE)‐positive cells from 1 to 12 hr after the injury, and after that M‐CSF became positive in Griffonia simplicifolia isolectin‐B4 (GSA‐I‐B4)‐positive cells from 24 to 72 hr in the boundary area around necrosis. These results suggest that neurons around the damaged area express M‐CSF in the early phase after injury, which may initially activate microglia, and these activated microglia also express M‐CSF later, causing further proliferation or migration of microglia themselves to eliminate damaged neurons or necrotic brain tissue. J. Neurosci. Res. 65:38–44, 2001. © 2001 Wiley‐Liss, Inc.
Neuroprotective effect of hypothermia at defined intraischemic time courses in cortical cultures
Authors: Varathan Sriranganathan , Shibuta Satoshi , Shimizu Tomoaki , Mashimo Takashi 
Published: August 2002

AbstractMany experimental and clinical studies have shown that hypothermia confers cerebroprotective benefits against ischemic insults. Because of the many conflicting reports on hypothermic neuroprotection, we undertook this cellular study to identify the optimal temperature or a range of temperatures for maximal neuroprotection at different times (6–24 hr) during ischemic insults. Cultured Wistar rat cortical neurons were exposed to oxygen deprivation at defined times and temperatures (37°C normothermia, 32°C mild hypothermia, 27°C moderate hypothermia, 22°C deep hypothermia, and 17°C profound hypothermia). The survival rate of neurons was evaluated by assessing viable neurons on photomicrographs. The normothermic group demonstrated a significantly lower survival rate of cultured neurons (6 hr, 80.3% ± 2.7%; 12 hr, 56.1% ± 2.1%; 18 hr, 34.2% ± 1%; 24 hr, 18.1% ± 2.2%) compared to hypothermic groups (P < 0.001). The survival rate for the profound hypothermic group was significantly reduced (P < 0.01) compared to other hypothermic groups (at 17°C: 12 hr, 85.9% ± 2.5%, 18 hr, 74.7% ± 3.7%, 24 hr, 58.7% ± 2.7%). Almost equal survival rates were observed among mild, moderate, and deep hypothermic groups following <18 hr exposure to hypoxia, but the deep hypothermic group showed a significantly higher survival rate (84.1% ± 1.6%; P < 0.001) when subjected to hypoxia for 24 hr. In conclusion, hypothermia offers marked neuroprotection against hypoxia, but attenuation of neuronal cell death was less with profound hypothermia compared to mild, moderate, and deep hypothermia. Deep hypothermia affords maximal protection of neurons compared to mild and moderate hypothermia during long‐lasting hypoxia (>18 hr). J. Neurosci. Res. 65:583–590, 2001. © 2001 Wiley‐Liss, Inc.
Long pressure series for Barcelona (Spain). Daily reconstruction and monthly homogenization
Authors: Rodríguez R. , Barriendos M. , Jones P.D. , Martín‐Vide J. , Peña J.C. 
Published: August 2002

AbstractDaily meteorological records for Barcelona, Spain, start unofficially in 1780. The records are of very good quality, although the metadata are far from complete. This study gives the general characteristics of the daily instrumental records, details of the data sources together with the reconstruction of the daily and monthly pressure series. In the second part of this paper, a separate time series made up of three (deterministic, periodic and random) components is analysed, and a methodological approach based on the cumulative deviation from the mean is then used to homogenize the monthly pressure series. Published in 2001 by John Wiley & Sons, Ltd.
Patterns of monthly rainfall shortage and excess in terms of the standardized precipitation index for Catalonia (NE Spain)
Authors: Lana X. , Serra C. , Burgueño A. 
Published: August 2002

AbstractSpatial and time behaviours of rainfall shortage and excess are analysed for Catalonia (NE Spain) using a database obtained from 99 rain gauges with monthly totals collected from 1961 to 1990. The distribution of monthly amounts for each rain gauge is modelled by means of the gamma or Poisson‐gamma distributions. Then, using an equiprobable transformation, monthly amounts described with these distributions are substituted by values given by the Standardized Precipitation Index (SPI), which follows a standardized normal distribution and provides a unique pluviometric scale. After that, principal component analysis (PCA) is applied to the set of monthly SPIs. A double regionalization of the 99 rain gauges, distinguishing between episodes of rainfall shortage and excess, is achieved by taking into account the rotated factor loadings (RFL) correlating rain gauges and principal components (PC). A time classification of rainfall shortage and excess episodes is also established, considering in this case the factor scores (FS) obtained after a PCA of variables based on monthly SPIs. The spatial regionalization achieved becomes a rough picture of the different topographic domains (Pyrenees, Pre‐Pyrenees, Central Basin, Littoral and Pre‐Littoral chains and Mediterranean coast), the climatic diversity of Catalonia being enhanced by these results. The time clustering suggests a quite complex behaviour of the rainfall shortage and excess episodes. Moreover, the spatial distribution of these time clusters is very disperse, in such a way that monthly shortage and excess sometimes affect the whole of Catalonia and sometimes just a small area. Besides results obtained from PCA and clustering algorithms, it is worth noticing that the severity of the episodes increases remarkably only for rainfall shortage. In addition, an analysis of the number of rain gauges affected by monthly shortage and excess shows an interesting fact: whereas the number of rain gauges associated with a shortage has an increasing tendency, a significant decreasing tendency for excess is detected in the period 1961–1990. Copyright © 2001 Royal Meteorological Society
Linking the North Atlantic to central Europe: a high‐resolution Holocene tephrochronological record from northern Germany
Authors: van den Bogaard Christel , Schmincke Hans‐Ulrich 
Published: August 2002

AbstractA high‐resolution Holocene tephrochronology for northern Germany has been established based on systematic tephrostratigraphical analysis of three peat bogs. Microscopic volcanic ash layers have been traced and characterised petrographically and by the chemical composition of the glass shards. At least 37 ash horizons representing 16 different explosive volcanic eruptions have been identified and many can be correlated between the three sites, up to 100 km apart. The tephra layers can be related to Icelandic volcanic sources and some correlated to the eruptions of Askja 1875, Hekla 3, Hekla Selsund, Hekla 4 and Hekla 5, as well as to unspecified eruptions of Icelandic volcanic systems, e.g. Torfajökull. The source volcanoes for some tephra layers remain unidentified. Some tephra layers were known previously from the North Atlantic region (e.g. Sluggan, Glen Garry), others have not been recorded previously in the literature (e.g. microlite tephra). This study provides the first comprehensive Holocene tephrostratigraphical record for northern Germany, complementing the North Atlantic tephrostratigraphical dating framework, effectively extending it into central Europe. The study shows that Icelandic ash layers are even more widespread than hitherto thought. Copyright © 2002 John Wiley & Sons, Ltd.
Distribution of modern dinoflagellate cysts from inshore areas along the coast of southern Norway
Authors: Grøsfjeld Kari , Harland Rex 
Published: August 2002

AbstractSurface sediment samples from inshore areas along the coast of Norway, from Kragerø in the south to Kristiansund in mid‐Norway, were analysed for their dinoflagellate cyst content in order to establish a modern reference data base. Ultimately these data should furnish a firm foundation for dinoflagellate cyst research in the area in terms of both their spatial and their temporal records. Our aim is to build a data base containing reference samples from the various fjords and inshore areas along the entire Norwegian coast. Dinoflagellate cysts have been recovered from all the samples studied and three main areas have been distinguished based upon their cyst assemblages; the western part of Skagerrak, the southwestern coast of Norway bordering the North Sea, and the west coast of Norway bordering the Norwegian Sea. The dinoflagellate cyst assemblages from these areas are, most probably, closely related to oceanographic parameters and reflect latitudinal or climatic trends along this stretch of the coast. Copyright © 2001 John Wiley & Sons, Ltd.
Surface‐enhanced Raman spectroscopy of 1H‐1,2,3‐triazolo[4,5‐b]pyridine on silver sols
Authors: Pergolese Barbara , Bigotto Adriano 
Published: August 2002

AbstractThe surface‐enhanced Raman (SER) spectra of 1H‐1,2,3‐triazolo[4,5‐b]pyridine adsorbed on silver hydrosols were recorded in the region 3500–100 cm−1. From the comparison of the SER and normal Raman spectra of 1H‐1,2,3‐triazolo[4,5‐b]pyridine both in the pure form and dissolved in alkaline solution, it can be deduced that the substance is dissociatively adsorbed on metal surface. In order to interpret the SER spectra, ab initio RHF calculations with a 6–31+G** basis set were performed to obtain the wavenumbers of the vibrational modes of the substance in the anionic form. Considering the relative enhancements of the Raman bands, on the basis of the description of normal modes given by the potential energy distribution it can be concluded that it interacts with silver sol essentially via the lone pairs of the nitrogen atoms, of both the pyridine and triazole rings, the ring π‐system playing a minor role, with a tilted orientation of the molecular plane with respect to the silver surface. Copyright © 2001 John Wiley & Sons, Ltd.
Resonance Raman spectra and transform analysis of anthracyclines and their complexes with DNA
Authors: Smulevich Giulietta , Mantini Anna R. , Feis Alessandro , Marzocchi Mario P. 
Published: August 2002

AbstractThe absorption, second‐derivative and resonance Raman spectra of some anthracyclines, namely idarubicin, epirubicin and 11‐deoxycarminomycin in H2O and D2O solutions, and their complexes with DNA in H2O solutions, were measured. Transform analysis that links resonance Raman band intensities to resonant absorption was applied to idarubicin, epirubicin and their complexes with DNA to obtain the Franck– Condon factors. The results allowed us to provide details on the nature of the resonance Raman active modes, the mechanism of their resonant enhancement and the chromophore–DNA interaction. In particular, an interpretation involving excited‐state charge transfer, associated in some cases with excited‐state proton transfer, is proposed. This helps to rationalize the observed variations of the intensities of Raman‐active modes of free anthracyclines in terms of variation of the transition moment direction. The intercalation of the chromophore among the DNA base pairs induces, via excitonic interactions, a change in both the magnitude and the direction of the transition moment of the chromophore. Copyright © 2001 John Wiley & Sons, Ltd.
Microspectrometric study of azobenzene chromophore orientations in a holographic diffraction grating inscribed on a p(HEMA‐co‐MMA) functionalized copolymer film
Authors: Labarthet F. Lagugné , Bruneel J. L. , Sourisseau C. , Huber M. R. , Börger V. , Menzel H. 
Published: August 2002

AbstractAn amorphous copolymer of methyl methacrylate (MMA, 60%) and hydroxyethyl methacrylate (HEMA, 40%), i.e. p(HEMA‐co‐MMA), was prepared by atom transfer radical polymerization (ATRP) and functionalized by complete esterification with the 2‐[4‐(4‐cyanophenylazo)phenoxy]acetic acid. An isotropic thin film (0.5 µm) of this copolymer with a 40% (molar fraction) azobenzene content was irradiated by interfering two orthogonal (±45°) linearly polarized laser beams (λ = 488 nm; irradiance = 1 W cm−2) and a permanent holographic diffraction grating was thus inscribed. AFM measurements revealed a nearly sinusoidal relief profile with a 2.5 µm period spacing and an amplitude of about 150 nm in the surface relief modulation (SRM). Using a confocal microspectrometric instrument we recorded various pre‐resonance enhanced polarized Raman spectra from a large grating area and obtained spatially resolved images of the Raman intensity variations, in order to gain new insight into the photoinduced orientation effects and the grating formation mechanisms. From analyses of the experimental data we extracted values of the second 〈P2〉 and fourth 〈P4〉 coefficients in the chromophore orientation functions at several positions of the SRM, in particular at the top and bottom regions: in general, we found that the weakly absorbing chromophores do not undergo strong orientation effects and, as expected, they keep an isotropic distribution at half‐slopes where the incident electric field was circularly polarized. Then, the corresponding normalized distribution functions were calculated using the information entropy theory. With respect to the sinusoidal relief surface, complex and broader distributions are found in the bottom and in the top regions, respectively, so that it appears that the mass transport phenomena have perturbed to some extent the primary photoinduced orientations. These results are compared with those we recently obtained using other highly birefringent copolymer samples. Copyright © 2001 John Wiley & Sons, Ltd.