bluuebunny/crossref_metadata_2025 huggingface dataset:
A family of lower‐ and higher‐order transversal linearization techniques in non‐linear stochastic engineering dynamics
Authors: Roy D.
Published: August 2004

Sample pathwise numerical integration of noise‐driven engineering dynamical systems cannot generally be performed beyond a limited level of accuracy, especially when the noise processes are modelled using (filtered) white noises. Recently, a locally transversal linearization (LTL) strategy has been proposed by the author (Proc Roy Soc London A 2001; 457:539–566) for direct integration of deterministic and stochastic non‐linear dynamical systems. The present effort is focussed on a host of extensions along with detailed theoretical error analyses of the linearization approach, especially as applied to problems in non‐linear stochastic engineering dynamics. Thus, to begin with, estimates of local and global error orders in the basic LTL scheme are obtained separately for the displacement and velocity vectors when the system is driven either by a set of additive noises or by an arbitrary combination of (independently evolving) additive and multiplicative noises. Following this, a new family of higher‐order LTL schemes is proposed in order to improve upon the basic LTL method and the associated error orders are established. A stepwise implementation of the lower‐ and higher‐order versions of the LTL method, along with certain computational aspects, is also outlined. The proposed schemes are numerically illustrated, to a limited extent, for a single degree‐of‐freedom (SDOF) and a two degree‐of‐freedom (TDOF) non‐linear engineering systems under additive and/or multiplicative white noise excitations. Copyright © 2004 John Wiley & Sons, Ltd.
Reduced modified quadratures for quadratic membrane finite elements
Authors: Long Craig S. , Groenwold Albert A.
Published: August 2004

Reduced integration is frequently used in evaluating the element stiffness matrix of quadratically interpolated finite elements. Typical examples are the serendipity (Q8) and Lagrangian (Q9) membrane finite elements, for which a reduced 2 × 2 Gauss–Legendre integration rule is frequently used, as opposed to full 3 × 3 Gauss–Legendre integration. This ‘softens’ these element, thereby increasing accuracy, albeit at the introduction of spurious zero energy modes on the element level. This is in general not considered problematic for the ‘hourglass’ mode common to Q8 and Q9 elements, since this spurious mode is non‐communicable. The remaining two zero energy modes occurring in the Q9 element are indeed communicable. However, in topology optimization for instance, conditions may arise where the non‐communicable spurious mode associated with the elements becomes activated. To effectively suppress these modes altogether in elements employing quadratic interpolation fields, two modified quadratures are employed herein. For the Q8 and Q9 membrane elements, the respective rules are a five and an eight point rule. As compared to fully integrated elements, the new rules enhance element accuracy due to the introduction of soft, higher‐order deformation modes. A number of standard test problems reveal that element accuracy remains comparable to that of the under‐integrated counterparts. Copyright © 2004 John Wiley & Sons, Ltd.
A direct stiffness analysis of a composite beam with partial interaction
Authors: Ranzi G. , Bradford M. A. , Uy B.
Published: August 2004

The use of the conventional semi‐analytical stiffness method in finite element analysis, in which interpolation polynomials are used to develop the stiffness relationships, leads to problems of curvature locking when beam‐type elements are developed for composite members with partial interaction between the materials of which it is comprised. The curvature locking phenomenon that occurs for composite steel–concrete members is quite well reported, and the general approach to minimizing the undesirable ramifications of curvature locking has been to use higher‐order polynomials with increasing numbers of internal nodes. This paper presents an alternate formulation based on a direct stiffness approach rather than starting from pre‐defined interpolation polynomials, and which does not possess the undesirable locking characteristics. The formulation is based on a more general approach for a bi‐material composite flexural member, whose constituent materials are joined by elastic shear connection so as to provide partial interaction. The stiffness relationships are derived, and these are applied to a simply supported and a continuous steel–concrete composite beam to demonstrate the efficacy of the method, and in particular its ability to model accurately both very flexible and very stiff shear connection that causes difficulties when implemented in competitive semi‐analytical algorithms. Copyright © 2004 John Wiley & Sons, Ltd.
A cell boundary element method for elliptic problems
Authors: Jeon Youngmok , Park Eun‐Jae , Sheen Dongwoo
Published: August 2004

An elementary analysis on the cell boundary element (CBEM) was given by Jeon and Sheen. In this article we improve the previous results in various aspects. First of all, stability and convergence analysis on the rectangular grids are established. Moreover, error estimates are improved. Our improved analysis was possible by recasting of the CBEM in a Petrov‐Galerkin setting. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
Estimating protein–ligand binding free energy: Atomic solvation parameters for partition coefficient and solvation free energy calculation
Authors: Pei Jianfeng , Wang Qi , Zhou Jiaju , Lai Luhua
Published: August 2004

Solvation energy calculation is one of the main difficulties for the estimation of protein–ligand binding free energy and the correct scoring in docking studies. We have developed a new solvation energy estimation method for protein–ligand binding based on atomic solvation parameter (ASP), which has been shown to improve the power of protein–ligand binding free energy predictions. The ASP set, designed to handle both proteins and organic compounds and derived from experimental n‐octanol/water partition coefficient (log P) data, contains 100 atom types (united model that treats hydrogen atoms implicitly) or 119 atom types (all‐atom model that treats hydrogen atoms explicitly). By using this unified ASP set, an algorithm was developed for solvation energy calculation and was further integrated into a score function for predicting protein–ligand binding affinity. The score function reproduced the absolute binding free energies of a test set of 50 protein–ligand complexes with a standard error of 8.31 kJ/mol. As a byproduct, a conformation‐dependent log P calculation algorithm named ASPLOGP was also implemented. The predictive results of ASPLOGP for a test set of 138 compounds were r = 0.968, s = 0.344 for the all‐atom model and r = 0.962, s = 0.367 for the united model, which were better than previous conformation‐dependent approaches and comparable to fragmental and atom‐based methods. ASPLOGP also gave good predictive results for small peptides. The score function based on the ASP model can be applied widely in protein–ligand interaction studies and structure‐based drug design. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Making optimal use of empirical energy functions: Force‐field parameterization in crystal space
Authors: Krieger Elmar , Darden Tom , Nabuurs Sander B. , Finkelstein Alexei , Vriend Gert
Published: August 2004

Today's energy functions are not able yet to distinguish reliably between correct and almost correct protein models. Improving these near‐native models is currently a major bottle‐neck in homology modeling or experimental structure determination at low resolution. Increasingly accurate energy functions are required to complete the “last mile of the protein folding problem,” for example during a molecular dynamics simulation. We present a new approach to reach this goal. For 50 high resolution X‐ray structures, the complete unit cell was reconstructed, including disordered water molecules, counter ions, and hydrogen atoms. Simulations were then run at the pH at which the crystal was solved, while force‐field parameters were iteratively adjusted so that the damage done to the structures was minimal. Starting with initial parameters from the AMBER force field, the optimization procedure converged at a new force field called YAMBER (Yet Another Model Building and Energy Refinement force field), which is shown to do significantly less damage to X‐ray structures, often move homology models in the right direction, and occasionally make them look like experimental structures. Application of YAMBER during the CASP5 structure prediction experiment yielded a model for target 176 that was ranked first among 150 submissions. Due to its compatibility with the well‐established AMBER format, YAMBER can be used by almost any molecular dynamics program. The parameters are freely available from www.yasara.org/yamber. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Solution structure of γ‐bungarotoxin: The functional significance of amino acid residues flanking the RGD motif in integrin binding
Authors: Shiu Jia‐Hau , Chen Chiu‐Yueh , Chang Long‐Sen , Chen Yi‐Chun , Chen Yen‐Chin , Lo Yu‐Hui , Liu Yu‐Chen , Chuang Woei‐Jer
Published: August 2004

γ‐Bungarotoxin, a snake venom protein isolated from Bungarus multicinctus, contains 68 amino acids, including 10 cysteine residues and a TAVRGDGP sequence at positions 30–37. The solution structure of γ‐bungarotoxin has been determined by nuclear magnetic resonance (NMR) spectroscopy. The structure is similar to that of the short‐chain neurotoxins that contain three loops extending from a disulfide‐bridged core. The tripeptide Arg‐Gly‐Asp (RGD) sequence is located at the apex of the flexible loop and is similar to that of other RGD‐containing proteins. However, γ‐bungarotoxin only inhibits platelet aggregations with an IC50 of 34 μM. To understand its weak activity in inhibiting platelet aggregation, we mutated the RGD loop sequences of rhodostomin, a potent platelet aggregation inhibitor, from RIPRGDMP to TAVRGDGP, resulting in a 196‐fold decrease in activity. In addition, the average Cα‐to‐Cα distance between R33 and G36 of γ‐bungarotoxin is 6.02 Å, i.e., shorter than that of other RGD‐containing proteins that range from 6.55 to 7.46 Å. These results suggested that the amino acid residues flanking the RGD motif might control the width of the RGD loop. This structural difference may be responsible for its decrease in platelet aggregation inhibition compared with other RGD‐containing proteins. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Evaluation and rehabilitation of a building affected by a gas explosion
Authors: Bob Corneliu
Published: August 2004

The paper deals with efficient solutions for rehabilitation of a block of flats affected by a gas explosion in December 2002. The first part of the paper is devoted to general aspects of the effects of explosions on buildings and personnel. The characteristic of the peak incident pressure as well as maximum reflected pressure are presented. The design procedures and rehabilitation solutions of the buildings subjected to blast loads are described. Rehabilitation solutions for general structural vulnerabilities as well as specific solutions for rehabilitation are presented for RC structures, steel structures and masonry structures. These solutions have been adopted from those already used to develop seismic retrofits. Special attention has been paid to carbon‐fibre‐reinforced plastic (CFRP) materials.

The second part presents a case study analysis and rehabilitation of a block of flats. The damage due to the explosion is presented for the different structural elements: those in direct contact with blast pressure and the surrounding structural members. Structural analysis comprises two important aspects: the behaviour of the structural members subjected to direct blast pressure and the analysis of the state stresses in the entire building.

The rehabilitation solutions were chosen in accordance with the actual stage of the building. New elements have been used instead of the completely destroyed structural members. RC coatings and columns were necessary to assure continuity and stability of vertical members with serious damage after explosion. Longitudinal beams have the role of connecting the new vertical members. Utilization of CFRP for strengthening of slightly damaged elements has the advantages of easy technology and short time of erection. The other technical and economical advantages of the rehabilitation solutions are: safe behaviour under seismic action; slight change of general stiffness of the structure; small cost of rehabilitation. The consolidation and finishing works were completed by the middle of 2003.
Are exponential‐type basis sets preferable to Gaussians?
Authors: Shavitt Isaiah
Published: August 2004

The relative merits of exponential‐type and Gaussian basis sets are discussed. It is argued that contracted Gaussian basis sets are not just an expedient replacement for exponential‐type basis sets but have desirable properties of their own that make them appropriate choices for molecular electronic structure calculation, apart from the ease of calculation of their multicenter integrals. A variety of studies are quoted showing that appropriately chosen contracted Gaussian basis sets can produce satisfactory results even for electronic properties that depend strongly on the values of the wave function in regions close to and far from the nuclei. Further, it is argued that the long‐range behavior of the wave function in regions of consequence for the calculation of energies and electronic properties can actually be represented better by such basis sets than by exponential‐type basis sets. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Many‐center Coulomb Sturmians and Shibuya–Wulfman integrals
Authors: Avery John
Published: August 2004

When momentum space is projected onto the surface of a unit 4‐D hypersphere by means of Fock's mapping, Coulomb Sturmian basis functions can be simply represented in terms of hyperspherical harmonics. The properties of these harmonics can be used to evaluate Shibuya–Wulfman integrals and other integrals that arise when the Sturmian basis functions are used in molecular calculations. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Effects of Qi‐training on anxiety and plasma concentrations of cortisol, ACTH, and aldosterone: a randomized placebo‐controlled pilot study
Authors: Lee Myeong Soo , Kang Chang‐Won , Lim Hyun‐Ja , Lee Myung‐Suk
Published: August 2004

The effects of Qi‐training on anxiety, and plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, and aldosterone in healthy young men was investigated. Thirty‐two subjects were randomly assigned to a sham control group or a Qi‐training group. Although the basal level of anxiety did not differ between the groups, there was a significant group by time interaction of the 1‐hour intervention; anxiety decreased by 26 per cent in the Qi‐training group and by 9 per cent in the control group. After Qi‐training, the plasma concentrations of ACTH, cortisol, and aldosterone decreased, but these levels did not change in the control group. These findings suggest that Qi‐training improves anxiety and has a significant effect on the hypothalamic–pituitary–adrenal axis. Copyright © 2004 John Wiley & Sons, Ltd.
State policies and the challenges in attracting foreign direct investment: A review of the Ghana experience
Authors: Mmieh Frederick , Owusu‐Frimpong Nana
Published: August 2004

Foreign direct investment (FDI) to low‐income countries has not only received much publicity in the past two decades due to its economic importance, but its overall flow to these countries has also significantly increased in both relative and absolute terms. However, only a few sub‐Saharan African countries have been successful in attracting significant FDI flows. This article examines Ghana's experience in attracting FDI. Thus, the main thrust of this article is threefold. First, it evaluates the main economic policy adopted by the government from 1981 to 2002 to reverse the post‐independence economic decline. Second, it examines how the policies facilitated the attraction of FDI inflows to Ghana. Finally, it reviews some of the problems that impede the attraction of value‐added FDI inflows to Ghana. Qualitative analysis of available evidence reveals that the implementation of the Structural Adjustment Program (SAP), the main economic reform policy, has led to an increase in the number of multinationals investing in Ghana. This article argues that Ghana's SAP has had some degree of success in many areas, including the lowering of inflation; promotion of an environment of financial stability; elimination of the licensing requirement; the opening of previously closed sectors; removal of tariff barriers that prohibit FDI inflows; abolishing exchange controls; and reducing opportunities for the foreign exchange black market. In spite of the developments, there are still serious challenges that hamper the attraction of FDI inflows into the country. This article contends that there is the need for urgent action to tackle these challenges. © 2004 Wiley Periodicals, Inc.
Detection on liver tissue sections of S‐phase markers in synchronized cycling rat hepatocytes by SIMS microscopy
Authors: Casiraghi Odile , Lombard Marie‐Noëlle , Halpern Sylvain , Fragu Philippe
Published: August 2004

Summry— The aim of this study was to localise two ionic S‐phase markers in tissue sections using SIMS microscopy: aluminium as a potential endogenous marker and bromine as an exogenous marker after in vivo injection of bromodeoxyuridine (BrdU). This study was performed in an experimental model of hyperplastic proliferation after partial hepatectomy in rat. Aluminium was never detected in nuclei which were positive or negative for tritiated thymidine uptake, as determined by autoradiography in tissue prepared by cryotechniques. In contrast, bromine of BrdU was found in hepatocyte nuclei. However, there was a discrepancy between SIMS bromine images and BrdU immunohistochemistry detection which appears more sensitive. This is probably due to problems of stereology intrinsic to the correlation method which requires serial sections for this multi‐instrumental approach.
Comparison of techniques for the assessment of polymorphonuclear leukocyte polarisation in suspension
Authors: Harkin Damien G , Gadd Stephen J , Bignold Leon P
Published: August 2004

Summry— Polarisation of polymorphonuclear leukocytes (PMN) is suspension was assessed using three techniques: 1) visual classification; 2) computerized morphometry; and 3) flow cytometry. While visual classification detected the formation, polarisation and type of cytoplasmic extensions produced by PMN, morphometry and flow cytometry detected only the formation of extensions. The area, perimeter and ellipticity were, in general, statistically different for each subtype of PMN‐shape identified by visual classification. Furthermore, the magnitude and direction of changes detected by flow cytometry were affected by the use of erythrocyte lysis (during isolation of the cells) and the fixative used prior to analysis. The findings of this study demonstrate that visual classification is a more sensitive, reliable and appropriate assay of PMN polarisation than current morphometric and flow cytometric methods.
Comparative evolution of endocytosis levels and of the cell surface area during the L929 cell cycle: A fluorescence study with TMA‐DPH
Authors: Illinger Dominique , Italiano Liliane , Beck Jean‐Paul , Waltzinger Caroline , Kuhry Jean‐Georges
Published: August 2004

Summry— 1‐[4‐(trimethylamino)phenyl]‐6‐phenylhexa‐1,3,5‐triene (TMA‐DPH), a membrane fluorescence probe, interacts with living cells by instantaneous partition between the external medium and the plasma membrane, where it becomes fluorescent. The corresponding fluorescence intensity is then proportional to the cell surface. On the other hand, once incorporated into the plasma membrane, TMA‐DPH follows this membrane in the constitutive intracellular traffic and behaves as a monitor for endocytosis. Using this tool on L929 synchronized cells, we showed that the endocytosis levels after 30 min uptake of the probe increased from G1 to mitosis, when they abruptly decreased. The cell surface remained constant throughout the cell cycle, except at the beginning of mitosis when it almost doubled.
Heat conductance, diffusion theory and intracellular metabolic regulation
Authors: Wheatley Denys N. , Malone P. Colm
Published: August 2004

Summary— Diffusion theory played a major role in the development of biology as an exact science. The question is raised, however, as to its relevance and applicability in the molecular interactions which occur in metabolism in the living cell. This review looks at diffusion theory from its inception and subsequent introduction into biology, its shortcomings with regard not only to whole‐body physiology, but more pertinently at the intracellular level, with its failure to offer a rational basis for metabolic regulation in the internum of the cell. The conclusion is reached that although diffusion inevitably occurs within cells, its role is of little importance with regard to most metabolic activity. In comparison, perfusion of the internal surfaces of the cell by streaming of the fluid compartment of the cytoplasm seems to be the modus operandi which allows molecular interactions to occur at rates far beyond those that diffusion would permit, and at the same time offers a mechanism which permits sensitive control of metabolic activity.
Monocyte‐endothelial cell interactions in vitro, with reference to the influence of interleukin‐1 and tumor necrosis factor
Authors: Fan Jianglin , Shimokama Tatsuro , Haraoka Seiji , Tokunaga Osamu , Watanabe Teruo
Published: August 2004

Summary— The interaction between monocytes and endothelial cells plays an important role in normal vascular biology and the pathogenesis of several vascular diseases. In the present study, interactions of freshly isolated human monocytes (Mos) and cultured umbilical vein endothelial cells (ECs) were quantitatively analyzed by a time lapse microcinematographic optical video system in vitro, with reference to Mo locomotion, adherence, and cytokine influence on these processes. The interaction between Mos and ECs was found to be a dynamic process. Without any stimulation of ECs, Mos generally possessed higher binding capacity to ECs and more active motile property than neutrophils and lymphocytes. The binding ratio of Mos to ECs varied from 0 to 8. Mos crawled over the surface of ECs or along the intercellular boundary areas of ECs by extending pseudopodia as long as 60 μm in length to traverse several ECs. Mos migrated into the subendothelium and could cause the distruption of the EC monolayer. In contrast, neutrophils or lymphocytes showed less adhesiveness to ECs and exhibited less dislocation when they moved on the ECs. Pretreatment of ECs with either human recombinant interleukin‐1β (IL‐1β) or tumor necrosis factor (TNF) (10–20 U/ml for 4–8 h) significantly increased adhesion rates of both Mos and neutrophils. Furthermore, the increased adhesion of neutrophils to stimulated ECs was accompanied by incremental increases in the rate of cellular movements. These phenomena were found to be associated with activation of EC surface adhesion molecules. In addition, by using the Boyden chamber assay, we found that IL‐1 and TNF did not produce any chemotactic activity for Mos with a concentration range of 10−3 to 103 U/ml. These results indicates that, in comparison with neutrophils and lymphocytes, Mos exhibited active adhesive and motive properties even on unstimulated EC surfaces, which could potentially interfere with the integrity of ECs. Upon exposure to cytokine stimulation, ECs increase the expression of adhesion molecules thereby enhancing both adhesion and locomotion of leukocytes. The distinctively higher affinity for binding to cultured ECs of blood Mos and their active motility relative to other circulating leukocytes may have great consequences in various physiological and pathological processes in vivo, including atherogenesis.
Characterization of membrane sugar‐specific receptors in cultured high endothelial cells from mouse peripheral lymph nodes
Authors: Bizourane Nadine , Mitterrand Michèle , Monsigny Michel , Kieda Claudine
Published: August 2004

Summary— The culture of specialized high endothelial cells (HEC) from lymphoid organs (peripheral lymph nodes (PLN) and Peyer's patches (PP)) was undertaken in order to study and characterize the cell surface molecules which are involved in lymphocyte recognition and allow homing. Cells were stimulated in vivo by a graft versus host (GVH) type of reaction before isolation and culture. The resulting adherent and growing cells were characterized as endothelial cells because of their typical aspect and their ability to produce angiotensin‐converting enzyme and factor VIII‐related antigen. They possess tissue‐specific endothelial addressins. MECA 79 antigen is present on cells isolated from PLN while MECA 367 antigen is detected on cells from PP. Surface receptors for glycans were studied cytochemically using neoglycoproteins and fluorescence microscopy and quantified by flow cytometry experiments which showed that the specificity of sugar receptors depends upon endothelial cell origin. Indeed, sugar receptors for α‐L‐fucosyl residues were specifically expressed by endothelial cells from PLN. These receptors were inducible upon action of activated lymphocyte‐conditioned medium. Further characterization of endothelial cells from peripheral lymph nodes indicates that they indeed mediate adhesion of lymphocytes in vitro. The role of protein‐sugar interactions in this process was assessed by inhibition experiments performed with the help of neoglycoproteins. Best inhibitory effects were obtained when endothelial cells had been preincubated with α‐L‐fucosyl‐BSA and when lymphoid cells were preincubated with β‐D‐galactosyl‐BSA. Concomitant inhibition assays indicate the participation of sugar specific receptors — endogeneous lectins — on the surface of both endothelial and lymphoid cells to achieve recognition and adhesion.
Culture of hybridoma and friend leukemia virus transformed cells in microgravity. Spacelab IML‐1 mission
Authors: Bechler Birgitt , Hunzinger Elisabeth , Müller Otfried , Cogoli Augusto
Published: August 2004

Summary— The behavior of two mammalian cell lines was investigated in Biorack during the 1st Spacelab international microgravity laboratory flight (IML‐1) in the ESA facility Biorack. The parameters determined were cell proliferation, biosynthesis of specific cell products, consumption of glucose, glutamine and production of ammonia and lactate respectively. Murine Friend leukemia virus‐transformed cells (Friend cells) were induced to differentiate and express hemoglobin (Hg) genes upon induction with dimethylsulfoxide (DMSO). No change was observed in all metabolic parameters including the production of Hg and the number of Hg‐positive cells. Electron microscopy analysis showed no difference in morphology, mean cell volume and mitotic index between the different cell samples, Murine hybridoma cells revealed an increase (+ 30–40%) of cell proliferation rate in microgravity, whereas the metabolic parameters, production of monoclonal antibodies included, were lower in the 0 g than in the 1 g controls. The results clearly show that not all mammalian cells undergo dramatic changes in microgravity and that the effects reported on human T lymphocytes represent a unique case.
Despite its high representation in extrachromosomal circular DNAs from Drosophila embryos, the dodecasatellite does not allow autonomous replication in cultured cells
Authors: Renault Sylvaine , Degroote Fabienne , Picard Georges
Published: August 2004

Summary— The dodecasatellite is a 11/12 bp tandemly repeated sequence which is overrepresented, with regard to its genomic representation, in extrachromosomal circular DNAs from D melanogaster embryos. Here we show that a bacterial plasmid carrying a cluster of dodecasatellite is not able to replicate efficiently in cultured cells. This observation does not support the hypothesis that the over‐representati results from an autonomous replication of dodecasatellite circular DNA molecules.
Posttranslational modifications and assembly characteristics of goldfish tubulin
Authors: Lessman Charles A. , Zhang Jianshe , MacRae Thomas H.
Published: August 2004

Summary— Cell‐free extracts from goldfish brain, ovarian follicles, testes and the cell line, ATCC CCL‐71, were analyzed for post‐translationally modified tubulins. All samples, with the exception of that from brain where the reverse was true, contained more tyrosinated than detyrosinated α‐tubulin. Additionally, extracts from brain and testes exhibited acetylated α‐tubulin whereas this isoform was not visualized on blots of cell‐free preparations from follicles and CCL‐71 cells. Assembly of brain and ovary tubulin was induced with taxol. Brain tubulin, partially purified through three cycles of assembly/disassembly was associated with a variety of putative microtubule‐associated proteins (MAPs), most of which had a high molecular mass. There were very few cold stable microtubules in brain preparations whereas, for ovary, purification of tubulin was hampered by significant losses of cold stable polymer. Comparison of brain and ovary showed there was no‐correlation between the extent of α‐tubulin detyrosination or acetylation and cold stability of microtubules. Moreover, cycled tubulin from ovary contained acetylated tubulin even though this was not observed on blots of cell‐free extracts from ovary or from follicles. Cultured goldfish cells contained extensive arrays of microtubules, many of which originated from discrete organizing centers. The results reveal the widespread distribution of posttranslationally modified tubulins in goldfish tissues, the different assembly/disassembly characteristics of tubulin from brain versus ovary, and the presence of putative neural MAPs, mostly with a high molecular mass.
Evaluation of fixative composition, fixative storage, and fixation duration on the fine structure and volume of root‐cell nucleoli
Authors: Dannenhoffer Joanne M. , Shen‐Miller J.
Published: August 2004

Summary— The effect of various combinations of three fixative compositions (glutaraldehyde buffered in veronal acetate, cacodylate, and piperazine‐N, N'‐bis[2‐ethanesulfonic acid]—PIPES], two fixative storage times (fresh vs 6 weeks), and two fixation durations (3 h vs 9 days) on nucleolar fine structure and nucleolar volume in three root cell‐types of oat seedlings (Avena sativa L, cv Seger) were evaluated. All fixatives show overall good preservation of fine structure. Nucleolar components are distinct and well delineated in cells fixed in solutions buffered with either cacodylate or veronal acetate; the components are more condensed when preserved in fixative buffered with PIPES. Nucleolar volume is greatest in cells fixed in the cacodylate fixative, and smallest in those preserved in the PIPES fixative. Among the treatments tested, the PIPES fixative evidently best maintains nucleolar volume. Distracting particulate deposits are abundant on nuclei and nucleoli in cells preserved in the veronal‐acetate fixative. Contrary to common assumptions, aging of buffered fixative at room temperature for 6 weeks seems to affect neither the general quality of cellular preservation nor the pH of the fixatives, although nucleolar volume is reduced by such treatment. Long‐period fixation (9 days) results in destruction of membrane integrity (mitochondria, plastids, ER), and shrinkage of organelles from the cytoplasm. Nucleolar volume is reduced with prolonged fixation.
Expression of the β‐subunit isoforms of the Na, K‐ATpase in rat embryo tissues, inner ear and choroid plexus
Authors: González‐Martínez Luis M. , Avila Julio , Martí Elisa , Lecuona Emilia , Martín‐Vasallo Pablo
Published: August 2004

Summary— We report evidence of the apical localization of the two Na, K‐ATPase β‐subunit isoforms in cells of the inner ear and of the choroid plexus of the rat. To this end, we generated isoform‐specific antisera against the human Na, K‐ATPase β1 and β2 subunits. These polyclonal rabbit antisera were raised against truncated β‐isoform proteins that were made in E coli with pET expression vectors. Deglycosylation of the native antigen with N‐endoglycosidase F shows four bands in the β1 isoform and five bands in the β2 iso‐form immunoblots. In E15 rat embryos, the β1 isoform was detected in brain, heart and kidney and the β2 isoform only in brain. While β‐subunit mRNA expression (Watts AG, Sanchéz‐Watts G, Emanuel JR, Levenson R 1991 Proc Natl Acad Sci USA 88, 7425–7429), and immunoblotting and enzymatic activity have been determined (Zlokovic BV, Mackic JB, Wang L, McComb JG, McDonough A 1993 J Biol Chem 268, 8019–8025), very little is known about the specific localization of each β‐isoform in the epithelia of choroid plexus and inner ear. Immunocytochemical preparations of 15‐day‐old whole rat embryos and adult rat brain showed an enhanced staining for the β1 and β2 isoforms in the apical membrane of the ampullary crests of the inner ear's semicircular ducts and in the cuboidal cells of the choroid plexus
The activation of protein kinase A by cyclic AMP is influenced by oestradiol and progesterone in supernatants from the anterior pituitary but not from hypothalamus of the female rat
Authors: Ostrowska Anna
Published: August 2004

Summary— The activation of protein kinase A (PKA) by cAMP was estimated in supernatant fractions from the hypothalamus (Hyp) and anterior pituitary (AP) of the female rat during the oestrous cycle and in ovariectomized and ovariectomized, ovarian steroid hormone treated animals. In both structures, the largest activation of PKA was found in dioestrus‐2, while the lowest one was in Hyp in dioestrus‐1 and in AP in oestrus. Ovariectomy had no influence on cAMP‐dependent activation of PKA from Hyp and AP. Treatment of ovariectomized rats with 17‐β‐oestradiol (E2), progesterone (P) or both abolished the activation of PKA by cAMP from AP and had no effect on hypothalamic PKA. These results indicate that ovarian steroids act specifically on AP processes via cAMP dependent pathway and regulation of PKA activity.
Two monoclonal antibodies against prolactin‐receptor are internalized in epithelial mammary cells without mimetic prolactin effect on casein secretion*
Authors: Seddiki Touria , Delpal Serge , Aubourg Alain , Ollivier‐Bousquet Michéle
Published: August 2004

Summary— Prolactin exerts an early stimulatory effect on casein secretion which was qualified as a secretagogue effect. After binding to its receptor, the hormone transits intracellularly through the mammary epithelial cell. When this transit is slowed down the secretagogue effect does not occur. Different monoclonal antibodies which bind to the rabbit prolactin receptor have been previously developed. One of them (A917) mimics prolactin effect on casein gene expression. Another (M110) blocks this prolactin effect. In order to study the respective role of the hormone and its receptor, we have examined the binding of the two monoclonal antibodies (M110 and A917), labeled with biotin or colloidal gold, to the receptor of lactating rabbit mammary epithelial cells in incubation. Subsequently, the intracellular movement of these antibodies and the secretory response have been measured. Irrespective of the labeling (biotin or colloidal gold) or the preparation of tissues (fragments or enzymatically dissociated cells), Ml 10 and A917 bound to the basal membrane of mammary epithelial cells. However, only M110 bound to apical membrane of dissociated cell when this membrane was in direct contact with the incubation medium, showing that the two antibodies discriminate the receptor located on the apical membrane. Following internalization, each antibody was carried via a peculiar pathway. M110 remained associated with the cells during a 1‐h incubation, mainly in endosomes, multivesicular bodies and lysosomes like vesicles. In contrast, A917 was very quickly detectable in endosomes, multivesicular bodies and vesicles of the Golgi region and was carried throughout the cell to the lumen of the acini. M110 and A917 were extremely rare in secretory vesicles containing casein micelles. When mammary fragments pulse labeled for 3 mm with 3H‐leucine were chased for 60 mm in the presence of prolactin, M110 or A917, only prolactin was able to increase casein secretion. These results show that two monoclonal antibodies against prolactin receptor are internalized after binding to the surface of the mammary cell. They are carried intracellularly by different routes. Internalization of these antibodies is not sufficient to mimic the secretagogue effect of prolactin.
Immunogold labelling of xylans and arabinoxylans in the plant cell walls of maize stem
Authors: Migné Carole , Prensier Gérard , Grenet Elisabeth
Published: August 2004

Summary— Polyclonal antibodies against 4‐O‐methyl‐glucuronoxylan and α L‐1‐3 arabinofuranosyl poly‐β‐d‐1‐4‐xylopyranosyl were raised from rabbits. An immunocytochemical technique was used to localize xylans and arabinoxylans in the plant cell walls of the apical internode of two maize lines of different digestibility. The sclerenchyma, fibres and xylem (lignified tissues) and the parenchyma (non‐lignified tissue) were studied. The arabinoxylans were more heavily labelled than the xylans in the lignified tissues of the less digestible maize whereas in the more digestible line the labelling of the two polysaccharides was similar. The xylans and arabinoxylans were localized in the secondary cell wall. In both maize lines, labelling increased from the base upwards of the apical internode, reflecting the changes in growth stage.
Organization and composition of the striated roots supporting the Golgi apparatus, the so‐called parabasal apparatus, in parabasalid flagellates
Authors: Brugerolle Guy , Viscogliosi Eric
Published: August 2004

Summary— In parabasalid flagellates, trichomonads and hypermastigids, the stack of cisternae of the Golgi apparatus are supported by striated roots attached to the basal bodies of flagella forming the so‐called parabasal apparatus. Monoclonal antibodies raised for several trichomonad species, Monocercomonas, Trichomonas and Tetratrichomonas, label the parabasal fibre in immunofluorescence or immunogold staining and protein bands in immunoblotting. Several antibodies cross‐react between trichomonad species, and one of them labels the homologous parabasal fibre in the hypermastigids: Trichonympha, Joenia, Pseudotrichonympha and Holomastigotoides. Considering the molecular mass range of the labelled proteins (100–135 kDa) and the lack of antibody cross‐reactivity with the striated root proteins (centrin, assemblin, kinetodesmal protein, ciliary root proteins of epithelial ciliated cells) of other organisms, these proteins recognized by these antibodies seem to represent a new class of protein forming striated roots. The occurrence and significance of parabasal organization in eukaryogenesis is discussed.
Antidiuretic response in the urinary bladder of Xenopus laevis: Presence of typical aggrephores and apical aggregates
Authors: Calamita Giuseppe , Gounon Pierre , Gobin Renée , Bourguet Jacques
Published: August 2004

The urinary bladder of the aquatic toad Xenopus laevis is known to exhibit a low permeability to water and a poor sensitivity to antidiuretic hormone. In order to precise the characteristics and the specific cellular mechanisms of this reduced hydroosmotic response we used a sensitive volumetric technique to monitor net water flow and studied the correlation between the anti‐diuretic hormone (ADH)‐induced net water flow and the fine ultrastructural appearence of the urinary bladder epithelium. Transmural net water flow was entirely dependent on the osmotic gradient across the preparation and not on the hydrostatic pressure difference. We observed the existence of a low but significant hydro‐osmotic response to arginine vasopressin. Freeze‐fracture electron microscopy demonstrated the presence of typical aggrephores in the subapical cytoplasm. The response to the hormone was accompanied by the appearance of typical intramembrane aggregates into the apical plasma membrane. Water permeability increase and apical aggregate insertion were both slowly but fully reversible. Except for the multilayered structure of the epithelium and the particularly low response to antidiuretic hormone, all the studied permeability and ultrastructural characteristics of the bladder were thus very similar to those observed in other sensitive epithelia such as the amphibian bladder and skin and the mammalian collecting duct which exhibit a high hydro‐osmotic response to the hormone.
Imaging surface of gold‐immunolabeled thin sections by atomic force microscopy
Authors: Saoudi Bachir , Lacapère Jean‐Jacques , Chatenay Didier , Pépin Régis , Derpierre Christine , Sartre Alain
Published: August 2004

Atomic force microscopy (AFM) has been used to image the surface of thin sections of fungal infected plant tissue, with or without post‐embedding immunocytochemical labeling with gold conjugates. Plant and fungal cells are easily identified from their size, shape and roughness. The cellular shape is similar to that observed by light or electron microscopy (LM or EM) and some internal organelles can even be individualized. The gold beads are easily observed and counted. Their dimensions varied according to the roughness of the surface, but fit with the expected sizes.
An unusual mechanosensitive cell in a crustacean exteroceptor
Authors: Crouau Yves
Published: August 2004

The ultrastructure and mechanosensitivity of a sensory organ in a terrestrial isopod are investigated. The mechanosensitivity of this sensory organ is demonstrated. Seven sensory cells are observed; one of them displays unusual ultrastructural features, a lamellar ciliary root and a tubular body‐like structure. The six other sensory cells are similar to usual chemosensitive cells. No sensory cell presents the characteristic cytological features of crustacean mechanosensitive exteroceptors.
Nanofilament dependent motility in dinoflagellates
Authors: Cachon Jean , Cachon Monique , Greuet Claude , Huitorel Philippe
Published: August 2004

Summary— In dinoflagellates, as in many eukaryotes, several kinds of nanofilaments have been described: some are organized in bundles showing a strict periodicity, some are not; most are contractile upon a rise in Ca2+ concentration, some are not. In any case, their contractile properties appear to be ATP independent. They are present in all cell types studied so far, and are typically found in association with the centrioles‐basal bodies where they are suggested to play a role in MTOC structure, position and function. Nanofilaments are all about 2–4 nm in diameter, interact with microtubules, and are insoluble filaments, though to a variable extent. We propose that the nanofilaments may play a structural and/or active role complementary to intermediate filaments.
Effects of retinoic acid metabolites on proliferation and differentiation of the clonal rhabdomyosarcoma cell line BA‐HAN‐1C
Authors: Ramp Uwe , Gerharz Claus Dieter , Eifler Edith , Biesalski Hans Konrad , Gabbert Helmut Erich
Published: August 2004

Summary— The clonal rat rhabdomyosarcoma cell line BA‐HAN‐IC is composed of proliferating mononuclear cells, some of which spontaneously fuse to terminally differentiated myotube‐like giant cells. This cell line has been shown to be susceptible to differentiation induction with all‐trans retinoic acid (RA). Since it is still unknown whether exclusively all‐trans RA itself or also its metabolites can act as inductive compounds in our cell line, we exposed BA‐HAN‐1C cells to the metabolites 4‐hydroxy RA, 4‐oxo RA and 5,6epoxy RA. Exposure to these RA metabolites resulted in a significant inhibition of proliferation (P < 0.001) and induction of cellular differentiation, as evidenced by a significant increase in the number of myotube‐like giant cells (P < 0.05) and a significant increase in creatine kinase activity (P < 0.05). However, differences in the inductive potency of these RA metabolites became apparent. Furthermore, RA metabolites exhibited a significantly weaker (P < 0.05) inductive activity when compared to all‐trans RA. Summarizing our results we could demonstrate that the endogenous metabolites 4‐hydroxy RA, 4‐oxo RA and 5,6‐epoxy RA are not merely deactivated cellular excretion products of all‐trans RA, but potent inducers of differentiation and inhibitors of proliferation, possibly contributing to the complex physiological actions of retinoic acid.
The proliferating cell marker monoclonal antibody Ki‐67 recognizes specific antigens associated with the nuclear envelope of the early Drosophila embryo
Authors: Callaini Giuliano , Riparbelli Maria Giovanna , Cintorino Marcella , Tripodi Sergio Antonio , Bianciardi Giorgio , Tosi Piero , Dallai Romano
Published: August 2004

Summary— Immunofluorescence and immunoelectron microscopy indicated that the antibody raised against the nuclear antigen Ki‐67 of mammalian cells recognized antigenic determinants of early Drosophila embryos, localized on the outside of the nuclear envelope. Hence, the nuclear envelope of Drosophila appears to share a similar epitope with the chromosome scaffold of mitotic mammalian cells. With the progression of mitosis the antigen persisted around the mitotic spindle region and was also found in the pole regions at metaphase and anaphase. The antibody also stained the equatorial regions of the spindles from anaphase to late telophase. The antibody may therefore be used as a biochemical marker of the nuclear envelope for studying nuclear membrane biogenesis and behavior during the mitotic divisions of the Drosophila embryo.
Advantages of the scanning ion microscopy for mapping halogen corticoids in normal and transformed cells in culture
Authors: Berry Jean‐Pierre , Chaintreau Marcel , Chassoux Danièle , Dennebouy Robert , Escaig Françoise , Galle Pierre , Rossignol Jean‐Michel , Slodzian George , Tlouzeau Sylvie
Published: August 2004

Summary— The intra‐cellular distribution of eight halogen glucocorticoids was investigated by ion microscopy in two cellular varieties of cultured non‐cancer cells (fibroblast 3T3) and cancer cells (human breast tumor cells MCF‐7). Two types of ion microscopy helped to determine this distribution, a direct imaging ion microscope (SMI 300) with low spatial resolution, and a scanning ion microscope (IMS4F), featuring high resolution, serving to obtain maps representing the intra‐cellular distribution of the fluorine elements and drugs present in these monolayer cultured cells. The fluorine images representative of the drugs containing fluorine showed that these drugs are essentially concentrated in the cell nuclei. In these nuclei, the distribution of these drugs is different from that of heterochromatin and of the nucleolus.
Galectin‐3 mRNA level depends on transformation phenotype in ras‐transformed NIH 3T3 cells
Authors: Hébert Eric , Monsigny Michel
Published: August 2004

Summary— The increase in galectin‐3 lectin content observed in tumours or in in vitro transformed cells suggests that this lectin is important in the transformation process. In the present study, we investigated the mRNA expression level of the galectin‐3, galectin‐I and macrophage mannose receptor in normal and ras‐transformed NIH 3T3 cells in relation to their transformation state. The galectin3 mRNA content in ras‐transformed cells is increased in fully transformed cells, with a maximum in ras‐transformed cells that have lost their growth anchorage‐dependence. Under the same conditions, the galectin‐1 mRNA level which was high in normal cells, increased slightly in transformed cells. The mRNA for the macrophage mannose receptor was not detected in 3T3 cells or in their ras‐transformed counterparts.