bluuebunny/crossref_metadata_2025 huggingface dataset:
Diacetyldiamidoximeester of Pentamidine, a Prodrug for Treatment of Protozoal Diseases: Synthesis, in vitro and in vivo Biotransformation
Authors: Clement Bernd , Bürenheide Anja , Rieckert Wolfgang , Schwarz Jörg
Published: September 2006

Pentamidine is an effective antimicrobial agent. To increase its poor oral bioavailability due to the strong basic amidine functionality, the less basicO‐acetylamidoxime prodrug, the diacetyldiamidoximeester, was used, which has greatly improved lipophilicity. The objectives of this investigation were the synthesis of all potential metabolites of the double prodrug, the conformational analysis of its structure, and to study the in vitro and in vivo biotransformation by ester cleavage and N‐reduction to pentamidine via four intermediate metabolites. The biotransformation of diacetyldiamidoximeester to pentamidine involving the reduction of the amidoxime function and the ester cleavage could be demonstrated. The kinetic parameters were determined. Amidoximes were efficiently metabolized by several enzyme systems located in microsomes and mitochondria of different organs including the final formation of the active metabolite pentamidine. The formation of pentamidine after oral administration of the diacetyldiamidoximeester to rats could be demonstrated as well.
Racial disparity in survival among patients with advanced/recurrent endometrial adenocarcinoma
Authors: Maxwell G. Larry , Tian Chunqiao , Risinger John , Brown Carol L. , Rose G. Scott , Thigpen J. Tate , Fleming Gini F. , Gallion Holly H. , Brewster Wendy R.
Published: September 2006

BACKGROUND.

Previous studies have reported shorter survival of black women compared with white women who had advanced/recurrent endometrial cancer. It has been suggested that this may reflect racially based differences in treatment.

METHODS.

The authors retrospectively reviewed data from 169 black women and 982 white women with International Federation of Gynecologic Oncology (FIGO) Stage III, Stage IV, or recurrent endometrial carcinoma who were participants in 1 of 4 Gynecologic Oncology Group randomized treatment trials of doxorubicin alone or combined with paclitaxel and/or cisplatin. Demographic, histologic, treatment, and outcome data were analyzed to estimate survival, and between‐group comparisons were performed.

RESULTS.

The pooled data revealed that black women were more likely to have papillary serous histology (P < .001), Stage IV disease (P < .001), and higher tumor grade (P < .001) compared with white women, and survival was worse among black women than among white women (median survival, 10.6 months vs. 12.2 months, respectively; P < .001). A Cox proportional hazards regression analysis that was adjusted for performance status, disease stage, tumor histology, tumor grade, and treatment demonstrated worse survival for black women (hazards ratio, 1.26, 95% confidence interval, 1.06–1.51; P = .010).

CONCLUSIONS.

The data from a large group of women with advanced/recurrent endometrial cancer suggested that a racial disparity in survival persists, despite the finding that black women and white women received similar treatment. Although the causes of racial disparity in endometrial cancer remain to be elucidated, socioeconomic, biologic, and cultural factors should be investigated to identify the etiologic origins of this multifactorial healthcare problem. Cancer 2006. Published 2006 by the American Cancer Society
Evaluating the potential effectiveness of codes: the statement strength evaluation method (SSEM)
Authors: Bondy Krista
Published: September 2006

The increasing popularity and use of codes requires a technique for being able to distinguish how different codes compare to each other and to stakeholder demands for increased social, environmental and economic responsibility of business. This paper presents the statement strength evaluation method (SSEM), which provides organizations with the ability to make comparisons between codes against a backdrop of stakeholder expectations. The SSEM evaluates six critical characteristics for each statement made in the code relating to each appropriate criterion. The criteria were developed through synthesis of a vast range of stakeholder concerns, resulting in 597 unique but overlapping criteria. This level of detail has been retained to ensure accurate comparison between different code types and ranges of content depending on varied contexts such as industry and operating locations (e.g. domestic versus international). A test of the SSEM using 13 third party codes revealed strengths and weaknesses of codes based on structure, and highlighted certain codes as potentially more effective in helping business to govern their CSR objectives. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
Acute insulin response is an independent predictor of type 2 diabetes mellitus in individuals with both normal fasting and 2‐h plasma glucose concentrations
Authors: Bunt Joy C. , Krakoff Jonathan , Ortega Emilio , Knowler William C. , Bogardus Clifton
Published: September 2006

Background

Earlier prospective studies have identified insulin action and secretion as predictors of T2DM in populations with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) (2‐h OGTT < 7.8 and 7.8–11 mmol/L, respectively). Fasting plasma glucose (FPG), an additional and recently modified (normal <5.6 mmol/L) diagnostic criterion is associated with insulin secretion. We wanted to establish whether insulin secretion persists as an independent predictor of T2DM in individuals with no clinical evidence of impaired glucose regulation based on FPG and 2‐h plasma glucose concentrations.

Methods

Insulin action (M, euglycemic‐hyperinsulinemic clamp), insulin secretion (acute insulin response (AIR), IVGTT), and adiposity (%Fat, DXA or densitometry) were compared at baseline in 358 Pima Indians (232M/126F, 18–44 years old) with normal glucose regulation of whom 61 (35M/26F) developed diabetes (DIAB) during a median follow‐up time of 7.6 years.

Results

In proportional‐hazard analysis, % Fat (HR = 1.52, p = 0.03), M (HR = 0.51, p = 0.04) and AIR (HR = 0.64, p = 0.003) predicted the development of diabetes after adjustment for age and sex. In regression analysis adjusting for age, sex, %Fat and M at baseline, the non‐diabetic group (NON‐DM) had a higher AIR (p = 0.0002) than the DIAB group; the positive association of AIR with adiposity observed in the NON‐DM group was absent in the DIAB group. Cumulative incidence rates (12y) for diabetes were highest (48%) in subjects with both M and AIR below the population median and lowest (11%) in subjects with both M and AIR above the population median.

Conclusion

AIR can predict diabetes prior to the current clinical indicators of impaired glucose regulation. Published in 2006 by John Wiley & Sons, Ltd. John Wiley & Sons, Ltd.
Solvent‐Induced Pore‐Size Adjustment in the Metal‐Organic Framework [Mg3(ndc)3(dmf)4] (ndc = naphthalenedicarboxylate)
Authors: Senkovska Irena , Kaskel Stefan
Published: September 2006

Two new compounds containing magnesium and the bidentate ligand 2,6‐naphthalenedicarboxylate (ndc), namely [Mg(dmf)2(H2O)4]·ndc (1) (dmf = N,N‐dimethylformamide) and [Mg3(ndc)3(dmf)4] (TUDMOF‐2) (2), have been obtained from Mg(NO3)2·6H2O and the pure acid using a solvothermal route. According to single‐crystal X‐ray studies both compounds are monoclinic. Complex 1 crystallizes in the space group P21/c [a = 12.317(3), b = 12.582(2), c = 15.353(3) Å, β = 110.96(3)°]. The compound consists of an isolated tetraaqua‐bis‐N,N‐dimethylformamide cation and the deprotonated ligand with hydrogen bonds linking the cations and anions. The metal‐organic framework 2 crystallizes in the space group C2/c [a = 13.451(3), b = 18.043(4), c = 20.937(5) Å, β = 99.79(3)°] with trinuclear magnesium clusters connected to six dicarboxylate ligands that link the clusters into a three‐dimensional network. In contrast to [Mg3(ndc)3(def)4] (def = N,N‐diethylformamide; 3), the dmf molecules coordinated to magnesium in TUDMOF‐2 (2) not only cause a distortion of the network but induce accessibility for the adsorption ofnitrogen. TUDMOF‐2 has a Langmuir surface area of520 m2 g–1 and a hydrogen adsorption capacity of 0.78 wt.‐% at 77 K and 760 Torr. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Mixed Amido/Imido/Guanidinato Complexes of Tantalum: Effects of Ligand Substitution on Thermal Properties
Authors: Baunemann Arne , Winter Manuela , Csapek Karoly , Gemel Christian , Fischer Roland A.
Published: September 2006

Mixed amido/imido/guanidinato tantalum complexes [Ta(NR1R2){C(NR1R2)(NR3)2}2(NR4)] [R1,R2 = methyl, ethyl; R3 = cyclohexyl (cy), isopropyl; R4 = tert‐butyl, n‐propyl] have been synthesized by the insertion of carbodiimides into tantalum–amide bonds. All compounds have been characterized by means of NMR spectroscopy, mass spectrometry, and CHN analysis. Additionally, single crystal structures of five compounds (4: R1 = Me, R2 = Et, R3 = iPr, R4 = tBu; 5: R1, R2 = Et, R3 = iPr, R4 = tBu; 6: R1, R2 = Me, R3 = cy, R4 = tBu; 8: R1, R2 = Et, R3 = cy, R4 = tBu; 9: R1, R2 = Et, R3 = iPr, R4 = nPr) have been determined and relevant structural issues are discussed. The thermal properties of all complexes have been investigated by TGA/DTA measurements. Thus, complexes originating from diisopropylcarbodiimide (iPr‐cdi) are significantly more volatile than complexes derived from dicyclohexylcarbodiimide (cy‐cdi). In contrast, variations of R1, R2, and R4 have only a small impact on the thermal behavior of the complexes. Finally, selected compounds have been pyrolyzed at 600 °C, and the decomposition products studied by GC‐MS and 1H NMR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Performance evaluation of a link adaptation scheme in IEEE 802.11e over IEEE 802.11a WLANs with QoS support
Authors: Vannuccini Gianluca , Bandinelli Matteo , Truong Hong Linh , Giuli Dino
Published: September 2006

Wireless Local Area Networks (WLANs) represent a powerful technology for accessing data, voice and video services in mobility. The literature dealing with IEEE 802.11 WLANs optimisation for supporting real‐time services performance is plentiful. IEEE Task Group E has been created with the aim of enhancing the Quality of Service (QoS) capabilities of the MAC IEEE 802.11, while several link adaptation algorithms have been proposed to optimise the rate selection in the IEEE 802.11a physical layer. In this work, the knowledge of the application type, provided by the MAC IEEE 802.11e layer, is exploited in a link adaptation strategy for the PHY IEEE 802.11a layer. The performance of the system is studied by using an event‐driven simulator, which implements the specifications of the IEEE 802.11e draft standard and the IEEE 802.11a standard. Simulation results show that the proposed scheme achieves both the link adaptation advantages and the required QoS support to real‐time services. Copyright © 2005 AEIT.
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

Trisomy 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

Mutations 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

Astroglia 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

Structural 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

Key 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

In 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

The 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

In 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

Drainages 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

Land 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

This 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

In 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
Hemostatic properties of glucosamine‐based materials
Authors: Fischer Thomas H. , Bode Arthur P. , Demcheva Marina , Vournakis John N.
Published: September 2006

Glucosamine‐ and N‐acetyl glucosamine‐containing polymers are being used in an increasing number of biomedical applications, including in products for surface (topical) hemostasis. The studies presented here investigate the relationship between the structure (conformation) and function (activation of hemostasis) of glucosamine‐based materials. Several polymer systems were studied, including fibers isolated from a microalgal source containing poly‐N‐acetyl glucosamine polymers that are organized in a parallel, hydrogen‐bonded tertiary structure and can be chemically modified to an antiparallel orientation; and gel formulation derivatives of the microalgal fibers consisting of partially deacetylated (F2 gel) and fully deacetylated (F3 gel) polymers. Comparison of the properties of the poly‐N‐acetyl glucosamine fiber‐derived materials with chitin, chitosan, and commercial chitosan‐based products are presented. Several studies were performed with the glucosamine‐based materials, including (1) an analysis of the ability of materials to activate platelets and turnover of the intrinsic coagulation cascade, (2) an examination of the viscoelastic properties of mixtures of platelet‐rich plasma and the glucosamine‐based materials via thromboelastography, and (3) scanning electron microscopic studies to examine the morphology of the glucosamine‐based materials. The results presented demonstrate that hemostatic responses to the glucosamine‐based materials studied are highly dependent on their chemical nature and tertiary/quaternary structure. The unique natural microalgal fibers were found to have strongly prohemostatic activity compared to the other materials studied. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Factors affecting the structure and properties of an injectable self‐setting calcium phosphate foam
Authors: Ginebra Maria‐Pau , Delgado José‐Angel , Harr Ingela , Almirall Amisel , Del Valle Sergio , Planell Josep A.
Published: September 2006

One of the main challenges in the investigation on calcium phosphate cements (CPC) lies in the introduction of macroporosity, without loosing the self‐setting ability and injectability, characteristic of the cement‐type materials. The benefits of macroporosity are related to the enhancement of bone regeneration mechanisms, such as angiogenesis and tissue ingrowth. In this work, the feasibility to obtain self‐setting injectable macroporous hydroxyapatite foams by the incorporation of a protein‐based foaming agent to a CPC is demonstrated. Albumen is combined with an α‐tricalcium phosphate [Ca3(PO4)2, α‐TCP] paste, which hydrolyzes to a calcium deficient hydroxyapatite during the setting reaction. A systematic study is presented, where the effect of different processing parameters is analyzed in terms of porosity, setting properties, injectability, and compressive strength. Self‐setting foams with porosities up to 70%, which maintain their porous structure after injection, are obtained. These injectable foams can be used both for direct in vivo applications and for the fabrication of low temperature tissue engineering scaffolds. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Histological assessment of titanium and polypropylene fiber mesh implantation with and without fibrin tissue glue
Authors: ten Hallers E.J. Olivier , Jansen John A. , Marres Henri A.M. , Rakhorst Gerhard , Verkerke Gijsbertus J.
Published: September 2006

Polypropylene (PP) and titanium (Ti) meshes are well‐known surgical implants that provoke a relative low foreign body reaction. Firm stabilization of the implant is important to prevent migration and subsequent failure of the operation. Fibrin tissue glues are commercially available adhesives and are widely accepted and applied in the medical field for hemorrhage, surgical bleeding, support of wound healing, wound and tissue gluing, sealing, and closure but also as antiadhesive agent in certain applications. The objective of this study was to evaluate the additional histological effect of fibrin glue application combined with two different types of meshes. Six pieces of mesh of each were subcutaneously implanted for 3, 6, and 12 weeks, with and without fibrin glue. After excision, processing, and staining, light microscopic analysis was performed on the sections, using subjective histological description and histomorphometry. Capsule quality, capsule thickness, interstitial quality, and total score were evaluated. To compare the samples with glue and without glue, analysis of variance (ANOVA) tests were carried out. No complications were observed. In general, the glue remnants remained visible at 3 and 6 weeks of implantation, accompanied by an inflammatory reaction and macrophage activity. At 12 weeks, all samples showed good tissue integration without evidence of glue. Evidently, the samples with glue demonstrated a prolonged inflammatory response and were surrounded by fibrous tissue capsules that were significantly thicker compared with the samples without glue (p < 0.05). © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Relationship of solvent to the photopolymerization process, properties, and structure in model dentin adhesives
Authors: Ye Qiang , Spencer Paulette , Wang Yong , Misra Anil
Published: September 2006

The ratio of the double‐bond content of monomer to polymer, i.e. degree of conversion (DC) has been used frequently as a convenient means of comparing the behavior and properties of dental composites and adhesives. The purpose of this investigation was to study the relationship of photopolymerization processes, bulk properties, and structure using model dentin adhesives cured in the presence of different ethanol content as an example. There was little difference in the DC of model BisGMA‐based adhesives cured in the presence of ethanol concentrations ranging from 0 to 40 wt %, but there were substantial differences in the mechanical properties. Ultimate tensile strength (UTS) and modulus of elasticity decreased with an increase in ethanol content. Polymer structure was revealed by thermal behavior in the glass transition temperature (Tg) region; these measurements were obtained by modulated temperature differential scanning calorimetry (MTDSC) technology, which removes the competing irreversible effects associated with release of volatiles and residual curing. Glass transition temperature of model adhesives decreased substantially with an increase in ethanol content. The DC based on the quantity of remaining double bond has been used extensively to characterize and provide a relative assessment of the quality of dentin adhesives and dental composites. Since polymers differing in linearity, and therefore crosslink density, may have a similar degree of conversion, the measurement of monomer/polymer conversion does not necessarily provide complete representation of the quality or durability of the polymer structure. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
iNOS‐mediated generation of reactive oxygen and nitrogen species by biomaterial‐adherent neutrophils
Authors: Patel Jasmine D. , Krupka Tianyi , Anderson James M.
Published: September 2006

Infection due to implanted cardiovascular biomaterials is a serious complication initiated by bacterial adhesion to the surface of the implant. The release of reactive oxygen species by neutrophils, particularly superoxide anion, is a well‐known bactericidal mechanism. Additionally, nitric oxide (NO) has also been identified as an important cytotoxic mediator in acute and chronic inflammatory responses with enhanced NO production by upregulation of inducible nitric oxide synthase (iNOS). The interaction of NO and superoxide anion will result in the formation of peroxynitrite (OONO−), a potent cytotoxic oxidant. In this study, we have shown that biomaterial‐induced neutrophil activation does not cause upregulation of iNOS and activation of iNOS‐mediated pathways. However, NO and O production does occur over time upon adhesion to a biomaterial and is modulated by biomaterial surface chemistry. With no stimulus, the polyethylene oxide‐modified polyurethane induced greater neutrophil activation than did the control as indicated by the increased production of NO and O over time. Adherent‐stimulated neutrophils generally produced lower amounts of NO over time in comparison with unstimulated cells. Furthermore, there is no evidence of peroxynitrite activity in unstimulated neutrophils adherent to the Elasthane 80A. However, upon stimulation with adherent Staphylococcus epidermidis, peroxynitrite formation did occur. Our results suggest that bactericidal mechanisms in neutrophils involving NO generation (NOS pathway) are further compromised than O producing pathways (NADPH oxidase) upon exposure to biomaterials, resulting in a diminished microbial killing capacity, which can increase the probability of device‐centered infections. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Synthesis and characterization of biocompatible Fe3O4 nanoparticles
Authors: Sun Jing , Zhou Shaobing , Hou Peng , Yang Yuan , Weng Jie , Li Xiaohong , Li Mingyuan
Published: September 2006

In this study, magnetite (Fe3O4) nanoparticles with a size range of 8–20 nm were prepared by the modified controlled chemical coprecipitation method from the solution of ferrous/ferric mixed salt‐solution in alkaline medium. In the process, two kinds of surfactant (sodium oleate and polyethylene glycol) were studied; then, sodium oleate was chosen as the apt surfactant to attain ultrafine, nearly spherical and well‐dispersed (water‐base) Fe3O4 nanoparticles, which had well magnetic properties. The size and size distribution of nanoparticles were determined by particle size analyzer. And the magnetite nanoparticles was characterized by X‐ray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), electron diffraction (ED) photography, Fourier transform infrared spectrometer (FT‐IR), and vibrating‐sample magnetometer (VSM). Also the effect of many parameters on the Fe3O4 nanoparticles was studied, such as reaction temperature, pH of the solution, stirring rate and concentration of sodium oleate. And the 5‐dimethylthiazol‐2‐yl‐2,5‐ diphenyltetrazolium bromide (MTT) assay was performed to evaluate the biocompatibility of magnetite nanoparticles. The results showed that the Fe3O4 nanoparticles coated by sodium oleate had a better biocompatibility, better magnetic properties, easier washing, lower cost, and better dispersion than the magnetite nanoparticles coated by PEG. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Amelogenin gene splice products A+4 and A−4 implanted in soft tissue determine the reorientation of CD45‐positive cells to an osteo‐chondrogenic lineage
Authors: Lacerda‐Pinheiro S. , Septier D. , Tompkins K. , Veis A. , Goldberg M. , Chardin H.
Published: September 2006

Several molecules such as bone morphogenetic protein‐7, bone sialoprotein (BSP), or amelogenin gene splice products (A+4 or A−4) have been shown to induce reparative dentin formation in a rat model. However, at the moment, the origin and the mechanism of differentiation of the pulp cells stimulated by the bioactive molecules remain poorly understood. The present investigation was undertaken to validate an ectopic oral mucosal mouse model to evaluate the effects of amelogenin gene splice product implantation in a non‐mineralizing tissue. Agarose beads, alone or coated with amelogenin gene splice products, were implanted in the mucosa of the cheeks in mouse. An immunohistochemical characterization of the recruited cells was undertaken for 3 days, 8 days, and 30 days after the implantation. The results showed that the implantation of agarose beads in mucosa induced the recruitment of inflammatory CD45 positive cells. When the beads were coated with amelogenin gene splice products (A+4 or A−4), the expression of osteo‐chondrogenic markers (RP59, Sox9, or BSP) was also observed. However, no mineralization nodule was observed, even after 30 days of implantation. The present investigation suggests that amelognin gene splice products have the capacity of recruiting among inflammatory cell mesenchymal progenitors that eventually differentiate into osteo‐chondrogenic cells. Altogether, the results obtained in the pulp model and the present data suggest the existence of different pathways of cell recruitment and differentiation in different cellular environments. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Tumor progression—targets for differential therapy
Authors: Pardee Arthur B.
Published: September 2006

Differential killing of the patient's cancer cells versus normal cells is a necessity for chemotherapy. Advantage can be taken of close regulations of gene expression and of enzyme activity that are essential for normal cell functioning, and that are altered during tumor progression. Summarized here is our research on four such progression changes of cancer cells; some deregulate proliferation control and others decrease programmed death (apoptosis). These processes will be illustrated with examples of potential chemotherapies based on them. Methods for discovery of such changes include Differential Display and microarrays. J. Cell. Physiol. 209: 589–591, 2006. © 2006 Wiley‐Liss, Inc.