bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in the Antioxidant Systems as Part of the Signaling Pathway Responsible for the Programmed Cell Death Activated by Nitric Oxide and Reactive Oxygen Species in Tobacco Bright-Yellow 2 Cells
Authors: de Pinto Maria Concetta , Tommasi Franca , De Gara Laura
Published: October 2002

Nitric oxide (NO) has been postulated to be required, together with reactive oxygen species (ROS), for the activation of the hypersensitive reaction, a defense response induced in the noncompatible plant-pathogen interaction. However, its involvement in activating programmed cell death (PCD) in plant cells has been questioned. In this paper, the involvement of the cellular antioxidant metabolism in the signal transduction triggered by these bioactive molecules has been investigated. NO and ROS levels were singularly or simultaneously increased in tobacco (Nicotiana tabacum cv Bright-Yellow 2) cells by the addition to the culture medium of NO and/or ROS generators. The individual increase in NO or ROS had different effects on the studied parameters than the simultaneous increase in the two reactive species. NO generation did not cause an increase in phenylalanine ammonia-lyase (PAL) activity or induction of cellular death. It only induced minor changes in ascorbate (ASC) and glutathione (GSH) metabolisms. An increase in ROS induced oxidative stress in the cells, causing an oxidation of the ASC and GSH redox pairs; however, it had no effect on PAL activity and did not induce cell death when it was generated at low concentrations. In contrast, the simultaneous increase of NO and ROS activated a process of death with the typical cytological and biochemical features of hypersensitive PCD and a remarkable rise in PAL activity. Under the simultaneous generation of NO and ROS, the cellular antioxidant capabilities were also suppressed. The involvement of ASC and GSH as part of the transduction pathway leading to PCD is discussed.
Soluble Invertase Expression Is an Early Target of Drought Stress during the Critical, Abortion-Sensitive Phase of Young Ovary Development in Maize
Authors: Andersen Mathias Neumann , Asch Folkard , Wu Yong , Jensen Christian Richardt , Næsted Henrik , Mogensen Vagn Overgaard , Koch Karen Elaine
Published: October 2002

To distinguish their roles in early kernel development and stress, expression of soluble (Ivr2) and insoluble (Incw2) acid invertases was analyzed in young ovaries of maize (Zea mays) from 6 d before (−6 d) to 7 d after pollination (+7 d) and in response to perturbation by drought stress treatments. The Ivr2 soluble invertase mRNA was more abundant than the Incw2 mRNA throughout pre- and early post-pollination development (peaking at +3 d). In contrast,Incw2 mRNAs increased only after pollination. Drought repression of the Ivr2 soluble invertase also preceded changes in Incw2, with soluble activity responding before pollination (−4 d). Distinct profiles of Ivr2and Incw2 mRNAs correlated with respective enzyme activities and indicated separate roles for these invertases during ovary development and stress. In addition, the drought-induced decrease and developmental changes of ovary hexose to sucrose ratio correlated with activity of soluble but not insoluble invertase. Ovary abscisic acid levels were increased by severe drought only at −6 d and did not appear to directly affect Ivr2 expression. In situ analysis showed localized activity and Ivr2 mRNA for soluble invertase at sites of phloem-unloading and expanding maternal tissues (greatest in terminal vascular zones and nearby cells of pericarp, pedicel, and basal nucellus). This early pattern of maternal invertase localization is clearly distinct from the well-characterized association of insoluble invertase with the basal endosperm later in development. This localization, the shifts in endogenous hexose to sucrose environment, and the distinct timing of soluble and insoluble invertase expression during development and stress collectively indicate a key role and critical sensitivity of the Ivr2soluble invertase gene during the early, abortion-susceptible phase of development.
Expression of Genes Involved in Anthocyanin Biosynthesis in Relation to Anthocyanin, Proanthocyanidin, and Flavonol Levels during Bilberry Fruit Development
Authors: Jaakola Laura , Määttä Kaisu , Pirttilä Anna Maria , Törrönen Riitta , Kärenlampi Sirpa , Hohtola Anja
Published: October 2002

The production of anthocyanins in fruit tissues is highly controlled at the developmental level. We have studied the expression of flavonoid biosynthesis genes during the development of bilberry (Vaccinium myrtillus) fruit in relation to the accumulation of anthocyanins, proanthocyanidins, and flavonols in wild berries and in color mutants of bilberry. The cDNA fragments of five genes from the flavonoid pathway, phenylalanine ammonia-lyase, chalcone synthase, flavanone 3-hydroxylase, dihydroflavonol 4-reductase, and anthocyanidin synthase, were isolated from bilberry using the polymerase chain reaction technique, sequenced, and labeled with a digoxigenin-dUTP label. These homologous probes were used for determining the expression of the flavonoid pathway genes in bilberries. The contents of anthocyanins, proanthocyanidins, and flavonols in ripening bilberries were analyzed with high-performance liquid chromatography-diode array detector and were identified using a mass spectrometry interface. Our results demonstrate a correlation between anthocyanin accumulation and expression of the flavonoid pathway genes during the ripening of berries. At the early stages of berry development, procyanidins and quercetin were the major flavonoids, but the levels decreased dramatically during the progress of ripening. During the later stages of ripening, the content of anthocyanins increased strongly and they were the major flavonoids in the ripe berry. The expression of flavonoid pathway genes in the color mutants of bilberry was reduced. A connection between flavonol and anthocyanin synthesis in bilberry was detected in this study and also in previous data collected from flavonol and anthocyanin analyses from other fruits. In accordance with this, models for the connection between flavonol and anthocyanin syntheses in fruit tissues are presented.
The Predicted Candidates of Arabidopsis Plastid Inner Envelope Membrane Proteins and Their Expression Profiles,
Authors: Koo Abraham J.K. , Ohlrogge John B.
Published: October 2002

Plastid envelope proteins from the Arabidopsis nuclear genome were predicted using computational methods. Selection criteria were: first, to find proteins with NH2-terminal plastid-targeting peptides from all annotated open reading frames from Arabidopsis; second, to search for proteins with membrane-spanning domains among the predicted plastidial-targeted proteins; and third, to subtract known thylakoid membrane proteins. Five hundred forty-one proteins were selected as potential candidates of the Arabidopsis plastid inner envelope membrane proteins (AtPEM candidates). Only 34% (183) of the AtPEM candidates could be assigned to putative functions based on sequence similarity to proteins of known function (compared with the 69% function assignment of the total predicted proteins in the genome). Of the 183 candidates with assigned functions, 40% were classified in the category of “transport facilitation,” indicating that this collection is highly enriched in membrane transporters. Information on the predicted proteins, tissue expression data from expressed sequence tags and microarrays, and publicly available T-DNA insertion lines were collected. The data set complements proteomic-based efforts in the increased detection of integral membrane proteins, low-abundance proteins, or those not expressed in tissues selected for proteomic analysis. Digital northern analysis of expressed sequence tags suggested that the transcript levels of most AtPEM candidates were relatively constant among different tissues in contrast to stroma and the thylakoid proteins. However, both digital northern and microarray analyses identified a number of AtPEM candidates with tissue-specific expression patterns.
An Early C-22 Oxidation Branch in the Brassinosteroid Biosynthetic Pathway
Authors: Fujioka Shozo , Takatsuto Suguru , Yoshida Shigeo
Published: October 2002

The natural occurrence of 22-hydroxylated steroids in cultured Catharanthus roseus cells and in Arabidopsis seedlings was investigated. Using full-scan gas chromatography-mass spectrometry analysis, (22S)-22-hydroxycampesterol (22-OHCR), (22S,24R)-22-hydroxyergost-4-en-3-one (22-OH-4-en-3-one), (22S,24R)-22-hydroxy-5α-ergostan-3-one (22-OH-3-one), 6-deoxocathasterone (6-deoxoCT), 3-epi-6-deoxoCT, 28-nor-22-OHCR, 28-nor-22-OH-4-en-3-one, 28-nor-22-OH-3-one, 28-nor-6-deoxoCT, and 3-epi-28-nor-6-deoxoCT were identified. Metabolic experiments with deuterium-labeled 22-OHCR were performed in cultured C. roseus cells and Arabidopsis seedlings (wild type and det2), and the metabolites were analyzed by gas chromatography-mass spectrometry. In both C. roseuscells and wild-type Arabidopsis seedlings, [2H6]22-OH-4-en-3-one, [2H6]22-OH-3-one, [2H6]6-deoxoCT, and [2H6]3-epi-6-deoxoCT were identified as metabolites of [2H6]22-OHCR, whereas the major metabolite in det2 seedlings was [2H6]22-OH-4-en-3-one. Analysis of endogenous levels of these brassinosteroids revealed thatdet2 accumulates 22-OH-4-en-3-one. The levels of downstream compounds were remarkably reduced compared with the wild type. Exogenously applied 22-OH-3-one and 6-deoxoCT were found to rescue det2 mutant phenotypes, whereas 22-OHCR and 22-OH-4-en-3-one did not. These results substantiate the existence of a new subpathway (22-OHCR → 22-OH-4-en-3-one → 22-OH-3-one → 6-deoxoCT) and reveal that the det2 mutant is defective in the conversion of 22-OH-4-en-3-one to 22-OH-3-one, which leads to brassinolide biosynthesis.
Customer relationship management systems: implementation risks and relationship dynamics
Authors: Corner Ian , Hinton Matthew
Published: October 2002

Addresses variables in the implementation of software applications for aspects of customer relationship management (CRM) systems in medium‐sized organisations. The objective is to identify those variables that present the greatest risks to effective and successful implementation in the light of the operating relationships between the main “actors” in multi‐channel CRM implementation projects. Bases theoretical development on two central themes. The first theme is that any implementation has risks that need to be managed and the second is that the dynamics of the relationships of the main actors are more complex where a system is acquired from external developers than with an internally developed system. Explores these assumptions using qualitative linear case studies, where success or failure has not been established at the start. Derives a model which represents a typical relationship dynamic for a CRM implementation. By establishing the nature of the risks involved within the context of a monitored relationship dynamic offers a framework for guidance in the implementation process.
Magnetic Superstructure in the Two-Dimensional Quantum Antiferromagnet SrCu
2
(BO
3
)
2
Authors: Kodama K. , Takigawa M. , Horvatić M. , Berthier C. , Kageyama H. , Ueda Y. , Miyahara S. , Becca F. , Mila F.
Published: October 2002

We report the observation of magnetic superstructure in a magnetization plateau state of SrCu
2
(BO
3
)
2
, a frustrated quasi–two-dimensional quantum spin system. The Cu and B nuclear magnetic resonance (NMR) spectra at 35 millikelvin indicate an apparently discontinuous phase transition from uniform magnetization to a modulated superstructure near 27 tesla, above which a magnetization plateau at 1/8 of the full saturation has been observed. Comparison of the Cu NMR spectrum and the theoretical analysis of a Heisenberg spin model demonstrates the crystallization of itinerant triplets in the plateau phase within a large rhomboid unit cell (16 spins per layer) showing oscillations of the spin polarization. Thus, we are now in possession of an interesting model system to study a localization transition of strongly interacting quantum particles.
Stimulated Raman Scattering in Hydrogen-Filled Hollow-Core Photonic Crystal Fiber
Authors: Benabid F. , Knight J. C. , Antonopoulos G. , Russell P. St. J.
Published: October 2002

We report on stimulated Raman scattering in an approximately 1-meter-long hollow-core photonic crystal fiber filled with hydrogen gas under pressure. Light was guided and confined in the 15-micrometer-diameter hollow core by a two-dimensional photonic bandgap. Using a pulsed laser source (pulse duration, 6 nanoseconds; wavelength, 532 nanometers), the threshold for Stokes (longer wavelength) generation was observed at pulse energies as low as 800 ± 200 nanojoules, followed by a coherent anti-Stokes (shorter wavelength) generation threshold at 3.4 ± 0.7 microjoules. The pump-to-Stokes conversion efficiency was 30 ± 3% at a pulse energy of only 4.5 microjoules. These energies are almost two orders of magnitude lower than any other reported energy, moving gas-based nonlinear optics to previously inaccessible parameter regimes of high intensity and long interaction length.
Synthesis of 1,4-anhydro-D-xylitol heteroanalogues of the naturally occurring glycosidase inhibitor salacinol and their evaluation as glycosidase inhibitors
Authors: Ghavami Ahmad , Johnston Blair D , Maddess Matthew D , Chinapoo Sarah M , Jensen Morten T , Svensson Birte , Pinto B Mario
Published: October 2002

The syntheses of two 1,4-anhydro-D-xylitol heteroanalogues (8 and 9) of the naturally occurring sulfonium ion, salacinol (3), containing a sulfur or nitrogen atom in the ring are described. Salacinol (3) is one of the active principles in the aqueous extracts of Salacia reticulata that are traditionally used in Sri Lanka and India for the treatment of Type 2 diabetes. The synthetic strategy relies on the nucleophilic attack of sulfur or nitrogen analogues of 1,4-anhydro-D-xylitol at the least-hindered carbon of 2,4-O-benzylidene-L-erythritol-1,3-cyclic sulfate. The sulfonium ion 8 inhibited barley-α-amylase (AMY1) and porcine pancreatic-α-amylase (PPA), with Ki values of 109 ± 11 and 55 ± 5 µM, respectively. In contrast, the ammonium ion 9 showed no significant inhibition of either AMY1 or PPA. Compounds 8 and 9 also showed no significant inhibition of glucoamylase.Key Words: glycosidase inhibitors, salacinol analogues, anhydro-D-xylitol heteroanalogues, enzyme inhibition.
The core oligosaccharide component fromMannheimia (Pasteurella) haemolyticaserotype Al lipopolysaccharide containsL-glycero-D-manno- andD-glycero-D-manno-heptoses: Analysis of the structure and conformation by high-resolution NMR spectroscopy
Authors: Brisson Jean-Robert , Crawford Ellen , Uhrín Duan , Khieu Nam Huan , Perry Malcolm B , Severn Wayne B , Richards James C
Published: October 2002

Previous studies from our laboratory have indicated that the lipopolysaccharide (LPS) from Mannheimia haemolytica serotype A1 contains both L-glycero-D-manno-heptose and D-glycero-D-manno-heptose residues. NMR methods making use of 1D1H selective excitation and 2D (1H,13C) and (1H,31P) heteronuclear experiments were used for the structural determination of the major core oligosaccharide components of the deacylated low-molecular-mass LPS obtained following sequential treatment with anhydrous hydrazine and aq KOH. The core oligosaccharide region was found to be composed of a branched octasaccharide linked to the deacylated lipid A moiety via a 3-deoxy-4-phospho-D-manno-oct-2-ulosonate residue having the structure,[Formula: see text]Heterogeneity was found to be present at several linkages. NMR methods were devised to distinguish between the diastereomeric forms of the heptose residues. Synthesized monosaccharides of L-D- and D-D-heptose were used as model compounds for analysis of the1H and13C NMR chemical shifts and proton coupling constants. Molecular modeling using a Monte Carlo method for conformational analysis of saccharides was used to determine the conformation of the inner core of the oligosaccharide and to establish the stereochemical relationships between the heptoses.Key words: LPS, NMR, conformation, oligosaccharide, heptose.
Synthesis and in vitro evaluation of substituted aryl- and hetarylmethyl phosphonate and phosphate  UMP derivatives as potential glucosyltransferase inhibitors
Authors: Bhattacharya Asish K , Stolz Florian , Kurzeck Jürgen , Rüger Wolfgang , Schmidt Richard R
Published: October 2002

The enzyme β (1[Formula: see text]4)-glucosyltransferase (BGT) catalyses the transfer of glucose from uridine diphosphoglucose (UDP-Glc) to 5-hydroxymethylcytosine (5-HMC) bases in double-stranded DNA. Potential inhibitors of BGT were developed by structure-based design and synthesized. The designed inhibitors 16 provide conformational mimicry of the transition state in glucosyltransfer reactions. The key synthetic steps involve a MichaelisArbuzov reaction followed by coupling with uridine-5'-morpholidophosphate as activated UMP derivative. The compounds were tested for in vitro inhibitory activity against BGT and the inhibition kinetics were examined. Three of the designed molecules were found to be potential inhibitors of BGT having IC50values in the micromolar (µM) range. Useful structureactivity relationships were established which provide guidelines for the design of future generations of inhibitors of BGT.Key words: β-glucosyltransferase, transition state, enzyme inhibitors, structure-based design, synthesis.
Thermolysis of a spiro-fused oxadiazoline: The carbonyl ylidecyclic carbenediradical sequence
Authors: Merkley Nadine , Warkentin John
Published: October 2002

Thermolysis of spiro-fused oxadiazoline 1 in benzene led to loss of N2 to form a carbonyl ylide intermediate. Most of the ylide fragmented to acetone and 4-phenyl-1,3-dioxane-2-ylidene, which could be trapped with tert-butyl alcohol. In the absence of the trapping agent, the major pathway followed by the carbene was fragmentation to a diradical, 5-phenyl-2-oxa-1-oxo-1,5-pentanediyl. The latter diradical coupled to α-phenyl-γ-butyrolactone and decarboxylated to afford cyclopropylbenzene. Other products from the reaction were those of apparent insertion of the carbene into a C-H bond of the benzene solvent and into a C-H bond of acetone. Such reactions appear to be without precedent  alternative, non-carbene mechanisms are proposed. Key words: dioxacarbene, carbonyl ylide, cyclopropylbenzene, diradical, lactone, oxadiazoline.
An effective strategy for structural elucidation of oligosaccharides through NMR spectroscopy combined with peracetylation using doubly 13C-labeled acetyl groups
Authors: Bendiak Brad , Fang Tammy T , Jones David NM
Published: October 2002

The use of NMR spectroscopy for the elucidation of larger carbohydrate structures isolated from natural sources is principally limited by severe overlap of 1H signals, poor sensitivity when experiments involve 13C nuclei, and difficulties in conclusively establishing linkage positions. Peracetylation of oligosaccharides with doubly 13C-labeled acetyl groups provides several major advantages for their structural elucidation when combined with specifically tailored NMR pulse sequences. The 2.54.7 Hz J-coupling constants between acetyl carbonyl-13C nuclei and protons of the sugar ring at the sites of acetylation enables these sites to be readily assigned. By inference, glycosidic linkage positions on monosaccharides can be unambiguously determined. This can be used in lieu of permethylation analysis, yet does not require degradation of oligosaccharides. Spectral dispersion in the directly detected (1H) dimension is increased ~2.62.7-fold due to the downfield shifting of sugar-ring protons at the positions of acetylation. Peracetylation also introduces three new frequency dimensions for NMR studies, namely the 13CO, 13CMe, and 1HMe frequencies of the acetyl groups. These frequencies can be correlated to sugar protons, either independently or in combination, in alternative 2-, 3-, or 4-D experiments. The use of HartmannHahn coherence transfer combined with zero-quantum dephasing periods permits purely absorptive in-phase multiplets to be extracted and enables accurate scalar couplings between ring protons to be measured, even in multidimensional experiments. Results are illustrated on a nonasaccharide-alditol derived from N-linked glycoproteins and on some smaller structures containing sialic acids and N-acetylhexosamines. Methods for small-scale sample acetylation using the superacylation catalyst, 4-dimethylamino pyridine, are described. A brief historical perspective pertinent to the fundamental contributions of Dr. R.U. Lemieux to the field of carbohydrate NMR is also presented.Key words: NMR, oligosaccharides, peracetylation, doubly 13C-labeled acetyl groups, tailored pulse sequences, heteronuclear HartmannHahn.
Reciprocal donor acceptor selectivity (RDAS): A new concept for "matching" donors with acceptors
Authors: Fraser-Reid Bert , Lopez J Cristobal , Radhakrishnan K V , Mach Mateusz , Schlueter Urs , Gomez Ana , Uriel Clara
Published: October 2002

Lemieux's extensive work on replacement reactions at the anomeric center helped to establish the fact that the O-2-protecting group of a donor exerts powerful control over stereoselectivity in glycoside coupling reactions. This manuscript shows that the O-2-protecting group of a donor also exerts powerful, indeed sometimes total, control over regioselectivity in glycosidation of diols. The latter acceptors also exhibit preferences over the donor, thereby providing evidence for the concept of reciprocal donor acceptor selectivity (RDAS). The latter concept is put to the test by simultaneously presenting an acceptor diol with equivalent amounts of two donors, in the hope of achieving double differential glycosidation leading to one-pot assembly of a trisaccharide. When the pair of donors did not conform to RDAS principles the reaction did not proceed beyond a dissacharide. However, when the pair was RDAS sanctioned, a single trisaccharide (out of four possibilities) was obtained.Key words: regiocontrolled glycosidation, armed and disarmed donors, di- and trioxolenium ions, oxocarbenium ion.
GROUP-THEORETIC APPROACH FOR SYMBOLIC TENSOR MANIPULATION
Authors: MANSSUR L. R. U. , PORTUGAL R. , SVAITER B. F.
Published: October 2002

We describe how Computational Group Theory provides tools for manipulating indexed objects (tensors, spinors, and so on) in explicit index notation. In particular, we present algorithms that put tensors with free and dummy indices obeying permutation symmetries into the canonical form. The method is based on algorithms for determining canonical double coset representatives of subgroups of the symmetric group. The complexity of the algorithms is polynomial on the number of indices in practical applications and allows one to address the simplification of tensor expressions with hundreds of indices, going beyond what is needed in practical applications.
GEOMETRY OF THEORY SPACE AND RG FLOWS
Authors: KAR SAYAN
Published: October 2002

The space of couplings of a given theory is the arena of interest in this article. Equipped with a metric ansatz akin to the Fisher information matrix in the space of parameters in statistics (similar metrics in physics are the Zamolodchikov metric or the O'Connor–Stephens metric) we investigate the geometry of theory space through a study of specific examples. We then look into renormalisation group flows in theory space and make an attempt to characterise such flows via its isotropic expansion, rotation and shear. Consequences arising from the evolution equation for the isotropic expansion are discussed. We conclude by pointing out generalisations and pose some open questions.
QUANTUM GEOMETRIC DESCRIPTION OF COSMOLOGICAL MODELS
Authors: DATE G.
Published: October 2002

This is a review talk describing the recent work of Martin Bojowald on Loop Quantum Cosmology.
QUANTUM-GRAVITY PHENOMENOLOGY: STATUS AND PROSPECTS
Authors: AMELINO-CAMELIA GIOVANNI
Published: October 2002

Over the last few years part of the quantum-gravity community has modified its attitude toward the possibility of finding experimental contexts that provide insight on non-classical properties of spacetime. I review those quantum-gravity phenomenology proposals which were instrumental in bringing about this change of attitude, and I discuss the prospects for the short-term future of quantum-gravity phenomenology.
Hebbian Imprinting and Retrieval in Oscillatory Neural Networks
Authors: Scarpetta Silvia , Zhaoping L. , Hertz John
Published: October 2002

We introduce a model of generalized Hebbian learning and retrieval in oscillatory neural networks modeling cortical areas such as hippocampus and olfactory cortex. Recent experiments have shown that synaptic plasticity depends on spike timing, especially on synapses from excitatory pyramidal cells, in hippocampus, and in sensory and cerebellar cortex. Here we study how such plasticity can be used to form memories and input representations when the neural dynamics are oscillatory, as is common in the brain (particularly in the hippocampus and olfactory cortex). Learning is assumed to occur in a phase of neural plasticity, in which the network is clamped to external teaching signals. By suitable manipulation of the nonlinearity of the neurons or the oscillation frequencies during learning, the model can be made, in a retrieval phase, either to categorize new inputs or to map them, in a continuous fashion, onto the space spanned by the imprinted patterns. We identify the first of these possibilities with the function of olfactory cortex and the second with the observed response characteristics of place cells in hippocampus. We investigate both kinds of networks analytically and by computer simulations, and we link the models with experimental findings, exploring, in particular, how the spike timing dependence of the synaptic plasticity constrains the computational function of the network and vice versa.
Factorial Hidden Markov Models and the Generalized Backfitting Algorithm
Authors: Jacobs Robert A. , Jiang Wenxin , Tanner Martin A.
Published: October 2002

Previous researchers developed new learning architectures for sequential data by extending conventional hidden Markov models through the use of distributed state representations. Although exact inference and parameter estimation in these architectures is computationally intractable, Ghahramani and Jordan (1997) showed that approximate inference and parameter estimation in one such architecture, factorial hidden Markov models (FHMMs), is feasible in certain circumstances. However, the learning algorithm proposed by these investigators, based on variational techniques, is difficult to understand and implement and is limited to the study of real-valued data sets. This chapter proposes an alternative method for approximate inference and parameter estimation in FHMMs based on the perspective that FHMMs are a generalization of a well-known class of statistical models known as generalized additive models (GAMs; Hastie & Tibshirani, 1990). Using existing statistical techniques for GAMs as a guide, we have developed the generalized backfitting algorithm. This algorithm computes customized error signals for each hidden Markov chain of an FHMM and then trains each chain one at a time using conventional techniques from the hidden Markov models literature. Relative to previous perspectives on FHMMs, we believe that the viewpoint taken here has a number of advantages. First, it places FHMMs on firm statistical foundations by relating them to a class of models that are well studied in the statistics community, yet it generalizes this class of models in an interesting way. Second, it leads to an understanding of how FHMMs can be applied to many different types of time-series data, including Bernoulli and multinomial data, not just data that are real valued. Finally, it leads to an effective learning procedure for FHMMs that is easier to understand and easier to implement than existing learning procedures. Simulation results suggest that FHMMs trained with the generalized backfitting algorithm are a practical and powerful tool for analyzing sequential data.
Origin of low-symmetry growth sectors in edingtonite and yugawaralite, and crystal structure of the k{011} and v{120} sectors of yugawaralite
Authors: Tanaka T. , Kimura R. , Akizuki M. , Kudoh Y.
Published: October 2002

Edingtonite and yugawaralite showing sectoral textures were studied by polarized optical microscopy and X-ray analysis. In edingtonite, the m{110} sector (2Vα = 22°) is optically triclinic and the c{001} sector (2Vα = 52°) is orthorhombic. In yugawaralite, the k{011} sector is optically monoclinic, whereas the v{120} sector is triclinic. Their crystal structures were determined. The results of refinement showed that the space groups of the k{011} (Rw = 4.5%) and v{120} (Rw = 5.1%) growth sectors are monoclinicPcand triclinicP1, respectively. In the v{120} sector, several interatomic distances, bond angles and site occupancies are different with respect to a symmetrical plane of the structure, and therefore the monocliniccglide is extinct. Thus, the X-ray symmetry correlates with the optical one. From the relationship between the surface and internal texture, the symmetry and sector can be explained by cation (Al/Si) ordering during non-equilibrium crystal growth.
Interaction of calmodulin with the cytoplasmic domain of platelet glycoprotein VI
Authors: Andrews Robert K. , Suzuki-Inoue Katsue , Shen Yang , Tulasne David , Watson Stephen P. , Berndt Michael C.
Published: October 2002

The platelet collagen receptor, glycoprotein VI (GPVI), and GPIb-IX-V, which binds von Willebrand factor, initiate platelet aggregation at low or high shear stress, respectively. We recently reported that positively charged, membrane-proximal sequences within cytoplasmic domains of GPIbβ and GPV of GPIb-IX-V bind calmodulin. We now show that GPVI also binds calmodulin as follows—(1) calmodulin coimmunoprecipitated with GPVI from resting platelet lysates using an anti-GPVI IgG, but partially dissociated in platelets activated by collagen or collagen-related peptide; (2) calmodulin coprecipitated from platelet lysates with maltose-binding protein (MBP)–GPVI cytoplasmic domain fusion protein, but not MBP alone; (3) GPVI-related synthetic peptide based on the membrane-proximal sequence, His269-Pro287, induced a shift in calmodulin migration on nondenaturing gels, an assay that identifies calmodulin-binding peptides. His269-Pro287 is analogous to the calmodulin-binding sequence in GPIbβ. The novel interaction of GPVI and calmodulin may regulate aspects of GPVI function.
von Willebrand factor cleaving protease (ADAMTS13) is deficient in recurrent and familial thrombotic thrombocytopenic purpura and hemolytic uremic syndrome
Authors: Remuzzi Giuseppe , Galbusera Miriam , Noris Marina , Canciani Maria Teresa , Daina Erica , Bresin Elena , Contaretti Silvia , Caprioli Jessica , Gamba Sara , Ruggenenti Piero , Perico Norberto , Mannucci Pier Mannuccio
Published: October 2002

Whether measurement of ADAMTS13 activity may enable physicians to distinguish thrombotic thrombocytopenic purpura (TTP) from hemolytic uremic syndrome (HUS) is still a controversial issue. Our aim was to clarify whether patients with normal or deficient ADAMTS13 activity could be distinguished in terms of disease manifestations and multimeric patterns of plasma von Willebrand factor (VWF). ADAMTS13 activity, VWF antigen, and multimeric pattern were evaluated in patients with recurrent and familial TTP (n = 20) and HUS (n = 29). Results of the collagen-binding assay of ADAMTS13 activity were confirmed in selected samples by testing the capacity of plasma to cleave recombinant VWF A1-A2-A3. Most patients with TTP had complete or partial deficiency of ADAMTS13 activity during the acute phase, and in some the defect persisted at remission. However, complete ADAMTS13 deficiency was also found in 5 of 9 patients with HUS during the acute phase and in 5 patients during remission. HUS patients with ADAMTS13 deficiency could not be distinguished clinically from those with normal ADAMTS13. In a subgroup of patients with TTP or HUS, the ADAMTS13 defect was inherited, as documented by half-normal levels of ADAMTS13 in their asymptomatic parents, consistent with the heterozygous carrier state. In patients with TTP and HUS there was indirect evidence of increased VWF fragmentation, and this occurred also in patients with ADAMTS13 deficiency. In conclusion, deficient ADAMTS13 activity does not distinguish TTP from HUS, at least in the recurrent and familial forms, and it is not the only determinant of VWF abnormalities in these conditions.
Age at infection affects the long-term outcome of transfusion-associated chronic hepatitis C
Authors: Minola Eliseo , Prati Daniele , Suter Fredy , Maggiolo Franco , Caprioli Flavio , Sonzogni Aurelio , Fraquelli Mirella , Paggi Silvia , Conte Dario
Published: October 2002

Before the introduction of hepatitis C virus (HCV) screening for blood donors, the risk of acquiring HCV infection as a result of a transfusion was about 10%. The aim of this study was to assess the frequency and rate of progression to cirrhosis in patients with transfusion-associated chronic HCV infection and identify possibly negative prognostic factors. Of 2477 consecutive patients with clinical or laboratory evidence of liver disease, 392 (16%) were anti-HCV– and HCV-RNA–positive, had anamnestic evidence of a single and precisely dated transfusion event, and showed no other causes of chronic liver disease; 268 (68%) underwent ultrasound-guided liver biopsy and were enrolled in the study. After a mean interval of 18.4 years, 54 patients (20.1%) had cirrhosis, which multivariate analysis showed to be independently associated with the duration of follow-up, age at infection and at the time of liver biopsy, and serum alanine aminotransferase levels at biopsy. The time necessary to have a 50% probability of developing cirrhosis in patients aged 21-30, 31-40, and more than 40 years was 33, 23, and 16 years, respectively. In comparison with those aged 20 years or less at infection, the risk ratio of developing cirrhosis over a period of 30 years for patients aged 21-30 and at least 31 years at infection was, respectively, 4.51 (95% confidence interval, 1.03-19.76) and 12.29 (95% confidence interval, 3.06-49.40). In patients with transfusion-associated chronic hepatitis C, the risk of cirrhosis is related to age at infection and disease activity. Our findings suggest that an aggressive therapeutic approach should be adopted in patients infected by HCV at an older age to prevent the progression to end-stage liver disease.
The Tel-Abl (ETV6-Abl) tyrosine kinase, product of complex (9;12) translocations in human leukemia, induces distinct myeloproliferative disease in mice
Authors: Million Ryan P. , Aster Jon , Gilliland D. Gary , Van Etten Richard A.
Published: October 2002

Several patients with clinical features of chronic myeloid leukemia (CML) have fusion of the TEL (ETV6) gene on 12p13 with ABL on 9q34 and express a chimeric Tel-Abl protein that contains the same portion of the Abl tyrosine kinase fused to Tel, an Ets family transcription factor, rather than Bcr. In a murine retroviral bone marrow transduction-transplantation model, a Tel (exon 1-5)–Abl fusion protein induced 2 distinct illnesses: a CML-like myeloproliferative disease very similar to that induced by Bcr-Abl but with increased latency and a novel syndrome characterized by small-bowel myeloid cell infiltration and necrosis, increased circulating endotoxin and tumor necrosis factor α levels, and fulminant hepatic and renal failure. Induction of both diseases required the Tel pointed homology oligomerization domain and Abl tyrosine kinase activity. Myeloid cells from mice with both diseases expressed Tel-Abl protein. CML-like disease induced by Tel-Abl and Bcr-Abl was polyclonal and originated from cells with multilineage (myeloid, erythroid, and B- and T-lymphoid) repopulating ability and the capacity to generate day-12 spleen colonies in secondary transplantations. In contrast to findings with Bcr-Abl, however, neither Tel-Abl–induced disease could be adoptively transferred to irradiated secondary recipient syngeneic mice. These results show that Tel-Abl has leukemogenic properties from distinct from those of Bcr-Abl and may act in a different bone marrow progenitor.
Comparison of chronic graft-versus-host disease after transplantation of peripheral blood stem cells versus bone marrow in allogeneic recipients: long-term follow-up of a randomized trial
Authors: Flowers Mary E. D. , Parker Pablo M. , Johnston Laura J. , Matos Alice V. B. , Storer Barry , Bensinger William I. , Storb Rainer , Appelbaum Frederick R. , Forman Stephen J. , Blume Karl G. , Martin Paul J.
Published: October 2002

In a previous multicenter phase III trial comparing peripheral blood stem cell transplantation (PBSCT) to bone marrow transplantation (BMT) from HLA-matched related donors, we found no statistically significant difference in the cumulative incidence of clinical extensive chronic graft-versus-host disease (GVHD) in the 2 groups. We have analyzed the results in more detail to determine whether the clinical characteristics of chronic GVHD after PBSCT might be distinct from those that occur after BMT. Clinical extensive chronic GVHD developed in 39 of 63 recipients of PBSCs and in 32 of 63 BM recipients who were alive and free of malignancy at day 100 after the transplantation. No significant differences were found in the time and type of onset of clinical extensive chronic GVHD or in the frequency of complications associated with severe morbidity. Involvement of skin and female genital tract was more frequent in PBSC recipients than in BM recipients. The cumulative incidence of chronic GVHD at 3 years was similar in the 2 groups, but the number of successive treatments needed to control chronic GVHD was higher after PBSCT than after BMT (P = .03), and the duration of glucocorticoid treatment was longer after PBSCT compared to BMT (P = .03). These results suggest that chronic GVHD after PBSCT may be more protracted and less responsive to current treatment than chronic GVHD after BMT. Assessment of the overall benefits of PBSCT compared to BMT will require continued long-term follow up of morbidity associated with chronic GVHD.
Targeting CB2 cannabinoid receptors as a novel therapy to treat malignant lymphoblastic disease
Authors: McKallip Robert J. , Lombard Catherine , Fisher Michael , Martin Billy R. , Ryu Seongho , Grant Steven , Nagarkatti Prakash S. , Nagarkatti Mitzi
Published: October 2002

In the current study, we examined whether ligation of CB2 receptors would lead to induction of apoptosis in tumors of immune origin and whether CB2 agonist could be used to treat such cancers. Exposure of murine tumors EL-4, LSA, and P815 to delta-9-tetrahydrocannabinol (THC) in vitro led to a significant reduction in cell viability and an increase in apoptosis. Exposure of EL-4 tumor cells to the synthetic cannabinoid HU-210 and the endogenous cannabinoid anandamide led to significant induction of apoptosis, whereas exposure to WIN55212 was not effective. Treatment of EL-4 tumor-bearing mice with THC in vivo led to a significant reduction in tumor load, increase in tumor-cell apoptosis, and increase in survival of tumor-bearing mice. Examination of a number of human leukemia and lymphoma cell lines, including Jurkat, Molt-4, and Sup-T1, revealed that they expressed CB2 receptors but not CB1. These human tumor cells were also susceptible to apoptosis induced by THC, HU-210, anandamide, and the CB2-selective agonist JWH-015. This effect was mediated at least in part through the CB2 receptors because pretreatment with the CB2 antagonist SR144528 partially reversed the THC-induced apoptosis. Culture of primary acute lymphoblastic leukemia cells with THC in vitro reduced cell viability and induced apoptosis. Together, the current data demonstrate that CB2 cannabinoid receptors expressed on malignancies of the immune system may serve as potential targets for the induction of apoptosis. Also, because CB2 agonists lack psychotropic effects, they may serve as novel anticancer agents to selectively target and kill tumors of immune origin.
Autologous stem cell transplantation followed by a dose-reduced allograft induces high complete remission rate in multiple myeloma
Authors: Kröger Nicolaus , Schwerdtfeger Rainer , Kiehl Michael , Sayer Herbert Gottfried , Renges Helmut , Zabelina Tatjana , Fehse Boris , Tögel Florian , Wittkowsky Georg , Kuse Rolf , Zander Axel Rolf
Published: October 2002

We evaluated toxicity, engraftment, chimerism, graft-versus-host disease (GVHD), and response to a dose-reduced allograft after cytoreductive autografting in 17 patients with advanced stage II/III multiple myeloma (MM). After autografting with melphalan (200 mg/m2) the patients received after a median interval of 119 days (range 60-210) a dose-reduced regimen consisting of fludarabine (180 mg/m2), melphalan (100 mg/m2), and antithymocyte globulin (3 × 10 mg/kg) followed by allografting from related (n = 7), mismatched related (n = 2), or unrelated (n = 8) donors to induce a graft-versus-myeloma effect. After dose-reduced allografting all patients became neutropenic (< 0.2 × 109/L) for at least 8 days. All patients engrafted with a median time for leukocyte (> 1 × 109/L) and platelet (> 20 × 109/L) counts of 16 (range, 11-24) and 23 days (range, 12-43), respectively. Complete donor chimerism was detected after a median of 30 days (range, 19-38). Acute GVHD stage II occurred in 4 patients (25%) and grade III GVHD in 2 patients (13%). Chronic GVHD developed in 40% of the patients, but only 1 patient experienced extensive chronic GVHD requiring further immunosuppressive therapy. Two patients died of alveolar hemorrhage and pneumonia, resulting in a day 100 mortality rate of 11%. The rate of complete remission with negative immunofixation increased from 18% after autografting to 73% after allografting. After a median follow-up of 17 months after autologous and 13 months after allogeneic transplantation 13 patients are alive and 12 of them free of relapse or progression. The tandem auto-allotransplant protocol is highly active and provides rapid engraftment with complete donor chimerism and tolerable toxicity.
Several types of mutations of the Abl gene can be found in chronic myeloid leukemia patients resistant to STI571, and they can pre-exist to the onset of treatment
Authors: Roche-Lestienne Catherine , Soenen-Cornu Valerie , Grardel-Duflos Nathalie , Laı̈ Jean-Luc , Philippe Nathalie , Facon Thierry , Fenaux Pierre , Preudhomme Claude
Published: October 2002

Targeting the tyrosine kinase activity ofBCR-ABL represents a very promising therapeutic strategy in chronic myeloid leukemia (CML). Despite strong efficacy of the tyrosine kinase inhibitor STI571, resistance has been observed in a significant proportion of patients in advanced CML stage or in Ph-positive acute lymphoid leukemia (ALL). We investigated in this study the mechanism of resistance to STI571 through point mutations in the tyrosine kinase domain and/or BCR-ABL gene amplification in 24 patients (16 in chronic phase and 8 in accelerated phase of the disease) who obtained no cytogenetic response to STI571 treatment. Screening for the already-described Thr315Ile point mutation in the ABL domain using a reverse transcription polymerase chain reaction restriction fragment length polymorphism (RT-PCR-RFLP) technique, 3 patients showed a proportion of mutated transcript at the time of resistance. The same technique failed to detect mutation at diagnosis, but a specific allele-specific oligonucleotide (ASO)–PCR on DNA for the Thr315Ile mutation and, after sequencing, for 2 newly described Phe311Leu and Met351Thr substitutions, showed the presence of rare mutated cells prior to STI571 therapy. Furthermore, the increased proportion of mutated cells during treatment detected by ASO-PCR strongly suggested clonal selection by the functional inhibiting effect of these mutations. Finally, no BCR-ABL gene amplification was detected by fluorescent in situ hybridization (FISH) in the 24 STI571-resistant patients. Our data support that in CML patients treated with STI571, ABL mutations are not restricted to the accelerated phase of the disease and that, at least in some cases, mutations seem to occur prior to STI571 therapy, probably as second mutational events during the course of CML.
γ-Globulins prepared from sera of multiparous women bind anti-HLA antibodies and inhibit an established in vivo human alloimmune response
Authors: Semple John W. , Kim Michael , Lazarus Alan H. , Freedman John
Published: October 2002

It has previously been shown that sera from multiparous women have increased levels of anti-idiotypic antibodies specific for anti-HLA molecules. γ-Globulins prepared from these sera may be superior to commercial preparations of intravenous γ-globulin (IVIg) for inhibiting HLA alloimmunization. To test this, F(ab′)2fragments prepared from either commercial IVIg or from the sera of men or multiparous women were coupled to CNBr-Sepharose and tested for their ability to bind F(ab′)2 fragments derived from polyspecific anti-HLA sera. As determined by flow cytometry, compared with columns coated with F(ab′)2 derived from commercial IVIg or sera from men, columns coated with F(ab′)2 prepared from the sera of multiparous women bound significantly more anti-HLA. In addition, intact IgG molecules prepared from the sera of multiparous women significantly neutralized the reactivity of the anti-HLA F(ab′)2 fragments. To determine whether the intact IgG molecules or their corresponding F(ab′)2 fragments could affect in vivo alloimmunity, they were tested for their ability to inhibit an established IgG human alloimmune response in humanized severe combined immunodeficient (SCID) mice. Compared with commercial IVIg, when intact IgG or F(ab′)2 fragments derived from multiparous women were administered to SCID mice making human anti-HLA antibodies, a significant reduction in anti-HLA reactivity was observed. The findings suggest that IgG molecules prepared from the sera of multiparous women have increased anti-idiotypic reactivity against anti-HLA antibodies, which can significantly inhibit an established human IgG alloimmune response in an Fc-independent manner.
Outcome of 154 patients with severe aplastic anemia who received transplants from unrelated donors: the Japan Marrow Donor Program
Authors: Kojima Seiji , Matsuyama Takaharu , Kato Shunichi , Kigasawa Hisato , Kobayashi Ryoji , Kikuta Atsushi , Sakamaki Hisashi , Ikuta Koichiro , Tsuchida Masahiro , Hoshi Yasutaka , Morishima Yasuo , Kodera Yoshihisa
Published: October 2002

We retrospectively analyzed results for 154 patients with acquired severe aplastic anemia who received bone marrow transplants between 1993 and 2000 from unrelated donors identified through the Japan Marrow Donor Program. Patients were aged between 1 and 46 years (median, 17 years). Seventy-nine donor-patient pairs matched at HLA-A, -B, and -DRB1 loci, as shown by DNA typing. Among the 75 mismatched pairs, DNA typing of 63 pairs showed that 51 were mismatched at 1 HLA locus (18 HLA-A, 11 HLA-B, 22 HLA-DRB1) and 12 were mismatched at 2 or more loci. Seventeen patients (11%) experienced either early or late graft rejection. The incidence of grade III/IV acute graft versus host disease and chronic graft versus host disease was 20% (range, 7%-33%) and 30% (range, 12%-48%), respectively. Currently, 99 patients are alive, having survived for 3 to 82 months (median, 29 months) after their transplantations. The probability of overall survival at 5 years was 56% (95% confidence interval, 34%-78%). Multivariate analysis revealed the following unfavorable factors: transplantation more than 3 years after diagnosis (relative risk [RR], 1.86; P = .02), patients older than 20 years (RR, 2.27; P = .03), preconditioning regimen without antithymocyte globulin (RR 2.28; P = .04), and HLA-A or -B locus mismatching as determined by DNA typing. Matching of HLA class I alleles and improvement of preparative regimens should result in improved outcomes in patients with severe aplastic anemia who receive transplants from unrelated donors.