bluuebunny/crossref_metadata_2025 huggingface dataset:
RGD‐containing peptide GCRGYGRGDSPG reduces enhancement of osteoblast differentiation by poly(L‐lysine)‐graft‐poly(ethylene glycol)‐coated titanium surfaces
Authors: Tosatti S. , Schwartz Z. , Campbell C. , Cochran D. L. , VandeVondele S. , Hubbell J. A. , Denzer A. , Simpson J. , Wieland M. , Lohmann C. H. , Textor M. , Boyan B. D.
Published: January 2004

Osteoblasts exhibit a more differentiated morphology on surfaces with rough microtopographies. Surface effects are often mediated through integrins that bind the RGD motif in cell attachment proteins. Here, we tested the hypothesis that modulating access to RGD binding sites can modify the response of osteoblasts to surface microtopography. MG63 immature osteoblast‐like cells were cultured on smooth (Ti sputter‐coated Si wafers) and rough (grit blasted/acid etched) Ti surfaces that were modified with adsorbed monomolecular layers of a comb‐like graft copolymer, poly‐(L‐lysine)‐g‐poly(ethylene glycol) (PLL‐g‐PEG), to limit nonspecific protein adsorption. PLL‐g‐PEG coatings were functionalized with varying amounts of an integrin‐receptor‐binding RGD peptide GCRGYGRGDSPG (PLL‐g‐PEG/PEG‐RGD) or a nonbinding RDGcontrol sequence GCRGYGRDGSPG (PLL‐g‐PEG/PEG‐RDG). Response to PLL‐g‐PEG alone was compared with response to surfaces on which 2–18% of the polymer sidechains were functionalized with the RGD peptide or the RDGpeptide. To examine RGD dose–response, peptide surface concentration was varied between 0 and 6.4 pmol/cm2. In addition, cells were cultured on uncoated Ti or Ti coated with PLL‐g‐PEG or PLL‐g‐PEG/PEG‐RGD at an RGD surface concentration of 0.7 pmol/cm2, and free RGDS was added to the media to block integrin binding. Analyses were performed 24 h after cultures had achieved confluence on the tissue culture plastic surface. Cell number was reduced on smooth Ti compared to plastic or glass and further decreased on surfaces coated with PLL‐g‐PEG or PLL‐g‐PEG/PEG‐RDG, but was restored to control levels when PLL‐g‐PEG/PEG‐RGD was present. Alkaline phosphatase specific activity and osteocalcin levels were increased on PLL‐g‐PEG alone or PLL‐g‐PEG/PEG‐RDG, but PLL‐g‐PEG/PEG‐RGD reduced the parameters to control levels. On rough Ti surfaces, cell number was reduced to a greater extent than on smooth Ti. PLL‐g‐PEG coatings reduced alkaline phosphatase and increased osteocalcin in a manner that was synergistic with surface roughness. The RDGpeptide did not alter the PLL‐g‐PEG effect but the RGD peptide restored these markers to their control levels. PLL‐g‐PEG coatings also increased TGF‐β1 and PGE2in conditioned media of cells cultured on smooth or rough Ti; there was a 20× increase on rough Ti coated with PLL‐g‐PEG. PLL‐g‐PEG effects were inhibited dose dependently by addition of the RGD peptide to the surface. Free RGDS did not decrease the effect elicited by PLL‐g‐PEG surfaces. These unexpected results suggest that PLL‐g‐PEG may have osteogenic properties, perhaps correlated with effects that alter cell attachment and spreading, and promote a more differentiated morphology. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 458–472, 2004
Vitronectin adsorption on surfaces visualized by tapping mode atomic force microscopy
Authors: Zhang Hailong , Bremmell Kristen , Kumar Sunil , Smart Roger St. C.
Published: January 2004

Vitronectin (Vn) is an abundant glycoprotein present in plasma and the extracellular matrix of most tissue and is an important medium required for bone cells to attach and spread on biomaterial surfaces. Hence, Vn adsorption is an initial and key step in implantation. In this study, adsorption of Vn molecules on mica and oxidized titanium substrates in Milli‐Q water (pH 5.6) and in simulated body fluid (SBF, pH 7.4) has been investigated using tapping mode atomic force microscopy. Conformation of the adsorbed proteins was determined from the images. The effect of adsorption time was investigated on mica surfaces. The protein first attaches to the surface, then immediately spreads out with different lateral dimensions of adsorbed protein and becomes aggregated. After 15 min of adsorption, globular Vn molecules form clusters of aggregates in extended chains on the mica surface. Globular Vn molecules appear flatter (i.e., oblate ellipsoids) and coalesce on the ridges of the uneven oxidized titanium surface. From cross‐sectional analyses of the Vn images, it was found that the contact areas of Vn molecules associated with Ti surfaces are larger than those with mica surfaces. This suggests that the different surface properties of substrates contribute to this different conformation of adsorbed Vn molecules. The larger contact areas of Vn associated with Ti substrates indicates higher affinity for the biomaterial oxidized titanium surface than for mica. In SBF, Vn interacted weakly with the mica surfaces and Vn molecules were easily desorbed during the imaging process. On oxidized titanium substrates, after 3 h of incubation time in Vn–SBF solution, images can be obtained showing adsorbed Vn aggregates on the oxidized titanium surface. In this case, the protein colloids are strongly adherent, with increased lateral dimensions compared with the adsorption on mica. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 479–488, 2004
Systematic variation in osteoblast adhesion and phenotype with substratum surface characteristics
Authors: Lim Jung Yul , Liu Xiaomei , Vogler Erwin A. , Donahue Henry J.
Published: January 2004

Time‐varying interactions of human fetal osteoblastic cells (hFOB 1.19) with materials of diverse chemical composition and surface energy, including biodegradable lactide/glycolide‐based polymers, were assessed using a combination of assays sensitive to different phases of cell‐substratum compatibility. Short‐term (minutes to hours) cell‐attachment‐rate assays were used to measure the earliest stages of cell‐surface interactions leading to adhesion. Proliferation‐rate assays quantifying viability of attached cells were applied as a measure of medium‐term (hours to days) cytocompatibility. Both attachment‐ and proliferation‐rate assays were found to strongly correlate with material surface energy, with the exception of a reproducible and significant adhesion preference for fully water‐wettable quartz over glass. No such adhesion/proliferation preference was observed for hydrophobized counterparts, and attachment to water‐wettable glass was significantly less than that to control tissue culture polystyrene. These results suggest that the amorphous SiOx surface was inhibitory to hFOB 1.19 growth whereas putatively crystalline quartz stimulated bioadhesion. Alkaline phosphatase activity was evaluated as a marker for long‐term (days) differentiation of hFOB 1.19 cells and did not strongly correlate with surface energy or, in the case of biodegradable polymers, chemical composition. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 504–512, 2004
Effect of cyclic mechanical stretch and titanium particles on prostaglandin E2 production by human macrophages in vitro
Authors: Fujishiro Takaaki , Nishikawa Tetsuo , Shibanuma Nao , Akisue Toshihiro , Takikawa Satoshi , Yamamoto Tetsuji , Yoshiya Shinichi , Kurosaka Masahiro
Published: January 2004

Early implant instability has been proposed as a critical factor in the onset and progression of aseptic loosening and periprosthetic osteolysis in total joint arthroplasties. Previous in vitro studies have reported that macrophages stimulated with cyclic mechanical strain release inflammatory mediators. Little is known, however, about the response of these cells to mechanical strain with particles, which is often a component of the physical environment of the cell. We therefore studied the production of prostaglandin E2 (PGE2), an important mediator in aseptic loosening and periprosthetic osteolysis in total joint arthroplasties, for human macrophages treated with mechanical stretch alone, titanium particles alone, and mechanical stretch and particles combined. A combination of mechanical stretch and titanium particles resulted in a statistically synergistic elevation of levels of PGE2 compared with the levels found with either stretch or particles alone. Exposure of human macrophages to mechanical stretch with particles upregulated the expression of cyclooxygenase (COX)‐2 mRNA but not COX‐1 mRNA, this expression resulting in a 97‐fold increase in PGE2 production compared to the nonstimulated cells. The current study is the first to investigate the effects of mechanical stretch with particles on cultured macrophages and include an investigation of the time course of PGE2 production and COX‐2 mRNA expression. Our results suggest that, while mechanical strain may be one of the primary factors responsible for macrophage activation and periprosthetic osteolysis, mechanical strain with particles load may contribute significantly to the osteolytic potential of macrophages in vitro. The synergistic effect observed between mechanical stretch and particles could accelerate implant loosening and implies that reduction in either cyclic mechanical strain or wear debris load would lead to a reduction of osteolysis. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 531–536, 2004
Transforming growth factor‐β1 accelerates bone bonding to a blended calcium phosphate ceramic coating: A dose‐response study
Authors: Szivek John A. , Nelson Ehren R. , Hajdu Steven D. , Yablonski Kelly , DeYoung Don W.
Published: January 2004

In vivo strain measurements can facilitate the study of the bone remodeling response to loading and load changes. Calcium phosphate ceramic (CPC) coatings have been used to attach strain gauges to bone for extended periods of time, but require up to 12 weeks for adequate CPC‐to‐bone bonding. Transforming growth factor beta 1 (TGF‐β1), an osteoinductive growth factor, was used as a surface enhancement to accelerate bone growth and bonding to CPC particles. The aim of this study was to find an optimal dosage of TGF‐β1 to accelerate the attachment process. CPC‐coated strain gauges were enhanced with doses of 0.5, 1.0, or 2.0 μg of TGF‐β1 per gauge. Gauges were placed on the femora of dogs, which were exercised daily and fed ad libitum. After 3, 6, and 12 weeks, gauge attachment was quantitatively assessed using mechanical testing and histomorphometry. Gauge attachment was also qualitatively assessed using back scatter electron microscopy. Agreement of the mechanical test results with both the back scatter electron microscopy images and histomorphometry results showed that the 1.0 μg per gauge dose of TGF‐β1 is an optimal dose to accelerate bone formation and attachment to CPC‐coated strain gauges. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 537–543, 2004
In search of evolutionary developmental mechanisms: The 30‐year gap between 1944 and 1974
Authors: Hall Brian K.
Published: January 2004

The approach I have elected in this retrospective of how I became a student of evo‐devo is both biographical and historical, a case study along the lines of Waddington's The Evolution of an Evolutionist ('75), although in my case it is the Evolution of an Evo‐devoist. What were the major events that brought me to developmental biology and from there to evo‐devo? They were, of course, specific to my generation, to the state of knowledge at the time, and to my own particular circumstances. Although exposed to evolution and embryology as an undergraduate in the 1960s, my PhD and post‐PhD research programme lay within developmental biology until the early 1970s. An important formative influence on my studies as an undergraduate was the work of Conrad Hal Waddington (1905–1975), whose writings made me aware of genetic assimilation and gave me an epigenetic approach to my developmental studies. The switch to evo‐devo (and my discovery of the existence of the neural crest), I owe to an ASZ (now SICB) symposium held in 1973. J. Exp. Zool. (Mol. Dev. Evol.) 302B:5–18, 2004. © 2004 Wiley‐Liss, Inc.
Kowalevsky, comparative evolutionary embryology, and the intellectual lineage of evo‐devo
Authors: Raff Rudolf A. , Love Alan C.
Published: January 2004

Alexander Kowalevsky was one of the most significant 19th century biologists working at the intersection of evolution and embryology. The reinstatement of the Alexander Kowalevsky Medal by the St. Petersburg Society of Naturalists for outstanding contributions to understanding evolutionary relationships in the animal kingdom, evolutionary developmental biology, and comparative zoology is timely now that Evo‐devo has emerged as a major research discipline in contemporary biology. Consideration of the intellectual lineage of comparative evolutionary embryology explicitly forces a reconsideration of some current conceptions of the modern emergence of Evo‐devo, which has tended to exist in the shadow of experimental embryology throughout the 20th century, especially with respect to the recent success of developmental biology and developmental genetics. In particular we advocate a sharper distinction between the heritage of problems and the heritage of tools for contemporary Evo‐devo. We provide brief overviews of the work of N. J. Berrill and D. T. Anderson to illustrate comparative evolutionary embryology in the 20th century, which provides an appropriate contextualization for a conceptual review of our research on the sea urchin genus Heliocidaris over the past two decades. We conclude that keeping research questions rather than experimental capabilities at the forefront of Evo‐devo may be an antidote to any repeat of the stagnation experienced by the first group of evolutionary developmental biologists over one hundred years ago and acknowledges Kowalevsky's legacy in evolutionary embryology. J. Exp. Zool. (Mol Dev. Evol.) 302B:19–34, 2004. © 2004 Wiley‐Liss, Inc.
Effects of land use on soil erosion and nitrogen loss in the hilly area of the Loess Plateau, China
Authors: Fu B. J. , Meng Q. H. , Qiu Y. , Zhao W. W. , Zhang Q. J. , Davidson D. A.
Published: January 2004

This study examines the effects of land use and slope angle on runoff, soil loss and nitrogen loss from hillslopes of the Loess Plateau in China. Farmland, wasteland and four forest treatments (sea buckthorn+poplar, immature sea buckthorn, mature sea buckthorn, and immature Chinese pine) were the types of land use that were compared. The results showed that July was the critical period for runoff, soil loss and nitrogen loss from farmland. Farmland was the most susceptible land use. Sea buckthorn+poplar, immature sea buckthorn, and mature sea buckthorn limited the runoff, soil loss and nitrogen loss. Farmland on slopes over 15 degrees should be abandoned because of the high erosion rate and nitrogen loss. Copyright © 2003 John Wiley & Sons, Ltd.
Multiple‐scale soil moisture distribution and its implications for ecosystem restoration in an arid river valley, China
Authors: Ma K.‐M. , Fu B.‐J. , Liu S.‐L. , Guan W.‐B. , Liu G.‐H. , Lü Y.‐H. , Anand M.
Published: January 2004

The spatial distribution of soil moisture and its multiple‐scale correlations to other environmental factors were examined along the Upper Minjiang River valley, China, a landscape subject to severe land degradation of soil and water erosion but also under investigation for potential ecosystem restoration. Results showed that: (1) Soil moisture was highest in the headwaters, and lowest in the arid valley, while moderate values characterized outside the arid valley. The polynomial model of soil moisture distribution on slopes was concave in the lightly disturbed headwaters, convex in the highly damaged arid valley, while convex on south facing slopes and concave on north facing slopes in highly damaged areas in better environmental condition. (2) Soil moisture was correlated with environmental factors at different scales, where elevation and air humidity were only correlated at the sample plot scale, light intensity and wind speed were found to be significant at both slope and site scales and slope and sample plot scales; while slope angle was correlated at all the three scales. From this we conclude that it is possible to improve soil moisture conditions in the arid valley by lowering slope angle and adding low‐cost irrigation systems. (3) The practical threshold of soil moisture for growing meadows, shrubs, and forests were 11ċ800 per cent, 3ċ925 per cent, and 16ċ078 per cent respectively; the arid valley displayed soil‐moisture conditions unfavourable to forest growth. The planned reforestation project is not ecologically reasonable. Reducing human disturbance and revegetating with natural shrubs and meadows may produce more effective results. Copyright © 2004 John Wiley & Sons, Ltd.
The development of sustainable earthworm populations at Calvert landfill site, UK
Authors: Butt K. R. , Lowe C. N. , Frederickson J. , Moffat A. J.
Published: January 2004

EarthwormsAllolobophora chloroticaandAporrectodea longawere inoculated into Calvert landfill site in spring 1992, in conjunction with the planting of two tree speciesAlnus glutinosaandAcer pseudoplatanus. Monitoring has taken place over a period of 11 years. Sampling in 2003 revealed that earthworm distribution no longer equated to the inoculation treatments; the worms had spread extensively. The presence ofA. glutinosahad a significant effect (p<0ċ01) on earthworm number (mean density 198 m−2) and biomass (34 g m−2) compared to plots whereA. pseudoplatanushad been planted and subsequently died (mean density 118 m−2; biomass 21 g m−2). Results suggest that tree presence may be critical to earthworm community development.

In 2002, the spread ofA. chloroticafrom the original points of inoculation had reached 60 m with the highest recorded population density at 108 m−2with a mass of 18ċ6 g m−2.A. longawas recorded at a distance of 132 m from the nearest point of inoculation with the highest recorded population density at 70 m−2with a mass of 49ċ3 g m−2, 10 m from the original inoculation grid. Other species recorded (and % of total) wereAporrectodea rosea(0ċ9)Lumbricus castaneus(7ċ4),Eiseniella tetraedra(21ċ5) andLumbricus rubellus(4ċ5). The two inoculated species,A. chlorotica(40ċ4) andA. longa(25ċ3), accounted for two thirds of the earthworms found on site. The highest earthworm community density was 213 m−2with a mass of 73ċ9 g m−2at 10 m from original point of inoculation.

In 1999, treatments of surface organic matter (OM), in the form of composted green waste, and rotavation were applied to non‐replicated plots of 50 m2with the effects on earthworm distribution and abundance recorded in 2002. Addition of OM alone led to an increase in number and mass (331 m−2; 95 g m−2) compared to the control (233 m−2; 51 g m−2), while rotavation alone (111 m−2; 36 g m−2) had a detrimental effect over the given time period.

This long‐term monitoring programme has demonstrated the development of sustainable earthworm communities on a landfill site. Natural nutrient accumulation and addition of OM on or into the soil‐forming material appeared to assist this process. This work may help to inform post‐capping treatment at similar landfill sites Copyright © 2004 John Wiley & Sons, Ltd.
Evaluation of alternative approaches to rainforest restoration on abandoned pasturelands in tropical North Queensland, Australia
Authors: Florentine S. K. , Westbrooke M. E.
Published: January 2004

The lag time for natural recruitment of tropical rainforest species in abandoned pastureland is very long, therefore artificial restoration techniques have been employed to accelerate natural seedling recruitment. The objectives of this study were to investigate: (1) the success/failure of establishment 502 seedlings belonging to 15 species from 11 families planted approximately ten years ago; and (2) the influence of different restoration techniques on enhancing natural recruitment during this period. The study was conducted in the wet tropical rainforest region of northeast Queensland, Australia as a completely randomized block design involving five treatments with two replicates. In each plot, 63 tropical rainforest seedlings from one or a combination of species were planted randomly. Two control plots were laid out where no seedlings were planted. Survival, height and diameter data were taken on the seedlings ten years after planting. Each 11×17 m2 plot was further divided into 187, 1×1 m2 subplots. Within each subplot all seedlings recruited were located and identified. Canopy cover was estimated using belt transects 1 m apart that ran in an east–west direction across the plots. Within each plot the percentage of grass, and the crown cover were estimated using the Braun‐Blanquet cover abundance scale. Survival rate of planted seedlings varied across the treatment plots. The survival rate ranged from 65 to 75 per cent for primary‐promoter species, 85 to 100 per cent in middle‐phase species and 42 to 57 per cent for mature‐phase species. No Pilidiostigma tropicum seedlings survived in any treatment. Fourteen species recruited naturally across the treatment plots. A total of 410 seedlings were naturally recruited from 11 different families in the ten‐year‐old reforested site. The highest natural recruitment (236 seedlings) occurred in Treatment 3, where Omalanthus novo‐guineensis seedlings were planted with eight primary‐promoter species, followed by 99 in Treatment 5 where a group of primary‐promoters, middle phase species and mature‐phase species were planted together, 36 in Treatment 4 (Alphitonia petriei planted with eight primary‐promoter species), 10 in Treatment 2 where only Omalanthus novo‐guineensis seedlings were planted, and 13 in control plots. Grass cover declined with increasing species diversity and increased canopy cover. The results indicate that the diversity of species used in restoration had a major influence on natural recruitment. Copyright © 2004 John Wiley & Sons, Ltd.
Wheat field erosion rates and channel bottom sediment sources in an intensively cropped northeastern Oregon drainage basin
Authors: Nagle G. N. , Ritchie J. C.
Published: January 2004

Sediment tracers were used to quantify erosion from cultivated fields and identify major source areas of channel bottom sediment within the Wildhorse Creek drainage, an intensively cropped tributary of the Umatilla River in northeastern Oregon, USA. Available data indicated that Wildhorse Creek was one of the largest sediment yielding tributaries of the Umatilla River. Carbon, nitrogen and the nuclear bomb‐derived radionuclide 137Cs were used as tracers to fingerprint sediment sources. Sediment was collected from the stream bottom and active floodplain and compared to samples from cultivated fields and channel banks. Samples were characterized on the basis of tracer concentrations and a simple mixing model was used to estimate the relative portion of bottom sediment derived from cultivated surface and channel banks. The results indicate that the amount of bottom sediment derived from cultivated surface sources was less than 26 per cent for the 1998 winter season, although this estimate has a high margin of error. Cesium‐137 was also used to estimate surface erosion from three cultivated fields in the watershed. Annual estimates of erosion since 1963 from the three sampled fields were from 3 to 7ċ5 t ha−1 yr−1. For the 1998 season, it appears that most channel‐bottom sediment was of subsurface origin with much of it likely coming from channel and gully banks indicating that significant reductions in sediment in Wildhorse Creek might be accomplished by the stabilization of eroding riparian areas and swales on the lower slopes of agricultural fields. Published in 2004 by John Wiley & Sons, Ltd.
A decision support system for soil and water conservation measures on agricultural watersheds
Authors: Sarangi A. , Madramootoo C. A. , Cox C.
Published: January 2004

Integrated watershed management (IWM) is vital in achieving agricultural sustainability in terms of both production and environmental protection. A decision support system (DSS) is useful in generating alternative decision scenarios for management of natural resources, facilitating the implementation of IWM concepts in an interactive and holistic way. The decision to implement an appropriate land use coupled with suitable soil and water conservation techniques not only enhances watershed health but also prevents sediment losses. Besides reducing basin fertility, such losses decrease the storage capacity of downstream reservoirs through silt deposition, which can, in turn, give rise to low biomass production and poorer flood control. In order to facilitate IWM, an effort was made to develop, in the Visual Basic programming language, a soil and water conservation DSS which considered both structural and cropping practices for arresting sediment loss. Input parameters to the DSS for a given tract of land included: mean slope; sediment loss; soil type; and land capability class (LCC). Outputs included decision criteria to choose among alternative structural measures and suggested cropping systems to serve as biological measures to reduce soil loss and conserve water. Structural watershed management measures included a variety of soil and water conservation structures widely adopted by farming communities throughout the world. The DSS is capable of providing sediment control solutions not only for small watersheds but also for larger drainage basins, by dividing the basin into smaller watersheds. The DSS was validated for a watershed on the Caribbean island of St Lucia and used to suggest measures for a 10° slope under specific soil type, sediment loss and LCC conditions. The measures proposed included bench terraces, graded contour bunds, conservation ditches, concrete chute spillways, diversion dams and conservation cropping systems. The measures actually adopted on‐site were conservation ditches, graded contour bunds and conservation cropping systems, a close parallel to the DSS's proposed measures. On slopes ranging from 5–55°, implementation of the suggested control measures resulted in a 34–37 per cent reduction in soil loss on the watershed. Copyright © 2004 John Wiley & Sons, Ltd.
Accurate measurement, using natural sunlight, of silicon solar cells
Authors: Keogh William M. , Blakers Andrew W.
Published: January 2004

The light source is very important when measuring solar cells. Commonly used light sources—good‐quality solar simulators—are expensive and have far from ideal characteristics. Computer modelling described in this work strongly suggests that testing of silicon solar cells under natural sunlight is simpler, cheaper, and more accurate than all but the most careful simulator measurements. Direct‐beam solar spectra were generated with the model SMARTS2 for a range of atmospheric conditions, and a broad range of silicon cells (efficiencies 6–25%) were then simulated under these spectra. These simulations showed that measurement uncertainty of less than 5% should be achievable. Climate data for locations within 45° of the equator show that the required atmospheric conditions should occur commonly in summer. Finally, it is shown that the important atmospheric conditions can be measured without expensive equipment. Copyright © 2004 John Wiley & Sons, Ltd.
Low‐temperature formation of local Al contacts to a‐Si:H‐passivated Si wafers
Authors: Plagwitz H. , Nerding M. , Ott N. , Strunk H. P. , Brendel R.
Published: January 2004

We have passivated boron‐doped, low‐resistivity crystalline silicon wafers on both sides by a layer of intrinsic, amorphous silicon (a‐Si:H). Local aluminum contacts were subsequently evaporated through a shadow mask. Annealing at 210°C in air dissolved the a‐Si:H underneath the Al layer and reduces the contact resistivity from above 1 Ω cm2to 14·9 m Ω cm2. The average surface recombination velocity is 124 cm/s for the annealed samples with 6% metallization fraction. In contrast to the metallized regions, no structural change is observed in the non‐metallized regions of the annealed a‐Si:H film, which has a recombination velocity of 48 cm/s before and after annealing. Copyright © 2004 John Wiley & Sons, Ltd.
Solar cell efficiency tables (version 23)
Authors: Green Martin A. , Emery Keith , King David L. , Igari Sanekazu , Warta Wilhelm
Published: January 2004

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July 2003 are reviewed. Copyright © 2004 John Wiley & Sons, Ltd.
Properties of ZnO/CdS/CuInSe2solar cells with improved performance
Authors: AbuShama Jehad A. M. , Johnston S. , Moriarty T. , Teeter G. , Ramanathan K. , Noufi R.
Published: January 2004

We report the growth and characterization of low‐bandgap record‐efficiency ZnO/CdS/CuInSe2thin‐film solar cells. The total area conversion efficiency for this cell is 14·5%. This result has been measured and confirmed at the National Renewable Energy Laboratory under standard reporting conditions (1000 W/m2, 25°C, AM1·5 Global). The improved performance of the CuInSe2solar cell is primarily due to a high current density. Material and device characterization data are presented.. Published in 2004 by John Wiley & Sons, Ltd.
A proteomic approach to study Salmonella typhi periplasmic proteins altered by a lack of the DsbA thiol: Disulfide isomerase
Authors: Agudo David , Mendoza María Teresa , Castañares Cristina , Nombela César , Rotger Rafael
Published: January 2004

Two‐dimensional electrophoresis (2‐DE) was used to analyze the pleiotropic effects of a deficiency in DsbA, a periplasmic disulfide‐bond oxidoreductase, in Salmonella typhi. With this aim, the dsbA gene was cloned and assayed for activity in a dsbA‐null mutant of Escherichia coli. A dsbA/chloramphenicol acetylase construct was then used to disrupt the wild‐type gene of S. typhi. The resultant dsbA‐null mutant of S. typhi, like the E. coli mutant, exhibited a lack of flagellation and of glucose‐1‐phosphatase activity. Periplasmic extracts from the parental and mutant strains were analyzed by 2‐DE using standard denaturing and nondenaturing conditions. Differences in protein expression were more marked in nondenaturing conditions. Ninety‐nine protein spots were analyzed by peptide mass fingerprinting, and 65 spots were identified by searching a S. typhi database. Twenty‐five spots were exclusively detected in the wild‐type strain, 10 were found only in the mutant strain, and 21 were common to both strains. We observed a lack of DsbA, glucose‐1‐phosphatase and flagellin in the dsbA‐null mutant, which explains two of the observed phenotypes. The AI‐2 autoinducer‐producing protein LuxS, which is involved in quorum‐sensing signalling was also absent.
Copper‐associated liver disease: A proteomics study of copper challenge in a sheep model
Authors: Simpson Deborah M. , Beynon Robert J. , Robertson Duncan H. L. , Loughran Michael J. , Haywood Susan
Published: January 2004

Sheep display a variant phenotype with respect to their susceptibility to copper and derivative pathology. The North Ronaldsay sheep are acutely sensitive to environmental copper while the Cambridge breed is much more copper‐tolerant. A study of protein expression in the liver of the two different breeds of sheep as a result of copper challenge would aid in the understanding of their differing pathophysiologies and contribute to knowledge of copper toxicosis in man. In this initial study, Cambridge breed sheep were challenged with oral copper and liver proteins were analyzed by two‐dimensional (2‐D) gel electrophoresis. Proteins whose expression pattern was modified by copper exposure were then identified by peptide mass fingerprinting using matrix assisted laser desorption/ionization‐time of flight (MALDI‐TOF) mass spectrometry. In conclusion, the pattern of changes in protein expression were consistent with an early adaptive response to oxidative challenge. This was followed by evidence of an impaired ability of the liver to compensate as copper loading increased, accompanied by oxidative stress‐induced injury.
Dissecting regulatory networks by means of two‐dimensional gel electrophoresis: Application to the study of the diauxic shift in the yeast Saccharomyces cerevisiae
Authors: Haurie Valérie , Sagliocco Francis , Boucherie Hélian
Published: January 2004

Using a proteomic approach based on the two‐dimensional (2‐D) gel analysis of synthesized proteins, we investigated the involvement of the Snf1 kinase pathway in the regulation of gene expression during the diauxic shift in Saccharomyces cerevisiae. For this purpose, we used a mutant strain deleted for SNF4, the gene coding for the activator subunit of Snf1p. The levels of synthesis of 82 spots were found to be affected by the absence of Snf4p at the diauxic shift. Half of the proteins which exhibit a reduced synthesis in the mutant strain are proteins whose genes are controlled by the transcriptional activator Cat8p, a target of Snf1p. Proteins with an increased level of synthesis in the mutant strain were also observed. Among them are glycolytic enzymes whose synthesis is strongly reduced when wild‐type cells enter the diauxic shift. This observation suggests that Snf1p exerts a negative control on the expression of glycolytic genes during the diauxic transition. The results obtained in this study were compiled with those previously obtained by similar proteomic approach with other regulatory factors involved in the diauxic shift. This compilation illustrates how 2‐D gel electrophoresis can be used to elucidate the network of regulators participating to complex biological process.
Proteomic analysis of the effect of heat stress on hexaploid wheat grain: Characterization of heat‐responsive proteins from non‐prolamins fraction
Authors: Majoul Thouraya , Bancel Emmanuelle , Triboï Eugène , Ben Hamida Jeannette , Branlard Gérard
Published: January 2004

The effect of heat stress on hexaploid wheat grain proteome was recently analyzed in our previous works. Proteomic tools allowed the characterization of heat‐responsive proteins of total endosperm, composed mainly of prolamins. The present work completes this study; our aim was to analyze the effect of heat stress on the water‐soluble fraction, composed essentially of albumins and globulins. These proteins were separated by two‐dimensional electrophoresis (2‐DE), visualized by Coomassie Brilliant Blue (CBB) staining and analyzed by Melanie‐3 software. Of the 43 heat‐changed proteins, 24 were found to be up‐regulated whereas 19 spot proteins were down‐regulated. All of these proteins were subjected to matrix‐assisted laser desorption/ionization‐time of flight‐mass spectrometry (MALDI‐TOF‐MS) followed by database searching which allowed the identification of 42 spots. Of these, some were enzymes involved in different metabolic pathways of plants, such as granule‐bound starch synthase and glucose‐1‐phosphate adenyltransferase, involved in the starch synthesis pathway; β‐amylase, involved in carbohydrate metabolism, and the ATP synthase β‐chain that was related to four heat‐decreased proteins. Moreover, five heat up‐regulated proteins showed similarities with small heat shock proteins while three other spots were related to elongation factors or eucaryotic translation initiation factors. Proteins involved in abiotic stresses or in plant defense mechanism were also identified and are discussed.
Application of proteomics in phylogenetic and evolutionary studies
Authors: Navas Alfonso , Albar Juan Pablo
Published: January 2004

There are few papers that deal specifically with evolutionary studies and proteomics. However, applying proteomics to these studies promises to open new perspectives apropos the construction of phylogenetic trees and the detection of evolutionary changes. Principles and methods of phylogenetic systematics could be used to compare and evaluate proteomes. This would permit the detection and characterization of specific proteins that have evolutionary value in defining monophyly, paraphyly, and polyphyly.
Systematic screening of reactive cysteine proteomes
Authors: Lindahl Marika , Florencio Francisco J.
Published: January 2004

Redox signalling constitutes a topic within the field of cellular signal transduction which is attracting increasing interest. A major challenge is to identify the components of redox signalling pathways. Proteins containing cysteines that may reversibly form disulphides are principal candidates as transmitters of redox signals. Thioredoxins are small proteins containing a highly reactive dithiol. Here we present a simple procedure to isolate and separate proteins that contain redox active cysteines using a site‐directed, histidine‐tagged mutant of thioredoxin, which forms stable mixed disulphides with its targets.
Proteomic analysis of diet‐induced hypercholesterolemic mice
Authors: Park Ji Young , Seong Je Kyung , Paik Young‐Ki
Published: January 2004

We report here a proteomic analysis of differentially expressed liver proteins of both C57BL/6J (B6, atherosclerosis‐susceptible strain) and C3H/HeJ mice (C3H, atherosclerosis‐resistant strain), which were fed either control or a high‐fat enriched atherogenic diet for eight weeks. We observed differential patterns of plasma lipids between the two strains when both were fed atherogenic diets. That is, although low density lipoprotein cholesterol level was highly elevated in both, the levels of total cholesterol and triglyceride in B6 mice were much lower than those in C3H mice when they were fed atherogenic diets. However, the high density lipoprotein cholesterol level was increased in the latter but decreased in the former. Histopathological observation revealed that more prominent lipid droplets were present in B6 mice than in C3H mice, when they were maintained on the atherogenic diets. Proteomic analysis of liver tissues of these two strains showed that a total of 30 proteins were significantly changed in the livers obtained from both strains after being fed the atherogenic diet. Of these, 14 protein spots including carbonic anhydrase III, senescence marker protein 30 and selenium binding protein 2 were differentially changed only in B6 mice, which was also confirmed in part by Western blotting. An additional 16 protein spots including glutathione S‐transferase subclass, apolipoprotein E and chaperonin proteins were changed in both strains. We also identified 28 proteins that were differentially expressed in the livers of both B6 and C3H mice, regardless of diet feeding condition. Of these, 4 protein spots in B6 mice and 11 protein spots in C3H mice were up‐regulated. Thirteen strain specific protein spots including antioxidant protein 2, apolipoprotein E and apolipoprotein A‐I were also detected in different positions in two‐dimensional electrophoresis. These results suggest a clear distinction in differential expression of oxidative stress proteins and lipid metabolism related proteins between the two strains in response to atherogenic diet feeding, which might account for their difference in susceptibility to atherogenesis.
Snake venomics: Characterization of protein families in Sistrurus barbouri venom by cysteine mapping, N‐terminal sequencing, and tandem mass spectrometry analysis
Authors: Juárez Paula , Sanz Libia , Calvete Juan J.
Published: January 2004

The protein composition of the crude venom of Sistrurus barbouri was analyzed by two‐dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. Proteins were separated by reversed phase high‐performance liquid chromatography and characterized by N‐terminal sequence analysis. The molecular mass and number of cysteine residues of the purified proteins were determined by matrix‐associated laser desorption/ionization‐time of flight mass spectrometry. Selected protein bands were subjected to in‐gel tryptic digestion and peptide mass fingerprinting. Analysis of the tandem mass spectrometry spectra of selected doubly‐charged peptide ions was done by collision‐induced dissociation in a quadrupole‐linear ion trap instrument. Our results show that the venom proteome of the pigmy rattlesnake S. barbouri is composed of proteins belonging to a few protein families, which can be structurally characterized by their disulfide bond contents.
Isolation of circulating human monocytes with high purity for proteomic analysis
Authors: Gonzalez‐Barderas Maria , Gallego‐Delgado Julio , Mas Sebastián , Duran Mari Carmen , Lázaro Alberto , Hernandez‐Merida Sergio , Egido Jesús , Vivanco Fernando
Published: January 2004

We describe a simple method for isolation of human blood monocytes with the high purity (95–98%) required for proteomic analysis, which avoids contamination by other blood cells (platelets and lymphocytes) and the most abundant plasma proteins (albumin and immunoglobulins). Blood monocytes were purified by gradient centrifugation followed by positive selection with specific monoclonal antibodies coupled to paramagnetic beads. The elution conditions of the positive selection step were modified to avoid contamination with albumin. This method is compatible with flow cytometry which was used to assess the purity of the cell population. From 28 mL of blood, 107 monocytes with > 96% purity are routinely obtained. From the isolated monocytes 200–250 μg of protein could be recovered. The whole method can be performed in three hours. Similar results were obtained using a negative selection step but with lower purity (92%), increased cost and longer time. After solubilization of monocytes, the proteins were analyzed by two‐dimensional gel electrophoresis (2‐DE) in the 3–10, 4–7, 6–9 and 6–11 pH range. DNA was the main contaminant that interfered with the 2‐DE and it was removed by treatment with DNAse. Image analysis of gels allowed the reproducible detection and quantification of 1500 spots in the 4–7 pH range and more than 2000 spots in total by combining (overlapping) 2‐D gels in the 4–7, 6–9 and 6–11 pH range. This method is useful for clinical studies of monocytes from a large number of patients due to its rapidity and reproducibility, which permits comparative analysis of normal versus pathological samples and which allows follow up of the expressed proteins of monocytes from each patient.
Proteomic analysis of lung biopsies: Differential protein expression profile between peritumoral and tumoral tissue
Authors: Alfonso Patricia , Catalá Myriam , Rico‐Morales María Luisa , Durante‐Rodríguez Gonzalo , Moro‐Rodríguez Ernesto , Fernández‐García Héctor , Escribano José M. , Álvarez‐Fernández Emilio , García‐Poblete Eduardo
Published: January 2004

The cellular proteome shows a dynamic profile and is subjected to changes in response to various stimuli and disease progression. Lung cancer remains the leading cause of cancer death in industrialized countries. In an attempt to find new disease markers, patients suffering from lung carcinoma have been selected to achieve differential protein expression patterns between normal and neoplasic tissue. After two‐dimensional electrophoresis, the spots of interest were digested and identified by matrix‐assisted laser desorption/ionization (MALDI) peptide mass fingerprinting. This information will provide a more comprehensive understanding of the disease progression and might constitute a method to complement histopathological diagnosis.
Proteomic analysis of the oxygen‐evolving complex of photosystem II under biotec stress: Studies on Nicotiana benthamiana infected with tobamoviruses
Authors: Pérez‐Bueno M. Luisa , Rahoutei Jaber , Sajnani Carlota , García‐Luque Isabel , Barón Matilde
Published: January 2004

We have previously shown that tobamovirus infection induces an inhibition of photosystem II electron transport, disturbing the oxygen‐evolving complex (OEC). In the infected plants, the OEC polypeptide pattern was modified when compared to healthy plants, the levels of the PsbP and PsbQ extrinsic proteins being lowered to different extents. In this work we have further investigated by two‐dimensional polyacrylamide gel electrophoresis (2‐DE) the changes on the OEC protein pattern of thylakoid membranes isolated from Nicotiana benthamiana Domin plants infected with the Spanish strain of pepper mild mottle virus. When the thylakoid membranes from healthy plants were analyzed for the presence of PsbO and PsbP proteins by 2‐DE (pI range 4–7) and further immunoassayed by using specific‐antisera against these two proteins, it was observed that four polypeptides cross‐reacted with each antiserum. These data, along with the N‐terminal amino acid sequence determined for the eight polypeptides, indicate that the N. benthamiana PsbO and PsbP proteins correspond to protein families. In the silver‐stained 2‐DE gels of thylakoid membranes isolated at different days postinoculation from virus‐infected plants, it was observed that the content of PsbP polypeptides decreased dramatically with respect to those of PsbO, during the progress of the infection. Interestingly, there was a differential decrease of the different PsbP proteins, indicative of a distinct regulation of their expression.
On optimal control of constrained linear systems with imperfect state information and stochastic disturbances
Authors: Perez Tristan , Haimovich Hernan , Goodwin Graham C.
Published: January 2004

We address the problem of finite horizon optimal control of discrete‐time linear systems with input constraints and uncertainty. The uncertainty for the problem analysed is related to incomplete state information (output feedback) and stochastic disturbances. We analyse the complexities associated with finding optimal solutions. We also consider two suboptimal strategies that could be employed for larger optimization horizons. Copyright © 2004 John Wiley & Sons, Ltd.
Feedback min‐max model predictive control using a single linear program: robust stability and the explicit solution
Authors: Kerrigan Eric C. , Maciejowski Jan M.
Published: January 2004

In this paper we introduce a new stage cost and show that the use of this cost allows one to formulate a robustly stable feedback min–max model predictive control problem that can be solved using a single linear program. Furthermore, this is a multi‐parametric linear program, which implies that the optimal control law is piecewise affine and can be explicitly pre‐computed so that the linear program does not have to be solved on‐line. We assume that the plant model is known, is discrete‐time and linear time‐invariant, is subject to unknown but bounded state disturbances and that the states of the system are measured. Two numerical examples are presented; one of these is taken from the literature, so that a direct comparison of solutions and computational complexity with earlier proposals is possible. Copyright © 2004 John Wiley & Sons, Ltd.
Mentoring relationships among African American women in graduate and professional schools
Authors: Patton Lori D. , Harper Shaun R.
Published: January 2004

The value of mentoring relationships among African American women in postbaccalaureate degree programs is emphasized and coupled with a discussion of the current shortage of same‐race, same‐sex mentors for African American female graduate and professional students.