bluuebunny/crossref_metadata_2025 huggingface dataset:
HIGH-ENERGYHADRON-INDUCEDDILEPTONPRODUCTION FROMNUCLEONS ANDNUCLEI
Authors: McGaughey P. L. , Moss J. M. , Peng J. C.
Published: July 2002

▪ Abstract  We review the production of high-mass lepton pairs in fixed-target experiments, including both Drell-Yan (DY) and heavy quarkonium production [J/ψ, ψ′, ϒ(1S), ϒ(2S), and ϒ(3S)]. In recent years, DY data have become standard input to the determination of parton density distributions. DY data have recently yielded the first measurement of the x dependence of the [Formula: see text], asymmetry of the proton. Similar to the observations in deeply inelastic scattering, precision measurements of the nuclear dependence of the proton-induced DY process exhibit shadowing at small target momentum fraction, x2. There is, however, no evidence of enhanced DY production from nuclear targets. Mean transverse momenta of DY pairs are observed to increase with target mass. These data, analyzed within a new theoretical framework, provide an estimation of the energy loss of fast quarks in nuclear matter. In contrast to the DY process, there are large nuclear effects in the production of all quarkonia. These effects show strong dependence on ptand xFbut do not scale with x2. Statistically less precise measurements of D meson (open-charm) production at small xFare consistent with no nuclear dependence.
MOLECULES IN OPTICAL, ELECTRIC, AND MAGNETIC FIELDS: A Personal Perspective
Authors: Buckingham A. D.
Published: July 2002

[Figure: see text]

▪ Abstract  Physical chemistry and theoretical chemistry have advanced over the past 50 years from being largely qualitative to having a mature status based firmly on the principles of quantum and statistical mechanics. My interest in the chemical elements and their compounds has prompted me to learn more about the nature of matter through the measurement and interpretation of optical, electric, and magnetic properties of molecules. In addition to holding intrinsic interest, such properties tell us about charge and current distributions and form the basis of electro-optics, magneto-optics, and nonlinear optics. They also help us understand the nature and strength of long-range intermolecular forces, the hydrogen bond, and molecular biology—topics that are apparently forever young.
Hierarchical Bayesian Models for Regularization in Sequential Learning
Authors: Freitas J. F. G. de , Niranjan M. , Gee A. H.
Published: July 2002

We show that a hierarchical Bayesian modeling approach allows us to perform regularization in sequential learning. We identify three inference levels within this hierarchy: model selection, parameter estimation, and noise estimation. In environments where data arrive sequentially, techniques such as cross validation to achieve regularization or model selection are not possible. The Bayesian approach, with extended Kalman filtering at the parameter estimation level, allows for regularization within a minimum variance framework. A multilayer perceptron is used to generate the extended Kalman filter nonlinear measurements mapping. We describe several algorithms at the noise estimation level that allow us to implement on-line regularization. We also show the theoretical links between adaptive noise estimation in extended Kalman filtering, multiple adaptive learning rates, and multiple smoothing regularization coefficients.
Exponential Convergence of Delayed Dynamical Systems
Authors: Chen Tianping , Amari Shun-ichi
Published: July 2002

We discuss some delayed dynamical systems, investigating their stability and convergence. We prove that under mild conditions, these delayed systems are global exponential convergent.
A Sparse Representation for Function Approximation
Authors: Poggio Tomaso , Girosi Federico
Published: July 2002

We derive a new general representation for a function as a linear combination of local correlation kernels at optimal sparse locations (and scales) and characterize its relation to principal component analysis, regularization, sparsity principles, and support vector machines.
Exploring the Self Through Algorithmic Composition
Authors: Alsop Roger
Published: July 2002

The author discusses his views on musical composition in the late twentieth century, focusing on the influence that communication and computer technology have had over his pursuit. He goes on to describe his use of computer-based algorithmic composition and how this particular approach enhances and refines his understanding of his own musical self-expression. He describes four computer algorithms, used in recent compositions and improvisations, that reflect his particular musical interests.
Presence in Virtual Theater
Authors: Reeve Carlton
Published: July 2002

Using empirical data, this research suggests that key features of a typical theatrical rehearsal process can significantly improve the sense of presence for participants within a shared virtual environment. Research of shared virtual environments (VEs) for the production of theater shows suggests that theater applications have specific requirements for presence. These can be summarized as characterization, repetition, and group dynamic, while the level of presence is dependent on the actor-avatar, actor-space, and actor-actor relationships.
Evolution of Adaptive Synapses: Robots with Fast Adaptive Behavior in New Environments
Authors: Urzelai Joseba , Floreano Dario
Published: July 2002

This paper is concerned with adaptation capabilities of evolved neural controllers. We propose to evolve mechanisms for parameter self-organization instead of evolving the parameters themselves. The method consists of encoding a set of local adaptation rules that synapses follow while the robot freely moves in the environment. In the experiments presented here, the performance of the robot is measured in environments that are different in significant ways from those used during evolution. The results show that evolutionary adaptive controllers solve the task much faster and better than evolutionary standard fixed-weight controllers, that the method scales up well to large architectures, and that evolutionary adaptive controllers can adapt to environmental changes that involve new sensory characteristics (including transfer from simulation to reality and across different robotic platforms) and new spatial relationships.
Adversarial Search by Evolutionary Computation
Authors: Hong Tzung-Pei , Huang Ke-Yuan , Lin Wen-Yang
Published: July 2002

In this paper, we consider the problem of finding good next moves in two-player games. Traditional search algorithms, such as minimax and α-β pruning, suffer great temporal and spatial expansion when exploring deeply into search trees to find better next moves. The evolution of genetic algorithms with the ability to find global or near global optima in limited time seems promising, but they are inept at finding compound optima, such as the minimax in a game-search tree. We thus propose a new genetic algorithm-based approach that can find a good next move by reserving the board evaluation values of new offspring in a partial game-search tree. Experiments show that solution accuracy and search speed are greatly improved by our algorithm.
An Emergence of Coordinated Communication in Populations of Agents
Authors: Kvasnicka Vladimir , Pospichal Jiri
Published: July 2002

The purpose of this article is to demonstrate that coordinated communication spontaneously emerges in a population composed of agents that are capable of specific cognitive activities. Internal states of agents are characterized by meaning vectors. Simple neural networks composed of one layer of hidden neurons perform cognitive activities of agents. An elementary communication act consists of the following: (a) two agents are selected, where one of them is declared the speaker and the other the listener; (b) the speaker codes a selected meaning vector onto a sequence of symbols and sends it to the listener as a message; and finally, (c) the listener decodes this message into a meaning vector and adapts his or her neural network such that the differences between speaker and listener meaning vectors are decreased. A Darwinian evolution enlarged by ideas from the Baldwin effect and Dawkins' memes is simulated by a simple version of an evolutionary algorithm without crossover. The agent fitness is determined by success of the mutual pairwise communications. It is demonstrated that agents in the course of evolution gradually do a better job of decoding received messages (they are closer to meaning vectors of speakers) and all agents gradually start to use the same vocabulary for the common communication. Moreover, if agent meaning vectors contain regularities, then these regularities are manifested also in messages created by agent speakers, that is, similar parts of meaning vectors are coded by similar symbol substrings. This observation is considered a manifestation of the emergence of a grammar system in the common coordinated communication.
An Interpretation of Plato's Cratylus
Authors: Keller Simon
Published: July 2002

Plato's main concern in the Cratylus, I claim, is to argue against the idea that we can learn about things by examining their names, and in favour of the claim that philosophers should, so far as possible, look to the things themselves. Other philosophical questions, such as that of whether we should accept a naturalist or a conventionalist theory of namng, arise in the dialogue, but are subordinate. This reading of the Cratylus, I say, explains certain puzzling facts about the dialogue's structure and dramatic emphasis, as well as making the dialogue look better on philosophical grounds. In support of my claim, I argue that Hermogenes' conventionalist theory of naming is quite sensible, and is not refuted by Socrates; that the main purpose of the etymological section is to undermine our con dence in etymology as a form of philosophical enquiry; and that the apparently tangential and inconclusive discussions in the nal section of the dialogue are best understood as illustrations of Plato's thesis about philosophical methodology.
EINE LITERARISCHE ANALYSE VON PSALM CXIV
Authors: Bauer Uwe
Published: July 2002

Die vorliegende literarische Analyse des cxiv. Psalms enthält zwei Teile (I/II): eine intratextuelle und eine intertextuelle Analyse. I: Nach der Feststellung des poetischen Charakters des Psalms anhand von Kriterien Niccaccis folgt eine makro- und eine mikropoetologische Untersuchung des gesamten Psalms sowie seiner vier Strophen, die die bisherigen poetologischen Untersuchungen (u. a. von Geller und Prinsloo) diskutiert und weiterführt. II: Nach einer Definition von Inter- bzw. Palintextualität (Stocker) werden dann die Beziehungen des Psalm zu anderen Texten innerhalb der Hebräischen Bibel untersucht. Ergebnis ist u. a., dass der Psalm zum Genre der präsentischen JhwhKönigs-Psalmen zu rechnen ist und dass es thematisch um den Antritt der Königsherrschaft Jhwhs sowohl über Israel als auch über die ganze Erde geht (Partikularismus → Universalismus).
SPECULATIVE HUNTING BY AN ARANEOPHAGIC SALTICID SPIDER
Authors: Clark Robert , Harland Duane , Jackson Robert
Published: July 2002

Portia fimbriata, an araneophagic jumping spider (Salticidae), makes undirected leaps (erratic leaping with no particular target being evident) in the presence of chemical cues from Jacksonoides queenslandicus, another salticid and a common prey of P.fimbriata. Whether undirected leaping by P.fimbriata functions as hunting by speculation is investigated experimentally. Our first hypothesis, that undirected leaps provoke movement by J. queenslandicus, was investigated using living P.fimbriata and three types of lures made from dead, dry arthropods (P.fimbriata, J. queenslandicus and Musca domestica). When a living P.fimbriata made undirected leaps or a spring-driven device made the lures suddenly move up and down, simulating undirected leaping, J. queenslandicus responded by waving its palps and starting to walk. There was no statistical evidence that the species from which the lure was made influenced J. queenslandicus' response in these tests. Our second hypothesis, that J. queenslandicus reaction to J. queenslandicus when J. queenslandicus reacted to lures simulating undirected leaping. In these tests, P.fimbriata responded by turning toward J. queenslandicus and waving its palps.
Crystal structure of mattheddleite: a Pb, S, Si phase with the apatite structure
Authors: Steele I. M. , Pluth J. J. , Livingstone A.
Published: July 2002

The crystal structure of mattheddleite (Pb5(Si1.5S1.5)O12(Cl0.57OH0.43), P63/m, a = 10.0056(6), c = 7.4960(9) Å) from Leadhills, Scotland has been determined to R = 0.065. The structure is that of apatite where Pb replaces Ca, equal amounts of S and Si replace P and the X anion is OH + Cl. The composition deduced from the structural refinement differs from that of microprobe analyses by giving full occupancy of the tetrahedral site and equal Si and S to preserve charge balance. We conclude that the microprobe analysis is incorrect possibly due to large and inaccurate absorption corrections. For the crystal analysed, the X anion position is zoned from an OH-rich interior to a Cl-rich exterior. The Pb(2) atom is disordered which may be analogous to the disordering of the Ca(2) site in Cl-rich, Ca apatites.
Fetal hemoglobin in sickle cell anemia: relationship to erythrocyte adhesion markers and adhesion
Authors: Setty B. N. Yamaja , Kulkarni Surekha , Dampier Carlton D. , Stuart Marie J.
Published: July 2002

To assess whether fetal hemoglobin (HbF) modulates the adhesion of sickle erythrocytes to endothelium, children with homozygous sickle cell anemia (SS disease) were studied, using this physiologically crucial period to evaluate the relationships between HbF and the major erythrocyte adhesion markers. The mean level of CD36+ erythrocytes was 2.59% ± 2.15% (± SD, n = 40) with an inverse relationship between CD36 positivity and F cells (R = −0.76, P < .000 00 002). In univariate analyses, significant correlations with various hematologic parameters and age were noted. Multiple regression analyses, however, revealed a relationship solely with F cells. Minimal levels of very late activation antigen-4+ (VLA4+) erythrocytes (0.31% ± 0.45%, n = 40) with relationships similar to those noted for CD36+ cells were also observed. The subpopulation of strongly adhesive stress reticulocytes was further assessed, using CD71 as their marker. The mean level of CD71+ erythrocytes was 5.81% ± 4.21%, with statistical correlates in univariate and multivariate analyses similar to those discussed above. When adhesion ratios were evaluated, inverse correlations were noted between basal and plasma-induced adhesion and F-cell numbers (R = −0.54, P < .0005;R = −0.53, P < .0006, n = 39). In addition, in analyses where basal or plasma-induced adhesion was the dependent variable and the independent variables included F cells and the various adhesion-related parameters, significant relationships solely with F cells were noted. The results demonstrate that SS patients with higher levels of F cells have concomitant decreases in the numbers of CD36+, VLA4+, and CD71+ erythrocytes and that these findings translate into less adherent erythrocytes. These findings extend knowledge regarding the protective effects of HbF in the pathophysiology of sickle cell disease.
Interaction between calmodulin and microtubule‐associated proteins prepared at different stages of brain development
Authors: Erneux Christophe , Passareiro Heloísa , Nunez Jacques
Published: July 2002

Rat brain microtubules were prepared at the adult stage and from immature (i.e., 4‐day‐old) animals. At an early stage of development, the composition of microtubule‐associated proteins is qualitatively different from that found at the adult stage [(1982) Eur. J. Biochem. 129, 465‐471]. The influence of calmodulin on the time course of assembly of second cycle microtubules was compared at both stages of brain development (i.e., microtubules originating from 4‐day‐old and adult animals). In the presence of Ca2+ the inhibition of microtubule assembly was more pronounced at a young stage of brain development than at the adult stage. Cross‐linking studies with 125I‐labeled calmodulin further established that the two major microtubule‐associated proteins, MAP2 and TAU were able to bind to calmodulin at both stages of brain development but with different intensities. The labeling with 125I‐labeled calmodulin was Ca2+‐dependent, specific, displaced by unlabeled calmodulin and trifluoperazine.
Transmembrane orientation of α‐helices and the organization of chlorophylls in photosynthetic pigment‐protein complexes
Authors: Breton Jacques , Nabedryk Eliane
Published: July 2002

UV CD and IR spectra of the water‐soluble bacteriochlorophyll‐protein antenna isolated from Prosthecochloris aestuarii indicate that about 50% of the protein is in a β‐sheet conformation while for the dominant antenna complexes isolated from bacteria (B800‐850) and from green plants (LHC), the α‐helix (45%) is more abundant than the β‐sheet (~ 10%) conformation. Furthermore, IR dichroism studies show that the α‐helical segments of a large variety of intrinsic membrane Chl‐protein complexes (antenna and reaction centers) are tilted on the average at 30–35° away from the membrane normal. The observation that in these complexes the Chl planes are also tilted at about the same angle suggests that the transmembrane orientation of the α‐helices determines the positioning of the Chl molecules in photosynthetic membranes.
Surface effects in preparation of cell‐size liposomes
Authors: Dimitrov D.S. , Li J. , Angelova M. , Jain R.K.
Published: July 2002

Effects of surface type and area were shown to be important in the yield of cell‐size liposomes, but not in determining their size. The liposomes were prepared by dissolving lipids in a chloroform‐methanol solution and then evaporating the solvent under nitrogen in the presence of glass beads. After evaporation of the solvent, which was rapid due to the increased surface area, the dried lipids were then swollen in water at high temperatures (higher than the phase transition of the lipids), which led to formation of giant liposomes. The number of liposomes prepared in the presence of pyrex glass beads, which increase more than 100‐times the surface area of lipid‐glass contact, is more than 5‐times larger than in the control experiments without glass beads. The yield of liposomes in the presence of another type of glass bead was almost the same as in the control experiments. These effects may be due to long‐ and short‐range intermolecular interactions in the glass/water/lipid system.
Tomato lectin resists digestion in the mammalian alimentary canal and binds to intestinal villi without deleterious effects
Authors: Kilpatrick David C. , Pusztai Arpad , Grant George , Graham Catherine , Ewen Stanley W.B.
Published: July 2002

Tomato lectin
Dietary lectin
Villus structure
Rat intestine
Human intestine
Reduction of EGF receptor synthesis by antisense RNA vectors
Authors: Hunts John , Merlino Glenn , Pastan Ira , Shimizu Nobuyoshi
Published: July 2002

An association has been observed between squamous cell carcinomas and elevated EGF receptor levels. The approach taken here to analyze this problem was to construct vectors which express antisense RNA for the EGF receptor. The plasmid vector used was derived from pSV2‐neo, which is readily selectable. Three EGF receptor cDNA fragments, a 5'‐, a middle and a 3'‐region were tested for differences in efficiency as antisense RNA. The results suggest that the 5'‐fragment was the most efficient.
Cleavage of specific sites of RNA by designed ribozymes
Authors: Koizumi Makoto , Iwai Shigenori , Ohtsuka Eiko
Published: July 2002

Two ribozymes were designed for site‐specific cleavage of RNA. A UA site in an undecaribonucleotide was cleaved by a ribozyme consisting of two partially paired oligoribonucleotides with chain lengths of 19 and 15. The other ribozyme, which consists of a 19‐mer and a 13‐mer, recognized a UC sequence at positions 42 and 43 of 5 S rRNA.
Pyruvate kinase type M2 is phosphorylated at tyrosine residues in cells transformed by Rous sarcoma virus
Authors: Presek Peter , Reinacher Manfred , Eigenbrodt Erich
Published: July 2002

Chicken embryo cells (CECs) contain pyruvate kinase (PK) type M2 (M2‐PK). Transformation of CECs by Rous sarcoma virus (RSV) leads to a reduction in the affinity of PK for the substrate phosphoenolpyruvate. In vitro, M2‐PK can be phosphorylated at tyrosine residues by pp60v‐src, the transforming protein of RSV. To study tyrosine phosphorylation of M2‐PK in intact RSV‐transformed cells, the protein was immunoprecipitated from 32P‐labeled normal and RSV‐SR‐A‐transformed CECs. Phosphoamino acid analysis of immunoprecipitated M2‐PK revealed that M2‐PK of both normal and transformed CECs contained phosphoserine and small amounts of phosphothreonine. Only M2‐PK of transformed CECs contained phosphotyrosine in addition. For enzyme kinetic studies M2‐PK was partially purified by chromatography upon DEAE‐Sephacel and hydroxyapatite. A decreased affinity for phosphoenolpyruvate was observed 3 h after the onset of transformation using the temperature‐sensitive mutant of RSV, ts‐NY 68. The kinetic changes were correlated with tyrosine phosphorylation of M2‐PK, but there is no direct evidence that they are caused by post‐translational modification of the enzyme.
The amyloid precursor protein of Alzheimer disease is expressed as a 130 kDa polypeptide in various cultured cell types
Authors: Autilio-Gambetti L. , Morandi A. , Tabaton M. , Schaetzle B. , Kovacs D. , Perry G. , Greenberg B. , Gambetti P.
Published: July 2002

The vascular and parenchymal amyloid deposits in Alzheimer disease (AD), normal aging and Down syndrome are mainly composed of a 4 kDa polypeptide (A4), which derives from a larger precursor protein (APP). There is evidence that APP is a transmembrane glycoprotein present in most tissues, but the characteristics of APP in intact cells are not yet known. In order to investigate this issue, we examined the immunoreactivity of fibroblasts of human and nonhuman cell lines with antisera raised to synthetic peptides corresponding to A4 and to two other domains of the APP. All three antisera recognized a 130 kDa polypeptide (APP‐130) in immunoblots from all cell lines. In fibroblasts, an additional polypeptide of 228 kDa (APP‐228) was recognized by the antiserum to A4. In immunoblots of two dimensional gels, APP‐130 showed a pI of 6.2, while APP‐228 failed to focus in the pH range of 4.7–7.0. Sequential extractions of cells with buffer and with Triton X‐100 indicate that APP‐130 is extractable with nonionic detergents at high ionic strength, whereas 228 kDa APP is a cystolic component. Immunofluorescence staining is consistent with an intracellular perinuclear and plasma membrane localization. It is concluded that APP‐130 and APP‐228 are two forms of the APP which result from extensive posttranslational modifications of a smaller original gene product. It is likely that APP undergoes similar posttranslational modifications in different cell types.
Generation of O−2 and tyrosine cation‐mediated chemiluminescence during the fertilization of sea urchin eggs
Authors: Takahashi Atsushi , Totsune-Nakano Hiroko , Nakano Minoru , Mashiko Shinro , Suzuki Nobutaka , Ohma Chikako , Inaba Humio
Published: July 2002

Sea urchin eggs emit light in the visible region during their fertilization. Judging from the chemiluminescence spectra, one of the excited species generated is considered to have originated from a tyrosine cation radical‐mediated reaction. Chemiluminescence probes such as luminol or a cypridina luciferin analog (2‐methyl‐6‐[p‐methoxyphenyl]‐3,7‐dihydroimidazo‐[1,2‐a]pyrazin‐3‐one) are useful for detecting the ovoperoxidase+H2O2 reaction associated with membrane hardening and O−
2 generation, respectively, during the fertilization of sea urchin eggs.
Methyl‐coenzyme M reductase preparations with high specific activity from H2‐preincubated cells of Methanobacterium thermoautotrophicum
Authors: Rospert S. , Böcher R. , Albracht S.P.J. , Thauer R.K.
Published: July 2002

The study of the nickel enzyme methyl‐coenzyme M reductase from methanogenic bacteria has been hampered until now by the fact that upon cell rupture the activity of the enzyme always dropped to at best only a few percent of its in vivo activity. We describe here that when Methanobacterium thermoautotrophicum cells were preincubated with 100% H2 before disintegration methyl‐coenzyme M reductase activity stayed high. The cell extracts with a specific activity of 2 U/mg protein exhibited two nickel‐derived EPR signals, designated MCR‐red1 and MCR‐red2, previously only observed in intact cells. The enzyme was purified 10‐fold to a specific activity of 20 U/mg in the presence of methyl‐coenzyme M, which stabilized both the activity and the EPR signal MCR‐red1. The enzyme preparation displayed an UV/Vis spectrum with an absorption maximum at 386 nm and a shoulder at 420 nm. Upon inactivation of the enzyme with O2 or CHCl3, the maximum at 386 nm and the EPR signals MCR‐red1 and MCR‐red2 disappeared.
Cellobiose oxidase of Phanerochaete chrysosporium enhances crystalline cellulose degradation by cellulases
Authors: Bao Wenjun , Renganathan V.
Published: July 2002

The effect of Phanerochuete chrysosporium cellobiose oxidase (CBO) on microcrystalline cellulose hydrolysis by Trichoderma cellulases was determined. Addition of 10 μg ml−1 CBO to a reaction mixture containing T. viride cellulase increased glucose and cellobiose production by 10% and 48%, respectively. Cellulose weight loss was also enhanced by 19%. Al higher concentrations (20–80 μg ml−1). CBO decreased glucose and cellobiose production. Cellulose weight loss at 60 μ ml−1 CBO was 76% compared to control cellulase reactions. This decrease appears to be due to inactivation of cellulase by H2O2 produced via CBO reaction, because addition of catalase enhances sugar production and cellulose weight loss. These findings suggest that at low, perhaps physiologically relevant concentrations, CBO enhances crystalline cellulose degradation by cellulases.
Antibodies against the major brain isofbrms of 14‐3‐3 protein
Authors: Martin Harry , Patel Yasmina , Jones David , Howell Steve , Robinson Karen , Aitken Alastair
Published: July 2002

14‐3‐3 proteins are apparently ubiquitous eukaryotic proteins that comprise a large number of isoforms. They have been implicated in the regulation of a wide range of biological processes [reviewed in Aitken et al. (1992) Trends Biochem. Sci. 17,498‐501]. We have raised specific antibodies against each mammalian brain isoform of 14‐3‐3 employing peptides synthesised from the amino‐tenninal regions. The peptides were, like the proteins from mammalian brain, N‐acetylated. The antiserum specific for the epsilon isoform did not recognise the recombinant form of this protein (lacking the N‐acetyl co‐translational modification) expressed inE. coliuntil it was chemically acetylated.
Comparison of the genetic maps of variola and vaccinia viruses
Authors: Shchelkunov Sergei N. , Resenchuk Sergei M. , Totmenin Alexei V. , Blinov Vladimir M. , Marennikova Svetlana S. , Sandakhchiev Lev S.
Published: July 2002

The complete genetic map of the variola major virus strain India‐1967 is built basing on the sequence data. The suggested map is compared with the maps of the sequenced genomic regions of Copenhagen and Western Reserve strains of vaccinia virus and Harvey strain of variola major virus. The principle differences revealed in the genomic organization of these viruses are discussed.
Induction of apoptosis in murine ACTH‐secreting pituitary adenoma cells by bromocriptine
Authors: Yin Dali , Kondo Sciji , Takeuchi Juji , Morimura Tatsuo
Published: July 2002

Bromocriptine, a dopamine agonist, is now an accepted primary therapeutic agent for patients with prolactinomas and other pituitary adenomas. In this study, we demonstrated that bromocriptine inhibited the proliferation of murine ACTH‐secreting pituitary adenoma (AtT‐20) cells. In addition, the antitumor activity of bromocriptine was inhibited both by actinomycin D and cycloheximide, suggesting that it was dependent on new RNA and protein synthesis. Interestingly, the results of DNA fragmentation assays and cell cycle analysis clearly demonstrated that bromocriptine induced apoptosis in AtT‐20 cells.
Analysis of the core components of Alzheimer paired helical filaments A gas chromatography/mass spectrometry characterization of fatty acids, carbohydrates and long‐chain bases
Authors: Goux Warren J. , Rodriguez Santiago , Sparkman Dennis R.
Published: July 2002

We have carried out a fatty acid and carbohydrate compositional analysis of the protease‐resistant core of paired helical filaments (prcPHF) isolated from six Alzheimer's diseased brains. Fatty acids, long‐chain bases and monosaccharides were characterized by gas chromatography/mass spectrometry (GC/MS) of fatty acid methyl esters, trimethylsilylated long‐chain bases, peracetylated alditol acetates and trimethylsilyl methyl glycosides. Glucose and mannose were found to be the only carbohydrate components. Four of the six prcPHF samples contained only glucose while the remaining two samples contained between 30–40% mannose in addition to glucose. None of the samples were found to contain either hydroxylated fatty acids or long‐chain bases. The average fatty acid profile of prcPHF was highest in stearic (C18:0) and palmitic acids (C16:0) with less than 10% unsaturated fatty acids. By comparing the carbohydrate and lipid composition of prcPHF to similar data for other brain glycolipids, it was determined that prcPHF is a unique glycolipid, distinct from cerebrosides, gangliosides or brain phospholipids. The fatty acid and carbohydrate composition of a glycolipid isolated from a population of normal brains according to the prcPHF protocol was found be identical to that of prcPHF glycolipid. It is possible that subtle differences in structure or indigenous factors are responsible for the initiation of PHF formation in vivo.
Transducin‐mediated, isoform‐specific interaction of recombinant rat nucleoside diphosphate kinases with bleached bovine retinal rod outer segment membranes
Authors: Orlov Nicolay Ya. , Orlova Tatiana G. , Nomura Koji , Hanai Nobuo , Kimura Narimichi
Published: July 2002

The properties of the binding of recombinant rat nucleoside diphosphate (NDP) kinase isoforms a and β (NDP kinase α and β respectively) to bleached bovine retinal rod outer segment (ROS) membranes were investigated. It was found that: (1) both NDP kinase isoforms interacted with ROS membranes in a pH‐, cation‐ and GTPγS‐dependent manner; (2) the retinal G‐protein transducin was an obligatory factor for the interaction; (3) the apparent affinity of NDP kinase a for ROS membranes was about 100‐fold higher than that of NDP kinase β; and (4) an α‐isoform‐specific peptide, corresponding to the sequence of the N‐terminal third (variable region), had the ability to displace bovine NDP kinase from ROS membranes. The results suggest the possible involvement of NDP kinases in cellular regulation via interaction with G‐proteins and provide a structural basis for the possible differential roles of mammalian NDP kinase isoforms in the cell.
Neurobehavioural, neurochemical and electrophysiological studies in 6‐hydroxydopamine lesioned and neural transplanted rats
Authors: Agrawal A.K. , Husain R. , Raghubir R. , Kumar Ashok , Seth P.K.
Published: July 2002

Unilateral injection of 6‐hydroxydopamine (6‐OHDA) into the caudate nucleus of rat caused degeneration of dopaminergic terminals, evidenced by significant (P⊂0.05) elevation of spontaneous and drug‐induced motor behaviour, enhanced DA receptor binding and significant increase in the neuronal firing rate of caudate neurons, suggesting supersensitivity of dopaminergic receptors. Eight weeks following the transplantation of embryonic cell suspensions from caudate at the lesioned site, a significant restoration of the enhanced 3H spiperone binding and neuronal activity of caudate neurons was observed in comparison with lesioned rats.

These results clearly demonstrate that transplanted embryonic neuronal tissue at the lesioned site is capable of restoring the neuronal deficits caused by 6‐OHDA as evidenced by significant amelioration in neurochemical, behavioral and electrophysiological alterations.
Phosphatidylserine delivery to endoplasmic reticulum‐derived vesicles of plant cells depends on two biosynthetic pathways
Authors: Vincent Patrick , Maneta-Peyret Lilly , Cassagne Claude , Moreau Patrick
Published: July 2002

Vesicles formed from endoplasmic reticulum (ER) by a cell‐free system of leek cells (Allium porrum) are enriched in phosphatidylserine (PS), especially species containing very long chain fatty acids (VLCFA, at least 20 carbon atoms). In plant cells, PS is formed either by PS synthase or the serine exchange enzyme, although it is not known which pathway(s) contribute(s) to PS delivery in the ER‐derived vesicles (EV), nor to what extent this occurs. Taking advantage of a cell‐free system, we have shown that PS enrichment originates mainly from the serine exchange enzyme which is the only pathway that synthesizes the VLCFA‐PS species. On the other hand, both enzymes synthesize PS with long chain fatty acids (up to 18 carbon atoms), but these species are given to the EV by PS synthase.
Characterization of the amsI gene product as a low molecular weight acid phosphatase controlling exopolysaccharide synthesis of Erwinia amylovora
Authors: Bugert Peter , Geider Klaus
Published: July 2002

The ams region, responsible for amylovoran synthesis of the fireblight pathogen Erwinia amylovora, contains the gene amsI encoding a 144 amino acid protein with homology to mammalian low molecular weight acid phosphatases [Bugert and Geider (1995) Mol. Microbiol. 15, 917–933]. A DNA fragment with amsI was cloned under the control of the lac promoter on a high copy number plasmid. The gene product of amsI is about 17 kDa in a protein expression system and had the enzymatic activity of an acid phosphatase. This is the first report about a low molecular weight acid phosphatase activity in prokaryotes. As part of the large ams transcript, expression of amsI was affected by the activator proteins RcsA and RcsB. Overexpression of amsI in E. amylovora caused a strong increase of acid phosphatase activity, but additionally a strong reduction in EPS synthesis, phenotypically similar to a mutation in the gene. The gene product may participate in changes of phosphorylation required for the biosynthesis of EPS such as recycling the lipid carrier diphosphate to the monophosphate form.
Structure of in‐serum transfecting DNA–cationic lipid complexes
Authors: Boukhnikachvili T , Aguerre-Chariol O , Airiau M , Lesieur S , Ollivon M , Vacus J
Published: July 2002

Noticeable modifications of in‐serum transfection efficiency of dioctadecylamidoglycyl‐spermine (DOGS)–DNA complexes are observed, depending on DNA condensation conditions. The structures of the complexes are studied, keeping in mind the variability of lipid polymorphism, by cryo‐transmission electron microscopy and X‐ray diffraction. By increasing both pH and ionic strength, well‐organised lamellar structures with a period of 65 Å replace supramicellar aggregates. A relationship between the structures and their in‐vitro transfection activity is established. Efficiency in the presence of serum is maintained when a lamellar arrangement is involved.
Activation of protein kinase B (Akt/RAC‐protein kinase) by cellular stress and its association with heat shock protein Hsp27
Authors: Konishi Hiroaki , Matsuzaki Hidenori , Tanaka Motonari , Takemura Yukitoshi , Kuroda Shun'ichi , Ono Yoshitaka , Kikkawa Ushio
Published: July 2002

Protein kinase B (PKB, also named as Akt or RAC‐protein kinase), that is activated by cellular stress such as heat shock and hyperosmotic treatment, was revealed to be activated by oxidative stress and by chemical stressors of CdCl2 and NaAsO2 by measuring the activity of the enzyme immunoprecipitated from the transfected COS‐7 cells. Upon stress treatment, a 30‐kDa phosphoprotein was co‐immunoprecipitated with PKB from the cells metabolic labeled with [32P]orthophosphate. The phosphoprotein was identified as Hsp27, a small heat shock protein, by immunoblot analysis and co‐immunoprecipitation. The association of Hsp27 was specific to PKB as the heat shock protein was not co‐immunoprecipitated with other protein kinases such as protein kinase C and PKN. When the cells were treated with H2O2, PKB was activated gradually and the association of Hsp27 with PKB increased concurrently with the enhancement of PKB activity. In heat‐shocked cells, activation of PKB and the association of Hsp27 were detected immediately after the treatment, and the association of the heat shock protein decreased while PKB kept stimulated activity when the cells were further incubated at 37°C. These results suggest that Hsp27 is involved in the activation process of PKB in the signal transduction pathway of various forms of stress.
Isolation and characterization of mutations affecting expression of the Δ9‐ fatty acid desaturase gene, OLE1, in Saccharomyces cerevisiae
Authors: Fujimori Ko , Anamnart Sarintip , Nakagawa Youji , Sugioka Shigemi , Ohta Daisaku , Oshima Yasuji , Yamada Yasuhiro , Harashima Satoshi
Published: July 2002

Expression of the Δ9‐ fatty acid desaturase gene, OLE1, of Saccharomyces cerevisiae is negatively regulated transcriptionally and post‐transcriptionally by unsaturated fatty acids. In order to isolate mutants exhibiting irregulation of OLE1 expression, we constructed an OLE1p–PHO5 fusion gene as a reporter consisting of the PHO5 gene encoding repressible acid phosphatase (rAPase) under the control of the OLE1 promoter (OLE1p). By EMS mutagenesis, we isolated three classes of mutants, pfo1, pfo2 and pfo3 (

ositive regulatory

actor for

LE1) mutants, which show decreased rAPase activity under derepression conditions (absence of oleic acid). Analysis of the transcription of OLE1 in these pfo mutants revealed that pfo1 and pfo3 mutants have a defect in the regulation of OLE1 expression at the transcriptional level while pfo2 mutants were suggested to have a mutation affecting OLE1 expression at a post‐transcriptional step. In addition, four other classes of mutants, nfo1, nfo2, nfo3 and nfo4 (

egative

actor for

LE1) mutants that have mutations causing strong expression of the OLE1p–PHO5 fusion gene under repression conditions (presence of oleic acid), were isolated. Results of Northern analysis of OLE1 as well as OLE1p‐PHO5 transcripts in nfo mutants suggested that these mutations occurred in genes encoding global repressors. We also demonstrated that TUP1 and SSN6 gene products are required for full repression of OLE1 gene expression, by showing that either tup1 or ssn6 mutations greatly increase the level of the OLE1 transcript.
Leptin interacts with glucagon‐like peptide‐1 neurons to reduce food intake and body weight in rodents
Authors: Goldstone Anthony P. , Mercer Julian G. , Gunn Irene , Moar Kim M. , Edwards C.Mark B. , Rossi Michela , Howard Jane K. , Rasheed Shahnawaz , Turton Mandy D. , Small Caroline , Heath Melanie M. , O'Shea Donal , Steere Joanna , Meeran Karim , Ghatei Mohammed A. , Hoggard Nigel , Bloom Stephen R.
Published: July 2002

The adipose tissue hormone, leptin, and the neuropeptide glucagon‐like peptide‐1 (7–36) amide (GLP‐1) both reduce food intake and body weight in rodents. Using dual in situ hybridization, long isoform leptin receptor (OB‐Rb) was localized to GLP‐1 neurons originating in the nucleus of the solitary tract. ICV injection of the specific GLP‐1 receptor antagonist, exendin(9–39), at the onset of dark phase, did not affect feeding in saline pre‐treated controls, but blocked the reduction in food intake and body weight of leptin pre‐treated rats. These findings suggest that GLP‐1 neurons are a potential target for leptin in its control of feeding.
Rapid and specific reactive oxygen species generation via NADPH oxidase activation during Fas‐mediated apoptosis
Authors: Suzuki Yoshihiro , Ono Yasushi , Hirabayashi Yoshio
Published: July 2002

To determine Fas‐induced reactive oxygen species (ROS) generation in cells sensitive to Fas‐mediated apoptosis, chemiluminescence, a strong indicator of ROS generation, was monitored after stimulation with agonistic anti‐Fas. Fas ligation resulted in a rapid and sustained ROS generation. The generation reached a maximum within 5 min and was still observed at least 40 min after the stimulation. No significant ROS generation was observed under conditions where apoptosis was absent. Furthermore, an NADPH oxidase inhibitor, diphenylene iodonium, prevented Fas‐mediated ROS generation, suggesting that Fas induces ROS generation via stimulation of the oxidase system.
HrpW of Erwinia amylovora, a new Hrp‐secreted protein
Authors: Gaudriault S , Brisset M.-N , Barny M.-A
Published: July 2002

Erwinia amylovora strain CFBP1430 secretes a protein called HrpW in a Hrp‐dependent manner. HrpW was detected in culture supernatant of the wild‐type strain grown on solid inducing hrp medium. This protein shares structural similarities with elicitors of the hypersensitive response such as HrpN of Erwinia amylovora and PopA of Ralstonia solanacearum. Furthermore, the C‐terminal region of HrpW is homologous to class III pectate lyases. An hrpW mutant is as aggressive as the wild‐type strain on pear and apple seedlings. It elicits the hypersensitive response on tobacco at a lower concentration than the wild‐type strain.
Telomerase activity in ‘immortal’ fish1
Authors: Klapper Wolfram , Heidorn Klaus , Kühne Karen , Parwaresch Reza , Guido Krupp
Published: July 2002

Eukaryotic chromosome termini consist of telomeres, short sequence repeats. According to the telomere hypothesis, DNA replication leads to telomere shortening, resulting in a cellular mitotic clock. Telomerase resets it by telomere synthesis. In mammals with a limited growth phase, telomerase activity in somatic tissues is restricted to stem cell derivatives with high proliferation potential. But other animals, like some fish, grow throughout their life with little senescence. All somatic cells require a high proliferation capacity and telomerase should be active in all cells, irrespective of fish age. Indeed, we detected high telomerase activities in all analyzed organs of rainbow trout (Oncorhynchus mykiss).
UV‐C radiation induces apoptotic‐like changes in Arabidopsis thaliana
Authors: Danon Antoine , Gallois Patrick
Published: July 2002

With a view to studying programmed cell death in plants at the molecular level, we report here for the first time that apoptotic‐like changes are induced by UV radiation in plant nuclei. In Arabidopsis thaliana seedlings a UV‐C dose of 10–50 kJ/m2 induces an oligonucleosomal DNA fragmentation which is reminiscent of the apoptotic DNA ladder described in animal cells. This DNA fragmentation was also detected in situ in protoplast nuclei as soon as 2 h after UV‐C treatment. Moreover, UV‐C induced a nuclear morphology characteristic of animal apoptotic nuclei. We propose that UV‐C induction constitutes a powerful tool to compare the cellular response to irreversible UV damage in plants to that in animals and to study programmed cell death in A. thaliana.
Expression of a functional barley sucrose‐fructan 6‐fructosyltransferase in the methylotrophic yeast Pichia pastoris
Authors: Hochstrasser Urs , Lüscher Marcel , De Virgilio Claudio , Boller Thomas , Wiemken Andres
Published: July 2002

The cDNA encoding sucrose‐fructan 6‐fructosyltransferase (6‐SFT) from barley (Hordeum vulgare) has been expressed in the methylotrophic yeast Pichia pastoris, using a translational fusion into vector pPICZαC, containing the N‐terminal signal sequence of Saccharomyces cerevisiae α‐factor to allow entry into the secretory pathway. Transformed Pichia produced and secreted a functional 6‐SFT which had characteristics similar to the barley enzyme, but had a pronounced additional 1‐SST activity when incubated with sucrose.
Stimulation of peripheral cannabinoid receptor CB2 induces MCP‐1 and IL‐8 gene expression in human promyelocytic cell line HL60
Authors: Jbilo Omar , Derocq Jean-Marie , Segui Michel , Le Fur Gérard , Casellas Pierre
Published: July 2002

Using the recently developed methodology of nucleic acid microarrays spotted with specific cDNAs probes belonging to different gene families, we showed for the first time that nanomolar concentrations of the cannabinoid ligand CP‐55940 upregulated the expression of two different members of the chemokine gene family: the α‐chemokine interleukin‐8 (IL‐8) and the β‐chemokine monocyte chemotactic protein‐1 (MCP‐1), in the promyelocytic cell line HL60 transfected with peripheral cannabinoid receptors (CB2). These genomic modulations observed on large‐scale cDNA arrays were first confirmed by Northern blot studies. Furthermore, ELISA evaluations in culture supernatants indicated that the cannabinoid‐induced activation of these two chemokine genes was followed by enhanced expression and secretion of the corresponding proteins. These upregulations initially observed in transfected HL60 cells overexpressing CB2 receptors, also occurred in normal non‐transfected HL60 cells. The enhancement of IL‐8 and MCP‐1 gene transcription and protein production was shown to be pertussis toxin sensitive attesting that this phenomenon was a Gi protein‐coupled receptor‐mediated process as expected for cannabinoid receptors. More specifically, the abolition of the cannabinoid‐induced effect by the specific CB2 antagonist SR 144528 indicated a strict peripheral cannabinoid‐mediated process. Altogether, our data highlight a possible new function of peripheral cannabinoid receptors in the modulation of immune and inflammatory responses.
Comparison of synthesis and antibacterial activity of temporin A
Authors: Harjunpää Irene , Kuusela Pentti , Smoluch Marek T. , Silberring Jerzy , Lankinen Hilkka , Wade David
Published: July 2002

Temporin A is a small, basic, highly hydrophobic, antibacterial peptide found in the skin of the European red frog, Rana temporaria. It was synthesized twice by the FastMoc solid phase method using amino acids protected at the Nα‐position with either 9‐fluorenylmethoxycarbonyl or 2‐(4‐nitrophenylsulfonyl)ethoxycarbonyl. The syntheses of temporin A demonstrates the difference between 2‐(4‐nitrophenylsulfonyl)ethoxycarbonyl and 9‐fluorenylmethoxycarbonyl amino acids. The purified peptide showed also antibacterial activity against clinically important Gram‐positive bacteria. It was found to have a moderately good activity against both methicillin resistant and sensitive strains of Staphylococcus aureus, but a weaker activity against vancomycin resistant strains of Enterococcus faecium.
Tryptophan mediated photoreduction of disulfide bond causes unusual fluorescence behaviour of Fusarium solani pisi cutinase
Authors: Prompers Jeanine J. , Hilbers Cornelis W. , Pepermans Henri A.M.
Published: July 2002

The fluorescence signal of the single tryptophan residue (Trp69) of Fusarium solani pisi cutinase is highly quenched. However, prolonged irradiation of the enzyme in the tryptophan absorption band causes an increase of the tryptophan fluorescence quantum yield by an order of magnitude. By using a combination of NMR spectroscopy and chemical detection of free thiol groups with a sulfhydryl reagent we could unambiguously show that the unusual fluorescence behaviour of Trp69 in cutinase is caused by the breaking of the disulfide bond between Cys31 and Cys109 upon irradiation, while the amide‐aromatic hydrogen bond between Ala32 and Trp69 remains intact. This is the first example of tryptophan mediated photoreduction of a disulfide bond in proteins.