bluuebunny/crossref_metadata_2025 huggingface dataset:
Microfabricated platform for studying stem cell fates
Authors: Chin Vicki I. , Taupin Philippe , Sanga Sandeep , Scheel John , Gage Fred H. , Bhatia Sangeeta N.
Published: October 2004

Platforms that allow parallel, quantitative analysis of single cells will be integral to realizing the potential of postgenomic biology. In stem cell biology, the study of clonal stem cells in multiwell formats is currently both inefficient and time‐consuming. Thus, to investigate low‐frequency events of interest, large sample sizes must be interrogated. We report a simple, versatile, and efficient micropatterned arraying system conducive to the culture and dynamic monitoring of stem cell proliferation. This platform enables: 1) parallel, automated, long‐term (∼days to weeks), live‐cell microscopy of single cells in culture; 2) tracking of individual cell fates over time (proliferation, apoptosis); and 3) correlation of differentiated progeny with founder clones. To achieve these goals, we used microfabrication techniques to create an array of ∼10,000 microwells on a glass coverslip. The dimensions of the wells are tunable, ranging from 20 to >500 μm in diameter and 10–500 μm in height. The microarray can be coated with adhesive proteins and is integrated into a culture chamber that permits rapid (∼min), addressable monitoring of each well using a standard programmable microscope stage. All cells share the same media (including paracrine survival signals), as opposed to cells in multiwell formats. The incorporation of a coverslip as a substrate also renders the platform compatible with conventional, high‐magnification light and fluorescent microscopy. We validated this approach by analyzing the proliferation dynamics of a heterogeneous adult rat neural stem cell population. Using this platform, one can further interrogate the response of distinct stem cell subpopulations to microenvironmental cues (mitogens, cell–cell interactions, and cell–extracellular matrix interactions) that govern their behavior. In the future, the platform may also be adapted for the study of other cell types by tailoring the surface coatings, microwell dimensions, and culture environment, thereby enabling parallel investigation of many distinct cellular responses. © 2004 Wiley Periodicals, Inc.
Catalytic Photooxidation of 4‐Methoxybenzyl Alcohol with a Flavin–Zinc(II)‐Cyclen Complex
Authors: Cibulka Radek , Vasold Rudolf , König Burkhard
Published: October 2004

Flavin–zinc(II)‐cyclen 10 contains a covalently linked substrate binding site (zinc(II)–cyclen) and a chromophore unit (flavin). Upon irradiation, compound 10 effectively oxidizes 4‐methoxybenzyl alcohol (11‐OCH3) to the corresponding benzaldehyde both in water and in acetonitrile. In the presence of air, the reduced flavin 10‐H2 is reoxidized, and so catalytic amounts of 10 are sufficient for alcohol conversion. The mechanism of oxidation is based on photoinduced electron transfer from the coordinated benzyl alcohol to the flavin chromophore. This intramolecular process provides a much higher photooxidation efficiency, with quantum yields 30 times those of the comparable intermolecular process with a flavin chromophore without a binding site. For the reaction in buffered aqueous solution a quantum yield of Φ = 0.4 is observed. The turnover number in acetonitrile is increased (up to 20) by high benzyl alcohol concentrations. The results show that the covalent combination of a chromophore and a suitable binding site may lead to photomediators more efficient than classical sensitizer molecules.
In Search of Ultrastrong Brønsted Neutral Organic Superacids: A DFT Study on Some Cyclopentadiene Derivatives
Authors: Vianello Robert , Liebman Joel F. , Maksić Zvonimir B.
Published: October 2004

An efficient but reasonably accurate B3LYP/6‐311+G(d,p)//B3LYP/6‐31G(d) computational procedure showed that pentasubstituted cyclopentadienes such as (CN)5C5H, (NO2)5C5H, and (NC)5C5H containing strongly electron‐withdrawing groups are neutral organic superacids of unprecedented strength. The boldface denotes the atom attached to the cyclopentadiene framework. All of them exhibit prototropic tautomerism by forming somewhat more stable structures with CNH, NO2H, and NCH exocyclic fragments, respectively. The acidity (ΔHacid) of these is lower, but only to a rather small extent. The ΔHacid enthalpies of these last three tautomers are estimated to be 271, 276, and 282 kcal mol−1, respectively. Hence, the most stable tautomers of (CN)5C5H and (NC)5C5H represent a legitimate target for synthetic chemists. On the other hand, (NO2)5C5H is less suitable for practical applications, because of its high energy density. The origin of the highly pronounced acidity of these compounds was analyzed by using the recently developed triadic formula. It is found that very high Koopmans' ionization energy (IE)${{{{\rm Koop}\hfill \atop n\hfill}}}$ of conjugate bases exerts a decisive influence on acidity. It follows as a corollary that the overwhelming effect leading to very high acidity is due to the properties of the final state. An alternative picture is offered by homodesmotic reactions, wherein the cyclic systems are compared with their linear counterparts. It is found that the acidity of cyclopentadiene (CP) is a consequence of aromatic stabilization in the CP− anion. The extreme acidity of pentacyanocyclopentadiene (CN)5C5H is due to aromatization of the five‐membered ring and a strong anionic resonance effect in the resultant conjugate base. The neutral organic superacids predicted by the present calculations may help to bridge the gap between existing very strong acids and bases.
Theoretical Studies of Aluminoxane Chains, Rings, Cages, and Nanostructures
Authors: Linnolahti Mikko , Luhtanen Tommi N. P. , Pakkanen Tapani A.
Published: October 2004

Alumina nanostructures and three families of aluminoxanes, linear, cyclic, and cagelike structures, have structures that resemble their isovalent electronic hydrocarbon analogues. Specific examples of each family are the counterparts of fullerene, allene, benzene, and cubane, respectively. The aluminoxanes and alumina nanostructures are related to each other; the latter can be regarded as a hydrogen‐ or alkyl‐free form of aluminoxane. By exploiting this relationship, the relative stabilities of the three families of aluminoxanes, alumina nanostructures, and alumina crystal lattices have been estimated. According to ab initio calculations, aluminoxane cages, which take the form of a truncated octahedron and related polyhedra, are favored. The stability of the preferred cage, T‐symmetric Al28O28H28, is practically equal to that of the α‐alumina crystal lattice.
Characterization of Isolated Ga2 Molecules by Resonance Raman Spectroscopy and Variations of GaGa Bonding
Authors: Himmel Hans‐Jörg , Gaertner Benjamin
Published: October 2004

Isolated Ga2 dimers were characterized in an argon matrix with the aid of resonance Raman and UV/Vis spectroscopy. The resonance Raman spectra gave evidence of not only the ν(GaGa) fundamental, but also four overtones. Each of the signals exhibits 69Ga/71Ga isotopic splitting leading to the triplet pattern characteristic of two equivalent Ga atoms. On the basis of the experimental data, a harmonic frequency and anharmonicity constant have been determined for Ga2. An estimate of the dissociation energy on the assumption of a Morse‐type potential energy curve results in a De value (upper limit) of about 145 kJ mol−1. The force constant (64.8±0.3 N m−1) and dissociation energy of Ga2 are compared with those of other diatomics and those of molecules featuring GaGa bonds.
Revision of the Dissociation Energies of Mercury Chalcogenides—Unusual Types of Mercury Bonding
Authors: Filatov Michael , Cremer Dieter
Published: October 2004

Mercury chalcogenides HgE (E=O, S, Se, etc.) are described in the literature to possess rather stable bonds with bond dissociation energies between 53 and 30 kcal mol−1, which is actually difficult to understand in view of the closed‐shell electron configuration of the Hg atom in its ground state (…︁4f145d106s2). Based on relativistically corrected many body perturbation theory and coupled‐cluster theory [IORAmm/MP4, Feenberg‐scaled IORAmm/MP4, IORAmm/CCSD(T)] in connection with IORAmm/B3LYP theory and a [17s14p9d5f]/aug‐cc‐pVTZ basis set, it is shown that the covalent HgE bond is rather weak (2–7 kcal mol−1), the ground state of HgE is a triplet rather than a singlet state, and that the experimental bond dissociation energies have been obtained for dimers (or mixtures of monomers, dimers, and even trimers) Hg2E2 rather than true monomers. The dimers possess association energies of more than 100 kcal mol−1 due to electrostatic forces between the monomer units. The covalent bond between Hg and E is in so far peculiar as it requires a charge transfer from Hg to E (depending on the electronegativity of E) for the creation of a single bond, which is supported by electrostatic forces. However, σ bonding between Hg and E is reduced by strong lone pair–lone pair repulsion to a couple of kcal mol−1. Since a triplet configuration possesses somewhat lower destabilizing lone pair energies, the triplet state is more stable. In the dimer, there is a HgHg π bond of bond order 0.66 without any σ support. Weak covalent Hg–O interactions are supported by electrostatic bonding. The results for the mercury chalcogenides suggests that all experimental dissociation energies for group‐12 chalcogenides have to be revised because of erroneous measurements.
The Jahn–Teller Effect of the TiIII Ion in Aqueous Solution: Extended Ab Initio QM/MM Molecular Dynamics Simulations
Authors: Kritayakornupong Chinapong , Plankensteiner Kristof , Rode Bernd M.
Published: October 2004

Combined ab initio quantum mechanical/molecular mechanical (QM/MM) molecular dynamics simulations, including only the first and the first and second hydration shells in the QM region, were performed for TiIII in aqueous solution. The hydration structure of TiIII is discussed in terms of radial distribution functions, coordination‐number distributions and several angle distributions. Dynamical properties, such as librational and vibrational motions and TiIIIO vibrations, were evaluated. A fast dynamical Jahn–Teller effect of TiIII(aq) was observed in the QM/MM simulations, in particular when the second hydration shell was included into the QM region. The results justify the computational effort required for the inclusion of the second hydration shell into the QM region and show the importance of this effort for obtaining accurate hydration‐shell geometries, dynamical properties, and details of the Jahn–Teller effect.
Two‐Photon Dissociation Spectroscopy of State‐Selected HCl+ and DCl+ Ions
Authors: Michel Michael , Weitzel Karl‐Michael
Published: October 2004

HCl+ and DCl+ ions were formed via the R(1) pump line of the f3Δ2(v′=0)←1∑+(v′′=0) REMPI process. For these ions, the two‐photon dissociation spectroscopy, resonance‐enhanced via the A2∑+(v′)←2Π3/2(v′′=0) transition, was investigated for various intermediate states of HCl+ (v′=4,5,6) and DCl+ (v′=6, 7, 8, 9). From the analysis of the data, spectroscopic parameters of the X and the A states were derived (including the Λ‐doubling in the X state and the spin–rotation coupling in the A state). Some of the parameters deviate considerably from literature data. The spectra provide clear evidence that the REMPI process employed for forming the ions has a very high rotational selectivity.
Functional involvement of P‐selectin and MAdCAM‐1 in the recruitment of α4β7‐integrin‐expressing monocyte‐like cells to the pregnant mouse uterus
Authors: Fernekorn Uta , Butcher Eugene C. , Behrends Jochen , Hartz Sylvia , Kruse Andrea
Published: October 2004

Leukocyte recruitment to the pregnant mouse uterus has been suggested to be associated with highly regulated expression of distinct patterns of vascular adhesion receptors. One of the most striking observations is the combined expression of mucosal addressin cell adhesion molecule‐1 (MAdCAM‐1) and P‐selectin by maternal vessels of the vascular zone during the critical period of initial placenta development. The predominant cell population within these vessels is of the monocyte/macrophage lineage and expresses the mucosal integrin α4β7, which represents the ligand for MAdCAM‐1; neutrophils and lymphocytes are rare. To directly assess the importance of identified adhesion receptors, we undertook long‐term in vivo inhibition studies using monoclonal antibodies to inhibit the contribution of MAdCAM‐1 in leukocyte trafficking to the decidua or to deplete α4β7+ leukocytes. In addition, implantation sites of mouse strains genetically deficient in specific adhesion receptors were investigated. Our results underline the importance of predicted adhesion pathways in the recruitment of monocyte‐like cells, especially those expressing α4β7. Interestingly, maternal/fetal units with inhibited recruitment of α4β7+ leukocytes or the absence of these cells are characterized by reduced size and frequency of uterine NK cells.
Homing of immature thymocytes to the subcapsular microenvironment within the thymus is not an absolute requirement for T cell development
Authors: Benz Claudia , Heinzel Kornelia , Bleul Conrad C.
Published: October 2004

T cell development is thought to occur in distinct microenvironments within the thymus. Namely, the subcapsular zone, the cortex and the medulla have been described to support expansion of the immature thymocyte pool, positive selection of useful specificities and elimination of potentially self‐reactive specificities, respectively. Consistent with this model, thymocytes show a highly ordered migration pattern and move into these niches in the expected sequence. Here we show that the chemokine receptor CCR9 plays a nonredundant role in the homing of immature thymocytes to the subcapsular zone. In CCR9‐deficient mice, T cells in early stages of development do not accumulate in their physiological microenvironment underneath the thymic capsule and are instead homogeneously distributed across the thymic cortex. Remarkably, this abnormality does not result in a detectable defect in T cell development in CCR9‐deficient mice, suggesting that the transit of immature thymocytes through the subcapsular microenvironment is not an absolute requirement for proper T cell development.
Backbone Flexibility and Counterion Effects on the Structure and Thermal Properties of Di(thiourea)zinc Dicarboxylate Coordination Polymers
Authors: Burrows Andrew D. , Donovan Adele S. , Harrington Ross W. , Mahon Mary F.
Published: October 2004

The reaction between [Zn(tu)4]Cl2 and the appropriate sodium dicarboxylate has been shown to give the coordination polymers [Zn(tu)2(μ‐succinate)]n (7), [Zn(tu)2(μ‐itaconate)]n (8), [Zn(tu)2(μ‐ethylmalonate)]n (9), [Zn(tu)2(μ‐1,3‐phenylenediacetate)]n (10) and {[Zn(tu)2(μ‐mesaconate)]·2H2O}n (11), all of which have been crystallographically characterised. The crystal structures of 7−9 demonstrate that these compounds form helical structures in which the dicarboxylates adopt conformations with the relative positions of the carboxylate groups similar to those in constrained anions such as phthalate. The role of the chloride counterion in the starting material has been explored by investigating the reactions of [Zn(tu)4](NO3)2 with a range of dicarboxylates. Although in the majority of cases the counterion was shown to have no effect, in the case of fumarate, a hydrated coordination polymer {[Zn(tu)2(μ‐fumarate)]·2H2O}n (12) was observed in addition to the anhydrous product [Zn(tu)2(μ‐fumarate)]n (1), which was formed as the sole product from [Zn(tu)4]Cl2. Thermogravimetric analyses are reported for compounds 1−12. The compounds {[Zn(tu)2(μ‐isophthalate)]·H2O}n 3 and 12 lose their included water before 140 °C, whereas the compounds {[Zn(tu)2(μ‐maleate)]·H2O}n 6 and 11 only lose their water molecules at higher temperatures with the onset of decomposition. This difference in behaviour can be related to the structural role of the water molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Supercritical fluid extraction–Oxidation technology to remediate PCB‐contaminated soils/sediments: An economic analysis
Authors: Zhou W. , Anitescu G. , Rice P.A. , Tavlarides L.L.
Published: October 2004

The remediation of PCB polluted soils/sediments, left to classical technologies such as incineration and bioremediation, is an overwhelming problem, given that vast amounts of spilled PCBs still exist in the environment after nearly three decades of PCB production ban. Other innovative, alternative cleanup technologies demonstrated that a better solution might exist. A two‐step remediation process proposed for real‐world PCB‐contaminated soils/sediments, based on supercritical fluid extraction (SCFE) and supercritical water oxidation (SCWO), is economically analyzed in this paper. The base case of the process consists of three 2.5‐m3 extractors operated in a 30‐min cycle and a 29‐m‐long SCWO tubular reactor (0.385 m i.d.), which can treat yearly 36,000 m3 of contaminated materials. To assess the commercial potential and the economic feasibility of the proposed process, capital and operational costs are analyzed and the results show total costs of the process in the range of $142–174/m3 sediment. Comparison with other alternative technologies suggests that the SCFE/SCWO process is economically feasible and attractive for the remediation of real‐world PCB highly contaminated soils/sediments. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 222–231, 2004
Selective catalytic reduction performance in steam–Methane reformer service: The chromium problem
Authors: O'Leary J.R. , Kunz R.G. , von Alten T.R.
Published: October 2004

Selective catalytic reduction (SCR) performance has been seen to deteriorate with catalyst age at a greater than expected rate in steam–methane reformers (SMRs) and ethylene plants. Loss of catalyst activity has been attributed to deposition of chromium oxide species from alloy furnace tubes and coils on the catalyst surface, thereby masking active catalyst sites. This deposit is visible to the naked eye as a brown or iridescent black discoloration along the passages of a flow‐through honeycomb catalyst, darkest at the entrance face, and gradually becoming lighter as one proceeds downstream. The color becomes more intense with increased exposure to flue gas. It is important for proper design and catalyst‐replacement strategy to understand the governing phenomena at a fundamental level, especially at a time when SCR is increasingly being turned to as best available control technology (BACT), to comply with the more stringent nitrogen oxides (NOx) regulations. This paper describes a correlation of previously unpublished experimental data from catalyst test sections (logs) exposed in the field over a period of several years at multiple SMR plant locations. Consistent with the observed color change, chromium pickup increases with time and varies with operating conditions from plant to plant. Any given log, at any given time, shows an exponential, or semilogarithmic, decrease in chromium concentration over its length. Activity decay of the catalyst has been correlated with the chromium concentration. This single correlation holds true for all of the different plants investigated and can be used to predict remaining catalyst life and optimize future catalyst designs. Scanning electron microscopy (SEM) results and surface analyses from the SCR catalyst and SMR reformer tubes are also discussed, along with suggested countermeasures to mitigate the effects of chromium oxide deposition. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 194–205, 2004
Biological treatment of condensate from aerobic digestion of biodegradable waste: A German example
Authors: Czermak Peter , Han Binbing , Jaganjac Azra , Grüneklee C. Eberhard , Wickramasinghe S. Ranil
Published: October 2004

Separation of household waste into recyclable, biodegradable, and nonbiodegradable components is required in Germany. Aerobic digestion of the biodegradable component can further minimize the waste volume. During aerobic digestion a hot humid exhaust stream, containing volatile organic and other low molecular weight compounds, is produced. Cooling this stream produces up to 350 L of condensate per ton of biodegradable feed material. Efficient treatment of this condensate is essential for a practical aerobic digestion process. Reuse of the condensate could lead to improved process economics. In this paper, condensate treatment by biological degradation using intermittent sparging has been investigated. An inorganic ultrafiltration membrane was used to separate the biomass from the treated water. It is shown that this one‐step intermittent nitrification/denitrification process may be used to reduce COD, total nitrogen, and ammonia nitrogen concentrations to acceptable values for direct discharge of the treated water into rivers. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 215–221, 2004
A review of bioremediation and natural attenuation of MTBE
Authors: Davis Lawrence C. , Erickson Larry E.
Published: October 2004

Methyl tert‐butyl ether (MTBE) has been the focus of much attention because it is used in large amounts and was reportedly relatively recalcitrant to bioremediation or natural attenuation. Beginning with a few papers a decade ago, evidence has been presented that, in fact, under suitable conditions it is amenable to bioremediation. Many species from widely disparate microbial genera are able to consume it either as a sole carbon source or as a cometabolite. Optimal conditions differ from site to site. Both aerobic and anaerobic conditions may permit MTBE degradation, with a range of electron acceptors, from oxygen through Fe(III), Mn(IV), sulfate, nitrate, and methanogenesis. MTBE metabolism in the vadose zone can be highly active. The published literature suggests that natural populations are adapting to MTBE, and reported rates of biodegradation appear to be larger in the more recent literature. Plants may serve as efficient conduits to withdraw MTBE from the wet subsurface, releasing it to the atmosphere or the vadose zone, where it may be metabolized or diffuse into the atmosphere where it is quickly photodegraded. The major remaining issues are the time required to attain specified criteria of cleanup or whether augmentation is necessary for effective remediation. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 243–252, 2004
Degradation of chlorinated organics by membrane‐immobilized nanosized metals
Authors: Meyer D.E. , Wood K. , Bachas L.G. , Bhattacharyya D.
Published: October 2004

The use of electronegative metals, such as Fe, has been extensively studied for the treatment of groundwater containing toxic chlorinated organics. Much of the recent work has been focused on the use of nanoscale particles with diameters from 2 to 100 nm. This work examines the use of bimetallic (Fe/Ni) nanoscale particles immobilized in a cellulose acetate domain for the destruction of trichloroethylene (TCE). The organic/inorganic hybrid film is synthesized using phase inversion with sodium borohydride reduction. The resulting nanoparticles have an average diameter of 24 nm. Using a small quantity of membrane‐immobilized metal (31 mg total, Fe:Ni = 4:1), it was possible to achieve over a 75% reduction in TCE levels in 4.25 h, with ethane as the only observable product. For shorter reaction times (<2 h), traces of cis‐ and trans‐DCE could be extracted from the baseline of the MS chromatogram. For longer reaction times, products of coupling reactions (butane and hexane) were observed. This corresponds to a surface‐area–normalized pseudo–first‐order rate constant, kSA, for the immobilized system of 3.7 × 10−2 L m−2 h−1. Analysis of the aqueous phase for metal content showed minimal leaching of the metals into the surrounding solution during treatment. Because various combinations of membranes containing immobilized metal nanoparticles can be achieved using the synthesis techniques presented, a more versatile platform for the application of zero‐valent treatment is possible. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 232–242, 2004
Modelling Approach for Planar Self‐Breathing PEMFC and Comparison with Experimental Results
Authors: Schmitz A. , Ziegler C. , Schumacher J. O. , Tranitz M. , Fontes E. , Hebling C.
Published: October 2004

This paper presents a model‐based analysis of a proton exchange membrane fuel cell (PEMFC) with a planar design as the power supply for portable applications.

The cell is operated with hydrogen and consists of an open cathode side allowing for passive, self‐breathing, operation. This planar fuel cell is fabricated using printed circuit board (PCB) technology. Long‐term stability of this type of fuel cell has been demonstrated.

A stationary, two‐dimensional, isothermal, mathematical model of the planar fuel cell is developed. Fickian diffusion of the gaseous components (O2, H2, H2O) in the gas diffusion layers and the catalyst layers is accounted for. The transport of water is considered in the gaseous phase only. The electrochemical reactions are described by the Tafel equation. The potential and current balance equations are solved separately for protons and electrons. The resulting system of partial differential equations is solved by a finite element method using FEMLAB (COMSOL Inc.) software.

Three different cathode opening ratios are realized and the corresponding polarization curves are measured. The measurements are compared to numerical simulation results. The model reproduces the shape of the measured polarization curves and comparable limiting current density values, due to mass transport limitation, are obtained.

The simulated distribution of gaseous water shows that an increase of the water concentration under the rib occurs. It is concluded that liquid water may condense under the rib leading to a reduction of the open pore space accessible for gas transport. Thus, a broad rib not only hinders the oxygen supply itself, but may also cause additional mass transport problems due to the condensation of water.
On the Stability of Selected Monomeric and Polymeric Aryl Sulfonic Acids on Heating in Water (Part 1)
Authors: Vogel C. , Meier‐Haack J. , Taeger A. , Lehmann D.
Published: October 2004

A number of low molecular weight sulfonated aromatic compounds: carboxamides, imides, sulfonamides, as well as sulfonated polymers; aramides and poly(styrene‐p‐sulfonic acid), were tested for their stability on heating in water and dilute acid to temperatures ranging from 130–200 °C. Desulfonation was observed with some compounds. Sulfonamide linkages were found to be stable, while carboxamide linkages and phthalimides were not.
Detection of apoptotic caspase activation in sera from patients with chronic HCV infection is associated with fibrotic liver injury
Authors: Bantel Heike , Lügering Andreas , Heidemann Jan , Volkmann Xandra , Poremba Christopher , Strassburg Christian P. , Manns Michael Peter , Schulze-Osthoff Klaus
Published: October 2004

Chronic hepatitis C virus (HCV) infection is characterized by inflammatory liver damage and is associated with a high risk of development of cirrhosis and hepatocellular carcinoma. Although histological examination of liver biopsies is currently the gold standard for the detection of early liver damage, there is a strong need for better noninvasive methods. We recently demonstrated that the proapoptotic activation of caspases is considerably enhanced in histological sections from HCV-infected liver tissue, suggesting an important role of apoptosis in liver damage. Here, we investigated whether caspase activation is detectable also in sera from patients with chronic HCV infection. Using a novel enzyme-linked immunosorbent assay that selectively recognizes a proteolytic neoepitope of the caspase substrate cytokeratin-18, we demonstrate that caspase activity is markedly increased in the sera of HCV patients. Interestingly, while 27% of patients with chronic HCV infection showed normal aminotransferase levels despite inflammatory and fibrotic liver damage, more than 50% of those patients exhibited already elevated serum caspase activity. Moreover, 30% of patients with normal aminotransferase but elevated caspase activity revealed higher stages of fibrosis. In conclusion, compared with conventional surrogate markers such as aminotransferases, detection of caspase activity in serum might be a more sensitive method of detecting early liver injury. Thus, measurement of caspase activity might provide a novel diagnostic tool, especially for patients with normal aminotransferases but otherwise undiagnosed histologically active hepatitis and progressive fibrosis. (Hepatology 2004;40:1078-1087.)
α-1 adrenergic receptor agonists modulate ductal secretion of BDL rats via Ca2+- and PKC-dependent stimulation of cAMP
Authors: LeSage Gene D. , Alvaro Domenico , Glaser Shannon , Francis Heather , Marucci Luca , Roskams Tania , Phinizy Jo Lynne , Marzioni Marco , Benedetti Antonio , Taffetani Silvia , Barbaro Barbara , Fava Giammarco , Ueno Yoshiyuki , Alpini Gianfranco
Published: October 2004

Acetylcholine potentiates secretin-stimulated ductal secretion by Ca2+-calcineurin-mediated modulation of adenylyl cyclase. D2 dopaminergic receptor agonists inhibit secretin-stimulated ductal secretion via activation of protein kinase C (PKC)-γ. No information exists regarding the effect of adrenergic receptor agonists on ductal secretion in a model of cholestasis induced by bile duct ligation (BDL). We evaluated the expression of α-1A/1C, -1β and β-1 adrenergic receptors in liver sections and cholangiocytes from normal and BDL rats. We evaluated the effects of the α-1 and β-1 adrenergic receptor agonists (phenylephrine and dobutamine, respectively) on bile and bicarbonate secretion and cholangiocyte IP3 and Ca2+ levels in normal and BDL rats. We measured the effect of phenylephrine on lumen expansion in intrahepatic bile duct units (IBDUs) and cyclic adenosine monophosphate (cAMP) levels in cholangiocytes from BDL rats in the absence or presence of BAPTA/AM and Gö6976 (a PKC-α inhibitor). We evaluated if the effects of phenylephrine on ductal secretion were associated with translocation of PKC isoforms leading to increased protein kinase A activity. α-1 and β-1 adrenergic receptors were present mostly in the basolateral domain of cholangiocytes and, following BDL, their expression increased. Phenylephrine, but not dobutamine, increased secretin-stimulated choleresis in BDL rats. Phenylephrine did not alter basal but increased secretin-stimulated IBDU lumen expansion and cAMP levels, which were blocked by BAPTA/AM and Gö6976. Phenylephrine increased IP3 and Ca2+ levels and activated PKC-α and PKC-β-II. In conclusion, coordinated regulation of ductal secretion by secretin (through cAMP) and adrenergic receptor agonist activation (through Ca2+/PKC) induces maximal ductal bicarbonate secretion in liver diseases. (Supplementary material for this article can be found on the Hepatology website (http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html). (Hepatology 2004;40:1116-1127))
A novel mechanism of liver allograft rejection facilitated by antibodies to liver sinusoidal endothelial cells†
Authors: Sumitran-Holgersson Suchitra , Ge Xupeng , Karrar Azza , Xu Bo , Nava Silvia , Broomé Ulrika , Nowak Grzegorz , Ericzon Bo-Göran
Published: October 2004

Liver sinusoidal endothelial cells (LSECs) may be implicated in the induction of liver allograft rejections. We studied the clinical consequences of LSEC-reactive antibodies and their functional capacity in modulating T-cell responses during acute rejections. Pre- and posttransplant sera and T lymphocytes from 95 liver transplant patients were used in this study. LSECs were isolated from normal healthy liver. Binding of antibodies to LSECs was detected using flow cytometry. To study whether LSEC antibodies facilitated cell-mediated immunity, a mixed cell culture (MCC) assay was used. Cytokines in the supernatants of MCC were measured by enzyme-linked immunosorbent assay. Liver biopsy sections were stained to detect the deposition of immunoglobulins in LSECs during rejections. The 2-year patient survival was 86.3%. A significantly higher number of patients with rejections had LSEC antibodies (35/50; 70%) than those without rejections (8/45; 18%) (P < .0001). Purified fractions of LSEC antibodies induced the expression of the costimulatory molecule CD86 on LSECs. A significantly higher number of patients with LSEC antibodies and rejections had an increased proliferation of T cells and markedly decreased levels of transforming growth factor β (TGF-β) in the MCC than those without antibodies and rejections (P < .0001, P < .0001, respectively). Deposition of antibodies in LSECs during rejection episodes was observed in the biopsies of patients with LSEC antibodies but not in those without LSEC antibodies. In conclusion, antibodies to LSECs may facilitate acute liver allograft rejections by down-regulating the immune modulating cytokine TGF-β and thus up-regulating alloreactive T-cell proliferation. (Hepatology 2004;40:1211-1221.)
Occult hepatitis B virus infection in a North American adult hemodialysis patient population
Authors: Minuk Gerald Y. , Sun Dong Feng , Greenberg Rebecca , Zhang Manna , Hawkins Kimberly , Uhanova Julia , Gutkin Adam , Bernstein Kevin , Giulivi Antonio , Osiowy Carla
Published: October 2004

Hepatitis B virus (HBV) infections continue to occur in adult hemodialysis units. A possible contributing factor is the presence of occult HBV (serum hepatitis B surface antigen [HBsAg] negative but HBV DNA positive). Two hundred forty-one adult hemodialysis patients were screened for occult HBV. HBV DNA testing was performed by real-time polymerase chain reaction (PCR) with 2 independent primer sets (core promoter and surface). Two (0.8%) of the 241 patients were HBsAg positive. Of the remaining 239 HBsAg-negative patients, 9 (3.8%) were HBV DNA positive. Viral loads in these individuals were low (102-104 viral copies/mL). Seven of the 9 (78%) were nt 587 mutation (sG145R mutant) positive. Demographic, biochemical, and HBV serological testing did not help to identify those with occult HBV. In conclusion, the prevalence of occult HBV in adult hemodialysis patients in this North American urban center is approximately 4 to 5 times higher than standard HBsAg testing would suggest. The majority of these infections are associated with low viral loads and a high prevalence of the sG145R mutant. Finally, the demographic, biochemical, and/or serological features of HBV DNA-positive subjects do not distinguish these individuals from the remainder of the dialysis patient population. (Hepatology 2004; 40:1072-1077.)
Mitochondrial permeability transition in acetaminophen-induced necrosis and apoptosis of cultured mouse hepatocytes
Authors: Kon Kazuyoshi , Kim Jae-Sung , Jaeschke Hartmut , Lemasters John J.
Published: October 2004

Acetaminophen overdose causes massive hepatic failure via mechanisms involving glutathione depletion, oxidative stress, and mitochondrial dysfunction. The ultimate target of acetaminophen causing cell death remains uncertain, and the role of apoptosis in acetaminophen-induced cell killing is still controversial. Our aim was to evaluate the mitochondrial permeability transition (MPT) as a key factor in acetaminophen-induced necrotic and apoptotic killing of primary cultured mouse hepatocytes. After administration of 10 mmol/L acetaminophen, necrotic killing increased to more than 49% and 74%, respectively, after 6 and 16 hours. MPT inhibitors, cyclosporin A (CsA), and NIM811 temporarily decreased necrotic killing after 6 hours to 26%, but cytoprotection was lost after 16 hours. Confocal microscopy revealed mitochondrial depolarization and inner membrane permeabilization approximately 4.5 hours after acetaminophen administration. CsA delayed these changes, indicative of the MPT, to approximately 11 hours after acetaminophen administration. Apoptosis indicated by nuclear changes, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, and caspase-3 activation also increased after acetaminophen administration. Fructose (20 mmol/L, an adenosine triphosphate-generating glycolytic substrate) plus glycine (5 mmol/L, a membrane stabilizing amino acid) prevented nearly all necrotic cell killing but paradoxically increased apoptosis from 37% to 59% after 16 hours. In the presence of fructose plus glycine, CsA decreased apoptosis and delayed but did not prevent the MPT. In conclusion, after acetaminophen a CsA-sensitive MPT occurred after 3 to 6 hours followed by a CsA-insensitive MPT 9 to 16 hours after acetaminophen. The MPT then induces ATP depletion-dependent necrosis or caspase-dependent apoptosis as determined, in part, by ATP availability from glycolysis. (Hepatology 2004;40:1170-1179.)
Quetiapine has a direct effect on the negative symptoms of schizophrenia
Authors: Tandon Rajiv
Published: October 2004

Second‐generation ‘atypical’ antipsychotics appear to be more effective than first‐generation ‘typical’ antipsychotics in improving negative symptoms in schizophrenia; it is unclear, however, if this greater improvement represents a direct beneficial effect or is mediated indirectly by an antidepressant effect or the absence of extrapyramidal symptoms (EPS). To address this issue with reference to quetiapine (‘Seroquel’), data were evaluated from four randomized, controlled clinical studies involving 1106 patients employing a path analysis model. The total effect of quetiapine on negative symptoms was measured using the Scale for Assessment of Negative Symptoms (SANS) total score. Indirect effects on negative symptoms via positive, depressive and EPS were assessed using appropriate instruments. Effect sizes were calculated by path analysis for the difference between treatment groups in change from baseline to endpoint in SANS total score. Analysis confirmed that quetiapine produced a greater overall improvement in negative symptoms than placebo (effect size 1.96); this was explained by a significant direct effect (p = 0.001; 44.2% of total improvement), and a secondary effect of improved positive symptoms (p < 0.001; 47.5% of total improvement), but was not a consequence of changes in depressive symptoms or EPS. Within the constraints of the path analysis methodology, these results indicate that quetiapine has a substantial direct effect on improving the negative symptoms of schizophrenia. Copyright © 2004 John Wiley & Sons, Ltd.
Corneal epithelial cell growth over tethered‐protein/peptide surface‐modified hydrogels
Authors: Jacob Jean T. , Rochefort James R. , Bi Jingjing , Gebhardt Bryan M.
Published: October 2004

In this study, we investigated the corneal epithelial cell growth rate and adhesion to novel hydrogels with (1) extracellular matrix proteins [fibronectin, laminin, substance P, and insulin‐like growth factor‐1 (IGF‐1)] and (2) peptide sequences [RGD and fibronectin adhesion‐promoting peptide (FAP)] tethered to their surface on poly(ethylene glycol) (PEG) chains. The growth rate to confluence of primary rabbit cornea epithelial cells was compared for plain polymethacrylic acid‐co‐hydroxyethyl methacrylate (PHEMA/MAA) hydrogels, PHEMA/MAA hydrogels coated with extracellular matrix proteins or peptides, and PHEMA/MAA hydrogels with tethered extracellular matrix proteins or peptides on the surface. The development of focal adhesions by the epithelial cells grown on the surfaces was determined by F‐actin staining. Little to no epithelial cell growth occurred on the plain hydrogel surfaces throughout the 15‐day culture period. Of the coated hydrogels, only the fibronectin‐coated surfaces showed a significant increase in cell growth compared to plain hydrogels (p < 0.009). However, even these surfaces reached a maximum of only 20% confluence. Laminin, fibronectin adhesion‐promoting peptide (FAP), and fibronectin/laminin (1:1) tether‐modified hydrogels all achieved 100% confluence by the end of the culture period, although the rates at which confluence was reached differed. F‐actin staining showed that focal adhesions were formed for the laminin, FAP, and fibronectin/laminin tether‐modified surfaces. The results support the hypothesis that tethering certain extracellular matrix proteins and/or peptides to the hydrogel surface enhances epithelial cell growth and adhesion, compared with that seen for protein‐coated or plain hydrogel surfaces. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 198–205, 2005
Effects of sodium hypochlorite gel and sodium hypochlorite solution on dentin bond strength
Authors: Arias Vanessa G. , Bedran‐de‐Castro Ana Karina B. , Pimenta Luiz André
Published: October 2004

The aim of this study was to determine the effect of 10% NaOCl gel and 10% NaOCl solution on dentin bond strengths of four adhesive systems. One hundred eighty bovine incisors were ground to achieve a flat polished surface, then divided into 12 groups: Gluma One Bond [G1 ‐ control; G2 ‐ NaOCl solution; G3 ‐ NaOCl gel]; Prime & Bond 2.1 [G4 ‐ control; G5 ‐ NaOCl solution; G6 ‐ NaOCl gel]; Single Bond [G7 ‐ control; G8 ‐ NaOCl solution; G9 ‐ NaOCl gel]; Prime & Bond NT [G10 ‐ control; G11 ‐ NaOCl solution; G12 ‐ NaOCl gel]. Dentin was etched, rinsed, and blot dried. For the experimental groups, after acid etching, 10% NaOCl solution or 10% NaOCl gel was applied for 60 s, rinsed, and blot dried. Composite resin was inserted and light cured. Shear bond strengths were tested with a crosshead speed of 0.5mm/min. The mean values MPa (SD) were analyzed with two‐way ANOVA and Tukey's tests (α < 0.01). Ten percent NaOCl solution significantly increased Gluma One Bond strength. No effect was observed for the other adhesives. The 10% NaOCl gel did not affect bond strengths. Ten percent NaOCl gel was less effective on collagen removal as compared to 10% NaOCl solution. The influence of collagen removal on bond strength is dependent on adhesive system, where both the solvent and the monomer can influence the results. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 339–344, 2005
An oxidative stress mechanism mediates chelerythrine‐induced heparin‐binding EGF‐like growth factor ectodomain shedding
Authors: Kim Jayoung , Lin Jianqing , Adam Rosalyn M. , Lamb Carolyn , Shively Sharon Baughman , Freeman Michael R.
Published: October 2004

Regulated shedding of cell surface proteins is a mechanism for rapid activation of autocrine and paracrine signaling. Here we report that chelerythrine, a protein kinase C (PKC) inhibitor that possesses a variety of biological functions, is a potent inducer of heparin‐binding epidermal growth factor‐like growth factor (HB‐EGF) shedding from the cell surface. Chelerythrine induced a time‐ and dose‐dependent shedding of an HB‐EGF–alkaline phosphatase (HB‐EGF‐AP) fusion protein expressed in MC2 rat prostate epithelial cells. The soluble form of HB‐EGF‐AP bound to heparin and exhibited potent biological activity as measured by DNA synthesis assay. Chelerythrine‐induced HB‐EGF shedding was metalloproteinase‐(MMP‐) mediated because specific MMP antagonists inhibited shedding by ≥60%. Chelerythrine stimulated production of reactive oxygen species, and antioxidants prevented chelerythrine‐induced HB‐EGF shedding, suggesting that the production of intracellular peroxides is necessary for this event. Consistent with this possibility, antioxidant‐ and MMP‐inhibitable shedding was also demonstrated when hydrogen peroxide was used as an inducer. Although JNK/SAPK and p38 MAPK pathways were activated by chelerythine, these signaling mechanisms were not required to mediate the shedding event. However, JNK signaling was involved in chelerythrine‐stimulated apoptosis. Our results suggest that HB‐EGF shedding induced by chelerythrine is mediated predominantly via the production of reactive oxygen species. © 2004 Wiley‐Liss, Inc.
Regulation of the GATA3 promoter by human T‐cell lymphotropic virus type I Tax protein
Authors: Gilli Simone Cristina Olenscki , Salles Tereza Sueko Ide , Saad Sara Teresinha Olalla
Published: October 2004

The Human T‐cell leukemia virus type I (HTLV‐I) non‐structural protein Tax plays a crucial role in cellular transformation. It activates the transcription factors of various cellular genes and interacts with cellular proteins. There is limited data available on the interaction between specific T‐cell transcription factor GATA3 and Tax. Implications for the significance of GATA3 in T‐cell development and function, T helper2 (Th2) differentiation, and a role of GATA3 during the immune response have been reported. To determine the effect of the Tax protein on GATA3 gene expression, we investigated the interaction between this protein and the GATA3 promoter and repressor regions. Results demonstrated an interaction between Tax and the GATA3 promoter via the transcription factor Sp1 and a role for Tax in the negative regulation of GATA3 expression, through its interaction with the repressor ZEB. This interaction may be involved in the pathophysiology of adult T‐cell leukemia/lymphoma (ATL) and tropical spastic paraparesis/HTLV‐I‐associated myelopathy (TSP/HAM). © 2004 Wiley‐Liss, Inc.
Secretory and basal cells of the epithelium of the tubular glands in the male Mullerian gland of the caecilian Uraeotyphlus narayani (Amphibia: Gymnophiona)
Authors: George Jancy M. , Smita Matthew , Kadalmani Balamuthu , Girija Ramankutty , Oommen Oommen V. , Akbarsha Mohammad A.
Published: October 2004

Caecilians are exceptional among the vertebrates in that males retain the Mullerian duct as a functional glandular structure. The Mullerian gland on each side is formed from a large number of tubular glands connecting to a central duct, which either connects to the urogenital duct or opens directly into the cloaca. The Mullerian gland is believed to secrete a substance to be added to the sperm during ejaculation. Thus, the Mullerian gland could function as a male accessory reproductive gland. Recently, we described the male Mullerian gland of Uraeotyphlus narayani using light and transmission electron microscopy (TEM) and histochemistry. The present TEM study reports that the secretory cells of both the tubular and basal portions of the tubular glands of the male Mullerian gland of this caecilian produce secretion granules in the same manner as do other glandular epithelial cells. The secretion granules are released in the form of structured granules into the lumen of the tubular glands, and such granules are traceable to the lumen of the central duct of the Mullerian gland. This is comparable to the situation prevailing in the epididymal epithelium of several reptiles. In the secretory cells of the basal portion of the tubular glands, mitochondria are intimately associated with fabrication of the secretion granules. The structural and functional organization of the epithelium of the basal portion of the tubular glands is complicated by the presence of basal cells. This study suggests the origin of the basal cells from peritubular tissue leukocytes. The study also indicates a role for the basal cells in acquiring secretion granules from the neighboring secretory cells and processing them into lipofuscin material in the context of regression of the Mullerian gland during the period of reproductive quiescence. In these respects the basal cells match those in the epithelial lining of the epididymis of amniotes. J. Morphol. 262:760–769, 2004. © 2004 Wiley‐Liss, Inc.