bluuebunny/crossref_metadata_2025_split huggingface dataset:
Habituation to stress and dexamethasone suppression in rats with selective basal forebrain cholinergic lesions
Authors: Helm K.A. , Ziegler D.R. , Gallagher M. 
Published: April 2004

AbstractPrevious studies suggest a role for basal forebrain cholinergic neurons in enhancing the inhibitory influence of the hippocampus and medial prefrontal cortex (mPFC) on glucocorticoid stress responses mediated by the hypothalamic‐pituitary‐adrenocortical (HPA) axis. An inhibitory action of the basal forebrain cholinergic (BFC) system may occur through facilitation of stress‐related information processing and maintenance of glucocorticoid receptor (GR) expression and negative feedback signaling in these target regions. The current study investigated the possibility that BFC input to the hippocampus contributes to habituation of the glucocorticoid response following repeated exposure to a stressor. Cholinergic lesions were made by microinjections of the immunotoxin 192 IgG‐saporin into the medial septum/vertical limb of the diagonal band, and 3 weeks later rats were subjected to six daily sessions of restraint stress. Blood samples taken before, during and after acute stress revealed a significant increase in peak activation and protracted elevation of corticosterone in cholinergic lesioned rats. After 5 days of repeated stress, however, both groups habituated to the stressor, as indicated by similarly low corticosterone profiles throughout both the response and recovery period. Against that habituated background, rats were administered a dexamethasone challenge on day 6, so that feedback status could be examined. Dexamethasone‐induced suppression of endogenous corticosterone before, during, and after stress was significantly attenuated in lesioned rats. The profile of dysfunction in glucocorticoid regulation after selective cholinergic lesions in young animals may be relevant to the adrenocortical hyperactivity and negative feedback deficits seen in conditions such as normal aging and Alzheimer's dementia, in which integrity of the basal forebrain cholinergic system is compromised. © 2004 Wiley‐Liss, Inc.
Hippocampal damage in mouse and human forms of systemic autoimmune disease
Authors: Ballok David A. , Woulfe John , Sur Monalisa , Cyr Michael , Sakic Boris 
Published: April 2004

AbstractSystemic lupus erythematosus (SLE) is frequently accompanied by neuropsychiatric (NP) and cognitive deficits of unknown etiology. By using autoimmune MRL‐lpr mice as an animal model of NP‐SLE, we examine the relationship between autoimmunity, hippocampal damage, and behavioral dysfunction. Fluoro Jade B (FJB) staining and anti‐ubiquitin (anti‐Ub) immunocytochemistry were used to assess neuronal damage in young (asymptomatic) and aged (diseased) mice, while spontaneous alternation behavior (SAB) was used to estimate the severity of hippocampal dysfunction. The causal relationship between autoimmunity and neuropathology was tested by prolonged administration of the immunosuppressive drug cyclophosphamide (CY). In comparison to congenic MRL +/+ controls, SAB acquisition rates and performance in the “reversal” trial were impaired in diseased MRL‐lpr mice, suggesting limited use of the spatial learning strategy. FJB‐positive neurons and anti‐Ub particles were frequent in the CA3 region. Conversely, CY treatment attenuated the SAB deficit and overall FJB staining. Similarly to mouse brain, the hippocampus from a patient who died from NP‐SLE showed reduced neuronal density in the CA3 region and dentate gyrus, as well as increased FJB positivity in these regions. Gliosis and neuronal loss were observed in the gray matter, and T lymphocytes and stromal calcifications were common in the choroid plexus. Taken together, these results suggest that systemic autoimmunity induces significant hippocampal damage, which may underlie affective and cognitive deficits in NP‐SLE. © 2004 Wiley‐Liss, Inc.
“I have often walked down this street before”: fMRI Studies on the hippocampus and other structures during mental navigation of an old environment
Authors: Rosenbaum R. Shayna , Ziegler Marilyne , Winocur Gordon , Grady Cheryl L. , Moscovitch Morris 
Published: April 2004

AbstractThe role of the hippocampus in recent spatial memory has been well documented in patients with damage to this structure, but there is now evidence that the hippocampus may not be needed for the storage and recovery of a spatial layout that was experienced long before injury. Such preservation may rely, instead, on a network of dissociable, extra‐hippocampal regions implicated in topographical orientation. Using functional magnetic resonance imaging (fMRI), we investigated this hypothesis in healthy individuals with extensive experience navigating in a large‐scale urban environment (downtown Toronto). Participants were scanned as they performed mental navigation tasks that emphasized different types of spatial representations. Tasks included proximity judgments, distance judgments, landmark sequencing, and blocked‐route problem‐solving. The following regions were engaged to varying degrees depending on the processing demands of each task: retrosplenial cortex, believed to be involved in assigning directional significance to locales within a relatively allocentric framework; medial and posterior parietal cortex, concerned with processing space within egocentric coordinates during imagined movement; and regions of prefrontal cortex, present in tasks heavily dependent on working memory. In a second, event‐related experiment, a distinct area of inferotemporal cortex was revealed during identification of familiar landmarks relative to unknown buildings in addition to activation of many of those regions identified in the navigation tasks. This result suggests that familiar landmarks are strongly integrated with the spatial context in which they were experienced. Importantly, right medial temporal lobe activity was observed, its magnitude equivalent across all tasks, though the core of the activated region was in the parahippocampal gyrus, barely touching the hippocampus proper. © 2004 Wiley‐Liss, Inc.
Olfactory learning‐induced increase in spine density along the apical dendrites of CA1 hippocampal neurons
Authors: Knafo Shira , Ariav Gal , Barkai Edi , Libersat Frederic 
Published: April 2004

AbstractWe have previously shown that rule learning of an olfactory discrimination task is accompanied by increased spine density along the apical dendrites of piriform cortex pyramidal neurons. The purpose of the present study was to examine whether such olfactory learning task, in which the hippocampus is actively involved, induces morphological modifications in CA1 pyramidal neurons as well. Rats were trained to discriminate positive cues in pairs of odors for a water reward. Morphological modifications were studied in Golgi‐impregnated neurons with light microscopy, 1 and 3 days after training completion. Spine densities were measured on the proximal region of apical dendrites and on basal dendrites after rule learning. Three days after training completion, the mean spine density on apical dendrites in neurons from trained rats was significantly higher by 20.5% than in neurons from pseudo‐trained and naive animals, which did not differ from each other. By contrast, there was no significant difference in spine density of basal dendrites among the three groups. As length and diameter of spiny dendritic segments did not change after learning, the learning‐related increase in spine density in neurons from trained rats may reflect a net increase in the number of excitatory synapses in the hippocampus following olfactory rule learning. © 2004 Wiley‐Liss, Inc.
Health insurance and savings over the life cycle—a semiparametric smooth coefficient estimation
Authors: Chou Shin‐Yi , Liu Jin‐Tan , Huang Cliff J. 
Published: April 2004

AbstractIndividuals save for future uncertain health care expenses. This is less efficient than pooling health risk through insurance. The provision of comprehensive health insurance may raise welfare by providing the missing market to smooth out consumption through the life cycle. We employ a semiparametric smooth coefficient model to examine the effects of the introduction of the National Health Insurance in Taiwan in 1995 on savings and consumption over the life cycle. The idea is to estimate the coefficients of health insurance which vary with age. Our results suggest that younger households are more sensitive to the risk reductions, and that they demonstrate a greater response in the reduction of their precautionary saving. Copyright © 2004 John Wiley & Sons, Ltd.
Poly(carbonate urethane) and poly(ether urethane) biodegradation: In vivo studies
Authors: Christenson Elizabeth M. , Dadsetan Mahrokh , Wiggins Michael , Anderson James M. , Hiltner Anne 
Published: April 2004

AbstractSeveral strategies have been used to increase the biostability of medical‐grade polyurethanes while maintaining biocompatibility and mechanical properties. One approach is to chemically modify or replace the susceptible soft segment. Currently, poly(carbonate urethanes) (PCUs) are being evaluated as a replacement of poly(ether urethanes) (PEUs) in medical devices because of the increased oxidative stability of the polycarbonate soft segment. Preliminary in vivo and in vitro studies have reported improved biostability of PCUs over PEUs. Although several studies have reported evidence of in vitro degradation of these new polyurethanes, there has been no evidence of significant in vivo degradation that validates a degradation mechanism. In this study, the effect of soft segment chemistry on the phase morphology, mechanical properties, and in vivo response of commercial‐grade PEU and PCU elastomers was examined. Results from dynamic mechanical testing and infrared spectroscopy suggested that the phase separation was better in PCU as compared with PEU. In addition, the higher modulus and reduced ultimate elongation of PCU was attributed to the reduced flexibility of the polycarbonate soft segment. Following material characterization, the in vivo biostability and biocompatibility of PEU and PCU were studied using a subcutaneous cage implant protocol. The results from the cage implant study and cell culture experiments indicated that monocytes adhere, differentiate, and fuse to form foreign body giant cells on both polyurethanes. It is now generally accepted that the reactive oxygen species released by these adherent macrophages and foreign body giant cells initiate PEU biodegradation. Attenuated total reflectance–Fourier transform infrared analysis of explanted samples provided evidence of chain scission and crosslinking in both polyurethanes. This indicated that the PCU was also susceptible to biodegradation by agents released from adherent cells. These results reinforce the need to evaluate and understand the biodegradation mechanisms of PCUs. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 407–416, 2004
Differentiation of preosteoblasts is affected by implant surface microtopographies
Authors: Schneider Galen B. , Zaharias Rebecca , Seabold Denise , Keller John , Stanford Clark 
Published: April 2004

AbstractOsteogenesis involves the recruitment of multipotent mesenchymal cells and the progressive differentiation of these cells into osteoblasts. The transcription factor Runx2 regulates osteoblast differentiation and expression of genes necessary for the development of a mineralized phenotype. The purpose of this study was to determine if preosteoblast cell differentiation associated with Runx2 and osteocalcin gene expression was influenced by implant surface microtopography. Human embryonic palatal mesenchymal cells (HEPM cells) were cultured on grooved or roughened cpTi implant discs. Cell phenotypes were evaluated with epifluorescent microscopy. Real‐time PCR was used for quantitative analysis of Runx2 and osteocalcin gene expression. HEPM cells mineralized when grown on rough and grooved implant surfaces relative to tissue culture plastic. Real‐time PCR showed significant (p < 0.05) increases in Runx2 and osteocalcin gene expression in cells cultured on rough and grooved implant microtopographies. These results suggest that preosteoblast cell differentiation is affected by implant surface microtopographies during osseointegration of dental implants. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 462–468, 2004
Forbidden induced subgraph characterization of cograph contractions
Authors: Zverovich Igor Ed. , Zverovich Inessa I. 
Published: April 2004

AbstractLet S1, S2,…,St be pairwise disjoint non‐empty stable sets in a graph H. The graph H* is obtained from H by: (i) replacing each Si by a new vertex qi; (ii) joining each qi and qj, 1 ≤ i # j ≤ t, and; (iii) joining qi to all vertices in H – (S1 ∪ S2 ∪ ··· ∪ St) which were adjacent to some vertex of Si. A cograph is a P4‐free graph. A graph G is called a cograph contraction if there exist a cograph H and pairwise disjoint non‐empty stable sets in H for which G ≃ H*. Solving a problem proposed by Le [2], we give a finite forbidden induced subgraph characterization of cograph contractions. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 217–226, 2004
Anthropogenic changes in the landscape of west Java (Indonesia) during historic times, inferred from a sediment and pollen record from Teluk Banten
Authors: van der Kaars Sander , van den Bergh Gert D. 
Published: April 2004

AbstractPalynological and charcoal analyses of shallow marine core 98‐28 from the northern coastal area of West Java provide a regional vegetation history during the last few centuries. Reliable chronostratigraphical control is provided by 210Pb analyses and the occurrence of the 1883 Krakatau ash/tsunami layer as a time marker. The results permit the distinction of four successive stages, reflecting increased disturbance and land clearance, with some evidence for the presence of deciduous lowland forests in the Banten area during the early Holocene. The establishment of coconut and pine plantations and the severe loss of biodiversity in the last few decennia are also echoed in the pollen record. The effect of the Krakatau eruption was insignificant compared with human impact on vegetation in the Banten area. Copyright © 2004 John Wiley & Sons, Ltd.
Holocene tephra horizons at Klocka Bog, west‐central Sweden: aspects of reproducibility in subarctic peat deposits
Authors: Bergman Jonas , Wastegård Stefan , Hammarlund Dan , Wohlfarth Barbara , Roberts Stephen J. 
Published: April 2004

AbstractThis paper presents one of the most extensive Holocene tephra records found to date in Scandinavia. Microtephra horizons originating from Icelandic eruptions were recorded in two ca. 2 m thick peat profiles at Klocka Bog in west‐central Sweden. Five of the microtephra horizons were geochemically correlated to the Askja‐1875, Hekla‐3, Kebister, Hekla‐4 and Lairg A tephras respectively. Radiocarbon‐based dating of these tephras broadly agree with previously published ages from Iceland, Sweden, Germany and the British Isles. The identification of the Lairg A tephra demonstrates a more widespread distribution than previously thought, extending the usefulness of Icelandic Holocene tephrochronology further north into west‐central Scandinavia. Long‐lasting snow cover and seasonal wind distribution in the lower stratosphere are suggested as factors that may be responsible for fragmentary tephra deposition patterns in peat deposits of subarctic Scandinavia. Copyright © 2004 John Wiley & Sons, Ltd.
A terrestrial record of Last Interglacial climate preserved by voluminous debris avalanche inundation in Taranaki, New Zealand
Authors: Newnham Rewi , Alloway Brent 
Published: April 2004

AbstractAt Airedale Reef, western North Island, New Zealand, a ca. 4 m thick volcanogenic debris avalanche deposit has facilitated the preservation of an enveloping sequence of peats with interbedded andesitic tephras spanning marine isotope (MIS) 5. The sequence closely overlies a wave‐cut terrace correlated to MIS 5e and, in turn, is overlain by andic beds with tephra interbeds including the Rotoehu and Kawakawa tephras deposited during early MIS 3 and mid‐MIS 2, respectively. Pollen analysis of the organic sequence shows a coherent pattern of fluctuating climate for the Last Interglacial–Last Glacial transition that corresponds with marine isotope stratigraphy and supports the contention that orbital variations were a primary factor in late Quaternary southern mid‐latitude climate change. A five‐stage subdivision of MIS 5 is clearly recognised, with marine isotope substage (MISS) 5b drier than MISS 5d, and the cooling transition from 5a to MIS 4 also may have been comparatively dry and characterised by natural fire, perhaps associated with volcanism. Several other examples of volcanic impact on vegetation and the landscape are evident. The Airedale Reef sequence exhibits strong similarities with fragmentary MIS 5 pollen records preserved elsewhere in New Zealand and enables the proxy record of southern mid‐latitude climatic variability during the Last Interglacial–Glacial cycle to be extended. Copyright © 2004 John Wiley & Sons, Ltd.
A Late‐glacial chironomid record from Hawes Water, northwest England
Authors: Bedford Alan , Jones Richard. T. , Lang Barbara , Brooks Stephen , Marshall Jim D. 
Published: April 2004

AbstractThis paper presents the results of a high‐resolution Late‐glacial chironomid stratigraphy from Hawes Water, a small carbonate lake in northern Lancashire. The samples were from a core taken from the terrestrialised margin of the present lake, which represents an intermediate depth between the true littoral and the profundal. The chironomid assemblage showed a high degree of sensitivity to both broad‐scale and short‐term temperature changes. Comparison with an existing proxy temperature record (δ18O) for the site confirmed the presence of four temperature inversions within the Late‐glacial Interstadial. A mean July air temperature inference model, derived from acid, soft‐water lakes in Norway and Svalbard, was applied to the data. Despite the absence of carbonate lakes within the Norwegian training set, there was a close similarity between trends in estimated July air temperature and the δ18O trace, with a particularly strong correspondence in the periods of clay deposition. This suggests that this model is highly robust. The inferred maximum Interstadial temperature was 13.4°C, dropping initially to 7.5°C in the Loch Lomond Stadial. Temperatures reach a maximum of nearly 10°C in this period, cool for a short period before rising rapidly to 13.2°C at the start of the Holocene. These temperatures are similar to but slightly higher than those estimated for Whitrig Bog, southeast Scotland, and lower than those inferred from coleopteran‐based models for sites in South Wales. Copyright © 2004 John Wiley & Sons, Ltd.
Small‐scale faulting, topographic steps and seismic ruptures in the Alhambra (Granada, southeast Spain
Authors: Azañón J. M. , Azor A. , Booth‐Rea G. , Torcal F. 
Published: April 2004

AbstractThe Alhambra (14th century AD) in Granada (southeast Spain) is built at the summit of a Pliocene to Lower Pleistocene conglomeratic formation. Tens of small‐scale normal faults crop out along the northern hillslope of the Alhambra, which have a N130–N150°E strike, dipping 65–75° mostly to the southwest. These are closely spaced faults (approximately 5–30 m) with centimetre to several metre displacements. Several topographic steps in this area coincide with hectometre‐ to kilometre‐scale faults with the same kinematics as the small‐scale ones. Some of these faults appear to be active and related to the present seismicity detected in this region, and associated with the cracks and other damage observed in the Alhambra. Several focal mechanisms calculated in this study are in accordance with the dominant NW–SE orientated normal faults. We interpret that the topographic steps of these faults are a consequence of repeated earthquakes during the past 800 ka. The last large earthquake of approximately 5.1 magnitude in this area occurred in 1431, destroying the Alixares Palace, the Arabian fence and part of the Alhambra wall. We consider the seismic risk associated with these faults to be moderate, as the displacement is partitioned into several hectometre‐ to kilometre‐scale faults. Copyright © 2004 John Wiley & Sons, Ltd.
Climatic change recorded by stable isotopes and trace elements in a British Holocene tufa
Authors: Garnett E. R. , Andrews J. E. , Preece R. C. , Dennis P. F. 
Published: April 2004

AbstractCombined stable isotope (δ18O and δ13C) and trace element (Mg, Sr) geochemistry from bulk tufa calcite and ostracod shell calcite from an early Holocene British tufa reveal clear records of Holocene palaeoclimatic change. Variation in δ18O is caused principally by change in the isotopic composition of Holocene rainfall (recharge), itself caused mainly by change in air temperature. The δ13C variability through much of the deposit reflects increasing influence of soil‐zone CO2, owing to progressive woodland soil development. Bulk tufa Mg/Ca and Sr/Ca are controlled by their concentrations in the spring water. Importantly, Mg/Ca ratios are not related to δ18O values and thus show no temperature dependence. First‐order sympathetic relationships between δ13C values and Mg/Ca and Sr/Ca are controlled by aquifer processes (residence times, CO2 degassing and calcite dissolution/reprecipitation) and probably record intensity of palaeorainfall (recharge) effects. Stable isotope records from ostracod shells show evidence of vital effects relative to bulk tufa data. The ostracod isotopic records are markedly ‘spiky’ because the ostracods record ‘snapshots’ of relatively short duration (years), whereas the bulk tufa samples record averages of longer time periods, probably decades.The δ18O record appears to show early Holocene warming, a thermal maximum at ca. 8900 cal. yr BP and the global 8200 yr BP cold event. Combined δ13C, Mg/Ca and Sr/Ca data suggest that early Holocene warming was accompanied by decreasing rainfall intensity. The Mg/Ca data suggest that the 8200 yr BP cold event was also dry. Warmer and wetter conditions were re‐established after the 8200 yr BP cold event until the top of the preserved tufa sequence at ca. 7100 cal. yr BP. Copyright © 2004 John Wiley & Sons, Ltd.
Kinetics of the gas‐phase reaction of CF3OC(O)H with OH radicals at 242–328 K
Authors: Chen L. , Kutsuna S. , Tokuhashi K. , Sekiya A. 
Published: April 2004

AbstractThe rate constants, k1, of the reaction of CF3OC(O)H with OH radicals were measured by using a Fourier transform infrared spectroscopic technique in an 11.5‐dm3 reaction chamber at 242–328 K. OH radicals were produced by UV photolysis of an O3–H2O–He mixture at an initial pressure of 200 Torr. Ozone was continuously introduced into the reaction chamber during UV irradiation. With CF3OCH3 as a reference compound, k1 at 298 K was (1.65 ± 0.13) × 10−14 cm3 molecule−1 s−1. The temperature dependence of k1 was determined as (2.33 ± 0.42) × 10−12 exp[−(1480 ± 60)/T] cm3 molecule−1 s−1; possible systematic uncertainty could add an additional 20% to the k1 values. The atmospheric lifetime of CF3OC(O)H with respect to reaction with OH radicals was calculated to be 3.6 years. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 337–344 2004