bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impaired cell cycle control of neuronal precursor cells in the neocortical primordium of presenilin‐1‐deficient mice
Authors: Yuasa Shigeki , Nakajima Mitsunari , Aizawa Hidenori , Sahara Naruhiko , Koizumi Ken‐Ichi , Sakai Tsuyoshi , Usami Mihoko , Kobayashi Shin‐Ichiro , Kuroyanagi Hidehito , Mori Hiroshi , Koseki Haruhiko , Shirasawa Takuji 
Published: October 2002

AbstractRecent studies have implicated presenilin‐1 (PS‐1) in the processing of the amyloid precursor protein and Notch‐1. We show that PS‐1 has biological effects on differentiation and cell cycle control of neuronal precursor cells in vivo using PS‐1‐deficient mice. The expression of Class III β‐tubulin was upregulated throughout the neocortical primordia of PS‐1‐deficient E14 embryos, especially on the ventricular surface. The increased speed of migration of the immature neurons from the ventricular zone outward in the PS‐1‐deficient neocortical primordia was indicated by an in vivo bromodeoxyuridine (BrdU)‐labeling assay and a DiI‐labeling assay in slice culture. Furthermore, we investigated the cell cycle of neuronal precursor cells in the neocortical ventricular zone using an in vivo cumulative BrdU‐labeling assay. The length of the cell cycle in the neocortical precursor cells of wild‐type mice was 11.4 hr whereas that of the PS‐1‐deficient mice was 15.4 hr. Among all phases of the cell cycle, S‐phase exhibited the most prominent change in length, increasing from 2.4 hr in the wild‐type mice to 7.4 hr in the mutant mice. The distribution of β–catenin was specifically affected in the ventricular zone of the PS‐1‐deficient mice. These findings suggest that PS‐1 is involved in the differentiation and the cell cycle control of neuronal precursor cells in the ventricular proliferating zone of the neocortical primordium. © 2002 Wiley‐Liss, Inc.
4‐Methylcatechol stimulates phosphorylation of Trk family neurotrophin receptors and MAP kinases in cultured rat cortical neurons
Authors: Sometani Ayako , Nomoto Hiroshi , Nitta Atsumi , Furukawa Yoshiko , Furukawa Shoei 
Published: October 2002

AbstractEffects of 4‐methycatechol (4MC), a potent stimulator of nerve growth factor and brain‐derived neurotrophic factor (BDNF) synthesis, on phosphorylation of cellular molecules in cultured rat cortical neurons were examined. 4MC stimulated tyrosine phosphorylation of various proteins of molecular weight from 10–300 kDa including Trks, which are high‐affinity neurotrophin receptors. Moreover, 4MC enhanced the phosphorylation of serine 133 of mitogen‐activated protein kinase (MAPK/ERK) in a dose‐dependent manner. Pretreatment of cultures with PD98059, a selective inhibitor of MAPK kinase (MEK‐1), inhibited 4MC‐induced phosphorylation of ERKs, demonstrating MEK‐1‐mediated activation. Therefore, it seems that 4MC triggered the phosphorylation of Trks, resulting in the activation of the subsequent MAPK/ERK signal cascade, or perhaps the involvement of BDNF action as 4MC can stimulate neuronal BDNF synthesis. The phosphorylation of MAPK/ERK was unaffected, however, in the presence of cycloheximide, a protein synthesis inhibitor, and K252a, a selective inhibitor of Trks, suggesting that the effect of newly synthesized BDNF was negligible on this event, and that primary sites of 4MC actions are not limited only to Trks. These results suggest that 4MC primarily activates multiple signal transduction molecules such as tyrosine kinases, including Trks. A significant increase in the survival rate of cortical neurons in the presence of 10 or 100 nM 4MC supported this idea, because the concentrations were much lower than those for stimulation of BDNF synthesis. Our results strongly suggest that the neurotrophic actions of 4MC found so far are mediated predominantly by direct activation of some intracellular signals including MAPK/ERK rather than by neurotrophin synthesis. © 2002 Wiley‐Liss, Inc.
Neuroplasticity in Alzheimer's disease
Authors: Teter Bruce , Ashford J. Wesson 
Published: October 2002

AbstractRamon y Cajal proclaimed in 1928 that “once development was ended, the founts of growth and regeneration of the axons and dendrites dried up irrevocably. In the adult centers the nerve paths are something fixed, ended and immutable. Everything must die, nothing may be regenerated. It is for the science of the future to change, if possible, this harsh decree.” (Ramon y Cajal, 1928). In large part, despite the extensive knowledge gained since then, the latter directive has not yet been achieved by ‘modern’ science. Although we know now that Ramon y Cajal's observation on CNS plasticity is largely true (for lower brain and primary cortical structures), there are mechanisms for recovery from CNS injury. These mechanisms, however, may contribute to the vulnerability to neurodegenerative disease. They may also be exploited therapeutically to help alleviate the suffering from neurodegenerative conditions. Published 2002 Wiley‐Liss, Inc.
Effects of enriched environments with different durations and starting times on learning capacity during aging in rats assessed by a refined procedure of the Hebb‐Williams maze task
Authors: Kobayashi Satoru , Ohashi Yasushi , Ando Susumu 
Published: October 2002

AbstractCognitive function as measured by the Hebb‐Williams maze task was examined in Fischer 344 male rats that had been exposed to an enriched environment for periods of variable duration and at different starting ages. In one experiment, rats were exposed to environmental enrichment from weaning until the age of 2.5, 15, or 25 months. The results of 12 problems of the Hebb‐Williams maze task showed that the enriched rearing condition improved the learning ability in all the age groups; however, factor analysis and ANOVA demonstrated that four of the 12 maze problems were not suitable for detecting the effect of age under different environmental conditions. Reanalysis of the results obtained with the other eight maze problems more clearly revealed both the effects of rearing condition and aging. The latter analysis demonstrated that the learning rate of rats reared under enriched conditions was faster than that of rats reared under standard social conditions. Short‐term (3‐month) exposure also had positive effects on cognitive function in both adult (11‐month‐old) and aged (22‐month‐old) animals. The effect of long‐term exposure to an enriched environment starting at weaning was much greater than that of short‐term exposure in aged rats, whereas the effects of both long‐term and short‐term exposure were almost the same in adult rats. These results show that aged animals still have appreciable plasticity in cognitive function, and suggest that environmental stimulation could benefit aging humans as well. © 2002 Wiley‐Liss, Inc.
Animal model of dementia induced by entorhinal synaptic damage and partial restoration of cognitive deficits by BDNF and carnitine
Authors: Ando Susumu , Kobayashi Satoru , Waki Hatsue , Kon Kazuo , Fukui Fumiko , Tadenuma Tomoko , Iwamoto Machiko , Takeda Yasuo , Izumiyama Naotaka , Watanabe Kazutada , Nakamura Hiroaki 
Published: October 2002

AbstractA rat dementia model with cognitive deficits was generated by synapse‐specific lesions using botulinum neurotoxin (BoNTx) type B in the entorhinal cortex. To detect cognitive deficits, different tasks were needed depending upon the age of the model animals. Impaired learning and memory with lesions were observed in adult rats using the Hebb‐Williams maze, AKON‐1 maze and a continuous alternation task in T‐maze. Cognitive deficits in lesioned aged rats were detected by a continuous alternation and delayed non‐matching‐to‐sample tasks in T‐maze. Adenovirus‐mediated BDNF gene expression enhanced neuronal plasticity, as revealed by behavioral tests and LTP formation. Chronic administration of carnitine over time pre‐ and post‐lesions seemed to partially ameliorate the cognitive deficits caused by the synaptic lesion. The carnitine‐accelerated recovery from synaptic damage was observed by electron microscopy. These results demonstrate that the BoNTx‐lesioned rat can be used as a model for dementia and that cognitive deficits can be alleviated in part by BDNF gene transfer or carnitine administration. © 2002 Wiley‐Liss, Inc.
Golden mean to longevity: Rareness of mitochondrial cytochrome b variants in centenarians but not in patients with Parkinson's disease
Authors: Tanaka Masashi , Fuku Noriyuki , Takeyasu Takeshi , Guo Li‐Jun , Hirose Raita , Kurata Miyuki , Borgeld Harm‐Jan W. , Yamada Yoshiji , Maruyama Wakako , Arai Yasumichi , Hirose Nobuyoshi , Oshida Yoshiharu , Sato Yuzo , Hattori Nobutaka , Mizuno Yoshikuni , Iwata So , Yagi Kunio 
Published: October 2002

AbstractTo test the hypothesis that centenarians are free from deleterious mitochondrial variations, we analyzed amino acid variations in the cytochrome b molecule of 64 Japanese centenarians. Although the frequencies of some variations, such as N260D and G251S, differed significantly between centenarians and patients with Parkinson's disease, the most striking feature of centenarian cytochrome b was the rareness of amino acid variations in contrast to the variety of amino acid replacements in patients with Parkinson's disease. These results suggest that centenarians are genetically hitting the “golden mean” (less variation from the consensus cytochrome b sequence or less mismatch with other subunits). A multiplex detection system for various deleterious variations in combination with genetic tests for longevity‐associated genotypes will be necessary to predict longevity or age‐related diseases. © 2002 Wiley‐Liss, Inc.
Elevated luteinizing hormone expression colocalizes with neurons vulnerable to Alzheimer's disease pathology
Authors: Bowen Richard L. , Smith Mark A. , Harris Peggy L.R. , Kubat Zvezdana , Martins Ralph N. , Castellani Rudolph J. , Perry George , Atwood Craig S. 
Published: October 2002

AbstractIn individuals with Alzheimer's disease (AD), there is a two‐fold elevation in the serum concentrations of the gonadotropins, luteinizing hormone (LH), and follicle stimulating hormone compared to age‐matched controls. Whether this plays a role in disease pathogenesis is unclear. Nonetheless, gonadotropins are known to cross the blood brain barrier and the highest density of gonadotropin receptors in the brain are found within the hippocampus. We report for the first time the localization of LH in the cytoplasm of pyramidal neurons. In addition, we find a significant increase in LH in the cytoplasm of pyramidal neurons and neurofibrillary tangles of AD brain compared to age‐matched control brain. Whereas the functional consequences of increased neuronal LH are unknown, it is notable that LH is primarily localized to those neurons that are known to be vulnerable to Alzheimer's disease‐related neurodegeneration. Elevated serum and cortical neuron levels of LH, coupled with the decline in sex steroid production, could play important roles in the pathogenesis of AD. © 2002 Wiley‐Liss, Inc.
Climatological analysis of wintertime extreme low temperatures in São Paulo City, Brazil: impact of sea‐surface temperature anomalies
Authors: Gonçalves F.L.T. , Silva Dias P.L. , Araújo G.P. 
Published: October 2002

AbstractA diagnostic climatological study of winter cold temperature extremes in the Metropolitan Area of São Paulo (MASP) is presented. This diagnosis is based on temperature data collected at the Meteorological Station of Parque Estadual das Fontes do Ipiranga (IAG/USP) from 1950 to 2000. The persistence of synoptic and climatological patterns has been studied through principal component (PC) analysis and the results are compared with monthly anomalies in sea‐surface temperature (SST) of the eastern Pacific and South Atlantic. The extreme cold air temperatures, on a monthly basis, have shown no significant change since 1950. On the other hand, the mean monthly air temperatures have shown a slight warming trend, in agreement with the South Atlantic Ocean warming trend. The PC indicates significant loadings of two SST anomaly types: a cold anomaly of the South Atlantic Ocean, and a warm anomaly off the southern Brazilian coast. The latter could also be responsible for some extreme cold events (for daily minimum temperatures) in the MASP, and to a dominant westerly wind direction (southwest to northwest). Both the cold events and the westerly wind direction were evident in such winters as 1953, 1975, 1978, 1981, and 1994. On the other hand, the cold mean monthly temperatures are very well correlated to a broad cold pool anomaly in the South Atlantic at around 25 to 35° S and 15 to 55° W—sometimes narrower (such as in 1979 and 1988), and sometimes broader (such as 1964 and 1990). Where there was a narrowing or a widening, the prevailing wind direction was from the south–southeast. Therefore, the conclusion of these results is that the SST anomalies in the South Atlantic Ocean have a dominant effect on the São Paulo winter temperature climatology. Copyright © 2002 Royal Meteorological Society.
Daily dataset of 20th‐century surface air temperature and precipitation series for the European Climate Assessment
Authors: Klein Tank A. M. G. , Wijngaard J. B. , Können G. P. , Böhm R. , Demarée G. , Gocheva A. , Mileta M. , Pashiardis S. , Hejkrlik L. , Kern‐Hansen C. , Heino R. , Bessemoulin P. , Müller‐Westermeier G. , Tzanakou M. , Szalai S. , Pálsdóttir T. , Fitzgerald D. , Rubin S. , Capaldo M. , Maugeri M. , Leitass A. , Bukantis A. , Aberfeld R. , van Engelen A. F. V. , Forland E. , Mietus M. , Coelho F. , Mares C. , Razuvaev V. , Nieplova E. , Cegnar T. , Antonio López J. , Dahlström B. , Moberg A. , Kirchhofer W. , Ceylan A. , Pachaliuk O. , Alexander L. V. , Petrovic P. 
Published: October 2002

AbstractWe present a dataset of daily resolution climatic time series that has been compiled for the European Climate Assessment (ECA). As of December 2001, this ECA dataset comprises 199 series of minimum, maximum and/or daily mean temperature and 195 series of daily precipitation amount observed at meteorological stations in Europe and the Middle East. Almost all series cover the standard normal period 1961–90, and about 50% extends back to at least 1925. Part of the dataset (90%) is made available for climate research on CDROM and through the Internet (at http://www.knmi.nl/samenw/eca).A comparison of the ECA dataset with existing gridded datasets, having monthly resolution, shows that correlation coefficients between ECA stations and nearest land grid boxes between 1946 and 1999 are higher than 0.8 for 93% of the temperature series and for 51% of the precipitation series. The overall trends in the ECA dataset are of comparable magnitude to those in the gridded datasets.The potential of the ECA dataset for climate studies is demonstrated in two examples. In the first example, it is shown that the winter (October–March) warming in Europe in the 1976–99 period is accompanied by a positive trend in the number of warm‐spell days at most stations, but not by a negative trend in the number of cold‐spell days. Instead, the number of cold‐spell days increases over Europe. In the second example, it is shown for winter precipitation between 1946 and 1999 that positive trends in the mean amount per wet day prevail in areas that are getting drier and wetter.Because of its daily resolution, the ECA dataset enables a variety of empirical climate studies, including detailed analyses of changes in the occurrence of extremes in relation to changes in mean temperature and total precipitation. Copyright © 2002 Royal Meteorological Society.
Luni‐solar tidal influences on climate variability
Authors: Treloar Norman C. 
Published: October 2002

AbstractA possible exogenous cause of some terrestrial climate variability on time scales of 1 to 100 years is examined. Luni‐solar effects, and especially the coincidences of New Moon with small perigee distance, produce important tidal perturbations. These influences have been resolved in two orthogonal directions, and the variability in the southern oscillation and sea‐surface temperature anomalies may be at least partly understandable as a reflection of these tidal components. The correlation between tidal components and these climate factors is significant. The predictability of tidal effects may make a contribution to improving the accuracy and lead time of climate forecasting. Copyright © 2002 Royal Meteorological Society.
Behaviour of carbon dioxide and water vapour flux densities from a disturbed raised peat bog
Authors: Nieveen Joost P. , Jacobs Adrie F. G. 
Published: October 2002

AbstractMeasurements of carbon dioxide and water vapour flux densities were carried out for a disturbed raised peat bog in the north of the Netherlands during an 18 month continuous experiment. Tussock grass (sp. Molinea caerulae) mainly dominated the vegetation of the bog area. The maximum leaf area index (LAI) of the vegetation reached a numerical value of about 1.7 in mid‐August.When the LAI is large enough (LAI > 0.2), a mean net uptake of carbon dioxide is observed with a clear daily pattern. The total evapotranspiration consists of a soil, an open water, and a plant transpiration part. When the LAI is large enough (LAI > 0.2), plant transpiration dominates the total evapotranspiration. The mean daily transpiration pattern, however, is not similar to the carbon dioxide uptake pattern.During the summer months, the daytime carbon dioxide uptake shows a single early morning maximum value followed by a decline in uptake during the rest of the day. The evapotranspiration, however, follows more or less the incoming short‐wave radiation pattern. Effects of the vapour pressure deficit are suggested as a possible cause of this discrepancy. Copyright © 2002 Royal Meteorological Society.
Atmospheric circulation and precipitation in Italy for the last 50 years
Authors: Brunetti Michele , Maugeri Maurizio , Nanni Teresa 
Published: October 2002

AbstractDaily precipitation series from 75 Italian stations, for the period 1951–95, are clustered into six regions and the average is calculated for each area. For each average series, the seasonal and annual total precipitation and the number of wet days are calculated. The relationship between precipitation and atmospheric circulation is examined using correlation analysis. Atmospheric circulation is represented by five indexes: the well known North Atlantic oscillation index, a blocking frequency index, a Mediterranean oscillation index based on the 500 hPa geopotential record for Algiers, a Western European zonal circulation index (WEZCI) constructed from Madrid + Barcelona and Trondheim + Lund surface pressure records, and a new Mediterranean circulation index (MCI) constructed from Marseille and Jerusalem surface pressure records. All the indexes are calculated using monthly series; then seasonal and yearly averages are obtained. The indexes that show the most interesting correlation with total precipitation and number of wet days are WEZCI and MCI. Trend analysis of the index series gives evidence of a signal connected to a strong increase in winter air pressure in the Mediterranean area starting around 1980. Copyright © 2002 Royal Meteorological Society.
Monthly mean rainfall frequency model for the central Chilean coast: some climatic inferences
Authors: Saavedra N. , Müller E. P. , Foppiano A. J. 
Published: October 2002

AbstractA simple empirical model giving the annual evolution of monthly mean rainfall frequency for any location along the central Chilean coast is proposed. Model hypotheses are discussed with reference to a climatic scenario, which has been found of value in developing simple empirical climatic models for coastal stations in Chile. Equations giving monthly mean rainfall frequency for any latitude as a function of the latitude of the location of maximum monthly mean pressure in Chile are presented. It is concluded that the proposed model adequately describes the observed annual evolution. Moreover, the model allows qualitative inferences to be made regarding the interaction mechanisms between the main meteorological centres of action on a regional scale, which may prove of value in identifying trends of regional climatic change. Copyright © 2002 Royal Meteorological Society.
Associations between continental‐scale snow cover anomalies and air mass frequencies across eastern North America
Authors: Leathers Daniel J. , Mote Thomas L. , Grundstein Andrew J. , Robinson David A. , Felter Kathleen , Conrad Kathleen , Sedywitz Lauren 
Published: October 2002

AbstractThe spatial extent of snow cover has been shown to affect diverse meteorological variables, including surface air temperatures, atmospheric moisture, longwave and shortwave radiation budgets, and sensible and latent heat fluxes. However, little research has directly addressed the role of snow cover extent in the production and/or maintenance of diverse air mass types. The major hypothesis of this study is that continental‐scale snow cover anomalies should influence air mass frequencies because of their important effects on land‐surface energy budgets. To test this hypothesis, satellite‐derived Northern Hemisphere snow cover data were used in conjunction with a unique air mass classification routine to ascertain the association between air mass frequencies and snow cover anomalies across eastern North America.Results indicate that continental‐scale snow cover anomalies are strongly associated with changes in the frequency of air masses over eastern North America. However, strong mid‐tropospheric circulation anomalies are often associated with the snow cover and air mass frequency changes, making it difficult to judge the relative importance of the snow cover anomaly to the variations in air mass frequency. During the months of November, December, January and April, circulation patterns are present that would lead to the observed snow cover anomalies and associated air mass frequency changes. Thus, we hypothesize that snow cover anomalies (resulting from the strong circulation anomalies) help to enhance changes in the air mass frequencies of the region. However, during the months of February and March no strong circulation anomalies are apparent, suggesting that during these months snow cover may play a dominant role in air mass frequency variations. Copyright © 2002 Royal Meteorological Society.
Long‐term changes in ozone mini‐hole event frequency over the Northern Hemisphere derived from ground‐based measurements
Authors: Krzyścin Janusz W. 
Published: October 2002

AbstractDecadal changes of ozone mini‐hole event appearance over the Northern Hemisphere midlatitudes are examined based on daily total ozone data from seven stations having long records (four decades or more) of ozone observations. The various threshold methods for accepting and rejecting the ozone minima as mini‐holes are examined. Mini‐hole event activity is seen to be rather stable when averaged over a decadal time scale if the mini‐holes are selected as large negative departures (exceeding 20%) relative to the moving long‐term total ozone reference. The results are compared with a previous ozone mini‐hole climatology derived from satellite data (TOMS measurements on board the Nimbus‐7 satellite for the period 1978–93). A nonlinear statistical model (MARS), which takes into account various total ozone dynamical proxies (from NCEP–NCAR reanalysis), is used to study dynamical factors responsible for the ozone extremes over Arosa in the period 1950–99. The model explains as much as 95% of the total variance of the ozone extremes. The model–observation differences averaged over the decadal intervals are rather smooth throughout the whole period analysed. It is suggested that the short‐term dynamical processes controlling the appearance of ozone extremes influenced the ozone field in a similar way before and after the onset of abrupt ozone depletion in the early 1980s. The analysis of the ozone profile and the tropopause pressure (from the ozonesondings over Hohenpeissenberg, 1966–99) during mini‐hole events shows ∼60% ozone reduction in the lower stratosphere and an approximately 50 hPa upward shift of the thermal tropopause there. Copyright © 2002 Royal Meteorological Society.