bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of acute cortisol and cocaine administration on attention, recall and recognition task performance in individuals with cocaine dependence
Authors: Hopper J. W. , Karlsgodt K. H. , Adler C. M. , Macklin E. A. , Lukas S. E. , Elman I.
Published: August 2004

This study investigated the effects of acute cocaine administration on cognition, and whether these can be modeled using exogenous hydrocortisone, because cocaine‐induced cortisol elevations may influence its cognitive effects. Twelve cocaine‐dependent individuals received an intravenous bolus of cortisol (0.5 or 0.2 mg/kg) and cocaine (0.2 mg/kg) in a double‐blind randomized placebo‐controlled and counterbalanced fashion. Cognitive testing included verbal tasks of vigilance attention, free recall and recognition memory before the boluses and at 20, 60 and 100 min thereafter. The statistical analysis investigated dose response effects while accounting for all sources of variance in the design. No effects of low dose cocaine were found on any variables. Low dose cortisol enhanced and high dose impaired vigilance attention, and a trend was found for the same dose response profile on twice‐heard words. An opposite trend, inconsistent with prior research on cortisol and cognition, was observed for recognition: low dose impaired and high dose enhanced recognition of once‐heard words, and a very weak trend was found for recognition of new words. These findings, though tempered by design limitations, suggest a complex non‐linear cortisol attention/recognition dose‐response relationship and call for further research to elucidate cortisol's effects on cognition and their role in the pathophysiology of cocaine dependence. Copyright © 2004 John Wiley & Sons, Ltd.
Water problems and hydrological research in the Yellow River and the Huai and Hai River basins of China
Authors: Liu Changming , Xia Jun
Published: August 2004

This paper deals with hydrological research in regard to the water resources crisis in the vulnerable areas found in the northern part of China. This area includes three main river basins, namely the basins of the Yellow (Huang) River, the Hai River and the Huai River. Several water problems are becoming very severe. Among them, two are the most critical: the Yellow River has been drained dry in the main course of its lower reaches and along its major tributaries, and the groundwater table has rapidly declined in the floodplains of the three rivers' downstream areas. To counter the problems, particularly the critical issues mentioned above, hydrological research, which serves as the basis of water development and management, has been carried out in the last two decades. This paper addresses three basic scientific problems in North China, namely: (a) water consumption and the capacity for saving water; (b) the changes in hydrological processes and water resources caused by natural change and human activities; and (c) the ability to supply water resources and water safety in terms of both quantity and quality within a changing environment. However, opportunities and challenges for ameliorating the problems exist, and new ideas and methodology to solve the problems have been proposed, such as the interface process study on the interactions in the soil–root interface, the plant–atmosphere interface, the soil–atmosphere interface, and the interface of soil water and groundwater. In order to manage water resources in a sustainable manner, the study of water resources' renewal ability as affected by natural change and human activity is addressed from the viewpoint of both water quantity and quality, and their integration. To reduce the vulnerability of water resources in regional water management, a paradigm of sustainable water resources utilization is also proposed, using water–heat balance, water–salt balance, water–sediment balance, and water supply–demand balance. This approach may help reveal the basic problems and point to possible approaches to solving the water problems in North China in the 21st century. Copyright © 2004 John Wiley & Sons, Ltd.
Hydrogen and oxygen isotopes in precipitation in the northern part of the North China Plain: climatology and inter‐storm variability
Authors: Yamanaka Tsutomu , Shimada Jun , Hamada Yohhei , Tanaka Tadashi , Yang Yonghui , Zhang Wanjun , Hu Chunsheng
Published: August 2004

To clarify the processes of atmospheric water vapour transport to the northern part of the North China Plain (NCP), isotopic variations in precipitation are investigated. Pattern of seasonal variation in the isotopic composition of precipitation over China can be classified into three types: winter depression, summer depression and intermediate. The northern NCP is located at the northern margin of the region where isotopic composition decreases in summertime, associated closely with the Asian summer monsoon. Inter‐storm variability of isotopic composition over the northern NCP during the monsoon season has an inverse relationship with atmospheric moisture content, although it cannot be accounted for by the amount effect. Thus, the isotopic composition is inferred to be primarily controlled by large‐scale monsoon activity, which supplies water vapour into the northern NCP, rather than by local precipitation processes. From an analysis based on a relationship between the deuterium excess and humidity conditions at possible oceanic source areas, it is revealed that precipitating water in the early monsoon season originates in the South China Sea, and its source area tends to shift to the East China Sea and/or Yellow Sea in the later period of the season. Copyright © 2004 John Wiley & Sons, Ltd.
Investigating the conversion coefficients for free water surface evaporation of different evaporation pans
Authors: Fu Guobin , Liu Changming , Chen Shulin , Hong Jialian
Published: August 2004

The conversion coefficients of free water surface evaporation were investigated. Comparisons were made between numerous evaporation tanks (pans) and a 20 m2 evaporation tank. Based on 6 years of evaporation data collected at Nansihu Lake Evaporation Station in Shandong Province, China, the following results have been obtained. First, conversion coefficients varied according to the evaporator type. The average yearly conversion coefficient was only 0·60 for ϕ20 evaporator (an evaporation pan with a diameter of 20 cm), whereas it was about 1·07 for the E601's pan, whose rim was about 7·5 cm above ground. Second, the conversion coefficient changes within a year had the same pattern among the evaporators evaluated. The monthly conversion coefficients had the minimum values in March or April, then increased with time, and reached their maximum values in August or September. After September, the conversion coefficients varied in different directions with time. Third, the conversion coefficients changed from year to year, but their variations between maximum and minimum values were between 0·06 and 0·16. Fourth, the installation modes, structures, and composition of the evaporators affected the evaporation amount. Fifth, the conversion coefficients at Nansihu and Yucheng stations for the same evaporator did not show a distinct difference. The E601 evaporator has almost the same conversion coefficients at six of seven stations spanning almost 20° in latitude from northern to southern China. Sixth, the yearly evaporation from a 100 m2 evaporation tank was almost the same as that from the 20 m2 evaporation tanks; however, the differences still existed in any given month. Copyright © 2004 John Wiley & Sons, Ltd.
Measurement and analysis of the redistribution of soil moisture and solutes in a maize field in the lower reaches of the Yellow River
Authors: Chen J. Y. , Tang C. Y. , Sakura Y. , Kondoh A. , Shen Y. J. , Song X. F.
Published: August 2004

The lower reaches of the Yellow River are basically a discharge zone with a high salt content, and the study area of Yucheng in Shandong Province became arable only after the water diversion project from the Yellow River was implemented in 1972. The sustainability of agriculture in this area is examined through the redistribution of soil moisture and solutes in the vertical profile based on the measurement of soil moisture, potential and solute content in a maize field at the Yucheng Experimental Station. Diurnal moisture fluctuations appear in the surface layers at 30 and 50 cm depths, and the daily water content at 90 cm depth decreases about a month after planting, due mainly to the effect of root water extraction, even reaching a level lower than that at 70 cm depth. Soil moisture obviously increases for the three layers at 30, 50, 90 cm depth, and the relevant peak‐time shifts from the surface 30 cm depth to the deep layer at 120 cm depth with a varied time lag in response to rainfall events, but there is little or no signal for the other layers due to the effects of soil properties, roots, and soil storage. The existence of a convergent zero flux plane may explain to some extent the accumulation of moisture and solutes in the layer at 120 cm depth. Though the chemical facies along the profile from the unsaturated surface to the deep saturated zone generally evolves in a direction of decreasing SO42 − and Cl−, a strong driving force upward and the accumulation of solute at 120 cm may change the redistribution pattern and three groups of this pattern were classified according to the evolution and concentration distribution profiles. The main factors affecting the moisture, solute and their distributions for the three groups are varied: rainfall, irrigation and evapotranspiration for the surface layer till 70 cm depth, root extraction for the accumulation layer of 70–120 cm depth, and the fluctuation of the groundwater table for the deep layer at 120–200 cm depth. The agriculture appears sustainable as long as diverted water from the Yellow River is available, but the high content of solute accumulation in the layer at about 120 cm depth is a potential risk. Copyright © 2004 John Wiley & Sons, Ltd.
Energy fluxes and the Priestley–Taylor parameter over winter wheat and maize in the North China Plain
Authors: Zhang Yongqiang , Liu Changming , Yu Qiang , Shen Yanjun , Kendy Eloise , Kondoh Akihiko , Tang Changyuan , Sun Hongyong
Published: August 2004

Surface energy fluxes above the canopies of well‐irrigated winter wheat and maize in the North China Plain were measured by the Bowen‐ratio energy balance technique in 1999–2000. Seasonal variation of the ratio of latent heat flux λE to available energy Rn − G showed that the ratio of λE to Rn − G exceeded 83% when leaf area index (LAI) varied from 2·0 to 6·0. The seasonal trend of evaporative fraction (EF) for winter wheat was similar to that of LAI before senescence stage, which is a critical factor controlling EF, which itself reflects the partitioning of available energy into λE. The Priestley–Taylor parameter α over the wheat and maize canopies changed greatly over the course of a growing season, and the seasonal average α of winter wheat was 1·17 and 1·26, and that of maize was 1·06 and 1·09 in the two consecutive years. α for winter wheat was exponentially correlated to 0–20 cm surface soil moisture, but not for maize and with the increase of soil depths, the correlation between α and soil moisture was weak. Under different soil moisture conditions, a linear correlation between extractable soil water and leaf water potential ψ for winter wheat was found. Copyright © 2004 John Wiley & Sons, Ltd.
Groundwater recharge from irrigated cropland in the North China Plain: case study of Luancheng County, Hebei Province, 1949–2000
Authors: Kendy Eloise , Zhang Yongqiang , Liu Changming , Wang Jinxia , Steenhuis Tammo
Published: August 2004

Effective management of limited water resources in the North China Plain requires reliable calculation of historical groundwater balances at local, sub‐watershed scales. These calculations typically are hindered by poorly constrained recharge estimates. Using a simple soil‐water balance model, we independently calculated annual recharge from irrigated cropland to unconfined alluvial aquifers underlying Luancheng County, Hebei Province, in the western part of the North China Plain, for 1949–2000. Model inputs include basic soil characteristics and daily precipitation, potential evapotranspiration, irrigation, crop root depth, and leaf‐area index; model outputs include daily actual evapotranspiration and areal groundwater recharge. Results indicate that areal recharge is not a constant fraction of precipitation plus irrigation, as previously assumed, but rather the fraction increases as the water inputs increase. Thus, model‐calculated recharge rates range from 5 to 109 cm year−1, depending on the quantity of precipitation and irrigation applied. The important implication is that, because this drainage recharges the underlying aquifer, improving irrigation efficiency by reducing seepage does not save water. This explains why successful efforts to reduce groundwater pumping for irrigation have had no effect on water‐table declines. So long as crop cover is extensive and all crop‐water requirements are met—which has been the case in Luancheng County since the 1960s—groundwater levels will continue to decline at a steady rate. Potential solutions include reducing the irrigated area, reintroducing fallow periods, and shifting water from agriculture to other, less consumptive uses. Copyright © 2004 John Wiley & Sons, Ltd.
Pre‐processing rainfall data from multiple gauges to improve TOPMODEL simulation results in a large semi‐arid region
Authors: Boston Trevor , Xia Jun , Zhu Yizhong
Published: August 2004

Modelling of semi‐arid regions presents some complex challenges that must be overcome to produce reliable simulation results. This paper discusses the findings of a calibration and cross‐validation process using TOPMODEL to simulate stream discharge from the semi‐arid Banqiao sub‐catchment located in Gansu Province, China. Rainfall was pre‐processed using two different methods and compared against the use of mean rainfall data from 10 gauging stations. The results indicate that correlating multiple rainfall gauge measurements against stream discharge and weighting the rainfall gauges according to correlation factors can be a useful means of obtaining more representative rainfall input. The second method used a transfer function model (TFM) equipped with a non‐linear rainfall filter function to generate effective rainfall. The TFM was calibrated repeatedly using different degrees of non‐linearity in the rainfall filter function until an optimal model was found. The effective rainfall used to generate the best TFM was applied in TOPMODEL. Applying the TFM effective rainfall to TOPMODEL allowed better simulation of discharge than use of either the correlation‐weighted or mean rainfall input. Although the R2 validation efficiencies or ‘goodness of fit’ generally lagged those seen during calibration, 90% of TOPMODEL validation runs using TFM effective rainfall and 60% of those using correlation‐weighted rainfall exceeded runs using mean rainfall. Copyright © 2004 John Wiley & Sons, Ltd.
Assessment of groundwater contamination by nitrates associated with wastewater irrigation: A case study in Shijiazhuang region, China
Authors: Tang C. , Chen J. , Shindo S. , Sakura Y. , Zhang W. , Shen Y.
Published: August 2004

In arid and semi‐arid regions there is usually a shortage of irrigation water; thus, wastewater water, as well as other low‐quality water resources, may become an important source of water and nutrients. However, (pre)treated wastewater may contain elements and compounds that can damage the environment. It also has the potential to affect water quality adversely in an aquifer that may be the source of drinking water in the area. In order to assess the impacts of wastewater on the environment, groundwater samples were taken and analysed in typical croplands in the North China Plain, where urban wastewater or groundwater have been used for irrigation for several decades. Concentrations of nitrate (NO3−) in groundwater in the study area varied from 50 to 130 mg l−1 in the croplands irrigated by wastewater, but in the croplands irrigated by pumping wells, away from the Dongming Canal, NO3− concentrations are less than 35 mg l−1. It was found that values of δ15N ranged from +5 to +13‰, and dominantly from +7 to +11‰, and the NO3− concentration in most wells with depths of less than 40 m was higher than the drinking water standard set by the WHO. Cluster analysis was used to classify the spatial distribution of nitrates resulting from the wastewater. Identification of chemical patterns is found to be effective for the comprehensive assessment of the spatial distribution of groundwater quality. It is also emphasized that the wastewater in this area controls the NO3− distribution in the groundwater, and should be used carefully to protect both soil and groundwater from NO3− pollution. Copyright © 2004 John Wiley & Sons, Ltd.
The renewability of water resources and its quantification in the Yellow River basin, China
Authors: Xia Jun , Wang Zhonggen , Wang Gangsheng , Tan Ge
Published: August 2004

The drying‐up events in the lower reaches of the Yellow River during the 1990s, which were the most serious problem of water resources issues in China, initiated this study of the concept of water resources renewability in the Yellow River basin. The problem of renewability linked with hydrological process impacted by climate change and human activity is addressed. A quantitative method was developed to analyse causes and propose countermeasures to improve renewability of water resources. The magnitude of renewability change in time and space within the river system can be represented using this method. According to the analysis using an observation data set, it is shown that the renewability of water resources of the Yellow Rive basin has had a significant declining trend since the 1950s. In particular, the renewability indicator in the downstream reaches was reduced to 0·2 during a bad situation during the 1990s. Using the renewability assessment, feasible strategies can be analysed and suggested. Copyright © 2004 John Wiley & Sons, Ltd.
Seasonal variation of energy partitioning in irrigated lands
Authors: Shen Yanjun , Zhang Yongqiang , Kondoh Akihiko , Tang Changyuan , Chen Jianyao , Xiao Jieying , Sakura Yasuo , Liu Changming , Sun Hongyong
Published: August 2004

The energy balance components were measured above the surface of an irrigated wheat and maize field over three successive years using the Bowen ratio technique. The experiments were carried out at Luancheng Experimental Station of Agro‐ecosystem (LESA), Heibei, China, from December 1999 through to September 2001. The seasonal course of energy balance over an irrigated field, the diurnal Bowen ratio patterns in different seasons, and the effect of leaf‐area index (LAI) and soil moisture on the energy balance are discussed. Over 3 years, the net radiation Rn varied from 31·6 to 668 · 1 W m−2, and the soil heat flux G varied from −12 · 7 to 170 · 9 W m−2. The latent heat flux LE also shows apparent correspondence with the development of phenology, e.g. LAI. The diurnal course of the Bowen ratio in different seasons can be categorized into three typical patterns: (1) a ‘wheat pattern’, characterized by a steep morning peak followed by a decrease with the daytime mean value of around 0·30; (2) a ‘maize pattern’, which is a relatively flat course with a daytime mean β of around 0·20–0·25; and (3) a ‘winter pattern’, with a near‐noon high peak with a daytime mean β of more than 10 times that those for wheat or maize. There are linear correlations between evaporative fraction (EF) and LAI for both wheat and maize before senescence seasons. The correspondence of EF appears more dependent on LAI for maize than for wheat. The EF does not appear correlated to soil water status, whereas the Bowen ratio is affected by extractable soil water content for wheat to some extent. No correlation for maize is found. Copyright © 2004 John Wiley & Sons, Ltd.
The dynamics of health in the British Household Panel Survey
Authors: Contoyannis Paul , Jones Andrew M. , Rice Nigel
Published: August 2004

This paper considers the dynamics of a categorical indicator of self‐assessed health using eight waves (1991–1998) of the British Household Panel Survey (BHPS). Our analysis has three focal points: the relative contributions of state dependence and heterogeneity in explaining the dynamics of health, the existence and consequences of health‐related sample attrition, and the investigation of the effects of measures of socioeconomic status, with a particular focus on educational attainment and income. To investigate these issues we use dynamic panel ordered probit models. There is clear evidence of health‐related attrition in the data but this does not distort the estimates of state dependence and of the socioeconomic gradient in health. The models show strong positive state dependence and heterogeneity accounts for around 30% of the unexplained variation in health. Copyright © 2004 John Wiley & Sons, Ltd.
Health care reform and the number of doctor visits—an econometric analysis
Authors: Winkelmann Rainer
Published: August 2004

This paper evaluates the German health care reform of 1997, using the individual number of doctor visits as outcome measure and data from the German Socio‐Economic Panel for the years 1995–1999. A number of modified count data models allow us to estimate the effect of the reform in different parts of the distribution. The overall effect of the reform was a 10% reduction in the number of doctor visits. The effect was much larger in the lower part of the distribution than in the upper part. Copyright © 2004 John Wiley & Sons, Ltd.
Architecture control of three‐dimensional polymeric scaffolds for soft tissue engineering. I. Establishment and validation of numerical models
Authors: Cao Yang , Davidson Malcolm R. , O'Connor Andrea J. , Stevens Geoffrey W. , Cooper‐White Justin J.
Published: August 2004

One of the most important functions of artificial three‐dimensional (3D) polymeric scaffolds is to serve as a physical support to provide tissues with an appropriate architecture for in vitro cell culture as well as in vivo tissue regeneration. The production of three‐dimensional (3D) polymeric scaffolds with tailored macroporous architecture is thus a crucial step in promoting controlled vascularization and tissue growth within host environments. In this study, 3D poly(lactic‐co‐glycolic acid) (PLGA) scaffolds were manufactured by a thermally induced phase‐separation (TIPS) technique. By controlling the quenching strategy, 3D interconnected PLGA scaffolds with tunable pore size and alignment were obtained and characterized with the use of scanning electron microscopy (SEM). A series of numerical heat‐transfer models were established in an effort to describe the cooling process within the PLGA freezing regime. Among them, a two‐dimensional (2D) solidification model has proved to be the most successful in describing the quenching of the polymer solution and has the potential to be used to infer the various 3D macroporous architectures created from different quenching conditions. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 81–89, 2004
Exchange transfusion with entirely synthetic red‐cell substitute albumin‐heme into rats: Physiological responses and blood biochemical tests
Authors: Huang Yubin , Komatsu Teruyuki , Yamamoto Hisashi , Horinouchi Hirohisa , Kobayashi Koichi , Tsuchida Eishun
Published: August 2004

Recombinant human serum albumin (rHSA) incorporating 2‐[8‐{N‐(2‐methylimidazolyl)}octanoyloxymethyl]‐5,10,15,20‐[tetrakis{α,α,α,α‐o‐(1‐methylcyclohexanoyl)amino}phenyl]porphinatoiron(II) [albumin‐heme (rHSA‐heme)] is an artificial hemoprotein which has the capability to transport O2 in vitro and in vivo. A 20% exchange transfusion with rHSA‐heme into anesthetized rats has been performed to evaluate its clinical safety by monitoring the circulation parameters and blood parameters for 6 h after the infusion. Time course changes in all parameters essentially showed the same features as those of the control group (without infusion) and rHSA group (with administration of the same amount of rHSA). Blood biochemical tests of the withdrawn plasma at 6 h after the exchange transfusion have also been carried out. No significant difference was found between the rHSA‐heme and rHSA groups, suggesting the initial clinical safety of this entirely synthetic O2‐carrier as a red‐cell substitute. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 63–69, 2004
Proteomic profiling of platelet proteins by trypsin immobilized self‐assembled monolayers digestion chip and protein identification using electrospray ionization tandem mass spectrometry
Authors: Tyan Yu‐Chang , Liao Jiunn‐Der , Jong Shiang‐Bin , Liao Pao‐Chi , Yang Ming‐Hui , Chang Yin‐Wei , Klauser Ruth , Himmelhaus Michael , Grunze Michael
Published: August 2004

Self‐assembled monolayers (SAMs) on coinage metal provide versatile modeling systems for studies of interfacial electron transfer, biological interactions, molecular recognition, and other interfacial phenomena. Recently, the bonding of enzyme to SAMs of alkanethiols onto Au electrode surfaces was exploited to produce a bio‐sensing system. In this work, the attachment of trypsin to a SAMs surface of 11‐mercaptoundecanoic acid was achieved using water soluble 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide and N‐hydroxysulfosuccinimide as coupling agent. Experimental results have revealed that the X‐ray Photoelectron Spectroscopy (XPS) C1s core levels at 286.3 and 286.5 eV (C with N), 288.1 eV (amide bond), and 289.3 eV (carboxyl) illustrate the immobilization of trypsin. These data were also in good agreement with Fourier‐Transformed Infrared Reflection‐Attenuated Total Reflection (FTIR‐ATR) spectra for the peaks valued at 1659.4 cm−1 (amide I) and 1546.6 cm−1 (amide II). Using electrospray ionization tandem mass spectrometry (ESI‐MS/MS) observations, analytical results have demonstrated the platelet proteins digestion of the immobilized trypsin on the functionalized SAMs surface. For such surfaces, platelet proteins were digested on the trypsin‐immobilized SAMs surface, which shows the enzyme digestion ability of the immobilized trypsin. The terminal groups of the SAMs structure can be further functionalized with biomolecules or antibodies to develop surface‐base diagnostics, biosensors, or biomaterials. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 90–97, 2004
The effect of different titanium and hydroxyapatite‐coated dental implant surfaces on phenotypic expression of human bone‐derived cells
Authors: Knabe Christine , Howlett Cameron Rolfe , Klar Falk , Zreiqat Hala
Published: August 2004

Roughened titanium (Ti) surfaces have been widely used for dental implants. In recent years, there has been the tendency to replace Ti plasma‐sprayed surfaces by sandblasted and acid‐etched surfaces in order to enhance osseous apposition. Another approach has been the utilization of hydroxyapatite (HA)‐coated implants. This study examines the effect of two roughened Ti dental implant surfaces on the osteoblastic phenotype of human bone–derived cells (HBDC) and compares this behavior to that for cells on an HA‐coated surface. Test materials were an acid‐etched and sandblasted Ti surface (Ti‐DPS), a porous Ti plasma‐sprayed coating (Ti‐TPS), and a plasma‐sprayed porous HA coating (HA). Smooth Ti machined surfaces served as control (Ti‐ma). HBDC were grown on the substrata for 3, 7, 14, and 21 days, counted and probed for various bone‐related mRNAs and proteins (type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase, and bone sialoprotein). All dental implant surfaces significantly affected cellular growth and the temporal expression of an array of bone‐related genes and proteins. HA‐coated Ti had the most effect on osteoblastic differentiation inducing a greater expression of an array of osteogenic markers than recorded for cells grown on Ti‐DPS and Ti‐TPS, thus suggesting that the HA‐coated surface may possess a higher potency to enhance osteogenesis. Furthermore, Ti‐DPS surfaces induced greater osteoblast proliferation and differentiation than Ti‐TPS. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 98–107, 2004
Biodegradable poly(ether‐ester) multiblock copolymers for controlled release applications: An in vivo evaluation
Authors: van Dijkhuizen‐Radersma R. , Roosma J. R. , Sohier J. , Péters F. L. A. M. A. , van den Doel M. , van Blitterswijk C. A. , de Groot K. , Bezemer J. M.
Published: August 2004

Multiblock poly(ether‐ester)s based on poly(ethylene glycol), butylene terephthalate, and butylene succinate segments were evaluated for their in vivo degradation and biocompatibility in order to establish a correlation with previously reported in vitro results. Porous polymer sheets were implanted subcutaneously for 32 weeks in rats. The degradation was monitored visually (histology), by molecular weight (GPC), and by copolymer composition (NMR). Substitution of the aromatic terephthalate units by aliphatic succinate units was shown to accelerate the degradation rate of the copolymers. Direct correlation of the in vivo and in vitro degradation of the porous implants showed a slightly faster initial molecular weight decrease in vivo. Besides hydrolysis, oxidation occurs in vivo due to the presence of radicals produced by inflammatory cells. In addition, the higher molecular weight plateau of the residue found in vivo indicated a higher solubility of the oligomers in the extracellular fluid compared to a phosphate buffer. Minor changes in the poly(ether‐ester) compositions were noted due to degradation. Microscopically, fragmentation of the porous implants was observed in time. At later stages of degradation, macrophages were observed phagocytozing small polymer particles. Both in vitro cytotoxicity studies and histology on in vivo samples proved the biocompatibility of the poly(ether‐ester)s. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 118–127, 2004
Fibrin‐filled scaffolds for bone‐tissue engineering: An in vivo study
Authors: Karp Jeffrey M. , Sarraf Feryal , Shoichet Molly S. , Davies John E.
Published: August 2004

Recently, fibrin sealants that typically contain supra physiological concentrations of fibrinogen and thrombin have been investigated as matrices to facilitate the delivery of cells within biodegradable scaffolds for tissue engineering applications. It is well known from in vitro experiments that the thrombin concentration present during fibrin polymerization influences the structural properties of fibrin, and these can affect cell invasion. This study was conducted to determine whether the structural properties of fibrin can affect bony wound healing in vivo. Drill hole defects were created in the distal femurs of 20 rats. Four experimental groups were used: nontreated defects, scaffolds alone, and scaffolds filled with fibrin polymerized with either a low thrombin concentration [fibrin(low T)] or a high thrombin concentration [fibrin(high T)]. The area of bone formed at 2, 5, and 11 days after implantation was determined histomorphometrically. After 5 days, scaffolds filled with fibrin(high T) were infiltrated with less bone than empty scaffolds (p < 0.05), but no statistical difference was found between the empty scaffolds and the scaffolds filled with fibrin(low T). After 11 days, both fibrin‐filled scaffolds significantly delayed bony wound healing (p < 0.004). Reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of the two fibrin formulations showed no difference in γ‐γ crosslink formation. This work demonstrates that fibrin sealants in their present state are not ideal for enhancing bone‐tissue invasion into scaffolds, and that the structural properties of fibrin matrices may be an important design parameter for maximizing host tissue invasion during wound healing. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 162–171, 2004
Osteogenic protein‐1 enhances osseointegration of titanium implants coated with peri‐apatite in rabbit femoral defect
Authors: Zhang Renwen , An Yuehuei , Toth Carol A. , Draughn Robert A. , Dimaano Nena M. , Hawkins Monica V.
Published: August 2004

This study evaluated the effect of osteogenic protein‐1 (OP‐1) carried by Peri‐Apatite (PA) on bone healing in the gap surrounding implants in a rabbit model. Cylindrical titanium implants (3 × 9 mm) were uniformly coated with PA precipitated from a calcium and phosphate solution. OP‐1 solution containing 60 μg OP‐1 was directly loaded on the implants immediately before implantation for the experimental group, whereas buffer solution was loaded on the implants for the control. The implant was placed in the distal femur and surrounded by a 1‐mm gap. The implants were retrieved and examined 6 weeks after implantation. Mechanical testing (push‐out) data showed that OP‐1 enhanced implant fixation by 80%. Histomorphometric measurements indicated that bone ingrowth in the initial gap expressed as a percentage of the whole gap was significantly higher in the specimens treated with OP‐1 than the control group (25.4% vs. 8.9%, p < 0.05). The percentage of the surface of implants, which was covered by bone, was significantly higher in the OP‐1‐treated group compared to the control group (65% vs. 25%, p < 0.05). This study suggests that OP‐1 can be loaded on orthopedic implants through PA to enhance the osseointegration of orthopedic implant. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 408–413, 2004
FTIR study of carbonate loss from carbonated apatites in the wide temperature range
Authors: Rau J.V. , Cesaro S. Nunziante , Ferro D. , Barinov S.M. , Fadeeva I.V.
Published: August 2004

The mineral constituent of bone tissue is a carbonate‐substituted apatite (CHA). The thermal stability of the CHA has been revealed to depend on the substitution type and degree, although relatively little is known about this behavior. The aim of this study was to investigate the carbonate loss from synthetic CHAs in equilibrium conditions in a wide temperature range. An approach based on FTIR spectroscopy of condensed gas phase was applied to evaluate the CO and CO2 release with increasing temperature. Four different CHAs were studied, which were prepared by either precipitation from solution or the solid‐state interaction. The samples differ from each other by the substitution degree. In one of the samples calcium was partially substituted by magnesium. Decomposition was shown to start at surprisingly low temperature, about 400°C, and the CO content increases monotonously with the increase of temperature. The CO2 content goes through a maximum due to its decomposition into carbon monoxide and oxygen, the temperature of this maximum being strongly dependent on the chemical synthesis route. Therefore, control of the sintering atmosphere with respect to the CO2/CO ratio is needed when preparing the carbonated apatite bioceramics. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 441–447, 2004
In vivo performance of dual ligand augmented endothelialized expanded polytetrafluoroethylene vascular grafts
Authors: Chan Bernard P. , Liu Wenge , Klitzman Bruce , Reichert William M. , Truskey George A.
Published: August 2004

In this study, we examined combinations of three approaches to improve the adhesion of endothelial cells (EC) onto expanded polytetrafluoroethylene (ePTFE) vascular grafts placed at the femoral artery of rats: (1) high‐affinity receptor‐ligand binding of RGD–streptavidin (SA) and biotin to supplement integrin‐mediated EC adhesion; (2) cell sodding to pressurize the seeded EC into the interstices of the ePTFE grafts; and (3) longer postseeding attachment time from 1 to 24 h prior to implantation. An in vitro system, which accounts for cell loss due to both graft handling and shear stress, was designed to optimize conditions for in vivo experiments. Results suggest that longer in vitro attachment time enabled the adherent EC to endure mechanical stresses by forming strong adhesions to the underlying extracellular matrix substrates; cell sodding helped to retain the adherent EC by physically docking the cells against the graft interstices; and the SA–biotin interaction enhanced the early attachment of EC but did not lead to better cell retention or reduced surface coverage of blood clot in the current study. Mechanical manipulation of cells during implantation is a limiting factor in maintaining a confluent EC layer on synthetic vascular grafts. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 52–63, 2005
Bone morphogenetic proteins in vertebrate hematopoietic development
Authors: Snyder Alexandra , Fraser Stuart T. , Baron Margaret H.
Published: August 2004

During embryonic development, the hematopoietic system is the first to generate terminally differentiated, functional cell types. The urgent necessity for the early formation of blood and blood vessels during embryogenesis means that the induction, expansion, and maturation of these systems must be rapidly and precisely controlled. Bone morphogenic proteins (BMPs) have been implicated in hematopoietic development in the vertebrate embryo and stimulate the proliferation and/or differentiation of human cord blood hematopoietic stem cells (HSC) and embryonic stem cells in vitro. Here we review the mechanisms of action and potential roles of these soluble signaling molecules in vertebrate hematopoiesis. © 2004 Wiley‐Liss, Inc.
Interactions among IQGAP1, Cdc42, and the cadherin/catenin protein complex regulate Sertoli‐germ cell adherens junction dynamics in the testis
Authors: Lui Wing Yee , Mruk Dolores D. , Cheng C. Yan
Published: August 2004

The movement of developing germ cells across the seminiferous epithelium during spermatogenesis involves extensive adherens junction (AJ) restructuring between Sertoli cells, as well as between Sertoli and germ cells. In this report, we show that the intricate interactions between Cdc42 (a Rho family protein of Mr ∼23 kDa originally identified in membranes of human platelets and placenta, and is the homolog of CDC42Sc, which is known to regulate of bud‐site assembly in Saccharomyces cerevisiae) and its effector, IQ motif containing GTPase activating protein (IQGAP1, Mr ∼189 kDa, it is also an actin‐binding protein known to interact with Cdc42 and Rac1 GTPases), regulate Sertoli‐germ cell, but not Sertoli‐Sertoli cell, AJ dynamics. Using testis lysates for immunoprecipitation (IP), IQGAP1 was shown to associate with E‐cadherin, N‐cadherin, and β‐catenin (but not β1‐integrin and nectin‐2), as well as with actin and vimentin (but not α‐tubulin). Moreover, IQGAP1 was found to localize to the periphery of both Sertoli and germ cells in the seminiferous epithelium, at sites of cell–cell contacts. Using fluorescent microscopy with dual fluorescent probes, IQGAP1 was found to co‐localize, at least in part, with N‐cadherin in the seminiferous epithelium consistent with their localization at the basal and apical ES. Using Sertoli‐germ cell cocultures, it was demonstrated that AJ assembly associated with a transient induction of Cdc42 and IQGAP1, which was not found when Sertoli cells were cultured alone. Lastly, a shift in the interactions of Cdc42, IQGAP1, β‐catenin, and N‐cadherin was detected in Sertoli‐germ cell cocultures using an Ca2+‐induced AJ disruption model, which was used to examine AJ disassembly and its reassembly. In the presence of Ca2+, IQGAP1 bound preferentially to Cdc42 rather than to β‐catenin. However, when Ca2+ was depleted from cocultures using EGTA, a Ca2+ chelating agent, IQGAP1 lost its affinity for Cdc42 and became tightly associated with β‐catenin, destabilizing cadherin‐mediated AJs between Sertoli and germ cells. Yet this shift of protein–protein interaction was not detected in Sertoli cells cultured alone. These results illustrate that the interactions among IQGAP1, Cdc42, and β‐catenin are crucial to the regulation of Sertoli‐germ cell, but not Sertoli‐Sertoli cell, AJ dynamics in the seminiferous epithelium. © 2005 Wiley‐Liss, Inc.
Chondrocytes isolated from tibial dyschondroplasia lesions and articular cartilage revert to a growth plate‐like phenotype when cultured in vitro
Authors: Wu Licia N.Y. , Ishikawa Yoshinori , Genge Brian R. , Wuthier Roy E.
Published: August 2004

We report here a comparative study of the development and behavior of chondrocytes isolated from normal growth plate tissue, tibial dyschondroplasic lesions, and from articular cartilage. The objective of these studies was to determine whether the properties exhibited by chondrocytes in dysplasic lesions or in articular cartilage were due to their cellular phenotype, their environment, or both. We had previously analyzed the electrolytes and amino acid levels in the extracellular fluid of avian growth plate chondrocytes. Using these data, we constructed a culture medium (DATP5) in which growth plate cells essentially recapitulate their normal behavior in vivo. Here, we used DATP5 to examine the behavior of chondrocytes isolated from lesions of tibial dyschondroplasia (TD). We found that once isolated from lesion and grown in this supportive medium, dysplasic chondrocytes behaved essentially like normal growth plate cells. These findings suggest that the cause of TD is local factors operating in vivo to prevent these cells from developing normally. With respect to articular chondrocytes, our data indicate that they more closely retain normal protein and proteoglycan synthesis when grown in serum‐free media. These cells readily induced mineral formation in vitro, both in the presence and absence of serum. However, in serum‐containing media, mineralization was significantly enhanced when the cells were exposed to retinoic acid (RA) or osteogenic protein‐1 (OP‐1). Our studies support previous work indicating the presence of autocrine factors produced by articular chondrocytes in vivo that prevent mineralization and preserve matrix integrity. The lack of inhibitory factors and the presence of supporting factors are likely reasons for the induction of mineralization by articular chondrocytes in vitro. © 2005 Wiley‐Liss, Inc.
Expression and localization of Muc4/sialomucin complex (SMC) in the adult and developing rat intestine: Implications for Muc4/SMC function
Authors: Rong Min , Rossi Edmund A. , Zhang Jin , McNeer Richard R. , van den Brande Jan M.H. , Yasin Mohammad , Weed Donald T. , Carothers Carraway Coralie A. , Thompson John F. , Carraway Kermit L.
Published: August 2004

Muc4/sialomucin complex (SMC) is a high molecular mass heterodimeric membrane mucin, encoded by a single gene, and originally discovered in a highly metastatic ascites rat mammary adenocarcinoma. Subsequent studies have shown that it is a prominent component of many accessible and vulnerable epithelia, including the gastrointestinal tract. Immunoblot and immunofluorescence analyses demonstrated that Muc4/SMC expression in the rat small intestine increases from proximal to distal regions and is located predominantly in cells at the base of the crypts. These cells were postulated to be Paneth cells, based on their location, morphology, and secretory granule content. Immunohistochemistry indicated the presence of Muc4/SMC in these granules. Muc4/SMC expression was higher in the rat colon than small intestine and was abundantly present in colonic goblet cells, but not in goblet cells in the small intestine. Immunohistochemistry also suggested the presence of MUC4 in human colonic goblet cells. Biochemical analyses indicated that rat colonic Muc4/SMC is primarily the soluble form of the membrane mucin. Analyses of Muc4/SMC during development of the rat gastrointestinal tract showed its appearance at embryonic day 14 of the esophagus and at day 15 at the surface of the undifferentiated stratified epithelium at the gastroduodenal junction, then later at cell surfaces in the more distal regions of the differentiated epithelium of the small intestine, culminating in expression as an intracellular form in the crypts of the small intestine at about day 21. Limited expression in the colon was observed during development before birth at cell surfaces, with expression as an intracellular form in the goblet cells arising during the second week after birth. These results suggest that membrane mucin Muc4/SMC serves different functions during development of the intestine in the rat, but is primarily a secreted product in the adult animal. © 2005 Wiley‐Liss, Inc.
Lineage‐negative bone marrow cells travel bidirectionally in the olfactory migratory stream but maintain hematopoietic phenotype
Authors: Moore Brian E. , Colvin Gerald A. , Dooner Mark S. , Quesenberry Peter J.
Published: August 2004

The mammalian olfactory system is a physiologically plastic region of the brain with the potential to support implanted stem cells. We performed direct injection of lineage‐negative (lin‐neg), green fluorescent protein‐positive (GFP+) bone marrow cells into the olfactory bulb to assess cell survival and motility within the central nervous system (CNS). Before direct injection of 100,000 lin‐neg cells, some of the C57/Bl mice received 1,000 cGy brain irradiation with the aim of disabling the endogenous reservoir of periventricular neural progenitor cells. Brain harvest took place up to 2 weeks after cell implantation. Brains were evaluated for presence of GFP positivity via fluorescence microscopy. Many GFP+ cells were identified within the turbinate neuroepithelium, olfactory bulb, and frontal lobe. Most of the cells that had traveled from the implantation site adopted an elongated, arborizing morphology consistent with cellular extensions arrayed in the direction of the rostral migratory stream (RMS). No difference was seen in brain‐irradiated versus non‐irradiated mice. Antibody staining revealed that these cells did not take on a neural, glial, or endothelial phenotype, while largely retaining their hematopoietic lineage as demonstrated by CD45 positivity. © 2005 Wiley‐Liss, Inc.
Establishment of human gastric epithelial (HGE) cell lines exhibiting barrier function, progenitor, and prezymogenic characteristics
Authors: Chailler Pierre , Ménard Daniel
Published: August 2004

The unavailability of human cell lines representative of the gastric glandular epithelium while able to form a functional barrier restricts the application of a cell culture approach to the field of gastric epithelial physiology. In the current study, we have characterized new non‐transfected clones isolated from gastric carcinoma cell lines known to express functional markers of the human gastric mucosa (J Cell Biochem 2001;81:241). Twenty‐one clones exhibiting epithelial‐type junctions (renamed HGE cell lines) were isolated from NCI‐N87 (ATCC CRL 5822), whereas only squamous cell lines could be generated from other native strains. Of these 21 clones, HGE‐17 and HGE‐20 formed dense coherent monolayers and displayed true epithelial phenotype. E‐cadherin and ZO‐1 proteins were consistently localized at the periphery of all cells which also generated transepithelial electrical resistance. Moreover, growth factors known to be trophic for the gastric mucosa were able to stimulate mitogenesis at subconfluence. HGE‐17 exhibited a poorly differentiated precursor‐like status and responded strongly to EGF/TGFα treatment in restitution assays. HGE‐20 cells, on the other hand, exhibited a higher degree of differentiation at the ultrastructural level as well as higher gastric lipase and pepsinogen levels. These latter zymogens were compartmentalized into granules which also contained mucin‐6 (MUC6, prezymogenic‐like status). Exogenous hormones, i.e., 1 μg/ml hydrocortisone and 5 μM retinoic acid, significantly increased enzyme levels in HGE‐20. In conclusion, HGE‐17 and HGE‐20 represent the first human gastric cell lines with true epithelial characteristics, opening a venue to important applications for the study of re‐epithelization, permeability, and regulation of digestive functions in the context of gastric physiology and pathology. © 2005 Wiley‐Liss, Inc.