bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of trisomy 8 on expression of genes located on chromosome 8 in different AML subgroups
Authors: Schoch Claudia , Kohlmann Alexander , Dugas Martin , Kern Wolfgang , Schnittger Susanne , Haferlach Torsten 
Published: September 2006

AbstractTrisomy 8 is the most frequently observed trisomy in acute myeloid leukemia (AML) occurring as a sole karyotype abnormality or in addition to other chromosome aberrations. It was the aim of this study to analyze the impact of trisomy 8 on the expression of genes located on chromosome 8 in distinct AML subgroups characterized by different chromosome abnormalities in addition to trisomy 8. Gene expression analyses were performed on a total of 567 AML cases comprising the following subgroups: +8 sole, +8 within a complex aberrant karyotype, +8 in addition to t(15;17), inv(16), t(8;21), 11q23/MLL, or other abnormalities, AML with normal karyotype and the before mentioned subgroups without trisomy 8. A significant higher mean expression of genes located on chromosome 8 was observed in subgroups with +8 in comparison to their respective control groups. A varying number of significantly higher expressed genes was identified in all comparisons. No gene was significantly overexpressed in all comparisons, and no distinct gene expression pattern was identified allowing the identification of cases with trisomy 8. In conclusion, the gain of chromosome 8 leads to a higher expression of genes located on chromosome 8. However, no consistent pattern of genes was identified, which shows a higher expression in all AML subtypes with trisomy 8. These data suggest that trisomy 8 rather provides a platform for a higher expression of chromosome 8 genes which are individually up‐regulated by the respective primary genetic abnormalities. Therefore, trisomy 8 in AML determines no specific disease characteristic but is a disease modulating secondary event. © 2006 Wiley‐Liss, Inc.
Characterization of the breast cancer associated ATM 7271T>G (V2424G) mutation by gene expression profiling
Authors: Waddell Nic , Jonnalagadda Jyoti , Marsh Anna , Grist Scott , Jenkins Mark , Hobson Karen , Taylor Malcolm , Lindeman Geoff J. , Tavtigian Sean V. , Suthers Graeme , Goldgar David , Oefner Peter J. , Taylor Darrin , Grimmond Sean , Khanna Kum Kum , Chenevix‐Trench Georgia 
Published: September 2006

AbstractMutations in ATM are responsible for the autosomal recessive disorder ataxia telangiectasia. Heterozygous mutations in ATM have been associated with an elevated risk of breast cancer. We previously reported one breast cancer family in which ATM 7271T>G (V2424G) segregated with disease, and apparently acted in a dominant negative manner. We now report the screening of 782 multiple‐case breast cancer families that identified two additional index cases with ATM 7271T>G. Phylogenetic sequence analysis showed that V2424 is a highly conserved residue, and that the 2424G variant is likely to interfere with function. To elucidate the consequences of this mutation, we expression profiled wild‐type, heterozygous, and homozygous lymphoblastoid cell lines (LCLs) from Scottish and Australian families using an oligonucleotide microarray. Cluster analysis revealed 77 genes that were differentially expressed in homozygous and heterozygous V2424G cells (compared to wild‐type) and 11 genes differentially expressed in the homozygous cells. We also evaluated the profiles of LCLs after exposure to ionizing radiation (IR) and identified 77 genes that were differentially expressed in wild‐type cells, but not in homozygous or heterozygous V2424G cells. We validated the expression differences by RT‐PCR in additional heterozygous V2424G LCLs from another breast cancer family. We found no consistent cytotoxicity or abrogation of ATM kinase activity after IR in seven heterozygous V2424G LCLs, compared to wild‐type LCLs, but did find an increase in the number of chromosomal aberrations. These data suggest that the V2424G missense mutation acts largely as a dominant negative in terms of the associated expression profiles. © 2006 Wiley‐Liss, Inc.
Plasticity of perisynaptic astroglia during synaptogenesis in the mature rat hippocampus
Authors: Witcher Mark R. , Kirov Sergei A. , Harris Kristen M. 
Published: September 2006

AbstractAstroglia are integral components of synapse formation and maturation during development. Less is known about how astroglia might influence synaptogenesis in the mature brain. Preparation of mature hippocampal slices results in synapse loss followed by recuperative synaptogenesis during subsequent maintenance in vitro. Hence, this model system was used to discern whether perisynaptic astroglial processes are similarly plastic, associating more or less with recently formed synapses in mature brain slices. Perisynaptic astroglia was quantified through serial section electron microscopy in perfusion‐fixed or sliced hippocampus from adult male Long‐Evans rats that were 65–75 days old. Fewer synapses had perisynaptic astroglia in the recovered hippocampal slices (42.4% ± 3.4%) than in the intact hippocampus (62.2% ± 2.6%), yet synapses were larger when perisynaptic astroglia was present (0.055 ± 0.003 μm2) than when it was absent (0.036 ± 0.004 μm2) in both conditions. Importantly, the length of the synaptic perimeter surrounded by perisynaptic astroglia and the distance between neighboring synapses was not proportional to synapse size. Instead, larger synapses had longer astroglia‐free perimeters where substances could escape from or enter into the synaptic clefts. Thus, smaller presumably newer synapses as well as established larger synapses have equal access to extracellular glutamate and secreted astroglial factors, which may facilitate recuperative synaptogenesis. These findings suggest that as synapses enlarge and release more neurotransmitter, they attract astroglial processes to a discrete portion of their perimeters, further enhancing synaptic efficacy without limiting the potential for cross talk with neighboring synapses in the mature rat hippocampus. © 2006 Wiley‐Liss, Inc.
Sensitivity of riparian ecosystems in arid and semiarid environments to moisture pulses
Authors: Williams D. G. , Scott R. L. , Huxman T. E. , Goodrich D. C. , Lin G. 
Published: September 2006

AbstractStructural and functional dynamics of riparian vegetation in arid and semiarid basins are controlled by hydrological processes operating at local, landscape and catchment scales. However, the importance of growing‐season precipitation as a control on evapotranspiration (ET) and carbon cycling in these ecosystems varies considerably across the riparian landscape, depending largely on access to the near‐surface water table. Here we describe key findings from ongoing ecohydrological studies along the Upper San Pedro River (USPR) in semiarid, south‐eastern Arizona, USA. Depth to the water table varies substantially across the riparian landscape along the USPR drainage, and is a key factor controlling the sensitivity of cottonwood (Populus fremontii) water‐source use, transpiration rate and photosynthetic metabolism to inputs of monsoonal moisture during the growing season. Landscape‐scale functional variation in cottonwood forests has been incorporated into spatially explicit ET models for estimating water balance components along the USPR. However, of greater importance for understanding controls on water and carbon exchange processes in the riparian corridor is the conversion of sacaton (Sporobolus spp.) grasslands on pre‐entrenchment floodplain terraces to communities dominated by the deep‐rooted woody legume, mesquite (Prosopis velutina). Mesquite is now the dominant cover in the riparian corridor and has increased by more than 300% in the USPR basin since 1972. The physiognomic shift from grassland to mesquite woodland on pre‐entrenchment floodplain terraces alters the sensitivity of ET and CO2 exchange to inputs of growing‐season precipitation. Because mature mesquite shrubs and trees have greater access to groundwater in these habitats than sacaton, ET and gross ecosystem production (GEP) are relatively decoupled from variation in monsoonal precipitation. However, decomposition of litter and soil organic matter in floodplain ecosystems remains highly coupled to monsoonal moisture inputs after mesquite encroachment. Responses of net ecosystem exchange of CO2 (NEE) to inputs of monsoonal rainfall are therefore not simple, but depend on vegetation composition and the connection of dominant plants to the water table. The heterogeneous vegetation patterns and groundwater depths in the riparian landscape offer unique opportunities for understanding fundamental ecohydrological processes linking carbon and water cycles in both riparian and upland ecosystems. Copyright © 2006 John Wiley & Sons, Ltd.
Partitioning of evapotranspiration and its relation to carbon dioxide exchange in a Chihuahuan Desert shrubland
Authors: Scott Russell L. , Huxman Travis E. , Cable William L. , Emmerich William E. 
Published: September 2006

AbstractKey to evaluating the consequences of woody plant encroachment on water and carbon cycling in semiarid ecosystems is a mechanistic understanding of how biological and non‐biological processes influence water loss to the atmosphere. To better understand how precipitation is partitioned into the components of evapotranspiration (bare‐soil evaporation and plant transpiration) and their relationship to plant uptake of carbon dioxide (CO2) as well as ecosystem respiratory efflux, we measured whole plant transpiration, evapotranspiration, and CO2 fluxes over the course of a growing season at a semiarid Chihuahuan Desert shrubland site in south‐eastern Arizona. Whole plant transpiration was measured using the heat balance sap‐flow method, while evapotranspiration and net ecosystem exchange (NEE) of CO2 were quantified using the Bowen ratio technique.Before the summer rainy season began, all water and CO2 fluxes were small. At the onset of the rainy season, evapotranspiration was dominated by evaporation and CO2 fluxes were dominated by respiration as it took approximately 10 days for the shrubs to respond to the higher soil moisture content. During the growing season, periods immediately following rain events (<2 days) were dominated by evaporation and respiration while transpiration and CO2 uptake peaked during the interstorm periods. The surface of the coarse, well‐drained soils dried quickly, rapidly reducing evaporation. Overall, the ratio of total transpiration to evapotranspiration was 58%, but it was around 70% during the months when the plants were active. Peak respiration responses following rain events generally lagged after the evaporation peak by a couple of days and were better correlated with transpiration. Transpiration and CO2 uptake also decayed rather quickly during interstorm periods, indicating that optimal plant soil moisture conditions were rarely encountered. NEE of CO2 was increasingly more negative as the growing season progressed, indicating a greater net uptake of CO2 and greater water use efficiency due mainly to decreases in respiration. Copyright © 2006 John Wiley & Sons, Ltd.
Shrubs, streamflow, and the paradox of scale
Authors: Wilcox Bradford P. , Owens M. Keith , Dugas William A. , Ueckert Darrell N. , Hart Charles R. 
Published: September 2006

AbstractIn this paper, we examine the linkage between woody plants and the water budget for three important woody plant communities in Texas, USA: saltcedar (Tamarix chinensis, Tamarix ramosissima), Ashe juniper (Juniperus ashei Buchholz), and mesquite (Prosopis glandulosa Torr. var. glandulosa). In most cases, these species are found in distinct physiographic and soil settings. Saltcedar is restricted to stream channels and floodplains; Ashe juniper is found mostly on karst limestone outcrops with shallow soils; and mesquite is found on deep soils. Because of these differences, changes in woody plant cover in each community will have a different effect on the water budget. For each type, we review the available literature and explicitly report the scale of observation (tree, stand, catchment, or landscape). A simple framework called the shrub–streamflow framework, which recognizes differences in response due to differences in physiographic setting, climate, and potential for deep drainage or subsurface flow, enables us to generalize the results. The fundamental premise of the framework is simple: for shrublands to be hydrologically sensitive to changes in woody plant cover, soil water or groundwater must be accessible to deep‐rooting plants but too deep for shallow‐rooting ones. Such a situation exists if groundwater is close to the surface (within 3–5 m and/or if deep drainage occurs (because of either high precipitation input or bypass flow in the soil). We argue that on an area basis, conversion of saltcedar stands to herbaceous plants in riparian regions has a much greater potential for increasing water yield than does conversion of woodlands to grasslands in upland regions where deep drainage does not occur. On upland sites where deep drainage does occur, conversion from woody to herbaceous vegetation may result in a savings of 40–80 mm year−1 of water. But such savings have been observed only up to the small‐catchment scale, and until further work is done it is uncertain whether they can be achieved at larger scales. Copyright © 2006 John Wiley & Sons, Ltd.
Soil water storage and rooting depth: key factors controlling recharge on rangelands
Authors: Seyfried Mark S. , Wilcox Bradford P. 
Published: September 2006

AbstractThe practice of removing woody vegetation to enhance water supply in semiarid rangelands in the United States continues to generate considerable interest, even though past research has yielded apparently contradictory results concerning its efficacy. In an attempt to elucidate the factors that determine whether and how woody vegetation removal affects water supply, we analysed the problem using a water balance approach. In our analysis, deep drainage is the water balance component associated with water supply. Because the herbaceous vegetation that replaces the woody plants generally has a shallower effective rooting depth (Rd), the amount of soil water potentially available for transpiration is reduced and more is available for deep drainage. The potential increase in deep drainage can be estimated from the capacity of the soil to store plant‐available water (Sc) and may be substantial. Our case study on sagebrush rangeland documents how Rd, and consequently Sc, changed after woody vegetation at the site was removed by burning. Using depth profiles of soil water content and matric potential, we showed that the Rd of the post‐fire vegetation was about 140 cm, 60 cm less than that of the pre‐fire vegetation, and that this resulted in a potential increase in deep drainage of about 6 cm of water—which in semiarid rangelands is substantial. Historical precipitation patterns indicate that there is nearly always sufficient net precipitation to generate the additional 6 cm of deep drainage at this site. However, in most of the area the soil depth is less than 140 cm, so that transpiration and deep drainage would be unaffected by the vegetation change and the overall water supply enhancement would be much less than 6 cm. These results indicate that the change in Sc that may follow woody shrub removal is an important criterion to evaluate sites for vegetation conversion. Copyright © 2006 John Wiley & Sons, Ltd.
Ecohydrology of root zone water fluxes and soil development in complex semiarid rangelands
Authors: Gutiérrez‐Jurado Hugo A. , Vivoni Enrique R. , Harrison J. Bruce J. , Guan Huade 
Published: September 2006

AbstractIn semiarid complex terrain, the landscape creates spatial niches for different types of vegetation through the effects of aspect, slope and curvature on the water and energy balance at the soil surface. The ecohydrology of rangelands is defined by the interaction of soils, plants and climate occurring on a topographic surface. While these interactions have been studied for subtle terrain, little is known about the controls exerted by terrain position, in particular terrain aspect, on ecosystem processes. Furthermore, differential plant establishment can lead to measurable differences in rates of soil development, which in turn can affect soil hydraulic properties and the surface water balance. In this study, we outline the physical mechanisms affecting plant establishment, soil development and hydrologic fluxes in semiarid complex terrain. We illustrate the interactions between vegetation, root zone water fluxes and soil development using, as an example, a small drainage basin in the Sevilleta National Wildlife Refuge (SNWR), New Mexico. In the study basin, opposing hillslopes are characterized by marked differences in ecosystem composition and soil profile properties, with the north‐facing hillslope dominated by one seed juniper (Juniperus monosperma) and the south‐facing slope consisting of creosote bush (Larrea tridentata). We assess the effect of terrain aspect on root zone hydrologic fluxes and soil development in the two ecosystems by using soil observations, hydraulic properties from pedotransfer functions (PTFs), and numerical modelling of vadose zone fluxes. Modelling results show marked differences in root zone fluxes in the north‐facing juniper and south‐facing creosote ecosystems. Differences in the amplitude and frequency of soil water content and pressure correspond to changes in soil profile and vegetation characteristics. For example, soil properties of the calcium carbonate (CaCO3) horizons and differential plant water uptake impact the simulated soil water pressure over an 8‐year period in the opposing ecosystems. It is believed that these variations in water fluxes reinforce the development of CaCO3 horizons present in the soil profiles, leading to a feedback between vegetation establishment, soil water fluxes and geomorphic processes in the catchment. Our results also indicate that soil properties and water fluxes compensate for large differences in evaporative demand and lead to similar actual evapotranspiration (AET) in the opposing slopes. Copyright © 2006 John Wiley & Sons, Ltd.
Surface water–groundwater interactions in semiarid drainages of the American southwest
Authors: Newman Brent D. , Vivoni Enrique R. , Groffman Armand R. 
Published: September 2006

AbstractDrainages are important features of semiarid landscapes because they are areas where surface water, groundwater, and terrestrial and aquatic ecosystems converge. Management of these critical ecohydrological systems requires a sound understanding of surface water–groundwater interactions. At the basin‐ to landscape‐scale, drainage density, location, and channel characteristics are formed upon a geomorphic and geologic template that limit where and how surface water–groundwater interactions occur. At smaller scales, semiarid surface water–groundwater interactions exhibit a high degree of temporal and spatial variability that links directly to biogeochemical characteristics and ecosystem dynamics. In this paper, we review key features of interactions in semiarid drainages, and supplement the discussion with new examples from the American southwest. We conclude by presenting a series of alternative conceptual models that describe surface water–groundwater interactions within semiarid drainages and highlight areas for future research. Copyright © 2006 John Wiley & Sons, Ltd.
Ecohydrological feedbacks and linkages associated with land degradation: a case study from Mexico
Authors: Huber‐Sannwald Elisabeth , Maestre Fernando T. , Herrick Jeffrey E. , Reynolds James F. 
Published: September 2006

AbstractLand degradation and desertification are major environmental problems of human societies in drylands of North and South America. Mexico is one of the most severely affected countries. An assessment of how both biophysical and socio‐economic processes simultaneously affect, and are affected by, land degradation is recognized as one of the most important and challenging topics in the research on global change. Towards meeting this challenge, in June 2004 an interdisciplinary mix of scientists assembled in Mexico to participate in a workshop convened by the ARIDnet network. The focus of the workshop was to apply a new conceptual framework—the Dahlem Desertification Paradigm (DDP)—to La Amapola, a small rural community located in the Central Plateau of Mexico. The DDP aims to advance understanding of global desertification issues by focusing on the interrelationships within coupled human‐environment systems that cause desertification. In this paper we summarize the conclusions of the La Amapola workshop. First, we present a brief review of some of the broader issues and concerns of global desertification, which led to the formation of ARIDnet and to the DDP. Second, we provide an overview of land degradation issues in La Amapola, highlighting examples of hydrological linkages between biophysical and socio‐economic factors. Third, we summarize our findings in a conceptual model, which highlights linkages between biophysical and socio‐economic factors in La Amapola, and the role of hydrology in desertification. Lastly, we discuss the results derived from the application of the major assertions of the DDP to La Amapola. The numerous feedbacks, linkages, and causal pathways between the biophysical and human dimensions suggest that hydrology is the fundamental component of the livelihoods of rural communities in this region of Mexico, and thus it is of central importance when evaluating desertification. Copyright © 2006 John Wiley & Sons, Ltd.
Thermal–mechanical study of functionally graded dental implants with the finite element method
Authors: Wang F. , Lee H.P. , Lu C. 
Published: September 2006

AbstractThis article investigates the thermal–mechanical performance of hydroxyapatite/titanium (HA/Ti) functionally graded (FG) dental implants with the three‐dimensional finite element method. The stresses induced by occlusal force for the present HA/Ti FG implant are calculated to compare with the corresponding stresses for the titanium dental implant. Thermal–mechanical effect of temperature variation due to daily oral activity is also studied. The HA/Ti FG dental implant performance is evaluated against the maximum von Mises stress, which is the general performance indicator, the first principal/tensile stress for mechanical failure of implant‐bone‐bond and the third principal/compressive stress for bone absorption. Simulation results indicate that under the influence of occlusal force only, the FG implants with different HA fraction along the implant length perform almost equally well, while the titanium implant sustains much higher von Mises stress. However, when thermal stress is also considered, the FG implant having HA fraction exponential index of m = 2 with temperature decrease of 20°C yields the highest first principal and von Mises stresses among all the FG and titanium implants. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Human gingival fibroblast response to electropolished NiTi surfaces
Authors: Es‐Souni Martha , Fischer‐Brandies Helge , Es‐Souni Mohammed 
Published: September 2006

AbstractIn the present study the in vitro biocompatibility of electropolished NiTi sheets is investigated. The assessment of cytotoxic effects due to potential Ni leaching from metal sheets was performed in direct contact with primary human fibroblast cultures using the 5‐bromo‐2′‐deoxyuridine cell proliferation assay and morphologic studies via light microscopy and scanning electron microscopy. To assess toxic effects related to Ni‐ions release, cells cultured in the presence of increasing concentrations of Ni2+ (NiSO4·6H2O) served as positive controls. It is shown that while the addition of NiSO4 caused severe proliferation decrease (˜80%) and morphologic damage at a concentration of 50 mg/L Ni2+ no negative effects were observed in fibroblasts cultured in the presence of electropolished NiTi sheets. The results are discussed in terms of surface topography effects on the biocompatibility of NiTi shape memory alloys. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007