bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aminopeptidase N mediates the utilization of the GSH precursor CysGly by cultured neurons
Authors: Dringen Ralf , Gutterer Jan Mirko , Gros Claude , Hirrlinger Johannes 
Published: August 2002

AbstractNeurons in culture rely on the supply of exogenous cysteine for their glutathione synthesis. After application of cysteine to neuron‐rich primary cultures, the glutathione content was doubled after a 4‐hr incubation. The dipeptide cysteinylglycine (CysGly) was able to substitute for cysteine as exogenous glutathione precursor. In kidneys, the ectopeptidase aminopeptidase N (ApN) has been reported to hydrolyze CysGly. Expression of mRNA of ApN in rat brain and cultured rat neurons was demonstrated by reverse transcriptase polymerase chain reaction and sequencing of the cDNA fragment obtained. In addition, the presence of ApN protein in cultured neurons was demonstrated by its immunocytochemical localization. In the presence of an activity‐inhibiting antiserum against ApN the utilization of CysGly as neuronal glutathione precursor was completely prevented, whereas that of cysteine plus glycine was not affected. The data presented demonstrates that cultured rat neurons express ApN and that this ectopeptidase participates in the utilization of CysGly as precursor for neuronal glutathione. © 2001 Wiley‐Liss, Inc.
Astrocytic and microglia cells reactivity induced by neonatal administration of glutamate in cerebral cortex of the adult rats
Authors: Martínez‐Contreras A. , Huerta M. , Lopez‐Perez S. , García‐Estrada J. , Luquín S. , Beas Zárate C. 
Published: August 2002

AbstractRecent studies confirm that astrocytes and neurons are associated with the synaptic transmission, particularly with the regulation of glutamate (Glu) levels. Therefore, they have the capacity to modulate the Glu released from neurons into the extracellular space. It has also been demonstrated an intense astrocytic and microglia response to physical or chemical lesions of the central nervous system. However, the persistence of the response of the glial cells in adult brain had not been previously reported, after the excitotoxic damage caused by neonatal dosage of monosodium glutamate (MSG) to newborn rats. In this study, 4 mg/g body weight of MSG were administered to newborn rats at 1, 3, 5, and 7 days after birth, at the age of 60 days the astrocytes and the microglia cells were analyzed with immunohistochemical methods in the fronto‐parietal cortex. Double labeling to glial fibrillary acidic protein (GFAP) and BrdU, or isolectin‐B4 and BrdU identified astrocytes or microglia cells that proliferated; immunoblotting and immunoreactivity to vimentin served for assess immaturity of astrocytic intermediate filaments. The results show that the neonatal administration of MSG‐induced reactivity of astrocytes and microglia cells in the fronto‐parietal cortex, which was characterized by hyperplasia; an increased number of astrocytes and microglia cells that proliferated, hypertrophy; increased complexity of the cytoplasm extension of both glial cells and expression of RNAm to vimentin, with the presence of vimentin‐positive astrocytes. This glial response to neuroexcitotoxic stimulus of Glu on the immature brain, which persisted to adulthood, suggests that the neurotransmitter Glu could trigger neuro‐degenerative illnesses. © 2002 Wiley‐Liss, Inc.
Fibroblast growth factor‐2 converts PACAP growth action on embryonic hindbrain precursors from stimulation to inhibition
Authors: Lelievre Vincent , Hu Zhongting , Byun Ji‐Yun , Ioffe Yevgeniya , Waschek James A. 
Published: August 2002

AbstractPituitary adenylyl cyclase activating peptide (PACAP) has been shown either to stimulate or to inhibit neural cell proliferation depending on the origin of the cell population. We show here that, depending on the presence or absence of fibroblast growth factor‐2 (FGF‐2, also called basic FGF), PACAP may either stimulate or inhibit DNA synthesis in neural precursors isolated from embryonic day 10.5 mouse hindbrain. In the absence of FGF‐2, PACAP stimulated 3H‐thymidine incorporation in a dose‐dependent manner. This stimulatory action was unaffected by antagonists of protein kinases A and C but was abolished in the presence of the MEK1/2 antagonist PD98059. In contrast, when FGF‐2 was present, PACAP inhibited DNA synthesis. This inhibitory action was insensitive to PD98059 but was fully blocked by the protein kinase A (PKA) inhibitor H89. The differential blockades by MEK1/2 and PKA inhibitors indicate that the FGF‐2‐induced switch in PACAP action on DNA synthesis was accomplished by a change in PACAP signaling pathways. We hypothesize that the actions of PACAP in the specific parts of the developing nervous system are determined in part by the presence or absence of FGFs and other growth factors. © 2002 Wiley‐Liss, Inc.
Efficacy of methylprednisolone therapy for the injured rat spinal cord
Authors: Rabchevsky Alexander G. , Fugaccia Isabella , Sullivan Patrick G. , Blades Deborah A. , Scheff Stephen W. 
Published: August 2002

AbstractCurrently the synthetic glucocorticosteroid methylprednisolone sodium succinate (MPSS) is the standard therapy after acute spinal cord injury (SCI) in humans based on reported neurological improvements. The mechanisms for its beneficial actions are not entirely clear, but experimental evidence suggests MPSS affords some degree of neuroprotection. As many studies with rat models of SCI have been unable to demonstrate improved behavioral outcome or tissue sparing after MPSS treatment, we chose to stereologically assess whether it alters lesion volume and tissue sparing over time, as well as long‐term behavioral recovery. Adult rats subjected to contusion SCI with the NYU impactor were administered either MPSS or saline for 24 hr beginning 5 min post injury. Over time the lesion dimensions were extremely dynamic, such that by 6 weeks post injury the volumes were reduced to a third of those seen after the first week. MPSS marginally reduced lesion volumes across time vs. controls, but the amount of spared gray and white matter remained unaltered between the two groups. Behavioral results further showed that MPSS failed to improve recovery of hind‐limb function. These findings add to the emerging scrutiny of MPSS as the standard therapy for acute SCI, as well as indicate the existence of a therapeutic window for tissue sparing restricted to the first several days after this type of SCI in rats. Equally important, our results caution the use of lesion volume dimensions or percent tissue sparing at the epicenter as indicators of therapeutic efficacy because neither reflects the actual amount of tissue sparing. © 2002 Wiley‐Liss, Inc.
BDNF dependence in neuroblastoma
Authors: Feng Xuan , Jiang Hong , Baik John C. , Edgar Cory , Eide Fernette F. 
Published: August 2002

AbstractNeuroblastomas are heterogeneous tumors arising from sympathetic precursors in the neural crest. Growth factor stimulation of neuroblastomas promote diverse biological responses (mitogenesis, differentiation, cell death) depending on the particular tumor studied. Here we show that brief treatment with retinoic acid (RA) rendered the human neuroblastoma lines SY5Y, NGP, SMS‐KCNR, and SK‐N‐SH dependent on brain‐derived neurotrophic factor (BDNF) for survival. The BDNF‐ and trkB‐expressing line SMS‐KCN was dependent on an autocrine BDNF/trkB survival without exposure to RA. We conclude that the BDNF/trkB pathway plays an important role in neuroblastoma survival and speculate on a possible role in tumor pathogenesis. J. Neurosci. Res. 64:355–363, 2001. © 2001 Wiley‐Liss, Inc.
A theoretical and empirical extension to the transformational leadership construct
Authors: Goodwin Vicki L. , Wofford J. C. , Whittington J. Lee 
Published: August 2002

AbstractThe contingent rewards subscale of the Multifactor Leadership Questionnaire (MLQ) was examined in an attempt to theoretically explain recent empirical results linking contingent rewards to transformational rather than transactional leadership. In Study 1, we supported the proposal that the items in the contingent rewards subscale represented two separate factors, an explicit and an implicit psychological contract. In addition, the implicit factor loaded with other transformational subscales and the explicit factor loaded with other transactional subscales. We confirmed these results in Study 2, and supported other hypotheses from transformational leadership theory using the contingent rewards revision. Implications for the transformational leadership construct are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
A multi‐rater assessment of organizational commitment: are self‐report measures biased?
Authors: Goffin Richard D. , Gellatly Ian R. 
Published: August 2002

AbstractMost investigations of organizational commitment have been conducted using self‐report measures, however, the veracity of self‐reports is often questioned. In a sample of 79 public‐sector administrative staff, we assessed two types of organizational commitment (affective and continuance) from the perspective of three different sources of raters (self, peer, and supervisor) to test three explanations of the factors influencing self‐report measures (observational opportunities, simple defensiveness, and moderated defensiveness). The pattern of correlations among the measures, analysed using the composite direct product multitrait–multirater approach, suggested that self‐report commitment measures are affected mainly by observations or experiences of the self‐reporter rather than by systematic bias related to defensive responding. This increases our confidence that scores from self‐report measures of affective and continuance commitment are veridical. Further, self‐ and peer‐based measures of commitment were largely redundant in the prediction of a job‐performance criterion whereas supervisory measures added unique predictive variance. Implications are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Have streamflow droughts in Europe become more severe or frequent?
Authors: Hisdal Hege , Stahl Kerstin , Tallaksen Lena M. , Demuth Siegfried 
Published: August 2002

AbstractChanges in the magnitude and frequency of droughts will have extensive impacts on water management, agriculture and aquatic ecosystems. With the projected global temperature increase, scientists generally agree that the global hydrological cycle will intensify and suggest that extremes will become or have already become more common. In this study, a pan‐European dataset of more than 600 daily streamflow records from the European Water Archive (EWA) was analysed to detect spatial and temporal changes in streamflow droughts. Four different time periods were analysed: 1962–1990, 1962–1995, 1930–1995 and 1911–1995. The focus was on hydrological droughts derived by applying the threshold level approach, which defines droughts as periods during which the streamflow is below a certain threshold. The Annual Maximum Series (AMS) of drought severity and the frequency of droughts in Partial Duration Series (PDS) were studied. Despite several reports on recent droughts in Europe, the non‐parametric Mann–Kendall test and a resampling test for trend detection showed that it is not possible to conclude that drought conditions in general have become more severe or frequent. The period analysed and the selection of stations strongly influenced the regional pattern. For most stations, no significant changes were detected. However, distinct regional differences were found. Within the period 1962–1990 examples of increasing drought deficit volumes were found in Spain, the eastern part of Eastern Europe and in large parts of the UK, whereas decreasing drought deficit volumes occurred in large parts of Central Europe and in the western part of Eastern Europe. Trends in drought deficit volumes or durations could, to a large extent, be explained through changes in precipitation or artificial influences in the catchment. Changes in the number of drought events per year were determined by the combined effect of climate and catchment characteristics such as storage capacity. The importance of the time period chosen for trend analysis is illustrated using two very long time series. Copyright © 2001 Royal Meteorological Society
Automated database of mesocyclones from the HIRLAM(INM)‐0.5° analyses in the western Mediterranean
Authors: Picornell M.A. , Jansà A. , Genovés A. , Campins J. 
Published: August 2002

AbstractAn automated procedure has been developed to detect and select mesoscale cyclones and describe their tracks by means of the numerical analysis model, the HIRLAM(INM)‐0.5°, operational at the Spanish Institute of Meteorology (INM). This procedure gives us a description of features of these cyclones, such as their frequency of appearance, geographical distribution and horizontal dimensions, and it also enables us to study the movement and the evolution of the cyclone centres. This procedure was developed in order to obtain an automated database of Mediterranean cyclones. To check the performance of this method, the distribution of cyclones was compared with the distribution obtained from a manual catalogue of mesoscale cyclones, and selected cases were studied using both methods. Some results obtained for the western Mediterranean are presented. A large number of cyclones are detected and most of them are located in specific zones, such as the Gulf of Genoa, south of the Pyrenees, south of the Iberian Peninsula and the Alboran Sea. The cyclones follow preferred tracks, which are different depending on the season. Copyright © 2001 Royal Meteorological Society
The role of eastern North Pacific tropical storms in the rainfall climatology of western Mexico
Authors: Englehart Phil J. , Douglas Arthur V. 
Published: August 2002

AbstractThis paper explores the role that tropical storms (TS) of the eastern North Pacific play in the rainfall climatology of western Mexico. It uses an 18‐station rainfall grid, along with a data base of storm tracks (1949–1997). TS rainfall is defined by a distance threshold, so that for each station in the grid, daily rainfall recorded when a TS is located within 550 km of the station is considered as TS‐derived; rainfall recorded in the absence of a TS or when a storm is beyond 550 km from a station is by default ‘non‐TS’ rainfall. A variety of statistics are presented to demonstrate the static associations that exist between TS activity and regional rainfall patterns. In sum, they clearly suggest that improved seasonal forecasts of TS activity in the eastern North Pacific will be critical to advancing seasonal climate prediction for Mexico. This study also addresses the interannual variability in TS and non‐TS rainfall. Principal component analysis is used to define the region's primary modes of rainfall variation. Considering the temporal behaviour of the rainfall modes, analyses reveal no statistically significant trends in TS rainfall. In contrast, non‐TS rainfall modes exhibit significant trends. This study provides support for the idea that these trends are partly tied to long‐period fluctuations in the ocean–atmosphere system. The results also indicate that while TS rainfall is not subject to trend behaviour, its year‐to‐year fluctuations, apparently, are linked to large‐scale processes like El Niño–Southern Oscillation (ENSO) and the state of North Pacific sea‐surface temperatures (SSTs). Copyright © 2001 Royal Meteorological Society
Trends in New Zealand daily temperature and rainfall extremes
Authors: Salinger M.J. , Griffiths G.M. 
Published: August 2002

AbstractTrends in daily temperature and rainfall indices are described for New Zealand. Two periods were examined: 1951–1998, to describe significant trends in temperature and rainfall parameters; and 1930–1998, to ascertain the effects of two main circulation changes that have occurred in the New Zealand region around 1950 and 1976.Indices examined included frequencies of daily maximum and minimum temperatures, above and below specified percentile levels and at those levels, as well as frequencies of these above and below fixed temperature thresholds. Extreme daily rainfall intensity and frequency above the 95th percentile and the length of consecutive dry day sequences were the rainfall indices selected.There were no significant trends in maximum temperature extremes (‘hot days’) but a significant increase in minimum temperatures was associated with decreases in the frequency of extreme ‘cold nights’ over the 48‐year period. There was a non‐significant tendency for an increase in the frequency of maximum temperature extremes in the north and northeast of New Zealand. A decline occurred in frequency of the minimum temperature 5th percentile (‘cold nights’) of 10–20 days a year in many locations. Trends in rainfall indices show a zonal pattern of response, with the frequency of 1‐day 95th percentile extremes decreasing in the north and east, and increasing in the west over the 1951–1996 period.Changes in the frequency of threshold temperatures above 24.9°C (25°C days) and below 0°C (frost days) are strongly linked to atmospheric circulation changes, coupled with regional warming. From 1930–1950 more south to southwest anomalous flow occurred relative to later years. In this period, 25°C days were less frequent in all areas except the northeast, and there was markedly more frost days in all but inland areas of the South Island compared with the 1951–1975 period. There was more airflow from the east and northeast from 1951 to 1975, the frequency of 25°C days increased and frost days decreased in many areas of New Zealand. In the final period examined (1976–1998), more prevalent airflow from the west and southwest was accompanied by more anticyclonic conditions. Days with a temperature of 25°C increased in the northeast only. Frost day frequencies decreased between 5 and 15 days a year in many localities, with little change in the west of the South Island and at higher elevation locations. Copyright © 2001 Royal Meteorological Society
Mid‐ and late‐Holocene climatic changes: a test of periodicity and solar forcing in proxy‐climate data from blanket peat bogs
Authors: Chambers Frank M. , Blackford Jeffrey J. 
Published: August 2002

AbstractA wide range of palaeoenvironmental evidence from the Holocene has suggested periodicities in the Earth's climate of 10s to 1000s of years. Identifying these millennial‐, century‐ and decadal periodicities, and their impacts, is critical in developing a fuller understanding of natural climate variability. Any solar‐induced climatic change needs to be distinguished from other causes of natural climate variability and from short‐term catastrophic events induced either by external or internal processes. Such events might themselves generate a periodicity, or in combination with other forcing factors they may contribute towards a periodicity (and so spuriously imply a universal and continuing periodicity in the climate record), or they may resonate with a solar‐induced periodicity. Here, evidence from peat records for periodicity in climate change over the mid to late Holocene is reviewed and this is followed by a test of the replicability of claimed periodicities using blanket peat data covering the past 2000 yr from four sites in the British Isles. Results suggest that the mires studied do go through phases of being responsive to periodic forcing factors, with ca. 200, ca. 80 and 60–50 yr wavelengths reflected in some data sets. However, the patterns shown are not consistent. This could be the result of local conditions at individual mires (human impact, sensitivity and vegetation succession) or of changes in the strength or nature of global forcing factors. Assessing a solar–mire link remains difficult because the century‐scale variations of the Sun show different intervals between solar minima, the durations of which are themselves unequal, and because the proxy‐climate data‐sets from peat profiles may themselves not be dated with sufficient precision and/or accuracy. Copyright © 2001 John Wiley & Sons, Ltd.
Cosmogenic radionuclide dating of glacial landforms in the Lahul Himalaya, northern India: defining the timing of Late Quaternary glaciation
Authors: Owen Lewis A. , Gualtieri Lyn , Finkel Robert C. , Caffee Marc W. , Benn Doug I. , Sharma Milap C. 
Published: August 2002

AbstractThe timing of glaciation in the Lahul Himalaya of northern India was ascertained using the concentrations of cosmogenic 10Be and 26Al from boulders on moraines and drumlins, and from glacially polished bedrock surfaces. Five glacial stages were identified: Sonapani I and II, Kulti, Batal and Chandra. Of these, cosmogenic exposure ages were obtained on samples representative of the Batal and Kulti glacial cycles. Stratigraphical relationships indicate that the Sonapani I and II are younger. No age was obtained for the Chandra glacial advance. Batal Glacial Stage deposits are found throughout the valley, indicating the presence of an extensive valley glacial system. During the Kulti Stage, glaciers advanced ca. 10 km beyond their current positions. Moraines produced during the Batal Stage, ca. 12–15.5 ka, are coeval with the Northern Hemisphere Late‐glacial Interstadial (Bølling/Allerød). Deglaciation of the Batal Glacial Stage was completed by ca. 12 ka and was followed by the Kulti Glacial Stage during the early Holocene, at ca. 10–11.4 ka. On millennial time‐scales, glacier oscillations in the Lahul Himalaya apparently reflect periods of positive mass‐balance coincident with times of increased insolation. During these periods the South Asian summer monsoon strengthened and/or extended its influence further north and west, thereby enhancing high‐altitude summer snowfall. Copyright © 2001 John Wiley & Sons, Ltd.
The geomorphological impact of Loch Lomond (Younger Dryas) Stadial plateau icefields in the central Lake District, northwest England
Authors: McDougall Derek A. 
Published: August 2002

AbstractDetailed geomorphological mapping has revealed evidence for the development of plateau icefields in the central fells of the English Lake District during the Loch Lomond (Younger Dryas) Stadial (ca. 12.9–11.5 ka). The largest plateau icefield system, which covered an area of approximately 55 km2 (including outlet glaciers), was centred on High Raise. To the west, smaller plateau icefields developed on Grey Knotts/Brandreth and Dale Head, covering areas of 7 km2 and 3 km2 respectively. The geomorphological impact of these plateau icefields appears to have been minimal on the summits, where the survival of blockfields and other frost‐weathered debris (mostly peat‐covered) implies the existence of at least patches of protective, cold‐based ice. Ice‐moulded bedrock at some plateau edges, however, documents a transition to wet‐based, erosive conditions. Prominent moraine systems were produced by outlet glaciers, which descended into the surrounding valleys where their margins became sediment traps for supraglacial debris and inwash. In some valleys, ice‐marginal moraines record successive positions of outlet glaciers, which actively backwasted towards their plateau source. This interpretation differs from that of previous workers, who assumed an alpine style of glaciation, with reconstructed glaciers emanating from corries and valley heads. It is likely that plateau icefields were more common at this time in upland Britain than hitherto has been appreciated. Copyright © 2001 John Wiley & Sons, Ltd.