bluuebunny/crossref_metadata_2025 huggingface dataset:
Modern classification of neoplasms: reconciling differences between morphologic and molecular approaches
Authors: Berman Jules
Published: August 2005

Background

For over 150 years, pathologists have relied on histomorphology to classify and diagnose neoplasms. Their success has been stunning, permitting the accurate diagnosis of thousands of different types of neoplasms using only a microscope and a trained eye. In the past two decades, cancer genomics has challenged the supremacy of histomorphology by identifying genetic alterations shared by morphologically diverse tumors and by finding genetic features that distinguish subgroups of morphologically homogeneous tumors.

Discussion

The Developmental Lineage Classification and Taxonomy of Neoplasms groups neoplasms by their embryologic origin. The putative value of this classification is based on the expectation that tumors of a common developmental lineage will share common metabolic pathways and common responses to drugs that target these pathways. The purpose of this manuscript is to show that grouping tumors according to their developmental lineage can reconcile certain fundamental discrepancies resulting from morphologic and molecular approaches to neoplasm classification.

In this study, six issues in tumor classification are described that exemplify the growing rift between morphologic and molecular approaches to tumor classification: 1) the morphologic separation between epithelial and non-epithelial tumors; 2) the grouping of tumors based on shared cellular functions; 3) the distinction between germ cell tumors and pluripotent tumors of non-germ cell origin; 4) the distinction between tumors that have lost their differentiation and tumors that arise from uncommitted stem cells; 5) the molecular properties shared by morphologically disparate tumors that have a common developmental lineage, and 6) the problem of re-classifying morphologically identical but clinically distinct subsets of tumors. The discussion of these issues in the context of describing different methods of tumor classification is intended to underscore the clinical value of a robust tumor classification.

A classification of neoplasms should guide the rational design and selection of a new generation of cancer medications targeted to metabolic pathways. Without a scientifically sound neoplasm classification, biological measurements on individual tumor samples cannot be generalized to class-related tumors, and constitutive properties common to a class of tumors cannot be distinguished from uninformative data in complex and chaotic biological systems. This paper discusses the importance of biological classification and examines several different approaches to the specific problem of tumor classification.
An evaluation of a morphine public health programme for cancer and AIDS pain relief in Sub-Saharan Africa
Authors: Logie Dorothy E , Harding Richard
Published: August 2005

Background

Despite growing HIV and cancer prevalence in Sub-Saharan Africa, and WHO advocacy for a public health approach to palliative care provision, opioid availability is severely limited. Uganda has achieved a morphine roll-out programme in partnership with the Ministry of Health. This study aimed to evaluate that programme by identifying challenges to implementation that may inform replication.

Methods

A multi-methods protocol appraised morphine regulation, storage, prescribing, and consumption in three phases: key informant interviews throughout the opioid supply chain, and direct observation and audit of clinical practice.

Results

Regulation had achieved its goal of preventing misuse and leakage from the supply chain. However, the Government felt that relaxation of regulation was now appropriate. Confusion and complexity in storage and authorisation rules led to discontinuation of opioid pain management at the patient level and also wasted service time in trying to obtain supplies to which they were entitled. Continued neglect to prescribe among clinicians and public fear of opioids led to under prescribing, and clinical skills showed some evidence of need for improvement with respect to physical assessment and follow-up.

Conclusion

The Ugandan programme offers a successful model for both advocacy and Governmental support in achieving opioid roll-out across health districts. Despite initial concerns, abuse of opioids has not been evident. Further work is required to ensure that available supplies of opioids are prescribed to those in need, and that clinical standards are met. However, the programme for roll-out has proved a useful model to expand opioid availability as the first step in improving patient care, and may prove a useful template for other Sub-Saharan African countries.
Relationship between Sialic acid and metabolic variables in Indian type 2 diabetic patients
Authors: Nayak B Shivananda , Bhaktha Geetha
Published: August 2005

Background

Plasma sialic acid is a marker of the acute phase response. Objective is to study the relationship between sialic acid relationship with metabolic variables in Indian type 2 diabetes with and without microvascular complications.

Research design and Methods

Fasting Venous blood samples were taken from 200 subjects of which 50 were of diabetes mellitus (DM) and nephropathy patients, 50 patients with type 2 diabetes and retinopathy, 50 patients with type 2 diabetes without any complications and 50 healthy individuals without diabetes. The Indian subject's aged 15–60 years with type 2 diabetes were recruited for the study. Simultaneously urine samples were also collected from each of the subjects. All the blood samples were analyzed for total cholesterol, triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), fasting and postprandial glucose on fully automated analyzer. Serum and urine sialic acid along with microalbumin levels were also estimated.

Results

There was a significantly increasing trend of plasma and urine sialic acid with severity of nephropathy (P < 0.001) and with degree of urinary albumin excretion (P < 0.001). Serum sialic acid correlated with increasing serum creatinine concentration (P < 0.001). Elevated serum sialic acid concentrations were also associated with several risk factors for diabetic vascular disease: diabetes duration, HbA1c, serum triglyceride and cholesterol concentrations, waist-to-hip ratio and hypertension. Significant correlations were found between sialic acid concentration and cardiovascular risk factors like LDL and TG in the diabetic subjects.

Conclusion

The main finding of this study is that elevated serum and urinary sialic acid and microalbumin concentrations were strongly related to the presence of microvascular complications like diabetic nephropathy and retinopathy and cardiovascular risk factors in Indian type 2 diabetic subjects. Further study of acute-phase response markers and mediators as indicators or predictors of diabetic microvascular complications is therefore justified.
Interferon-gamma alters the phagocytic activity of the mouse trophoblast
Authors: Albieri Andréa , Hoshida Mara S , Gagioti Sonia M , Leanza Eduardo C , Abrahamsohn Ises , Croy Anne , Ashkar Ali A , Bevilacqua Estela
Published: August 2005

Interferon-gamma (IFN-gamma) mediates diverse functions in bone marrow-derived phagocytes, including phagocytosis and microbe destruction. This cytokine has also been detected at implantation sites under both physiological and pathological conditions in many different species. At these particular sites, the outermost embryonic cell layer in close contact with the maternal tissues, the trophoblast exhibits intense phagocytic activity. To determine whether IFN-gamma affects phagocytosis of mouse-trophoblast cells, ectoplacental cone-derived trophoblast was cultured and evaluated for erythrophagocytosis. Phagocytic activity was monitored ultrastructurally and expressed as percentage of phagocytic trophoblast in total trophoblast cells. Conditioned medium from concanavalin-A-stimulated spleen cells significantly enhanced trophoblast phagocytosis. This effect was blocked by pre-incubation with an anti-IFN-gamma neutralizing antibody. Introduction of mouse recombinant IFN-gamma (mrIFN-gamma) to cultures did not increase cell death, but augmented the percentage of phagocytic cells in a dose-dependent manner. Ectoplacental cones from mice deficient for IFN-gamma receptor alpha-chain showed a significant decrease of the phagocytosis, even under mrIFN-gamma stimulation, suggesting that IFN-gamma-induced phagocytosis are receptor-mediated. Reverse transcriptase-PCR analyses confirmed the presence of mRNA for IFN-gamma receptor alpha and beta-chains in trophoblast cells and detected a significant increase in the mRNA levels of IFN-gamma receptor beta-chain, mainly, when cultured cells were exposed to IFN-gamma. Immunohistochemistry and Western blot analyses also revealed protein expression of the IFN-gamma receptor alpha-chain. These results suggest that IFN-gamma may participate in the phagocytic activation of the mouse trophoblast, albeit the exact mechanism was not hereby elucidated. Protective and/or nutritional fetal benefit may result from this physiological response. In addition, our data also shed some light on the understanding of trophoblast tolerance to inflammatory/immune cytokines during normal gestation.
A balance of FGF, BMP and WNT signalling positions the future placode territory in the head
Authors: Litsiou Anna , Hanson Sven , Streit Andrea
Published: August 2005

The sensory nervous system in the vertebrate head arises from two different cell populations: neural crest and placodal cells. By contrast, in the trunk it originates from neural crest only. How do placode precursors become restricted exclusively to the head and how do multipotent ectodermal cells make the decision to become placodes or neural crest? At neural plate stages,future placode cells are confined to a narrow band in the head ectoderm, the pre-placodal region (PPR). Here, we identify the head mesoderm as the source of PPR inducing signals, reinforced by factors from the neural plate. We show that several independent signals are needed: attenuation of BMP and WNT is required for PPR formation. Together with activation of the FGF pathway, BMP and WNT antagonists can induce the PPR in naïve ectoderm. We also show that WNT signalling plays a crucial role in restricting placode formation to the head. Finally, we demonstrate that the decision of multipotent cells to become placode or neural crest precursors is mediated by WNT proteins:activation of the WNT pathway promotes the generation of neural crest at the expense of placodes. This mechanism explains how the placode territory becomes confined to the head, and how neural crest and placode fates diversify.
Drug Testing in Blood: Validated Negative-Ion Chemical Ionization Gas Chromatographic–Mass Spectrometric Assay for Enantioselective Measurement of the Designer Drugs MDEA, MDMA, and MDA and Its Application to Samples from a Controlled Study with MDMA
Authors: Peters Frank T , Samyn Nele , Lamers Caroline TJ , Riedel Wim J , Kraemer Thomas , de Boeck Gert , Maurer Hans H
Published: August 2005

Background: The enantiomers of the designer drugs 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyethylamphetamine (MDEA) differ in their pharmacologic and toxicologic potency. The aim of this study was to develop an assay for measuring these enantiomers in small plasma volumes and to analyze samples from a controlled study with MDMA.

Methods: The analytes were extracted from ≤0.2 mL of plasma by mixed-mode solid-phase extraction. After derivatization with S-(−)-heptafluorobutyrylprolyl chloride, the resulting diastereomers were separated by gas chromatography (HP-5MS) within 17 min and detected by mass spectrometry in the negative-ion chemical ionization mode. The method was fully validated and applied to samples from a controlled study in which a single dose of racemic MDMA (75 mg) was administered.

Results: The derivatized enantiomers were well separated and detected with good sensitivity. The assay was linear (per enantiomer) at 1–50 μg/L for MDA and 5–250 μg/L for MDMA and MDEA. Analytical recovery, accuracy, repeatability, and intermediate precision data were within required limits. Extraction yields were 82.1%–95.3%. In the study samples, concentrations of R-(−)-MDMA significantly exceeded those of S-(+)-MDMA. Their ratios (R vs S) were always >1.0 and increased over time. Concentrations of S-(+)-MDA exceeded those of R-(−)-MDA, their ratios (R vs S) also increasing over time but remaining <1.0.

Conclusions: This assay enables sensitive, reliable, and fast enantioselective measurement of MDA, MDMA, and MDEA in small volumes of plasma. The controlled study data confirm previous findings of MDMA and MDA enantiomer ratios (R vs S) increasing over time after ingestion of racemic MDMA.
Biological and environmental characterization of marine macroalgal assemblages in Potter Cove, South Shetland Islands, Antarctica
Authors: Quartino María L. , Zaixso Héctor E. , Boraso de Zaixso Alicia L.
Published: August 2005

We describe the macroalgal assemblages in Potter Cove and their distribution by depth, substratum, irradiation, nutrients, salinity, water temperature and light period. We determined groups by using K-means, the Hellinger index and the maximum Calinski-Harabasz pseudo-F-statistic as stopping rule. Indicator species were assessed with the IndVal index. Relationships between groups and environmental factors were determined by correspondence analysis, and results were validated by a canonical correspondence analysis of species and environment. To compare the group biodiversities we used species richness and diversity indices and abundance biomass comparisons curves. Analysis with incidence data discriminated one shallow Iridaea assemblage and one deep Himantothallus assemblage. Analysis using biomass discriminated three facies, the first in the upper zone (Iridaea cordata, Monostroma hariotii, Adenocystis utricularis, Enteromorpha bulbosa), the second (Desmarestia menziesii, D. antarctica, Ascoseira mirabilis, Curdiea racovitzae, Gigartina skottsbergii, Kallymenia antarctica, Neuroglossum delesseriae, Phaeurus antarcticus, Gymnogongrus turquetii) at intermediate depth and the third (H. grandifolius, D. anceps, Georgiella confluens, Ballia callitricha, Plocamium cartilagineum), coincident with the deep qualitative assemblage, was found in a less disturbed environment. The difference in species composition between the groups was mainly related to depth as an environmental variable. The high specific diversity at intermediate depths can be explained by the presence of patches in different successional stages caused by iceberg scouring.
Using Fish Biomarkers to Monitor Improvements in Environmental Quality
Authors: Facey Douglas E. , Blazer Vicki S. , Gasper Meredith M. , Turcotte Cynthia L.
Published: August 2005

The percentage of splenic tissue occupied by macrophage aggregates and hepatosomatic index (HSI) were evaluated in rock bass Ambloplites rupestris from Burlington Harbor, Vermont. In 1992, fish collected from the inner Burlington Harbor area had a significantly greater percentage of splenic tissue occupied by macrophage aggregates and greater HSI than did fish from reference sites. These biomarkers often are correlated with exposure to various contaminants (e.g., polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and some heavy metals, which were found in Burlington Harbor sediments during surveys in 1990 and 1991). Contaminants are believed to have entered Burlington Harbor through the city's main sewage treatment plant, which discharged effluent into the harbor for many years. In 1994, the city completed a significant upgrade of this treatment plant, which included an extension of the effluent pipe beyond the inner harbor area. In 1999, rock bass were again collected from Burlington Harbor as an index of whether there was any improvement in environmental quality. Our data showed a significantly lower percentage of splenic tissue occupied by macrophage aggregates and significantly lower HSI among nine age-4 rock bass in 1999 than among six age-4 rock bass in 1992. The significant changes in these biomarkers suggest decreased exposure to contaminants. Our study reinforces the value of macrophage aggregates and HSI as biomarkers of environmental contamination, and the correlation with remedial action shows their potential utility in documenting improvements in environmental conditions.
Weaving the tapestry: Tying themes and threads together
Authors: Lawrence Randee Lipson
Published: August 2005

The final chapter highlights five themes that thread through this volume: awareness of self, awareness of others, community building, social action, and art as a context for learning.
Juvenile onset Huntington disease resulting from a very large maternal expansion
Authors: Nahhas F.A. , Garbern J. , Krajewski K.M. , Roa B.B. , Feldman G.L.
Published: August 2005

We report a 5½‐year‐old girl with a maternal family history of Huntington disease (HD), who presented clinically with unbalanced gait, impaired speech, and increasing difficulty with fine motor control. Onset of symptoms began at the age of 3½ years. The suspected diagnosis of juvenile HD, based upon her family history, was confirmed by DNA analysis. At age 7, the patient died secondary to complications of her underlying disorder. Juvenile‐onset Huntington disease is uncommon, predominantly transmitted by fathers and is always associated with very large expansions of the CAG repeat. Interestingly, this patient inherited a large CAG size expansion from her mother, who herself had symptoms of HD at the age of 18. Molecular analysis revealed that the mother had 70 CAG repeats whereas our patient had ∼130 CAG repeats. This is the largest reported CAG expansion from a maternal transmission that has been confirmed molecularly and it demonstrates that very large expansions can also occur through the maternal lineage. © 2005 Wiley‐Liss, Inc.
Novel Fluorescent Phosphonic Acid Esters for Discrimination of Lipases and Esterases
Authors: Schmidinger Hannes , Birner‐Gruenberger Ruth , Riesenhuber Gernot , Saf Robert , Susani‐Etzerodt Heidrun , Hermetter Albin
Published: August 2005

Lipases and esterases are responsible for carboxylester hydrolysis inside and outside cells and are useful biocatalysts for (stereo)selective modification of synthetic substrates. Here we describe novel fluorescent suicide inhibitors that differ in structure and polarity for screening and discrimination of lipolytic enzymes in enzyme preparations. The inhibitors covalently react with the enzymes to form fluorescent lipid–protein complexes that can be resolved by gel electrophoresis. The selectivities of the inhibitors were determined by using different (phospho)lipase, esterase and cholesterol esterase preparations. The results indicate that formation of an inhibitor–enzyme complex is highly dependent on the chemical structure of the inhibitor. We identified inhibitors with very low specificity, and other derivatives that were highly specific for certain subgroups of lipolytic enzymes such as lipases and cholesterol esterases. A combination of these substrate‐analogous activity probes represents a useful toolbox for rapid identification and classification of serine hydrolase enzymes.
High‐Resolution Solid‐State NMR Studies on Uniformly [13C,15N]‐Labeled Ubiquitin
Authors: Seidel Karsten , Etzkorn Manuel , Heise Henrike , Becker Stefan , Baldus Marc
Published: August 2005

Understanding of the effects of intermolecular interactions, molecular dynamics, and sample preparation on high‐resolution magic‐angle spinning NMR data is currently limited. Using the example of a uniformly [13C,15N]‐labeled sample of ubiquitin, we discuss solid‐state NMR methods tailored to the construction of 3D molecular structure and study the influence of solid‐phase protein preparation on solid‐state NMR spectra. A comparative analysis of 13C′, 13Cα, and 13Cβ resonance frequencies suggests that 13C chemical‐shift variations are most likely to occur in protein regions that exhibit an enhanced degree of molecular mobility. Our results can be refined by additional solid‐state NMR techniques and serve as a reference for ongoing efforts to characterize the structure and dynamics of (membrane) proteins, protein complexes, and other biomolecules by high‐resolution solid‐state NMR.
NMR Spectroscopy of Paramagnetic Metalloproteins
Authors: Bertini Ivano , Luchinat Claudio , Parigi Giacomo , Pierattelli Roberta
Published: August 2005

This article deals with the solution structure determination of paramagnetic metalloproteins by NMR spectroscopy. These proteins were believed not to be suitable for NMR investigations for structure determination until a decade ago, but eventually novel experiments and software protocols were developed, with the aim of making the approach suitable for the goal and as user‐friendly and safe as possible. In the article, we also give hints for the optimization of experiments with respect to each particular metal ion, with the aim of also providing a handy tool for nonspecialists. Finally, a section is dedicated to the significant progress made on 13C direct detection, which reduces the negative effects of paramagnetism and may constitute a new chapter in the whole field of NMR spectroscopy.
An Improvement in the Bending Ability of a Hinged Trisaccharide with the Assistance of a Sugar––Sugar Interaction
Authors: Yuasa Hideya , Izumi Takuhiro , Mitsuhashi Nobuyuki , Kajihara Yasuhiro , Hashimoto Hironobu
Published: August 2005

Hinged di‐ and trisaccharides incorporating 2,4‐diamino‐β‐D‐xylopyranoside as a hinge unit (Hin) were synthesized. Bridging of the diamino group of Hin by carbonylation or chelation to a metal ion results in a conformational change from 4C1 to 1C4, which in turn causes a bending of the oligosaccharides. In this study, the bending abilities of the hinged oligosaccharides were compared, in terms of the reactivities toward carbonylation and chelation. Di‐ or trisaccharides containing a 6‐O‐glycosylated mannopyranoside or galactopyranoside at their reducing ends had bending abilities similar to that of the Hin monosaccharide, probably because there were neither attractive nor repulsive interactions between the reducing and nonreducing ends. However, when Hin was attached at O2 of methyl mannopyranoside (ManαMe), the bending ability was dependent on the nonreducing sugar and the reaction conditions. Typically, a disaccharide—Hinβ(1,2)ManαMe—was difficult to bend under all the tested reaction conditions, and the bent population in the presence of ZnII was only 4 %. On the other hand, a trisaccharide—Manα(1,3)Hinβ(1,2)ManαMe—was bent immediately after the addition of ZnII or HgII, and the bent population reached 75 %, much larger than those of all the other hinged trisaccharides ever tested (<40 %). This excellent bending ability suggests an attractive interaction between the reducing and nonreducing ends. The extended conformation was recovered by the addition of triethylenetetramine, a metal ion chelator. Reversible, quick, and efficient bending of the hinged trisaccharide was thus achieved.
Anionic Organic Guests Incorporated in Zeolites: Adsorption and Reactivity of a Meisenheimer Complex in Faujasites
Authors: Herance José Raul , Concepción Patricia , Doménech Antonio , Bourdelande José Luis , Marquet Jordi , García Hermenegildo
Published: August 2005

Zeolites are suitable microporous hosts for positively charged organic species, but it is believed that they cannot adsorb organic anions. Pure Meisenheimer complex, derived from reduction of 2,4‐dinitroaniline with NaBH4, was adsorbed inside faujasite cavities. Evidence for the internal incorporation of this negatively charged reaction intermediate comes from 1) XPS elemental analysis as a function of the depth of penetration into the particle, 2) the remarkable blue shift in λmax of the Meisenheimer complex adsorbed on zeolite (ca. 470 nm) as compared to that in acetonitrile (580 nm) and 3) from the lack of reactivity with size‐excluded hydride‐acceptor reagents. Evidence is provided in support of an adsorption mechanism in which a neutral ion pair (alkali metal ion+Meisenheimer anion) is the actual species being adsorbed. In fact it appears that there is remarkable increase in the association constant for the ion‐pair complex within the zeolite cavities as compared to DMF solution. Although this mechanism of adsorption as an ion‐pair complex has precedents in the adsorption of some inorganic salts, what is novel is the notable increase in the stability and persistence of the Meisenheimer anion (a anionic reaction intermediate) as a result of zeolite inclusion. Adsorbed Meisenheimer complex exhibits much lower reactivity towards electron acceptors, oxygen, and water. Cyclic voltammetry of zeolite‐modified electrodes reveals for the Meisenheimer complex adsorbed on LiY a reversible redox peak that is not observed in solution and has been interpreted as arising from site isolation and stabilisation of the electrochemically generated species.
Heme–heme interactions in tetramers and dimers of hemoglobin subunits: DeVoe theory calculations
Authors: Woody Robert W.
Published: August 2005

Detectable exciton couplets arising from heme–heme interactions in the hemoglobin (Hb) tetramers of HbO2 and deoxyHb were predicted by DeVoe theory (Woody, in: Optical properties and structure of tetrapyrroles. Berlin: Walter deGruyter & Co.; 1985. p 239–259). This prediction was supported by the observation of an exciton couplet in the CD difference spectrum between the Hb tetramer and the αβ dimer of HbCO (Goldbeck et al., Biochem Biophys Res Commun 1997;235:610–614). In this paper, DeVoe theory is used to calculate the heme–heme interactions in the CO complex of the Hb tetramer (α2β2) and dimer (αβ), the systems studied by Goldbeck et al. The couplet strength of the resulting theoretical CD difference spectrum agrees well with experiment, thus confirming that heme–heme interactions contribute significantly to the CD of HbCO. Given that the heme–heme distances in HbCO are 25 Å and more, it is highly likely that heme–heme interactions also contribute significantly to the CD of other multi‐heme proteins, e.g., cytochrome c3, cytochrome oxidase, cytochrome bc1, etc., where the hemes are in closer proximity. © 2005 Wiley‐Liss, Inc. Chirality 17:450–455, 2005.
Synthesis, Characterization and Molecular Structures of Yttrium Trifluoroacetate Complexes with O‐ and N‐Donors: Complexation vs. Hydrolysis
Authors: Zhang Jianyong , Morlens Stéphanie , Hubert‐Pfalzgraf Liliane G. , Luneau Dominique
Published: August 2005

Dehydration and complexation reactions of [Y(TFA)3(H2O)3] (1; TFA = O2CCF3) were investigated with O‐ and N‐donor ligands in order to obtain suitable precursors for MOD (Metal Organic Deposition). Anhydrous adducts such as [Y2(μ,η2‐TFA)4(η1‐TFA)2(OHC2H4OiPr)4] (3), [Y2(μ,η2‐TFA)4(η1‐TFA)2(OHC2H4OC2H4OMe)2] (4), or [Y(TFA)3(triglyme)] (5) were isolated. The reactions with N‐donor ligands are more complex and afford mixed‐ligand derivatives such as [Y(TFA)3(H2O)2(LL)]m [LL = TMEDA (9), Me2NC2H4NMeC2H4NMe2 (10)] and, in the case of primary amines, yttrium oxohydroxo derivatives such as [H3O][Y3(μ3‐OH)(μ‐O)3(η1‐TFA)3(H2O)6(en)3] (6; en = NH2C2H4NH2). All complexes were characterized by elemental analysis, FT‐IR, and by single‐crystal X‐ray diffraction for 3, 4, and 6. All structurally characterized complexes contain on eight‐coordinate Y centers. Perfluorobutyrate and difluoroacetate derivatives were also prepared. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Stereoselective Construction of a Highly Functionalized Taxoid ABC‐Ring System: the C2–C9 Oxa‐Bridge Approach
Authors: Hamon Sylvain , Birlirakis Nicolas , Toupet Loïc , Arseniyadis Siméon
Published: August 2005

The goal of this investigation is to assemble the 20‐carbon unit 1 of the taxoid diterpene skeleton with a high level of stereocontrol by means of a three‐reaction sequence developed in this laboratory. The strategy involves seven C–C bond‐forming operations together with eighteen functional group transformations, circumventing the stereoselectivity issue altogether. Furthermore, there is no isomer formation and hence no need for chromatographic separation. A temporary oxa‐bridge (C2/C9) was used as a problem‐solving approach. The key step in the planned sequence was based on achieving the last C–C bonding between C11 and C12, following a successful C11 functionalization. X‐ray analyses of 8b, 17, 18, 19, 20, and 21, together with extensive use of 800 MHz 1H (200 MHz 13C) NMR spectra, support the suggested structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Inviscid flow modelling using asymmetric implicit finite difference schemes
Authors: de Lange H. C.
Published: August 2005

Asymmetric spatial implicit high‐order schemes are introduced and, based on Fourier analysis, the dispersion and damping are calculated depending on the asymmetry parameter. The derived schemes are then applied to a number of inviscid problems. For incompressible convection problems the proposed asymmetric schemes (applied as upwind schemes) lead to stable and accurate results. To extend the applicability of the proposed schemes to compressible problems acoustic upwinding is used. In a two‐dimensional compressible flow example acoustic and conventional upwinding are combined. Evaluation of all presented results leads to the conclusion that, of the studied schemes, the implicit fifth order upwinding scheme with an asymmetry parameter of about 0.5 leads to the optimal results. Copyright © 2005 John Wiley & Sons, Ltd.
Novel Copolyanhydrides Combining Strong Inherent Fluorescence and a Wide Range of Biodegradability: Synthesis, Characterization and in vitro Degradation
Authors: Jiang Hongliang , Chen Dian , Zhao Pengcheng , Li Yan , Zhu Kangjie
Published: August 2005

Summary: In this work, a novel diacid monomer was synthesized in a very convenient scheme. The monomer is derived from naturally occurring products and emits strong fluorescence when polymerized to polyanhydride. The chemical structure of the monomer dCPS is as follows: HOC(O)ArOC(O)(CH2)2C(O)OArCOOH. Copolyanhydrides composed of dCPS and sebacic acid were further prepared by melt copolycondensation, and characterized by IR, NMR, UV‐Vis, DSC and fluorometry. The emission wavelength (λem) of the copolymers could be tuned by the excitation wavelength (λex). Fluorescence intensity increased with the increase of dCPS content. The microspheres fabricated from the copolymer with dCPS content as low as 10% could be clearly visualized with fluorescence microscopy. Either blue or green images of the microspheres could be captured with an excitation of UV and visible light. The degradation rate of the copolyanhydrides decreased as the dCPS fraction increased, and the degradation duration could be modulated from several days to more than three months. In addition, it was found that the copolyanhydrides displayed surface degradation characteristics. In view of the advantages of the novel copolyanhydrides, such as easy preparation, unique inherent luminescent properties, and widely adjustable degradation rate, they might be useful for biomedical engineering.

Fluorescence spectra of P(dCPS:SA) excited at 462 nm and the fluorescent micrograph of the P(dCPS:SA) microsphere.

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Fluorescence spectra of P(dCPS:SA) excited at 462 nm and the fluorescent micrograph of the P(dCPS:SA) microsphere.
Adsorption of Chitosan onto Poly(D,L‐lactic acid) Particles: A Physico‐Chemical Investigation
Authors: Messai Isabelle , Delair Thierry
Published: August 2005

Summary: Particles of poly(D,L‐lactic acid) (PLA) obtained by emulsification‐diffusion were surface‐modified by adsorption of chitosan. Thus, positively charged biodegradable carriers were obtained as potential carriers for DNA. Various physico‐chemical parameters, susceptible to impact the elaboration of such colloids, were investigated. External parameters were the ionic strength and the nature of the buffer; pH was fixed at 4.5 in order to ensure the ionisation of both counterparts. Internal parameters were the molar mass of chitosan and its degree of acetylation (DA). Kinetically, the adsorption of chitosan was spontaneous. Adsorption isotherms of chitosan were established using two different assays for chitosan, one based on the formation of a covalent bond, and the other on the formation of an ion pair. Two adsorption regimes were evidenced in ammonium acetate buffer. The amount of adsorbed chitosan increased with its molar mass up to a limit due to steric hindrance and with the DA. The latter effect could be explained by a reduction of the molecular dimensions of chitosan with DA. On storing, desorption of chitosan was dependent on the molar mass of the polysaccharide and, to a lesser extent, on the DA.

Complexation isotherm of chitosan onto PLA particles.

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Complexation isotherm of chitosan onto PLA particles.
Structural Design of P(BMA‐co‐VTES)/TEOS Hybrid Membranes for Removal of Benzene from Water by Pervaporation
Authors: Ohshima Tadahiro , Matsumoto Moritoshi , Miyata Takashi , Uragami Tadashi
Published: August 2005

Summary: The pervaporation performance of optimized poly(butylmetacrylate‐co‐vinyltriethoxysilane)/tetraethoxysilane (P(BMA‐co‐VTES)/TEOS) hybrid membranes for the removal of benzene from water was investigated. P(BMA‐co‐VTES)/TEOS hybrid membranes prepared by the sol–gel reaction were modified by annealing and trimethylsilylation to enhance the performance of these membranes. The annealing and trimethylmethoxysilane (TMS)‐modifications of P(BMA‐co‐VTES)/TEOS hybrid membranes gave more hydrophobic membranes compared with untreated P(BMA‐co‐VTES)/TEOS hybrid membranes and, consequently, the amount of benzene sorbed in the modified P(BMA‐co‐VTES)/TEOS hybrid membranes increased significantly. When an aqueous solution of dilute benzene was permeated by pervaporation through the annealed and TMS‐modified P(BMA‐co‐VTES)/TEOS hybrid membranes, the annealing treatment enhanced the benzene/water selectivity significantly. This result was attributed to a decrease in residual silanol groups in the annealed hybrid membranes and the formation of an optimum cross‐linked structure of the annealed P(BMA‐co‐VTES)/TEOS hybrid membranes.

Benzene concentration in the permeate for an aqueous solution of benzene through untreated (○) and annealed (•) P(BMA‐co‐VTES)/TEOS hybrid membranes during PV.

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Benzene concentration in the permeate for an aqueous solution of benzene through untreated (○) and annealed (•) P(BMA‐co‐VTES)/TEOS hybrid membranes during PV.
Packing and Uniaxial Alignment of Liquid Crystalline Oligofluorenes
Authors: Chi Chunyan , Lieser Günter , Enkelmann Volker , Wegner Gerhard
Published: August 2005

Summary: Liquid crystalline oligomers of 9,9‐bis(2‐ethylhexyl)fluorene of defined degree of polymerization 4, 5, 6, and 7 were investigated by X‐ray diffraction in the non‐oriented and in the aligned state. The diffraction data give evidence for a smectic B type phase for all of the oligomers. Quenching below the glass transition does not change the structure of the liquid crystalline phase. This allows to align spin‐coated films of these oligomers on rubbed polyimide substrates to give monodomain films. These are stable against thermal disordering below Tg, e.g. at room temperature. The degree of alignment is characterized by the dichroic spectra and polarized fluorescence spectra. Dichroic ratios and polarization ratios increase substantially with the chain length and values as high as D = 23 and P = 41 are obtained for the heptamer. The type of packing of the oligomers in the LC phase is discussed based on the X‐ray single crystal structure of models. In one such model the packing of the 2‐ethylhexyl side chains could be fully resolved, while the other model reveals the torsional angle between adjacent fluorene units in the same molecule as 144.2° which corroborates earlier work based on fiber diffraction of corresponding polyfluorenes.

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Dielectric Relaxation of Side‐Chain Liquid Crystalline Ionomers Containing Alkaline Metal Ions
Authors: Nikonorova Natalia A. , Barmatov Evgeny B. , Pebalk Dimitry A. , Diaz‐Calleja Ricardo , Kremer Friedrich
Published: August 2005

Summary: Two sets of side‐chain, liquid‐crystalline ionomers based on copolymers of butyl acrylate and 4‐{[6‐(acryloyloxy)hexyl]oxy}benzoic acid containing 2.5–20 mol‐% of lithium or rubidium ions were studied. As the content of ions of alkali metals increases, segmental mobility markedly decreases. As compared with rubidium‐containing ionomers, ionomers containing lithium ions are characterized by a far more efficient decrease in their dielectric relaxation times because ionic radius of lithium ions is lower than that of rubidium ions.

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A New Method to Purify Highly Phosphonated Block Copolymers and Their Effect on Calcium Carbonate Mineralization
Authors: Wang Tongxin , Rother Gudrun , Cölfen Helmut
Published: August 2005

Summary:Highly phosphonated double hydrophilic block copolymers (DHBCs) were synthesized through chain transfer radical polymerization or polymerization from a macro‐initiator. The DHBCs can be purified by a reprecipitation technique, in which any of the side products or precursors without phosphonate groups can be removed completely. This method provides a new route to purify other functional macromolecules with carboxylic, sulfonate groups etc. apart from dialysis and ultrafiltration. In addition, crystallization results show that the phosphonate groups have a strong influence on calcium carbonate mineralization. They can control the morphology of calcium carbonate from smooth spherical structures to porous structures even at a rather low concentration due to the strong effect of the phosphonate groups on crystallization of the mineral.

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An Application of Silica‐Based Monolithic Membrane Emulsification Technique for Easy and Efficient Preparation of Uniformly Sized Polymer Particles
Authors: Hosoya Ken , Bendo Mitsuko , Tanaka Nobuo , Watabe Yoshiyuki , Ikegami Tohru , Minakuchi Hiroyoshi , Nakanishi Kazuki
Published: August 2005

Summary: Uniformly sized polymer particles were prepared by an emulsification and polymerization technique utilizing a silica monolithic membrane, namely the “silica monolithic membrane emulsification technique”. In this paper, we utilized silica monolithic membrane as a device for the preparation of uniformly sized polymer particles. A mixture of monomers, diluents and oil‐soluble initiator was emulsified into a continuous medium through the silica monolithic membrane and polymerized. The particles obtained had a higher size uniformity than that of particles prepared by previously reported membrane emulsification techniques, such as the Shirasu Porous Glass (SPG) emulsification technique. Through the silica monolithic membrane emulsification technique, we could prepare particles having availability as a possible packing material for solid‐phase extraction (SPE) and high performance liquid chromatography (HPLC).

SEM photograph of silica particles prepared through capillary plate membrane.

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SEM photograph of silica particles prepared through capillary plate membrane.
Compatibilization of Polyamide‐6/Polyarylate Blends by Means of an Ionomer
Authors: Retolaza Aritz , Eguiazábal José Ignacio , Nazábal Jon
Published: August 2005

Summary: Polyamide‐6 (PA6)/polyarylate of bisphenol A (PAr) blends rich in PA6 and modified with an additional 15% poly[ethylene‐co‐(methacrylic acid)] partially neutralized with zinc (PEMA‐Zn) as a compatibilizer were obtained by melt mixing. Their phase structure, morphology, and mechanical performance were compared with those of the corresponding binary blends. The ternary blends were composed of a PA6 amorphous matrix and a dispersed PAr‐rich phase in which reacted PA6 and PEMA‐Zn were present. Additionally, minor amounts of a crystalline PA6 phase, and a PEMA‐Zn phase were also present. The chemical reactions observed led to a clear decrease in the dispersed particle size when PEMA‐Zn was added, indicating compatibilization. Consequently, the mechanical behavior of the blends with PEMA‐Zn improved, leading, mainly in the case of the blend with 10% PAr, to significant increases in both ductility and impact strength with respect to those of the binary blends. These increases were more remarkable than the slight decrease in stiffness as a consequence of the rubbery nature of the compatibilizer.

Cryogenically fractured surface of the PA6/PAr‐PEMA‐Zn 70/30‐15 ternary blend.

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Cryogenically fractured surface of the PA6/PAr‐PEMA‐Zn 70/30‐15 ternary blend.
One‐Step Cationic Poly(D,L‐lactic acid) Particle Synthesis by Diafiltration and Interactions with Plasmid DNA
Authors: Messai Isabelle , Delair Thierry
Published: August 2005

Summary: Diafiltration was used for the one step preparation of cationic poly(D,L‐lactic acid) particles in the presence of poly(ethylenimine) (PEI). First, parameters impacting the formation of plain PLA particles were investigated: the chemical nature of the solvent and the polymer concentration within the organic phase. Then, PEI was added to the organic solution and this mixture was subsequently dialyzed against water. The molecular architecture of the polycation was essential and colloidal particles were only obtained with a branched PEI of 25 000 g · mol−1. Increasing the PEI concentration in the mixture led to a particle mean size reduction and a zeta‐potential increase. In any case, a maximum of 8% of the initial PEI input was recovered at the interface. Finally, the study of the interactions of these colloids with DNA showed that the amount of DNA bound at the saturation plateau increased with increasing inputs of PEI in the formulation.

SEM micrograph of cationic poly(D,L‐lactic acid) particles.

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SEM micrograph of cationic poly(D,L‐lactic acid) particles.
Diversification of CDK11 transcripts during chicken testis development and regression
Authors: Francone Victor P. , Mezquita Jovita
Published: August 2005

CDK11 (cyclin‐dependent kinase 11, formerly known as PITSLRE) is a serine/threonine kinase that associates with the cyclin L2 regulatory partner. CDK11 catalytic activity has been associated with apoptosis, transcription, and RNA processing. Here, we identify novel chicken testis CDK11 transcripts that differ in their 5′UTR, 3′UTR, splicing of the exon 6, and polyadenylation. We have also characterized the differential expression of CDK11 in somatic tissues, during testis development and upon testicular regression by diethylstilbestrol (DES) treatment. The heterogeneity of CDK11 transcripts presented in this study suggests new possibilities for post‐transcriptional regulation. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
A mouse gene encoding a novel member of the WD family of proteins is highly conserved and predominantly expressed in the testis (Wdr13)
Authors: Suresh Amritha , Shah Vanya , Rani Deepa Selvi , Singh Bhupendra N. , Prasad Gogineni Uma , Subramanian Subbaya , Kumar Satish , Singh Lalji
Published: August 2005

Wdr13, a novel member of the WD family of proteins and the mouse homolog of WDR13 is localized to the locus XA1.1 and is predominantly expressed in the testis. The expression begins at the early stages of gonadal development and is maintained throughout the adult life with a predominant expression in the germ cells of adult testis. RNA in situ hybridization on the testis and brain sections indicated a cytoplasmic expression of the transcript. The alternatively spliced transcripts of the gene are generated by different methods and showed a differential pattern of expression, suggesting functional diversity. The expression of the gene in the unfertilized egg and in the neural stem cells indicated the functional significance of the gene from the early stages of development. The nuclear localization of the mouse WDR13 protein suggested a regulatory function. Evolutionary analysis of the gene indicated an extensive functional conservation across diverse species. Comparison of the genomic organization of the different homologs revealed a varied organization in the invertebrate homolog and the retention of the functionally significant introns in the same. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
A note on trees, tables, and algorithms
Authors: Goddard Wayne , Hedetniemi Stephen T.
Published: August 2005

Several algorithms for optimal vertex subsets in trees are given by simple tables. In this article we investigate the properties of and operations on these tables. We use known techniques for combining tables to correct a table in the literature; give a necessary and sufficient condition for a table to correspond to some tree property; discuss the question of dividing one table by another; explain how to derive a table from a set of representatives; and apply this to finding the table for the parameter external redundance. All of this is facilitated by computer software. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
The element connectivity parameterization formulation for the topology design optimization of multiphysics systems
Authors: Ho Yoon Gil , Young Kim Yoon
Published: August 2005

In spite of the success of the element‐density‐based topology optimization method in many problems including multiphysics design problems, some numerical difficulties, such as temperature undershooting, still remain. In this work, we develop an element connectivity parameterization (ECP) formulation for the topology optimization of multiphysics problems in order to avoid the numerical difficulties and yield improved results. In the proposed ECP formulation, finite elements discretizing a given design domain are not connected directly, but through sets of one‐dimensional zero‐length links simulating elastic springs, electric or thermal conductors. The discretizing finite elements remain solid during the whole analysis, and the optimal layout is determined by an optimal distribution of the inter‐element connectivity degrees that are controlled by the stiffness values of the links. The detailed procedure for this new formulation for multiphysics problems is presented. Using one‐dimensional heat transfer models, the problem of the element‐density‐based method is explained and the advantage of the ECP method is addressed. Copyright © 2005 John Wiley & Sons, Ltd.
Solving eigenvalue problems by implicit decomposition
Authors: Luo Jenn‐Ching
Published: August 2005

This paper presents three innovative methods for solving eigenvalue problems for differential equations based upon the techniques of implicit decomposition developed by Luo and Friedman. An eigenvalue problem can be written as an approximate algebraic system of the form [K]{X} + λ[M]{X} = 0 by employing finite elements. These methods provide robust techniques to compute the real eigenpair, λ and {X}, where [K] and [M] can be asymmetric, indefinite, and even singular.
Semigroup linearization for nonlinear parabolic equations
Authors: Epperson James F.
Published: August 2005

We present an algorithm for nonlinear parabolic equations that uses a linear semigroup approach to decouple the nonlinearity, thus allowing simpler techniques to be used for the solution. The basic method is applicable only to a restricted class of problems, but can be extended with little loss of utility. Stability and error estimates are given, along with example computations.