bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpolation of bathymetry data from the Sea of Galilee: A noise attenuation problem
Authors: Guitton Antoine , Claerbout Jon
Published: April 2004

We process a bathymetry survey from the Sea of Galilee. This data set is contaminated with non‐Gaussian noise in the form of spikes inside the lake and at the track ends. There is drift on the depth measurements leading to vessel tracks in the preliminary depth images. The drift comes from different seasonal and human conditions during data acquisition, e.g., wind and water levels. We derive an inversion scheme that produces a much‐reduced noise map of the Sea of Galilee. This inversion scheme includes preconditioning and iteratively reweighted least squares with the proper weighting function to remove the non‐Gaussian noise. We remove the ship tracks by adding a modeling operator inside the inversion that accounts for the drift in the data. We then approximate the model covariance matrix with a prediction error filter that enhances details inside the lake. Unfortunately, the prediction error filter slightly degrades the frequency content of the final depth map. Our images of the Sea of Galilee show ancient shorelines and, inside the lake, rifting features.
Javelin Diagrams: A Graphical Tool for Probabilistic Sensitivity Analysis
Authors: Felli James C. , Hazen Gordon B.
Published: April 2004

To demonstrate post hoc robustness of decision problems to parameter estimates, analysts may conduct a probabilistic sensitivity analysis, assigning distributions to uncertain parameters and computing the probability of decision change. In contrast to classical threshold proximity methods of sensitivity analysis, no appealing graphical methods are available to present the results of a probabilistic sensitivity analysis. Here we introduce an analog of tornado diagrams for probabilistic sensitivity analysis, which we call javelin diagrams. Javelin diagrams are graphical augmentations of tornado diagrams displaying both the probability of decision change and the information value associated with individual parameters or parameter sets. We construct javelin diagrams for simple problems, discuss their properties, and illustrate their realistic application via a probabilistic sensitivity analysis of a seven-parameter decision analysis from the medical literature.
Multistage Monte Carlo Method for Solving Influence Diagrams Using Local Computation
Authors: Charnes John M. , Shenoy Prakash P.
Published: April 2004

The main goal of this paper is to describe a new multistage Monte Carlo (MMC) simulation method for solving influence diagrams using local computation. Global methods have been proposed by others that sample from the joint probability distribution of all the variables in the influence diagram. However, for influence diagrams having many variables, the state space of all variables grows exponentially, and the sample sizes required for good estimates may be too large to be practical. In this paper, we develop a MMC method, which samples only a small set of chance variables for each decision node in the influence diagram. MMC is akin to methods developed for exact solution of influence diagrams in that we limit the number of chance variables sampled at any time. Because influence diagrams model each chance variable with a conditional probability distribution, the MMC method lends itself well to influence diagram representations.
Long-Distance Access Network Design
Authors: Berger Rosemary T. , Raghavan S.
Published: April 2004

Long-distance telephone companies in the United States pay access fees to local telephone companies to transport calls that originate and terminate on their networks. These charges form the largest portion of the cost of providing long-distance service. Recent changes in the structure of access rates, which were mandated by the Federal Communications Commission (FCC), have created opportunities for long-distance companies to better manage access costs. In this paper, we develop an optimization-based approach to the economic design of access networks. Our novel solution approach combines stochastic aspects of the problem with a challenging discrete facility location problem in a three-phase algorithm. Computational results indicate a potential cost savings of hundreds of millions of dollars annually for long-distance companies.
On the Depth and Dynamics of Online Search Behavior
Authors: Johnson Eric J. , Moe Wendy W. , Fader Peter S. , Bellman Steven , Lohse Gerald L.
Published: April 2004

This paper examines search across competing e-commerce sites. By analyzing panel data from over 10,000 Internet households and three commodity-like products (books, compact discs (CDs), and air travel services), we show that the amount of online search is actually quite limited. On average, households visit only 1.2 book sites, 1.3 CD sites, and 1.8 travel sites during a typical active month in each category. Using probabilistic models, we characterize search behavior at the individual level in terms of (1) depth of search, (2) dynamics of search, and (3) activity of search.

We model an individual's tendency to search as a logarithmic process, finding that shoppers search across very few sites in a given shopping month. We extend the logarithmic model of search to allow for time-varying dynamics that may cause the consumer to evolve and, perhaps, learn to search over time. We find that for two of the three product categories studied, search propensity does not change from month to month. However, in the third product category we find mild evidence of time-varying dynamics, where search decreases over time from already low levels. Finally, we model the level of a household's shopping activity and integrate it into our model of search. The results suggest that more-active online shoppers tend also to search across more sites. This consumer characteristic largely drives the dynamics of search that can easily be mistaken as increases from experience at the individual level.
50th Anniversary Article: The Evolution of Research on Information Systems: A Fiftieth-Year Survey of the Literature in Management Science
Authors: Banker Rajiv D. , Kauffman Robert J.
Published: April 2004

The development of the information systems (IS) literature in Management Science during the past 50 years reflects the inception, growth, and maturation of several different research streams. The five research streams we identify incorporate different definitions of the managerial problems that relate to IS, the alternate theoretical perspectives and different methodological paradigms to study them, and the levels of the organization at which their primary results impact managerial practice. The decision support and design science research stream studies the application of computers in decision support, control, and managerial decision making. The value of information research stream reflects relationships established based on economic analysis of information as a commodity in the management of the firm. The human-computer systems design research stream emphasizes the cognitive basis for effective systems design. The IS organization and strategy research stream focuses the level of analysis on the locus of value of the IS investment instead of on the perceptions of a system or its user. The economics of information systems and technology research stream emphasizes the application of theoretical perspectives and methods from analytical and empirical economics to managerial problems involving IS and information technologies (IT). Based on a discussion of these streams, we evaluate the IS literature's core contributions to theoretical and managerial knowledge, and make some predictions about the road that lies ahead for IS researchers.
D‐Amino Acid Homopiperazine Amides: Discovery of A‐320436, a Potent and Selective Non‐Imidazole Histamine H3‐Receptor Antagonist
Authors: Curtis Michael P. , Dwight Wesley , Pratt John , Cowart Marlon , Esbenshade Timothy A. , Krueger Kathy M. , Fox Gerard B. , Pan Jia Bao , Pagano Thomas G. , Hancock Arthur A. , Faghih Ramin , Bennani Youssef L.
Published: April 2004

Structure‐activity relationships of homopiperazine‐containing alkoxybiaryl nitriles employing various D‐amino acid moieties and their N‐furanoyl analogues were undertaken. This led to A‐320436, a potent and selective non‐imidazole H3‐receptor antagonist possessing balanced affinity for both rat and human H3‐receptors. This compound was shown to demonstrate in vitro and in vivo functional antagonism and is non‐neurotoxic at doses (i.p.) up to 163 mg/kg in a general observation test.
Loading of the Antigen‐Presenting Protein CD1d with Synthetic Glycolipids
Authors: Wallner Fredrik K. , Chen Liying , Moliner Annalena , Jondal Mikael , Elofsson Mikael
Published: April 2004

CD1 proteins present mammalian and microbial lipid and glycolipid antigens to different subsets of T cells. Few such antigens have been identified and the binding of these to CD1 molecules has mainly been studied by using responding T cells in cellular assays or recombinant solid‐phase CD1 proteins. In the present study we use four different glycolipids, some of which contain tumor‐associated carbohydrate antigens, to develop a procedure to easily detect binding of glycolipids to CD1 proteins on viable cells. Two of these glycolipids are novel glycoconjugates containing α‐D‐N‐acetylgalactosamine (α‐GalNAc) that were prepared by a combined solution and solid‐phase approach. The key step, a Fischer glycosylation of 9‐fluorenylmethoxycarbonylaminoethanol with GalNAc, furnished the α‐glycoside 4 in 34 % yield. Cells were incubated with glycolipids and stained with monoclonal antibodies specific for the carbohydrate part. The level of glycolipid bound to cells was then determined by flow cytometry with a secondary antibody labeled with fluorescein isothiocyanate. All four glycolipids were found to bind to CD1d but with different selectivity. The loading was dose dependent and could be inhibited by an established CD1d ligand, α‐galactosylceramide. Through use of this procedure, glycolipids were selectively loaded onto CD1d expressed on professional antigen‐presenting cells for future use as cellular vaccines. Moreover, the glycolipids described in this study represent novel CD1d‐binding ligands that will be useful derivatives in the study of CD1d‐dependent immune responses, for example, against tumors.
Fluorescent Labelled Thiourea‐Bridged Glycodendrons
Authors: Krist Pavel , Vannucci Luca , Kuzma Marek , Man Petr , Sadalapure Kashinath , Patel Anupama , Bezouška Karel , Pospíšil Milan , Petruš Ladislav , Lindhorst Thisbe K. , Křen Vladimír
Published: April 2004

GlcNAc‐coated glycodendrimers, which are polyvalent glycomimetics, display strong in vitro affinity for the rat natural killer cell protein‐1A (NKR‐P1A), a C‐type lectin‐like receptor of natural killer (NK) cells in rats, humans and some strains of mice. Administration of these compounds in vivo results in a substantial increase in the antitumour activity with involvement of the natural cell immunity. To clarify the in vitro and in vivo fate of these molecules, we synthesized labelled glycodendron analogues of the previously studied glycodendrimers. Labelling with fluorescent tags enabled the localization of the glycodendrons in white blood cells, tumours and other tissues by using different imaging techniques such as fluorescence and confocal microscopy. These studies are useful for probing the mechanism of action and fate of artificial ligands and the cell receptors involved.
The Molecular Mechanism of Membrane Proteins Probed by Evanescent Infrared Waves
Authors: Nyquist Rebecca M. , Ataka Kenichi , Heberle Joachim
Published: April 2004

The catalytic action of membrane proteins is vital to many cellular processes. Yet the molecular mechanisms remain poorly understood. We describe here the technique of evanescent infrared difference spectroscopy as a tool to decipher the structural changes associated with the enzymatic action of membrane proteins. Functional changes as minute as the protonation state of individual amino acid side chains can be observed and linked to interactions with a ligand, agonist, effector, or redox partner.
Neem—An Omnipotent Plant: A Retrospection
Authors: Brahmachari Goutam
Published: April 2004

Neem (Azadirachta indica A. Juss.) has universally been accepted as a wonder tree because of its diverse utility. Multidirectional therapeutic uses of neem have been known in India since the Vedic times. Besides its therapeutic efficacies, neem has already established its potential as a source of naturally occurring insecticide, pesticide and agrochemicals. Safe and economically cheaper uses of different parts of neem in the treatment of various diseases and in agriculture are discussed in this article. It further deals with the active chemical constituents of various neem formulations. Commercially available neem products are also mentioned along with their respective applications. Furthermore, evaluation of safety aspects of different parts of neem and neem compounds along with commercial formulations are also taken into consideration. Systematic scientific knowledge on neem reported so far is thus very useful for the wider interests of the world community.
Autodisplay of Active Sorbitol Dehydrogenase (SDH) Yields a Whole Cell Biocatalyst for the Synthesis of Rare Sugars
Authors: Jose Joachim , von Schwichow Steffen
Published: April 2004

Whole cell biocatalysts are attractive technological tools for the regio‐ and enantioselective synthesis of products, especially from substrates with several identical reactive groups. In the present study, a whole cell biocatalyst for the synthesis of rare sugars from polyalcohols was constructed. For this purpose, sorbitol dehydrogenase (SDH) from Rhodobacter sphaeroides, a member of the short‐chain dehydrogenase/reductase (SDR) family, was expressed on the surface of Escherichia coli using Autodisplay. Autodisplay is an efficient surface display system for Gram‐negative bacteria and is based on the autotransporter secretion pathway. Transport of SDH to the outer membrane was monitored by SDS‐PAGE and Western blotting of different cell fractions. The surface exposure of the enzyme could be verified by immunofluorescence microscopy and fluorescence activated cell sorting (FACS). The activity of whole cells displaying SDH at the surface was determined in an optical test. Specific activities were found to be 12 mU per 3.3×108 cells for the conversion of D‐glucitol (sorbitol) to D‐fructose, 7 mU for the conversion D‐galactitol to D‐tagatose, and 17 mU for the conversion of L‐arabitol to L‐ribulose. The whole cell biocatalyst obtained by surface display of SDH could also produce D‐glucitol from D‐fructose (29 mU per 3.3×108 cells).
Development of Novel 1,2,3,4‐Tetrahydroisoquinoline Derivatives and Closely Related Compounds as Potent and Selective Dopamine D3 Receptor Ligands
Authors: Mach Ulrich R. , Hackling Anneke E. , Perachon Sylvie , Ferry Sandrine , Wermuth Camille G. , Schwartz Jean‐Charles , Sokoloff Pierre , Stark Holger
Published: April 2004

Based on N‐alkylated 1,2,3,4‐tetrahydroisoquinoline derivatives, which are structurally related to the partial agonist BP 897, a series of novel, selective dopamine D3 receptor antagonists has been synthesised. Derivatisation included changes in the arylamide moiety and the tetrahydroisoquinoline substructure leading to compounds with markedly improved selectivities and affinities in the low nanomolar concentration range. From the 55 structures presented here, (E)‐3‐(4‐iodophenyl)‐N‐(4‐(1,2,3,4‐tetrahydroisoquinolin‐2‐yl)butyl)acrylamide (51) has high affinity (Ki(hD3)=12 nM) and a 123‐fold preference for the D3 receptor relative to the D2 receptor subtype. Its pharmacological profile offers the prospect of a novel radioligand as a tool for various dopamine D3‐receptor‐related in vitro and in vivo investigations.
Cover Picture: DDI‐μFIA—A Readily Configurable Microarray‐Fluorescence Immunoassay Based on DNA‐Directed Immobilization of Proteins (ChemBioChem 4/2004)
Authors: Wacker Ron , Niemeyer Christof M.
Published: April 2004

The cover picture shows the self‐assembly of antibody molecules tagged with short DNA oligomers at surfaces containing arrays of complementary oligonucleotides. In their full paper on p. 453 ff, Wacker and Niemeyer report that this DNA‐directed immobilization (DDI) of antibodies forms the basis of a variety of readily configurable immunoassays that allow for the simultaneous and highly reproducible detection of various antigens from biological samples. DDI‐based assays are particularly suited for analyses in microfuluidic systems, such as the plastic, capillary‐driven microfluidic microtiterplate shown at the bottom. Graphical materials are courtesy of CHIMERA BIOTEC and STEAG microParts, Dortmund.
Studies on the dehydrative cyclization of epimeric 4‐(L‐xylo and L‐lyxo‐tetritol‐1‐yl)‐2‐phenyl‐2H‐1,2,3‐triazoles. Circular dichroism and NMR assignment of the formed anomeric C‐nucleoside L‐threofuranosyl triazole analogs
Authors: Sallam Mohammed A.E. , Louis Farida F.
Published: April 2004

Dehydrative cyclization of epimeric 4‐(L‐xylo‐ and L‐lyxo‐tetritol‐1‐yl)‐2‐phenyl‐2H‐1,2,3‐triazoles afforded the anomeric α and β‐L‐threofuranosyl analogs. The anomeric configuration of the formed anomeric C‐nucleoside analogs was determined by circular dichroism and NMR spectroscopy. Chirality 16:331–335, 2004. © 2004 Wiley‐Liss, Inc.
Aluminum chloride‐mediated kinetic resolution of racemic γ‐substituted‐γ‐lactones
Authors: Patil Sudhir T. , Karnik Anil V.
Published: April 2004

Preparation of chiral γ‐substituted‐γ‐lactones (1) through kinetic resolution is described. (S)‐(–)‐1‐Phenylethylamine (2) in the presence of anhydrous AlCl3 shows satisfactory levels of enantioselection in reaction with racemic γ‐substituted‐γ‐lactones 1, where (R)‐1 remains unreacted, while (S)‐1 is enantioselectively converted to the ring‐opened amide (S,S)‐4. The enantiopurity of (R)‐(+)‐ γ‐substituted γ‐lactones recovered ranges from 62–98% ee. Chirality 16:336–338, 2004. © 2004 Wiley‐Liss, Inc.
Fibroblast growth factor receptor‐3 is expressed in undifferentiated intestinal epithelial cells during murine crypt morphogenesis
Authors: Vidrich Alda , Buzan Jenny M. , Ilo Chibuzo , Bradley Leigh , Skaar Kirstin , Cohn Steven M.
Published: April 2004

Prior studies have demonstrated that fibroblast growth factor receptor‐3 (FGFR‐3) regulates proliferation of undifferentiated intestinal epithelial cells in vitro. However, the function(s) of FGFR‐3–mediated signaling during intestinal development and epithelial differentiation in vivo remain unknown. The goal of this study was to define the temporal, regional, and cell‐specific patterns of FGFR‐3 expression and its ligands during normal intestinal ontogeny and epithelial regeneration. Both the IIIb and IIIc isoforms of FGFR‐3 mRNA, which result from differential splicing of the FGFR‐3 primary transcript, were detected in mouse small intestine as early as embryonic day 16. FGFR‐3 levels peaked in the small intestine from 7 to 21 days after birth and decreased thereafter to reach the low levels observed in adult mice. FGFR‐3 IIIb and IIIc mRNA levels were highest in the duodenum and proximal jejunum with lower levels of both seen in the distal jejunum, ileum, and colon. FGFR‐3 was expressed in a subset of proliferating undifferentiated crypt epithelial cells located in the intervillous epithelium and in the lower half of nascently forming crypts but not in differentiated epithelial cell types. FGFR‐3 IIIb was the dominant isoform expressed in both small intestinal and colonic crypts. Expression of FGF1, FGF2, and FGF9, known ligands of FGFR‐3, paralleled patterns of FGFR‐3 expression during gut development. These data suggest that signaling through FGFR‐3 plays a role in regulating morphogenic events involved in formation of intestinal crypts and/or the fate of epithelial stem cells. Developmental Dynamics 230:114–123, © 2004 Wiley‐Liss, Inc.
Cadherin‐2 function in the cranial ganglia and lateral line system of developing zebrafish
Authors: Kerstetter A.E. , Azodi E. , Marrs J.A. , Liu Q.
Published: April 2004

Cadherins are cell surface molecules that mediate cell–cell adhesion through homophilic interactions. Cadherin‐2 (also called N‐cadherin), a member of classic cadherin subfamily, has been shown to play important roles in development of a variety of tissues and organs, including the nervous system. We recently reported that cadherin‐2 was strongly expressed by the majority of cranial ganglia and lateral line system of developing zebrafish. To gain insight into cadherin‐2 role in the formation of these structures, we have used several markers to analyze zebrafish embryos injected with a specific cadherin‐2 antisense morpholino oligonucleotide (cdh2MO). We find that development of several cranial ganglia, including the trigeminal, facial, and vagal ganglia, and the lateral line ganglia and neuromasts of the cdh2MO‐injected embryos are severely disrupted. These phenotypes were confirmed by analyzing a cadherin‐2 mutant, glass onion. Our results suggest that cadherin‐2 function is crucial for the normal formation of the zebrafish lateral line system and a subset of cranial ganglia. Developmental Dynamics 230:137–143, 2004. © 2004 Wiley‐Liss, Inc.
Regional expression of L‐type calcium channel subunits during cardiac development
Authors: Acosta Lourdes , Haase Hannelore , Morano Ingo , Moorman Antoon F.M. , Franco Diego
Published: April 2004

The contraction of cardiomyocytes is initiated by the entrance of extracellular calcium through specific calcium channels. Within the myocardium, L‐type calcium channels are most abundant. In the heart, the main pore‐forming subunit is the α1C, although there is a larger heterogeneity on auxiliary β subunits. We have analyzed the distribution pattern of different α1C and β subunits during cardiac development by immunohistochemistry. We observed homogeneous expression of α1C and β subunits within the early tubular heart, whereas regional differences are observed during the late embryogenesis. β2 and β4 show differential expression within the embryonic myocardium. α1CD1 displays only a transient enhanced expression in the ventricular conduction system. In adult heart, the expression of the different calcium channel subunits analyzed is homogeneous along the entire myocardium except for α1CD1 that is practically undetectable. These findings suggest that β subunits might play a major role in conferring calcium handling heterogeneity within the developing embryonic myocardium, while α1C subunits might contribute just transiently. Developmental Dynamics 230:131–136, 2004. © 2004 Wiley‐Liss, Inc.
Expression of chicken slug and snail in mesenchymal components of the developing central nervous system
Authors: Marin Faustino , Nieto M. Angela
Published: April 2004

Slug and Snail are members of the Snail family of zinc‐finger transcription factors. They are involved in triggering epithelial–mesenchymal transitions during the development of the neural crest and the mesoderm. We have analyzed by in situ hybridization their expression in the nervous system of chicken embryos at mid‐gestation stages, from 4 to 15 days of incubation. We show that Slug and Snail show specific and nonoverlapping expression patterns in mesenchymal structures associated to the developing central nervous system. While Slug is expressed in the meninges and in the pericytes/vascular smooth muscle cells (vSMCs) of the brain, the spinal cord and other embryonic tissues, Snail is expressed in the stroma of the choroid plexus of both the hindbrain and the forebrain. Developmental Dynamics 230:144–148, 2004. © 2004 Wiley‐Liss, Inc.
Expression analyses of zebrafish transferrin, ifabp, and elastaseB mRNAs as differentiation markers for the three major endodermal organs: Liver, intestine, and exocrine pancreas
Authors: Mudumana Sudha Puttur , Wan Haiyan , Singh Malkeet , Korzh Vladimir , Gong Zhiyuan
Published: April 2004

In the present work, three zebrafish cDNA clones encoding transferrin, intestinal fatty acid binding protein (IFABP), and elastaseB were cloned and their expression patterns in early zebrafish development were characterized as differentiation markers for the three major endoderm organs: liver, intestine, and exocrine pancreas. transferrin and ifabp mRNAs exhibit a biphasic expression pattern during early development. transferrin mRNAs were first expressed at ∼7 hours postfertilization (hpf) in the yolk syncytial layer (YSL) and later in the liver rudiment (from ∼48 hpf) and in the esophagus transiently (72–96 hpf). Ifabp mRNAs were initially expressed in the YSL at the ventral side during late epiboly (8–9 hpf), spread throughout the YSL of later stage embryos, and appeared in the intestine rudiment at ∼36 hpf. In contrast to the transferrin and ifabp mRNAs, elastaseB mRNAs were not expressed in the yolk sac or YSL, and these transcripts were detected exclusively in the exocrine pancreas after ∼56 hpf. Developmental Dynamics 230:165–173, 2004. © 2004 Wiley‐Liss, Inc.
Expression patterns of nectins and afadin during epithelial remodeling in the mouse embryo
Authors: Okabe Noriko , Ozaki‐Kuroda Kumi , Nakanishi Hiroyuki , Shimizu Kazuya , Takai Yoshimi
Published: April 2004

Cell–cell adhesion plays key roles in tissue morphogenesis and organogenesis. Nectins are Ca2+‐independent immunoglobulin‐like cell adhesion molecules connected to the actin cytoskeleton through afadin. Nectins play roles in a variety of cell–cell junctions in cooperation with or independently of cadherins. Here, we examined the cellular localization of nectins and afadin throughout primitive streak, neural plate, and early organogenesis stages of mouse development. Nectin and afadin localization coincided with a honeycomb‐shaped meshwork of actin filaments at adherens junctions of polarized epithelia, including neuroepithelium, epithelial somites, and facial primordia. As organogenesis progressed, nectin‐2 expression was maintained in general columnar epithelia, whereas nectin‐1 and ‐3 became highly concentrated at sites of neural morphogenesis. Moreover, nectin‐1 was highly expressed in keratinocytes of the skin, developing hair follicles, and epithelium of developing teeth. These results suggest that nectins and afadin are involved in dynamic epithelial remodeling during mouse development. Developmental Dynamics 230:174–186, 2004. © 2004 Wiley‐Liss, Inc.
Identification, cloning and expression analysis of the pluripotency promoting Nanog genes in mouse and human
Authors: Hart Adam H. , Hartley Lynne , Ibrahim Marilyn , Robb Lorraine
Published: April 2004

The murine Nanog gene, a member of the homeobox family of DNA binding transcription factors, has been shown recently to maintain pluripotency of embryonic stem cells. We have used a sequence homology and expression screen to identify and clone the mouse and human Nanog genes and characterized their phylogenetic context and expression patterns. We report here the gene structure and expression patterns of the mouse Nanog gene, the human Nanog and Nanog2 genes, and six processed human Nanog pseudogenes. Mouse Nanog expression is high in undifferentiated embryonic stem cells and is down‐regulated during embryonic stem cell differentiation, concomitant with loss of pluripotency. Murine embryonic Nanog expression is detected in the inner cell mass of the blastocyst. After implantation, Nanog is detectable at embryonic day (E) 6 in proximal epiblast in the region of the presumptive primitive streak. Expression extends distally as the streak elongates during gastrulation and remains restricted to epiblast. Nanog RNA is down‐regulated in cells ingressing through the streak to form mesoderm and definitive endoderm. Nanog expression also marks the pluripotent germ cells of the nascent gonad at E11.5–E12.5 and is highly expressed in germ cell tumour and teratoma‐derived cell lines. Reverse transcriptase‐polymerase chain reaction analysis detected mouse Nanog expression at low levels in several adult tissues. The human Nanog genes are expressed in embryonic stem cells and down‐regulated in all adult tissues and differentiated cell lines examined. High levels of human Nanog expression were detected by Northern analysis in the undifferentiated N‐Tera embryonal carcinoma cell line. The conservation in gene sequence, structure, and expression of mouse and human Nanog and Nanog2 genes may reflect a common role in the maintenance of pluripotency in both species. Developmental Dynamics 230:187–198, 2004. © 2004 Wiley‐Liss, Inc.
Structure, Bonding, and Tyrosinase‐Like Reactivity of Copper Complexes Coordinated by Mononucleating Tridentate N−O−N Type Ligands
Authors: Cheng Yen‐Ting , Chen Hsiao‐Lan , Tsai Shiou‐Yuan , Su Chan‐Cheng , Tsang Huan‐Sheng , Kuo Ting‐Shen , Tsai Yi‐Chou , Liao Fen‐Ling , Wang Sue‐Lein
Published: April 2004

Copper complexes with mononucleating tridentate ligands of the N−O−N type, including 1,3‐bis(benzimidazol‐2‐yl)‐2‐oxapropane (bbmo), 1,3‐bis(N‐methylbenzimidazol‐2‐yl)‐2‐oxapropane (bbMemo), 1,3‐bis(N‐n‐propylbenzimidazol‐2‐yl)‐2‐oxapropane (bbPrmo), and 1,3‐bis(pyrid‐2‐yl)‐2‐oxapropane (bpmo), were tested for the oxygenation of phenols. Mixed ligand copper complexes of [Cu(N−O−N)(N−N)](ClO4)2, where N−N denotes 2,2′‐bipyridine (bipy), 1,10‐phenanthroline (phen), ethylenediamine (en), and/or N,N,N′,N′‐tetramethylethylenediammine (tmen), were prepared and characterized by elemental analyses, and electronic, vibrational, and epr spectroscopic measurements. The molecular structures of fac‐[Cu(bbMemo)(bipy)(H2O)](ClO4)2(H2O) (1a), fac‐[Cu(bbMemo)(phen)](ClO4)2(CH3CN) (4a), fac‐[Cu(bbPrmo)(phen)](ClO4)2 (5a), and fac‐[Cu(bpmo)(bipy)(ClO4)](ClO4) (7a) were determined by X‐ray diffraction methods. The structures of these complexes are square pyramids or elongated octahedra with the heterocycle nuclei forming the basal or equatorial planes. The terminal heterocycles of the facially coordinated tridentate ligands are nearly perpendicular to the basal or equatorial planes. Similar structures are proposed for the remaining complexes, based on spectroscopic data. Both stoichiometric and catalytic oxidation reactions of 2,4‐di‐tert‐butylphenol and 2,4‐di‐tert‐butylphenolate with dioxygen adducts of [Cu(bbPrmo)]+ at room temperature afforded 3,3′,5,5′‐tetra‐tert‐butyl‐2,2′‐biphenol and 3,5‐di‐tert‐butyl‐o‐quinone. Similar reactions with the dioxygen adduct of [Cu(bpmo)]+ yielded only 3,3′,5,5′‐tetra‐tert‐butyl‐2,2′‐biphenol. In light of the tyrosinase‐like reactivity, the possible intermediates, [(bbPrmo)2Cu2(μ‐η2:η2‐peroxo)]2+, [(bbPrmo)2Cu2(μ‐oxo)2]2+, and [(bpmo)2Cu2(μ‐oxo)2]2+ are proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Properties of Organometallic Sulfur‐Rich Dithiolate Complexes [M(L)(C8H4S8)] (M = RhIII and IrIII; L = η5‐C5H5 and η5‐C5Me5) and Their Oxidation
Authors: Kawabata Kazuhiro , Nakano Motohiro , Tamura Hatsue , Matsubayashi Gen‐etsu
Published: April 2004

[Rh(η5‐C5H5)(C8H4S8)] and [M(η5‐C5Me5)(C8H4S8)] [M = RhIII and IrIII. C8H4S82− = 2‐{(4,5‐ethylenedithio)‐1,3‐dithiole‐2‐ylidene}‐1,3‐dithiole‐4,5‐dithiolate(2−)] were prepared by reactions of [NMe4]2[C8H4S8] with [Rh(η5‐C5H5)Cl2]2 or [M(η5‐C5Me5)Cl2]2 (M = Rh and Ir). They exhibit oxidation potentials of between +0.16 and +0.24 V (versus Ag/Ag+) with oxidation of the dithiolate ligand. The geometries and electronic states of their one‐electron‐oxidized species [M(L)(C8H4S8)]+ and [RhX(L)(C8H4S8)] (M = Rh and Ir; X = Br and I; L = η5‐C5H5 and η5‐C5Me5), obtained by reactions of the above complexes with bromine, iodine, or the ferrocenium cation are discussed based on their ESR spectra. The oxidized η5‐C5Me5‐metal complexes exhibit electrical conductivities of between 10−6 and 10−4 S cm−1, while some oxidized η5‐C5H5‐Rh complexes show conductivities of between 10−3 and 10−2 S cm−1 measured for compacted pellets at room temperature. The X‐ray crystal structures of the two‐electron‐oxidized species [MI(η5‐C5Me5)(C8H4S8)](I3) (M = Rh and Ir) were also clarified. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Anchoring of Copper(II) Acetylacetonate onto an Activated Carbon Functionalised with a Triamine
Authors: Silva Ana Rosa , Martins Magda , Freitas M. Madalena A. , Figueiredo José Luís , Freire Cristina , de Castro Baltazar
Published: April 2004

Copper(II) acetylacetonate was anchored onto a triamine functionalised activated carbon by Schiff condensation using a four‐step procedure: (i) oxidation of activated carbon with nitric acid; (ii) treatment with thionyl chloride to convert carbon surface carboxylic acids into acyl chlorides; (iii) condensation of acyl chloride functionalities with amine groups of bis(3‐aminopropyl)amine (trien); and (iv) Schiff condensation between free amine groups of bound trien with the oxygen atoms of acetylacetonate coordinated to the copper(II) ion. The same complex was also anchored to the unmodified activated carbon and to the acyl chloride functionalised carbon prepared in (ii). The resulting carbon‐based materials were characterised by elemental analysis, surface techniques (SEM and XPS), temperature programmed desorption, and nitrogen adsorption at 77 K and EPR spectroscopy for the materials with copper(II) complexes. Data from all techniques provided evidence for (i) the covalent binding of trien to acyl chloride functionalities; and (ii) the irreversible attachment of [Cu(acac)2] to all carbon‐based materials. Data for the materials with copper(II) proved conclusively that only the immobilisation procedure based on Schiff condensation with trien led to copper(II) complexes in which the metal centre remains four‐coordinate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Self‐Assembly of Novel Silver Polymers Based on Flexible Sulfonate Ligands
Authors: Sun Daofeng , Cao Rong , Bi Wenhua , Li Xiaoju , Wang Yanqin , Hong Maochun
Published: April 2004

Self‐assembly reactions of sulfonates with AgNO3 in the presence of secondary N‐ or P‐containing ligands result in the formation of four new silver‐sulfonate polymers, [Ag(PIP)]n·[Ag(pesp)]n·2nH2O (1), [Ag2(pesp)(dabco)]n·5nH2O (2), [{Ag(pesp)1/2(hmt)1/4}·0.5H2O]n (3) and [Ag(PPh3)(pesp)1/2]n·nMeOH (4), whose structures change from one‐dimensional chains to three‐dimensional open frameworks based on the secondary ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Crystal Engineering of the Coordination Architecture of Metal Polycarboxylate Complexes by Hydrothermal Synthesis: Assembly and Characterization of Four Novel Cadmium Polycarboxylate Coordination Polymers Based on Mixed Ligands
Authors: Dai Jing‐Cao , Wu Xin‐Tao , Hu Sheng‐Min , Fu Zhi‐Yong , Zhang Jian‐Jun , Du Wen‐Xin , Zhang Han‐Hui , Sun Rui‐Qing
Published: April 2004

Four novel compounds, [Cd(tp)(bpp)]n (1), [Cd(tp)(bpy)]n (2), [{Cd4(bpa)4(bpy)6}·(bpy)0.5·7H2O]n (3) and [Cd2{(Htp)(tp)1.5}(bpe)]n (4) [tp = terephthalate, bpp = 1,3‐bis(4‐pyridyl)propane, bpy = 4,4′‐ bipyridine, bpa = 4,4′‐biphenyldicarboxylate, bpe = 1,2‐bis(4‐pyridyl)ethane], of cadmium(II) polycarboxylate coordination polymers based on mixed ligands were obtained by a hydrothermal method. Complex 1 (C21H18CdN2O4) crystallizes in the orthorhombic Pbca space group [a = 11.9401(0) Å, b = 16.8148(3) Å, c = 20.2743(3) Å, and Z = 8]. Complex 2 (C18H12CdN2O4) belongs to the monoclinic C2/m space group [a = 20.299(3) Å, b = 10.720(1) Å, c = 11.764(2) Å, β = 110.944(2)°, and Z = 6]. Complex 3 (C121H98Cd4N13O23) belongs to the monoclinic P21/c space group [a = 23.2208(0) Å, b = 11.8103(1) Å, c = 45.4670(6) Å, β = 104.516(1)°, and Z = 4]. Complex 4 (C32H23Cd2N2O10) belongs to the monoclinic P21/n space group [a = 6.9896(1) Å, b = 22.6294(1) Å, c = 19.7738(3)Å, β = 99.380(1)°, and Z = 4].The CdII centers in the four compounds are bridged by mixed polycarboxylate ligands with bpy and related species to form the twofold parallel interpenetration topology of an undulating 2D 44 net for 1, a twofold interpenetration topology of a 3D α‐Po net for 2, a fourfold interpenetration topology of a 3D 5‐connected borazone 4664 net for 3 and an interesting 3D spiral pipe‐like structure with a bolt for 4. These four compounds exhibit strong fluorescent emissions at 549 and 582 nm (λex = 532 nm) for 1, 493 nm (λex = 360 nm) for 2, 413 and 424 nm (λex = 315 nm) for 3 and 350 nm (λex = 220 nm) for 4 in the solid state at room temperature. These are novel structural topologies and could be significant in the field of photoactive materials. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Bis(phosphane oxide) Adducts of Rh2(MTPA)4 — Kinetics and Chirality Discrimination
Authors: Gáti Tamás , Simon András , Tóth Gábor , Szmigielska Anna , Maj Anna M. , Pietrusiewicz K. Michał , Moeller Stefan , Magiera Damian , Duddeck Helmut
Published: April 2004

The symmetrical bis(phosphane oxide) 1 and its chiral derivatives 2 and 3 form a variety of adduct species with the dirhodium complex [Rh−Rh] which can be identified by low‐temperature 1H and 31P NMR spectroscopy by using varying [Rh−Rh]:ligand ratios. The asymmetric bis(phosphane oxide) 3 shows a distinct preference for binding through the Ph2P=O (Pa) as compared to the tBu(Ph)P=O (Pb) functionality due to the bulky tert‐butyl group. The chiral bis(phosphane oxides) 2 and 3 form complex mixtures of various adduct species. Nevertheless, it is possible to monitor enantiomeric compositions from various NMR signal duplications at 213 K and even at room temperature or slightly elevated temperatures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis and Characterization of Homoleptic Lanthanide Guanidinate Complexes and Their Catalytic Activity for the Ring‐Opening Polymerization of Trimethylene Carbonate
Authors: Zhou Liying , Yao Yingming , Zhang Yong , Xue Mingqiang , Chen Jinglei , Shen Qi
Published: April 2004

Two methods to synthesize homoleptic guanidinate lanthanide complex are described. The samarium guanidinate complex [Sm{Ph2NC(NCy)2}3]·2C7H8 (1) can be synthesized by the metathesis reaction of lithium guanidinate with anhydrous samarium trichloride in a 3:1 molar ratio. The analogous complexes [Ln{Ph2NC(NCy)2}3]·2C7H8 [Ln = Yb (2), Nd (3)] can also be synthesized by the insertion reaction of N,N′‐dicyclohexylcarbodiimide into the Ln−N bond of [(THF)4Li][Ln(NPh2)4] in a 3:1 molar ratio in good yield. Complexes 1−3 were characterized by elemental analysis, IR and 1H NMR spectroscopy. The molecular structures of complexes 1 and 3 were further determined by X‐ray diffraction techniques. These complexes showed high activity for the ring‐opening polymerization of trimethylene carbonate (TMC), giving polymers with Mw/Mn ranging from 1.41−1.73. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Oxidative Addition of RX to Soluble and Polymer‐Bound Molybdenum Carbonyl Complexes
Authors: Heinze Katja , Jacob Volker , Feige Christian
Published: April 2004

Oxidative addition of PhSnCl3 or allyl halides to molybdenum tetracarbonyl complexes proceeds both in solution and on polymer matrices. The structures of the soluble MoII complexes have been determined by single‐crystal X‐ray diffraction in the solid state and by NMR and IR spectroscopy in solution. The identity and stability of the polymer‐bound complexes have been elucidated by spectroscopic techniques directly on the solid support and by releasing the complexes from the support. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
At‐line Determination of Glucose, Ammonia, and Acetate in High Cell Density Cultivations of Escherichia coli
Authors: Peuker T. , Riedel M. , Kaiser C. , Ellert A. , Lenz K. , Elsholz O. , Luttmann R.
Published: April 2004

A sophisticated measurement system for at‐line determination of the main C‐source glucose, the by‐product acetate, and the N‐source ammonium for high cell density cultivations (HCDC) of Escherichia coli K12 TG1 is presented. One flow diffusion technique (FDA) system is used for glucose measurement in the range of 0.5 up to 40 gL–1 in the cultivation broth. Another FDA system detects the amount of the undesired by‐product acetate. The ammonium concentration in the range of 0.2 to 2.5 gL–1 is determined on‐line by a flow injection analysis (FIA) system. For verification purposes, an HPLC system which is also connected to the bioreactor for at‐line measurements is utilized. Several HCDC with cell densities of more than 100 gL–1 have been carried out. The courses of growth‐determining substrates have been detected at‐line. All used systems have shown an excellent compliance with off‐line measurements.
Applications of the Liquid Cyclone in Biological Separations
Authors: Ortega‐Rivas E.
Published: April 2004

Hydrocyclone technology has been suggested as a practical alternative in solid/liquid separations involving biological materials. This paper reviews applications of hydrocyclones in food processing, considering the non‐Newtonian nature of most suspensions treated in the food industry. The hydrocyclone is easy to install and operate, and requires very limited space. It represents an unsophisticated piece of equipment, which runs in a continuous manner and it can be operated at lower costs than most solid/liquid separation techniques. Hydrocyclones have been used in the food industry for the refining of starch, to separate gossypol from cottonseed protein in cottonseed oil processing, and for some other applications, such as multi‐stage mixer/separator extraction systems for soluble coffee. More recently, some other applications in biological systems, which will be discussed in this article, have also been tested.
Transgenic Tobacco Expressing Zephyranthes candida Agglutinin Showing Enhanced Resistance to Aphids
Authors: Pang Y. , Shen G. , Qi H. , Tan F. , Sun X. , Tang K.
Published: April 2004

Aphid is one of the most serious, sap‐sucking insect pests which cause significant losses of crop yields. The aim of this study is to investigate whether transgenic plants expressing Zephyranthes candida agglutinin (ZCA) could confer enhanced resistance to aphids. Tobacco was transformed with a plasmid, pCAMBIAZCA, containing the marker genes nptII and gusA and the Zephyranthes candida agglutinin gene (zca) via Agrobacterium tumefaciens‐mediated transformation. Twenty‐six independent transgenic plants were regenerated. Western blot analysis revealed ZCA expression at various levels in transgenic plants. Insect bioassay tests showed that transgenic plants expressing a high level of ZCA significantly inhibited the growth of the population of peach potato aphids (Myzus persicae Sulzer). This is the first report in which transgenic plants expressing ZCA conferred enhanced resistance to aphids. Our study suggests the zca gene could be a useful candidate for genetic engineering strategies in plants to provide aphid resistance.
Biofilm Growth and Bed Fluidization in a Fluidized Bed Reactor Packed with Support Materials of Low Density
Authors: Saucedo‐Terán R.A. , Ramírez‐Baca N. , Manzanares‐Papayanopoulos L. , Bautista‐Margulis R. , Nevárez‐Moorillón G.V.
Published: April 2004

Support materials of low‐density for fluidized bed reactors provide several operational advantages, including lower energy requirements and proper biofilm growth balance. The aim of this investigation was to study the extent of biofilm growth and bed fluidization in an experimental reactor, using polyester resin (ρpr = 1220 kg/m3) and vitrified expanded perlite (ρvep = 1710 kg/m3) as alternative support materials to conventional silica sand. A noteworthy amount of biofilm was observed to be attached to both support materials from the very beginning of the bioreactor operation. Nevertheless, there were significant variations in biofilm growth and activity over the course of the experimental trials. For both perlite and polyester beds, the highest biofilm mass and the highest total number of mesophilic bacteria were observed between the 7th and the 10th day, showing a steady state trend at the end of the experimental runs. The chemical oxygen demand (COD) removal levels were concomitant with biofilm mass and total mesophilic bacteria changes, although the polyester bed efficiency was slightly higher than that for the perlite bed. As expected, the polyester bed was fluidized at a lower re‐circulation flow compared to the perlite bed. Reactor back‐washing was not required for these support materials since biomass excess was adequately separated by means of a special internal device. The efficiencies of removal of organic matter achieved were acceptable (up to 78 %) despite the low volume of the support material (25 %) and the low hydraulic retention time (30 min).
Enzyme Production of Pleurotus ostreatus Evaluated by the Three‐Way Principal Component Analysis
Authors: Morais H. , Ramos C. , Forgacs E. , Jakab A. , Cserhati T.
Published: April 2004

The effect of the composition of culture media and fermentation time on the production of β‐glucosidase, xylanase, laccase, manganese‐dependent and independent peroxidases by the edible fungus Pleurotus ostreatus was determined. Culture medium separately containing potato, pepper, and tomato extracts and the enzyme activities were assessed to 31.5 days of fermentation. Three‐dimensional principal component analysis (3D‐PCA) followed by the plots of the first two elements of component matrices was employed for the elucidation of the similarities and dissimilarities between the parameters. It was established that the dimensionality of the original 3D matrix (9, 5, 4) could be reduced to 2, 1, 2 with 4.54 % loss of information. The plots demonstrated that the culture media displayed large differences in their capacity to promote enzyme production and that the presence of pepper and tomato extracts exerted the greatest influence on the enzyme activities. The effect of the fermentation time was manifested only after 14 d of fermentation and the highest differences were observed after 28 and 31.5 d of fermentation. Except laccase and manganese‐dependent peroxidase, the enzyme activities also differed considerably dependent on the composition of the fermentation broth. 3D‐PCA followed by the plots of component matrices is a valuable tool for the simultaneous assessment of three dimensional data matrices in biotechnological processes.
Relation between Citric Acid Production and Respiration Rate of Aspergillus niger in Solid‐State Fermentation
Authors: Prado F.C. , Vandenberghe L.P.S. , Lisboa C. , Paca J. , Pandey A. , Soccol C.R.
Published: April 2004

Among the organic acids produced industrially, citric acid is the most important in quantitative terms. Solid‐state fermentation (SSF) has been an alternative method for citric acid production using agro‐industrial residues such as cassava bagasse (CB). The use of CB as a substrate can avoid environmental problems caused by its disposal into the environment. This study was developed to verify the influence of the treated bagasse amount, and consequently, the influence of the gelatinization degree of CB starch on citric acid production by SSF in Erlenmeyer flasks, horizontal drums, and trays. The best results were obtained in a horizontal drum bioreactor using 100 % of treated CB. However, trays showed advantages and good perspectives for large‐scale citric acid production due to economic reasons such as energy costs. A kinetic study was also carried out in order to compare citric acid production in glass columns (laboratory scale) and horizontal drum bioreactors (semi‐pilot scale). This study was accomplished in order to follow the influence of aeration on citric acid accumulation. In addition, the production of CO2 was evaluated as an indirect method of biomass estimation. Citric acid production was higher in glass columns (309.70 g/kg of dry CB) than in HD bioreactors (268.94 g/kg of dry CB). Finally, it was possible to show that citric acid production was favored by a limited biomass production, which occurred with low aeration rates. Biomass production is related to CO2 production and as a result, a respirometry analysis could be used for biomass estimation.