bluuebunny/crossref_metadata_2025 huggingface dataset:
Cherry Picking: Should Sellers Let Buyers Sort?
Authors: Ferrier Peyton M
Published: December 2007

Agricultural goods sold in supermarkets often vary significantly in quality. Yet, when these goods are sold at a single price, consumers may expend significant time and effort to sort goods for quality. From the standpoint of sellers, the resources expended on sorting only serve to reallocate high quality goods to consumers who sort intensively and low quality goods to consumers who sort minimally or not at all. Because these lower quality goods are less attractive to consumers who do not sort, sellers may be forced to lower prices. Why then do sellers allow sorting when they might prevent it?This paper presents a demand model where sellers choose whether to allow sorting. Sellers may allow consumer sorting when it fosters the distribution of qualities that occurs under quality discrimination, despite the associated reduction in the total gains to trade through sorting costs and quality efficiency loss. In general, sorting may allow sellers to improve the quality of goods for marginal consumers who constrain price-setting for sellers with market power. The total effect on price, amount sold and welfare is ambiguous due to the role of market power. Simulations are provided to demonstrate these effects.
European Union Policy on Bioenergy and the Role of Sustainability Criteria and Certification Systems
Authors: Schlegel Stephanie , Kaphengst Timo
Published: December 2007

The EU has set ambitious targets to raise the share of renewable energies, particularly biofuels. With an increasingly controversial public debate and more scientific evidence about the downsites of biofuels, recently the European Unions biofuel targets have been bound to the condition that they have to be produced sustainable. Therefore the European Commission is currently developing sustainability criteria for biofuels.Establishing certification schemes is a possible strategy to ensure that bioenergy crops are produced in a sustainable manner. However, many questions with regard to the design and implementation of sustainability criteria and certification schemes remain unsolved.This article discusses the role that bioenergy plays in the European policy context and the approach the EU is currently following in order to ensure the sustainability of biofuels. It addresses the limits of the chosen approach, concluding that certification schemes can not serve as the only safeguard for sustainable bioenergy, but need to be complemented by other tools and policies.
Catalyst-Adsorbent Configurations in Enhancing Adsorptive Reactor Performance
Authors: Rawadieh Saleh , Gomes Vincent G
Published: December 2007

Fixed-bed columns containing solid catalysts and adsorbents were employed for simultaneous reaction and separation. The models developed for propene metathesis were validated with experimental data for configurations with and without the effect of pressure swing reaction. The models for the mass and momentum transfer in the catalyst bed and adsorber were solved using orthogonal collocation within the method of lines. The reactor/separator performances were tested for beds with varying numbers of layers of catalysts and adsorbents which were arranged sequentially. The pressure reaction columns behaved as reactor/separators in series. As the number of layers increased, a homogeneous distribution of the catalyst and adsorbent was approached in the limit. These configurations with variable catalyst/adsorbent distributions were investigated for propene metathesis reaction, in terms of product purity, selectivity, conversion, recovery, yield and productivity. Improved reactor performance was observed with a pressure swing separation system and in particular with close to well-mixed reactor/separator configurations.
MnCu Oxides for Wet Oxidation of Orange II
Authors: Castelo-Branco Isabel M. L. , Santos Regina C. , Quinta-Ferreira Rosa M.
Published: December 2007

The catalytic wet oxidation of an azo dye was investigated at 180°C and 15 bar of oxygen partial pressure. The effects of different catalysts were examined under operating conditions selected in pre-runs of non-catalytic oxidation and thermolysis (absence of oxygen). Manganese - copper catalysts with different molar ratios were tested and MnCu5 (50% Mn and 50% Cu) was found to be the most effective, giving almost complete dye degradation and 56.8% TOC removal after 60 minutes of reaction. Moreover, this catalyst revealed to be stable regarding metal leaching and catalyst poisoning due to sulphur or carbon depositions.
CFD Simulation of Fluid Dynamics in a Gas-Solid Jetting Fluidized Bed
Authors: Wang Qicheng , Zhang Kai , Sun Guogang , Brandani Stefano , Gao Jinsen , Jiang Jianchun
Published: December 2007

A thorough understanding of fundamental parameters, such as transient and time-averaged gas and solid velocities, is helpful for designing and manipulating the gas-solid jetting fluidized beds. In this study, a new two-fluid model developed in our group is used to investigate numerically the gas and solid velocities in the gas-solid jetting fluidized beds by adding the user-defined Fortran subroutines in the platform of CFX 4.4, a commercial CFD software package. Simulation is carried out in a two-dimensional fluidized bed 2.0 m high and 0.3 m wide equipped with a nozzle in the centre at the inlet. Resin, belonging to Geldart B Group, is selected as the solid material. The numerical results show that the solid movement is predominantly upward in the center of the bed, whilst it is primarily downward in the outer region of the bed. Particles exchange between these two regions across their neighboring boundary. Gas interchange between the jet and the emulsion phase becomes obvious with the jet evolution. The time-averaged distributions of gas and solid velocities in the bed are greatly influenced by jet gas velocity, and the effect of the static bed height can be ignored. These numerical computations provide helpful information for designing and scaling up the jetting fluidized bed.
Ni-MCM-41 Type Mesoporous Catalysts Synthesized by One-Pot Hydrothermal Procedure for Steam Reforming of Ethanol
Authors: Ozdogan Ekin , Dogu Timur , Dogu Gulsen
Published: December 2007

In the present study, Ni incorporated MCM-41 structured mesoporous catalysts with a Ni/Si atomic ratio of 0.036 and 0.15 were prepared by a direct hydrothermal synthesis procedure. These catalysts had surface area values of 860.5 m2/g (Ni-MCM-41 having a Ni/Si ratio of 0.036) and 944.9 m2/g (Ni-MCM-41 having a Ni/Si ratio of 0.15). They also had narrow pore size distributions with average pore diameters of 2.7-2.6 nm respectively. Ni MCM-41 synthesized by the one-pot hydrothermal synthesis procedure showed very high activity and relatively high hydrogen yield in steam reforming of ethanol in a temperature range between 300-550°C. Besides the steam reforming reaction, formation of some formaldehyde and small amounts of ethylene were also observed at low temperatures for the catalyst containing a Ni/Si ratio of 0.036. The disappearance of formaldehyde and the formation of some methane at high temperatures indicated the increased significance of cracking in addition to reforming and dehydration reactions. The increase of the Ni/Si ratio makes the catalyst more active at lower temperatures.
Advances in Chemical Oxidation of Total Reduced Sulfur from Kraft Mills Atmospheric Effluents
Authors: Petre Catalin Florin , Piché Simon , Normandin André , Larachi Faical
Published: December 2007

Chemical oxidation techniques in use for the reduction of malodorous total reduced sulfur (TRS) emissions in the kraft mills atmospheric effluents were reviewed with an emphasis on recent industrial improvements in chlorine dioxide (ClO2) oxidation of TRS as well as on laboratory developments of an iron-based chemistry process. The ClO2 approach was implemented successfully at the industrial scale in two Québec kraft mills. The approach consisted in mixing the non-condensable gases (NCG) containing the TRS with gaseous chlorine dioxide obtained either as a residue from a bleach plant vent stream or through vaporization of fresh solution. Full-scale tests have shown that the amount of chlorine dioxide injected or mixed in the NCG was sufficient to reduce the TRS load below the 10 ppmv-regulated levels in a cost efficient way as compared with incineration. A prospective approach validated in laboratory conditions and using the iron redox chemistry for alkaline oxidative scrubbing of TRS is being investigated at Laval University to reduce the odor pollution and to convert TRS into valuable sulfur. Two configurations were evaluated, one consisting of homogeneous Fe(III) sequestered in trans-1,2-diaminocyclohexanetetraacetic acid (cdta) chelates and another of heterogeneous Fe(III) as Fe/Ce oxides-hydroxides mixtures. The relative performances, advantages and weaknesses of the various chemical oxidation processes were discussed. In addition, the fundamentals of the alkaline oxidative scrubbing of TRS using the iron-based alkaline approach were summarized in terms of the gas-liquid thermodynamic equilibria and of the homogeneous and heterogeneous iron redox reactions.
The Dissolution Kinetics of Tincal in Phosphoric Acid Solutions
Authors: Abali Yuksel , Bayca Salih U , Guler Ayse E
Published: December 2007

In this study, the dissolution kinetics of tincal in phosphoric acid solutions was investigated. The effects of reaction temperature, acid concentration, solid to liquid ratio, particle size and stirring speed were determined in the experiments. The results showed that the dissolution rate increased with increasing acid concentration, reaction temperature, stirring speed and increased with decreasing particle size and solid to liquid ratio. The dissolution rate was found to be based on the first order pseudo homogenous reaction model. The activation energy of the tincal in phosphoric acid solution was determined as 42.28 kJ.mol-1.
SFGP 2007 - Natural Gas/Hydrogen Mixture Combustion in a Porous Radiant Burner
Authors: Gauthier Ségolène , Lebas Etienne , Baillis Dominique
Published: December 2007

Within the context of reducing the green house gas emissions, substituting hydrogen for natural gas could have a great environmental impact, but hydrogen has different combustion characteristics than natural gas. This paper reports results of experimental tests of premixed combustion of natural gas-hydrogen mixtures in a porous burner made of open cell metallic foam. The technology of porous radiant burners shows environmental and economical advantages compared to traditional diffusion flame burners. The tests showed that substituting natural gas for hydrogen in a porous burner reduces the pollutant emissions of CO and NOx and the quantity of CO2 produced. For specific powers below 500 kW/m2, the emissions were below the "Blue Angel" label values. But working conditions are limited by hydrogen addition and the equivalence ratio has to be lowered to prevent flashback. The radiant combustion mode is more difficult to obtain with mixtures containing hydrogen and it disappears completely for mixtures with more than 80% vol. hydrogen.
Vulnerability Assessment of Power Grid Using Graph Topological Indices
Authors: Kim Charles J , Obah Obinna B
Published: December 2007

This paper presents an assessment of the vulnerability of the power grid to blackout using graph topological indexes. Based on a FERC 715 report and the outage reports, the cascading faults of summer WSCC 1996 are reconstructed, and the graphical property of the grid is compared between two cases: when the blackout triggering lines are removed simulating the actual sequence of cascading outages and when the same number of randomly selected lines are removed. The investigation finds that the critical path lengths of the triggering events of the July and August outages of 1996 WSCC blackout are higher than those of no-outage and arbitrary events. In addition, the small world-ness index for each of the outage triggering events is much smaller than that of normal or any no-outage scenario, indicating that events of shifting a network from small world to a random network would be more likely cascaded to wide area outage.
Engineering Research to Improve Cassava Processing Technology
Authors: Kolawole Oladele Peter , Agbetoye Leo Ayodeji Sunday
Published: December 2007

Cassava is an important food crop, and equipment development for processing it in the developing world requires more research as industrial processing of cassava is still limited. Research efforts made by local engineers need scientific improvement to meet the Millennium Development Goals (MDGs), aimed at poverty reduction over a stipulated period of time with globally defined measurable indicators of progress. The World Summit on Sustainable Development (WSSD), the Report of the Commission for Africa (popularly referred to as the Tony Blair Report), and the New Partnership for African Development (NEPAD) are targeted at re-positioning Africa in the world economy. The need for rapid cassava processing equipment and new equipment development to significantly improve stages involved in its production process is highlighted in this paper.
The Katrina Effect: Was There a Bright Side to the Evacuation of Greater New Orleans?
Authors: Vigdor Jacob L
Published: December 2007

This paper uses longitudinal data from Current Population Surveys conducted between 2004 and 2006 to estimate the net impact of Hurricane Katrina-related evacuation on various indicators of well-being. While evacuees who have returned to the affected region show evidence of returning to normalcy in terms of labor supply and earnings, those who persisted in other locations exhibit large and persistent gaps, even relative to the poor outcomes of individuals destined to become evacuees observed prior to Katrina. Evacuee outcomes are not demonstrably better in destination communities with lower initial unemployment or higher growth rates. The impact of evacuation on total income was blunted to some extent by government transfer payments and by self-employment activities. Overall, there is little evidence to support the notion that poor underemployed residents of the New Orleans area were disadvantaged by their location in a relatively depressed region.
Proposal for a standardised identification of the mono‐exponential terminal phase for orally administered drugs
Authors: Scheerans Christian , Derendorf Hartmut , Kloft Charlotte
Published: December 2007

The area under the plasma concentration‐time curve from time zero to infinity (AUC0–inf) is generally considered to be the most appropriate measure of total drug exposure for bioavailability/bioequivalence studies of orally administered drugs. However, the lack of a standardised method for identifying the mono‐exponential terminal phase of the concentration‐time curve causes variability for the estimated AUC0–inf. The present investigation introduces a simple method, called the two times tmax method (TTT method) to reliably identify the mono‐exponential terminal phase in the case of oral administration. The new method was tested by Monte Carlo simulation in Excel and compared with the adjusted r squared algorithm (ARS algorithm) frequently used in pharmacokinetic software programs. Statistical diagnostics of three different scenarios, each with 10 000 hypothetical patients showed that the new method provided unbiased average AUC0–inf estimates for orally administered drugs with a monophasic concentration‐time curve post maximum concentration. In addition, the TTT method generally provided more precise estimates for AUC0–inf compared with the ARS algorithm. It was concluded that the TTT method is a most reasonable tool to be used as a standardised method in pharmacokinetic analysis especially bioequivalence studies to reliably identify the mono‐exponential terminal phase for orally administered drugs showing a monophasic concentration‐time profile. Copyright © 2007 John Wiley & Sons, Ltd.
Molecular basis for skeletal variation: insights from developmental genetic studies in mice
Authors: Kappen C. , Neubüser A. , Balling R. , Finnell R.
Published: December 2007

Skeletal variations are common in humans, and potentially are caused by genetic as well as environmental factors. We here review molecular principles in skeletal development to develop a knowledge base of possible alterations that could explain variations in skeletal element number, shape or size. Environmental agents that induce variations, such as teratogens, likely interact with the molecular pathways that regulate skeletal development.Birth Defects Res (Part B), 80:425–450, 2007. © 2007 Wiley‐Liss, Inc.
Materialgesetz‐Formulierung für Riss‐Kontaktelemente in FEM‐Berechnungen
Authors: Fischer Jürgen
Published: December 2007

Bei FEM‐Berechnungen von Stahlbetontragwerken mit diskretem Rissverlauf unter Verwendung von Kontaktelementen besteht bei Mixed‐Mode Beanspruchungen der Risse die Schwierigkeit, dass hierfür keine allgemein anerkannten Materialgesetzformulierungen existieren. Es wird daher ein Vorschlag unterbreitet, wie ein solches Materialgesetz für die Kontaktelemente aussehen könnte, welches eine Kopplung des Rissverhaltens senkrecht und parallel zum Riss berücksichtigt und auf bisher vorliegenden Forschungsergebnissen basiert. Am Beispiel von Dübelauszugsversuchen wird gezeigt, dass mit diesem Vorschlag sehr gute Ergebnisse erzielt werden können.
Low‐temperature synthesis of 2′‐deoxyadenosine using immobilized psychrotrophic microorganisms
Authors: Fernández‐Lucas J. , Condezo L.A. , Quezada M.A. , Sinisterra J.V.
Published: December 2007

Selective biocatalyzed synthesis of 2′‐deoxyadenosine from 2′‐deoxypyrimidine nucleosides was carried out using free or immobilized whole cells. The reaction was performed at 57°C without secondary reactions. Two psychrotrophic microorganisms, Bacillus psychrosaccharolyticus and Psychrobacter immobilis, are described for the first time as active and specific strains for the synthesis of 2′‐deoxyadenosine. Adenosine deaminase activity was not detected. Whole cells were immobilized in different matrixes. Calcium alginate and calcium pectate gave the best biocatalysts. The synthesis of 2′‐deoxyadenosine follows an apparent first order kinetic expression. External mass transfer control was negligible as deduced from ks, NA, and Ω values. Internal mass transfer was the rate controlling step according to ηT and ϕ values. Biotechnol. Bioeng. 2008;100: 213–222. © 2007 Wiley Periodicals, Inc.
An efficient approach to automate the manual trial and error calibration of activated sludge models
Authors: Sin Gürkan , De Pauw Dirk J.W. , Weijers Stefan , Vanrolleghem Peter A.
Published: December 2007

An efficient approach is introduced to help automate the rather tedious manual trial and error way of model calibration currently used in activated sludge modeling practice. To this end, we have evaluated a Monte Carlo based calibration approach consisting of four steps: (i) parameter subset selection, (ii) defining parameter space, (iii) parameter sampling for Monte Carlo simulations and (iv) selecting the best Monte Carlo simulation thereby providing the calibrated parameter values. The approach was evaluated on a formerly calibrated full‐scale ASM2d model for a domestic plant (located in The Netherlands), using in total 3 months of dynamic oxygen, ammonia and nitrate sensor data. The Monte Carlo calibrated model was validated successfully using ammonia, oxygen and nitrate data collected at high measurement frequency. Statistical analysis of the residuals using mean absolute error (MAE), root mean square error (RMSE) and Janus coefficient showed that the calibrated model was able to provide statistically accurate and valid predictions for ammonium, oxygen and nitrate. This shows that this pragmatic approach can perform the task of model calibration and therefore be used in practice to save the valuable time of modelers spent on this step of activated sludge modeling. The high computational demand is a downside of this approach but this can be overcome by using distributed computing. Overall we expect that the use of such systems analysis tools in the application of activated sludge models will improve the quality of model predictions and their use in decision making. Biotechnol. Bioeng. 2008;100: 516–528. © 2007 Wiley Periodicals, Inc.
Efficiency assessment of the one‐step production of astaxanthin by the microalga Haematococcus pluvialis
Authors: Del Río Esperanza , Acién F. Gabriel , García‐Malea M. Carmen , Rivas Joaquín , Molina‐Grima Emilio , Guerrero Miguel G.
Published: December 2007

Continuous cultivation of Haematococcus pluvialis under moderate nitrogen limitation represents a straightforward strategy, alternative to the classical two‐stage approach, for astaxanthin production by this microalga. Performance of the one‐step system has now been validated for more than 40 combinations of dilution rate, nitrate concentration in the feed medium, and incident irradiance, steady state conditions being achieved and maintained in all instances. Specific nitrate input and average irradiance were decisive parameters in determining astaxanthin content of the biomass, as well as productivity of the system. The growth rate of the continuous photoautotrophic cultures was a hyperbolic function of average irradiance. As long as specific nitrate input was above the threshold value of 2.7 mmol/g day, cells performed green and astaxanthin was present at basal levels only. Below the threshold value, under moderate nitrogen limitation conditions, astaxanthin accumulated to reach cellular levels of up to 1.1% of the dry biomass. Increasing irradiance resulted in enhancement of astaxanthin accumulation when nitrogen input was limiting, but never under nitrogen sufficiency. Mean daily productivity values of 20.8 ± 2.8 mg astaxanthin/L day (1.9 ± 0.3 g dry biomass/L day) were consistently achieved for a specific nitrate input of about 0.8 mmol/g day and an average irradiance range of 77–110 µE/m2 s. Models relating growth rate and astaxanthin accumulation with both average irradiance and specific nitrate input fitted accurately experimental data. Simulations provided support to the contention of achieving efficient production of the carotenoid through convenient adjustment of the determining parameters, and yielded productivity estimates for the one‐step system higher than 60 mg astaxanthin/L day. The demonstrated capabilities of this production system, as well as its product quality, made it a real alternative to the current two‐stage system for the production of astaxanthin‐rich biomass. Biotechnol. Bioeng. 2008;100: 397–402. © 2007 Wiley Periodicals, Inc.
Simultaneous nitrification, denitrification, and phosphorus removal from nutrient‐rich industrial wastewater using granular sludge
Authors: Yilmaz Gulsum , Lemaire Romain , Keller Jurg , Yuan Zhiguo
Published: December 2007

The biological removal of nitrogen and phosphorus from nutrient‐rich abattoir wastewater using granular sludge has been investigated. A lab‐scale sequencing batch reactor, seeded with granular sludge developed using synthetic wastewater, was operated for 13 months under alternating anaerobic and aerobic conditions. It is demonstrated that the granules could be sustained and indeed further developed with the use of abattoir wastewater. The organic, nitrogen, and phosphorus loading rates applied were 2.7 gCOD L−1 day−1, 0.43 gN L−1 day−1, and 0.06 gP L−1 day−1, respectively. The removal efficiency of soluble COD, soluble nitrogen and soluble phosphorus were 85%, 93%, and 89%, respectively. However, the high suspended solids in the effluent limited the overall removal efficiency to 68%, 86%, and 74% for total COD, TN, and TP, respectively. This good nutrient removal was achieved through the process known as simultaneous nitrification, denitrification, and phosphorus removal, likely facilitated by the presence of large anoxic zones in the center of the granules. The removal of nitrogen was likely via nitrite optimizing the use of the limited COD available in the wastewater. Accumulibacter spp. were found to be responsible for most of the denitrification, further reducing the COD requirement for nitrogen and phosphorus removal. Mineral precipitation was evaluated and was not found to significantly contribute to the overall nutrient removal. It is also shown that the minimum HRT in a granular sludge system is not governed by the sludge settleability, as is the case with floccular sludge systems, but likely by the limitations associated with the transfer of substrates in granules. Biotechnol. Bioeng. 2008;100: 529–541. © 2007 Wiley Periodicals, Inc.
Surfactants from Biomass: A Two‐Step Cascade Reaction for the Synthesis of Sorbitol Fatty Acid Esters Using Solid Acid Catalysts
Authors: Corma Avelino , Hamid Sharifah B. A. , Iborra Sara , Velty Alexandra
Published: December 2007

Sorbitol fatty esters have been prepared through a two‐step catalytic process which involves the protection of the polyalcohol by ketalization followed by esterification with the fatty acid. Inorganic molecular sieves with different pore topologies as well as heteropolyacids (HPA) were used as acid catalysts to perform both the ketalization and the esterification step. These catalysts are found to hydrolyze the ketal function and promote the esterification between the free hydroxy groups and oleic acid in a cascade process. The results show a positive shape‐selectivity effect when the process is carried out using tridirectional, and especially monodirectional (mordenite), zeolites, such that the ratio of mono‐ to higher esters and the hydroxy number of the final product are increased as compared to those obtained for the homogeneous‐catalyzed process.
Adolescent depression: diagnosis, treatment, and educational attainment
Authors: Fletcher Jason M.
Published: December 2007

In this paper, I use nationally representative longitudinal data to examine adolescent depression and educational attainment. First, I examine the individual, family, and community‐level determinants of adolescent depression, diagnosis, and treatment. I find that male and minority adolescents who score high on depression scales are less likely to be diagnosed as depressed or receive treatment than female and non‐Hispanic white adolescents. Additionally, I find several community‐level variables to be important determinants of depression, diagnosis, and treatment. Second, I examine the importance of adolescent depression for educational attainment. Although it is uncontroversial to expect a negative relationship, most previous research uses cross‐sectional data, making it difficult to adequately determine the magnitude of the effect. I find that depressive symptoms are related to educational attainment along multiple margins: dropping out of high school, college enrollment, and college type. These relationships are only found for adolescent females, and there are several interesting results across income groups. Overall, these findings suggest that further attempts to diagnose and treat adolescents with depressive symptoms are needed and that additional treatment options may be required to combat the important relationship between adolescent depression and human capital accumulation for females. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of weight loss on outcomes in patients with head and neck cancer undergoing concomitant chemoradiotherapy
Authors: Capuano Giorgio , Grosso Alessandra , Gentile Pier Carlo , Battista Michele , Bianciardi Federico , Di Palma Annamaria , Pavese Ida , Satta Francesco , Tosti Michela , Palladino Anna , Coiro Guido , Di Palma Mario
Published: December 2007

Background.

The purpose of this study was to determine the influence of weight loss on outcome in patients with head and neck cancer undergoing concomitant chemoradiotherapy (CCRT): treatment interruption, infections, mortality, and hospital readmission rate.

Methods.

Forty patients with head and neck cancer were enrolled. All patients were counseled to follow a nutritional program during CCRT. Body weight was evaluated at baseline, at the end, and 30 days after radiochemotherapy.

Results.

Ninety percent of compliant patients with nutritional program maintained body weight (mean, 1 ± 2.4 kg) and 100% of noncompliant patients continued to lose weight (mean, −9 ± 4 kg; p < .001). A reduction greater than 20% of prediagnosis weight significantly correlated with treatment interruption (p = .003), infections (p = .002), early mortality (p = .011), hospital readmission rate (p = .001), and survival (log‐rank test: z = −2.722, p = .006).

Conclusion.

In patients with head and neck cancer undergoing CCRT, the early nutritional management reduces weight loss and improve outcome. © 2007 Wiley Periodicals, Inc. Head Neck, 2008
Undifferentiated pleomorphic sarcoma of the parotid gland: A rare pediatric case
Authors: Chang Ray C. , Dave Sandeep P. , Robinson Philip G.
Published: December 2007

Background.

Undifferentiated pleomorphic sarcoma, or malignant fibrous histiocytoma (MFH) of the head and neck is an uncommon malignancy that is exceedingly rare in the pediatric population. Although MFH was once considered the most common soft tissue sarcoma in adults, recently authors have questioned its existence as a distinct pathologic entity.

Methods.

In light of this debate, we present a case of MFH with giant cells involving the parotid gland, and we review its pathology.

Results.

We describe a 6‐year‐old male with parotid gland MFH. Diagnosis was fraught with difficulty, typical of this disease. He was treated with a combination of chemotherapy and radiation therapy with a good initial response.

Conclusion.

The classification of MFH has been recently debated. Nevertheless, our case is the second report of pediatric MFH involving the parotid gland. Surgical resection is the preferred treatment, but combined chemoradiation may be necessary in the head and neck region. © 2007 Wiley Periodicals, Inc. Head Neck, 2008
Adenosine monophosphate–activated protein kinase modulates the activated phenotype of hepatic stellate cells
Authors: Caligiuri Alessandra , Bertolani Cristiana , Guerra Cristina Tosti , Aleffi Sara , Galastri Sara , Trappoliere Marco , Vizzutti Francesco , Gelmini Stefania , Laffi Giacomo , Pinzani Massimo , Marra Fabio
Published: December 2007

Adiponectin limits the development of liver fibrosis and activates adenosine monophosphate–activated protein kinase (AMPK). AMPK is a sensor of the cellular energy status, but its possible modulation of the fibrogenic properties of hepatic stellate cells (HSCs) has not been established. In this study, we investigated the role of AMPK activation in the biology of activated human HSCs. A time-dependent activation of AMPK was observed in response to a number of stimuli, including globular adiponectin, 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR), or metformin. All these compounds significantly inhibited platelet-derived growth factor (PDGF)-stimulated proliferation and migration of human HSCs and reduced the secretion of monocyte chemoattractant protein-1. In addition, AICAR limited the secretion of type I procollagen. Knockdown of AMPK by gene silencing increased the mitogenic effects of PDGF, confirming the negative modulation exerted by this pathway on HSCs. AMPK activation did not reduce PDGF-dependent activation of extracellular signal-regulated kinase (ERK) or Akt at early time points, whereas a marked inhibition was observed 24 hours after addition of PDGF, reflecting a block in cell cycle progression. In contrast, AICAR blocked short-term phosphorylation of ribosomal S6 kinase (p70S6K) and 4E binding protein-1 (4EBP1), 2 downstream effectors of the mammalian target of rapamycin (mTOR) pathway, by PDGF. The ability of interleukin-a (IL-1) to activate nuclear factor kappa B (NF-κB) was also reduced by AICAR.

Conclusion

: Activation of AMPK negatively modulates the activated phenotype of HSCs. (Hepatology 2007.)
Epithelial expression of angiogenic growth factors modulate arterial vasculogenesis in human liver development
Authors: Fabris Luca , Cadamuro Massimiliano , Libbrecht Louis , Raynaud Peggy , Spirlì Carlo , Fiorotto Romina , Okolicsanyi Lajos , Lemaigre Frederic , Strazzabosco Mario , Roskams Tania
Published: December 2007

Intrahepatic bile ducts maintain a close anatomical relationship with hepatic arteries. During liver ontogenesis, the development of the hepatic artery appears to be modulated by unknown signals originating from the bile duct. Given the capability of cholangiocytes to produce angiogenic growth factors and influence peribiliary vascularization, we studied the immunohistochemical expression of vascular endothelial growth factor (VEGF), angiopoietin-1, angiopoietin-2, and their cognate receptors (VEGFR-1, VEGFR-2, Tie-2) in fetal human livers at different gestational ages and in mice characterized by defective biliary morphogenesis (

Hnf6

−/−). The results showed that throughout the different developmental stages, VEGF was expressed by developing bile ducts and angiopoietin-1 by hepatoblasts, whereas their cognate receptors were variably expressed by vascular cells according to the different maturational stages. Precursors of endothelial and mural cells expressed VEGFR-2 and Tie-2, respectively. In immature hepatic arteries, endothelial cells expressed VEGFR-1, whereas mural cells expressed both Tie-2 and Angiopoietin-2. In mature hepatic arteries, endothelial cells expressed Tie-2 along with VEGFR-1. In early postnatal

Hnf6

−/− mice, VEGF-expressing ductal plates failed to incorporate into the portal mesenchyma, resulting in severely altered arterial vasculogenesis.

Conclusion:

The reciprocal expression of angiogenic growth factors and receptors during development supports their involvement in the cross talk between liver epithelial cells and the portal vasculature. Cholangiocytes generate a VEGF gradient that is crucial during the migratory stage, when it determines arterial vasculogenesis in their vicinity, whereas angiopoietin-1 signaling from hepatoblasts contributes to the remodeling of the hepatic artery necessary to meet the demands of the developing epithelium. (Hepatology 2008.)
The methionine connection: Homocysteine and hydrogen sulfide exert opposite effects on hepatic microcirculation in rats
Authors: Distrutti Eleonora , Mencarelli Andrea , Santucci Luca , Renga Barbara , Orlandi Stefano , Donini Annibale , Shah Vijay , Fiorucci Stefano
Published: December 2007

Increased intrahepatic resistance in cirrhotic livers is caused by endothelial dysfunction and impaired formation of two gaseous vasodilators, nitric oxide (NO) and hydrogen sulfide (H2S). Homocysteine, a sulfur-containing amino acid and H2S precursor, is formed from hepatic methionine metabolism. In the systemic circulation, hyperhomocystenemia impairs vasodilation and NO production from endothelial cells. Increased blood levels of homocysteine are common in patients with liver cirrhosis. In this study, we demonstrate that acute liver perfusion with homocysteine impairs NO formation and intrahepatic vascular relaxation induced by acetylcholine in methoxamine-precontracted normal livers (7.3% ± 3.0% versus 26% ± 2.7%;

P

< 0.0001). In rats with mild, diet-induced hyperhomocystenemia, the vasodilating activity of acetylcholine was markedly attenuated, and incremental increases in flow induced a greater percentage of increases in perfusion pressure than in control livers. Compared with normal rats, animals rendered cirrhotic by 12 weeks' administration of carbon tetrachloride exhibited a greater percentage of increments in perfusion pressure in response to shear stress (

P

< 0.05), and intrahepatic resistance to incremental increases in flow was further enhanced by homocysteine (

P

< 0.05). In normal hyperhomocysteinemic and cirrhotic rat livers, endothelial dysfunction caused by homocysteine was reversed by perfusion of the livers with sodium sulfide. Homocysteine reduced NO release from sinusoidal endothelial cells and also caused hepatic stellate cell contraction; this suggests a dual mechanism of action, with the latter effect being counteracted by H2S.

Conclusion:

Impaired vasodilation and hepatic stellate cell contraction caused by homocysteine contribute to the dynamic component of portal hypertension. (Hepatology 2008.)
Phyllanthus urinaria ameliorates the severity of nutritional steatohepatitis both in vitro and in vivo
Authors: Shen Bo , Yu Jun , Wang Shiyan , Chu Eagle S.H. , Wong V. W.S. , Zhou Xin , Lin Ge , Sung Joseph J.Y. , Chan Henry L.Y.
Published: December 2007

Hepatic oxidative stress plays a critical role in metabolic forms of steatohepatitis. Phyllanthus urinaria, an herbal medicine, has been reported to have potential antioxidant properties. We tested the effects of

P. urinaria

on nutritional steatohepatitis both

in vitro

and

in vivo

. Immortalized normal hepatocytes (AML-12) or primary hepatocytes were exposed to control, the methionine-and-choline-deficient (MCD) culture medium, in the presence or absence of

P. urinaria

for 24 hours. Hepatocyte triglyceride, release of alanine aminotransferase, lipoperoxides, and reactive oxygen species production were determined. Age-matched C57BL/6 and db/db mice were fed control or MCD diet for 10 days with or without

P. urinaria

. Hepatic steatosis, necroinflammation, triglycerides, and lipid peroxide levels were determined. Hepatic expression of inflammatory factors and lipid regulatory mediators were assayed.

P. urinaria

reduced steatosis and alanine aminotransferase (ALT) levels in culture of hepatocytes in a dose-dependent manner. Phyllanthus prevented MCD-induced hepatic fat accumulation and steatohepatitis in mice. This effect was associated with repressed levels of hepatic lipid peroxides, reduced expression of cytochrome P450-2E1, pro-inflammatory tumor necrosis factor alpha, interleukin-6, dampened activation of inflammatory c-Jun N-terminal kinase (JNK) and nuclear factor kappa B (NF-κB), increased expression of lipolytic cytochrome P450 (Cyp4a10), and suppressed transcriptional activity of lipogenic CCAAT/enhancer binding protein β (C/EBPβ). Hepatic acyl co-enzyme A oxidase that regulated hepatic beta-oxidation of fatty acid and other lipid regulators were not affected by

P. urinaria

. In conclusion,

P. urinaria

effectively alleviated the steatohepatitis induced by the MCD, probably through dampening oxidative stress, ameliorating inflammation, and decreasing lipid accumulation. (Hepatology 2008.)
Natural killer T cells exacerbate liver injury in a transforming growth factor β receptor II dominant-negative mouse model of primary biliary cirrhosis
Authors: Chuang Ya-Hui , Lian Zhe-Xiong , Yang Guo-Xiang , Shu Shang-An , Moritoki Yuki , Ridgway William M. , Ansari Aftab A. , Kronenberg Mitchell , Flavell Richard A. , Gao Bin , Gershwin Eric M.
Published: December 2007

Primary biliary cirrhosis (PBC) is an organ-specific autoimmune liver disease characterized by the presence of antimitochondrial antibodies and the destruction of small intrahepatic bile ducts with portal inflammation. In previous studies, we reported that both CD1d expression and the frequency of CD1d-restricted natural killer T (NKT) cells were increased in the livers of patients with PBC. To define a specific role of CD1d-restricted NKT cells in the pathogenesis of PBC, particularly early events, we investigated the function of hepatic CD1d-restricted NKT cells in our transforming growth factor β (TGF-β) receptor II dominant-negative (dnTGFβRII) mouse model of PBC. We generated CD1d−/− and CD1d+/− dnTGFβRII mice and performed a comparative study of liver immunopathology. We report herein that these dnTGFβRII mice demonstrate a massive increase of hyperactive CD1d-restricted NKT cells within the hepatic tissues. CD1d−/−dnTGFβRII mice, which lack CD1d-restricted CD1d-restricted NKT cells, exhibit significantly decreased hepatic lymphoid cell infiltrates and milder cholangitis compared with CD1d+/−dnTGFβRII mice. Interestingly, there was a significant increase in the production of interferon-γ in hepatic CD1d-restricted NKT cells activated by α-galactosylceramide in young but not older dnTGFβRII mice, suggesting an age-dependent role of CD1d-restricted NKT cells.

Conclusion:

These data demonstrate that CD1d-restricted NKT cells in dnTGFβRII mice are a critical factor in liver injury. (Hepatology 2008.)
Susceptibility of chimeric mice with livers repopulated by serially subcultured human hepatocytes to hepatitis B virus
Authors: Utoh Rie , Tateno Chise , Yamasaki Chihiro , Hiraga Nobuhiko , Kataoka Miho , Shimada Takashi , Chayama Kazuaki , Yoshizato Katsutoshi
Published: December 2007

We previously identified a small population of replicative hepatocytes in long-term cultures of human adult parenchymal hepatocytes (PHs) at a frequency of 0.01%-0.09%. These hepatocytes were able to grow continuously through serial subcultures as colony-forming parenchymal hepatocytes (CFPHs). In the present study, we generated gene expression profiles for cultured CFPHs and found that they expressed cytokeratin 19, CD90 (Thy-1), and CD44, but not mature hepatocyte markers such as tryptophan-2,3-dioxygenase (TO) and glucose-6-phosphatase (G6P), confirming that these cells are hepatic progenitor-like cells. The cultured CFPHs were resistant to infection with human hepatitis B virus (HBV). To examine the growth and differentiation capacity of the cells

in vivo

, serially subcultured CFPHs were transplanted into the progeny of a cross between albumin promoter/enhancer-driven urokinase plasminogen activator-transgenic mice and severe combined immunodeficient (SCID) mice. The cells were engrafted into the liver and were able to grow for at least 10 weeks, ultimately reaching a maximum occupancy rate of 27%. The CFPHs in the host liver expressed differentiation markers such as TO, G6P, and cytochrome P450 subtypes and could be infected with HBV. CFPH-chimeric mice with a relatively high replacement rate exhibited viremia and had high serum levels of hepatitis B surface antigen.

Conclusion:

Serially subcultured human hepatic progenitor-like cells from postnatal livers successfully repopulated injured livers and exhibited several phenotypes of mature hepatocytes, including susceptibility to HBV.

In vitro

–expanded CFPHs can be used to characterize the differentiation state of human hepatic progenitor-like cells. (Hepatology 2008.)
Constructive episodic simulation: Temporal distance and detail of past and future events modulate hippocampal engagement
Authors: Addis Donna Rose , Schacter Daniel L.
Published: December 2007

Behavioral, lesion and neuroimaging evidence show striking commonalities between remembering past events and imagining future events. In a recent event‐related fMRI study, we instructed participants to construct a past or future event in response to a cue. Once an event was in mind, participants made a button press, then generated details (elaboration) and rated them. The elaboration of past and future events recruited a common neural network. However, regions within this network may respond differentially to event characteristics, such as the amount of detail generated and temporal distance, depending on whether the event is in the past or future. To investigate this further, we conducted parametric modulation analyses, with temporal distance and detail as covariates, and focused on the medial temporal lobes and frontopolar cortex. The analysis of detail (independent of temporal distance) showed that the left posterior hippocampus was responsive to the amount of detail comprising both past and future events. In contrast, the left anterior hippocampus responded differentially to the amount of detail comprising future events, possibly reflecting the recombination of details into a novel future event. The analysis of temporal distance revealed that the increasing recency of past events correlated with activity in the right parahippocampus gyrus (Brodmann area (BA) 35/36), while activity in the bilateral hippocampus was significantly correlated with the increasing remoteness of future events. We propose that the hippocampal response to the distance of future events reflects the increasing disparateness of details likely included in remote future events, and the intensive relational processing required for integrating such details into a coherent episodic simulation of the future. These findings provide further support for the constructive episodic simulation hypothesis (Schacter and Addis (2007) Philos Trans R Soc Lond B Biol Sci 362:773–786) and highlight the involvement of the hippocampus in relational processing during elaboration of future events. © 2007 Wiley‐Liss, Inc.
Consumer benefits from increased competition in shopping outlets: Measuring the effect of Wal‐Mart
Authors: Hausman Jerry , Leibtag Ephraim
Published: December 2007

Non‐traditional retail outlets, including supercenters, warehouse club stores, and mass merchandisers, have nearly doubled their share of consumer food‐at‐home expenditures in the U.S. from 1998 to 2003. Wal‐Mart supercenters have had the biggest impact on food retailing as they compete most closely with traditional supermarkets and offer many identical food items at an average price about 15%–25% lower than traditional supermarkets. We consider consumer benefits from this market share growth and estimate the effect on consumer welfare of entry and expansion into new geographic markets. We calculate the compensating variation that arises from both the direct variety effect of the entry of supercenters and the indirect price effect that arises from the increased competition that supercenters create and find the average effect of the total compensating variation to be 25% of food expenditures. Since we find that lower income households tend to shop more at these lower priced outlets, a significant decrease in consumer surplus arises from restricting entry and expansion of supercenters into new geographic markets. Copyright © 2007 John Wiley & Sons, Ltd.
Complementarities in automobile production
Authors: Biesebroeck Johannes Van
Published: December 2007

The number of different car and light truck models produced in North America has increased enormously over the last decades. The data suggests that producing this increased variety of vehicles is associated with a productivity penalty. We show that manufacturers can adopt complementary activities to reduce this penalty. Flexible technology, defined as the ability to assemble models derived from different ‘platforms’ on the same assembly line, and bringing previously outsourced activities in‐house are two such activities that we identify. Both are costly themselves, in terms of lower productivity, but they reduce the cost of producing greater variety. The results are robust to controlling for the endogeneity of the adoption decisions using activity‐specific instruments, as proposed by Athey and Stern (2003). Copyright © 2007 John Wiley & Sons, Ltd.