bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency-Dependent Breakdown of Wave Propagation Into Fibrillatory Conduction Across the Pectinate Muscle Network in the Isolated Sheep Right Atrium
Authors: Berenfeld Omer , Zaitsev Alexey V. , Mironov Sergey F. , Pertsov Arkady M. , Jalife José
Published: July 2002

Atrial fibrillation (AF) may result from stationary reentry in the left atrium (LA), with fibrillatory conduction toward the right atrium (RA). We hypothesize that periodic input to the RA at an exceedingly high frequency results in disorganized wave propagation, compatible with fibrillatory conduction. Simultaneous endocardial and epicardial optical mapping (di-4-ANEPPS) was performed in isolated, coronary-perfused sheep RA. Rhythmic pacing of Bachmann’s bundle allowed well-controlled and realistic conditions for LA-driven RA. Pacing at increasingly higher frequencies (2.0 to 6.0 Hz) led to increasing delays in activation distal to major branching sites of the crista terminalis and pectinate bundles, culminating in spatially distributed intermittent blockade at or above ≈6.5 Hz. At this “breakdown frequency,” the direction of RA propagation became completely variable from beat to beat and thus transformed into fibrillatory conduction. Such frequency-dependent changes were independent of action potential duration. Rather, the spatial boundaries between proximal and distal frequencies correlated well with branch sites of the pectinate musculature. Thus, there exists a breakdown frequency in the sheep RA below which activity is periodic throughout the atrium and above which it is fibrillation-like. The data are consistent with the ideas that during AF, high-frequency activation initiated in the LA undergoes fibrillatory conduction toward the RA, and that sink-to-source effect at branch points of the crista terminalis and pectinate muscles is important in determining the complexity of the arrhythmia.
The Origins of Human Rights Regimes: Democratic Delegation in Postwar Europe
Authors: Moravcsik Andrew
Published: July 2002

Most formal international human rights regimes establish international committees and courts that hold governments accountable to their own citizens for purely internal activities. Why would governments establish arrangements so invasive of domestic sovereignty? Two views dominate the literature. “Realist” theories assert that the most powerful democracies coerce or entice weaker countries to accept norms; “ideational” theories maintain that transnational processes of diffusion and persuasion socialize less-democratic governments to accept norms. Drawing on theories of rational delegation, I propose and test a third “republican liberal” view: Governments delegate self-interestedly to combat future threats to domestic democratic governance. Thus it is not mature and powerful democracies, but new and less-established democracies that will most strongly favor mandatory and enforceable human rights obligations. I test this proposition in the case of the European Convention on Human Rights—the most successful system of formal international human rights guarantees in the world today. The historical record of its founding—national positions, negotiating tactics, and confidential deliberations—confirms the republican liberal explanation. My claim that governments will sacrifice sovereignty to international regimes in order to dampen domestic political uncertainty and “lock in” more credible policies is then generalized theoretically and applied to other human rights regimes, coordination of conservative reaction, and international trade and monetary policy.
Class Versus Industry Cleavages: Inter-Industry Factor Mobility and the Politics of Trade
Authors: Hiscox Michael J.
Published: July 2002

Domestic political conflict has been a constant companion to international trade, but the nature of that conflict has varied greatly in Western democracies over the last two centuries. Political battles over trade policy appear to have sometimes divided societies along broad class lines and at other times split them into narrow industry-based coalitions. I argue that this diversity stems from historical and cross-national variation in inter-industry factor mobility. Class coalitions are more likely where factor mobility is high, whereas narrow, industry-based coalitions are more likely where mobility is low. Evidence from six Western economies for the last two centuries indicates that levels of factor mobility have varied historically and cross-nationally in accord with industrialization and regulation. This variation corresponds broadly with observable differences in the formation of trade policy coalitions.
The Nuclear Taboo: The United States and the Normative Basis of Nuclear Non-Use
Authors: Tannenwald Nina
Published: July 2002

We have recently witnessed the fiftieth anniversary of the bombing of Hiroshima and Nagasaki, the only use of nuclear weapons in warfare. The non-use of nuclear weapons since then remains the single most important phenomenon of the nuclear age. Yet we still lack a full understanding of how this tradition arose and is maintained and of its prospects for the future. The widely cited explanation is deterrence, but this account is either wrong or incomplete. Although an element of sheer luck no doubt has played a part in this fortuitous outcome, this article argues that a normative element must be taken into account in explaining why nuclear weapons have not been used since 1945. A normative prohibition on nuclear use has developed in the global system, which, although not (yet) a fully robust norm, has stigmatized nuclear weapons as unacceptable weapons of mass destruction. Without this normative stigma, there might have been more “use.” This article examines this phenomenon in the context of the nuclear experience of the United States.
Transitivity
Authors: Bowers John
Published: July 2002

It is argued in this article that there is a functional category Tr (= transitivity) located between v/Pr and V, which is universally present in all transitive sentences, regardless of whether they are active, passive, middle, or impersonal in form. Tr may contain a probe with (object) φ-features and assign accusative Case. In contrast to v/Pr, Tr does not assign a θ-role in its specifier position. Hence, the functions of the traditional light verb category “v” are split between v/Pr and Tr. Empirical evidence from English, Russian, Scottish Gaelic, Icelandic, Ukrainian, and German supports this claim.
Common and Distinct Neural Substrates for Pragmatic, Semantic, and Syntactic Processing of Spoken Sentences: An fMRI Study
Authors: Kuperberg G. R. , McGuire P. K. , Bullmore E. T. , Brammer M. J. , Rabe-Hesketh S. , Wright I. C. , Lythgoe D. J. , Williams S. C. R. , David A. S.
Published: July 2002

Extracting meaning from speech requires the use of pragmatic, semantic, and syntactic information. A central question is: Does the processing of these different types of linguistic information have common or distinct neuroanatomical substrates? We addressed this issue using functional magnetic resonance imaging (fMRI) to measure neural activity when subjects listened to spoken normal sentences contrasted with sentences that had either (A) pragmatical, (B) semantic (selection restriction), or (C) syntactic (subcategorical) violations sentences. All three contrasts revealed robust activation of the left-inferior-temporal/fusiform gyrus. Activity in this area was also observed in a combined analysis of all three experiments, suggesting that it was modulated by all three types of linguistic violation. Planned statistical comparisons between the three experiments revealed (1) a greater difference between conditions in activation of the left-superior-temporal gyrus for the pragmatic experiment than the semantic/syntactic experiments; (2) a greater difference between conditions in activation of the right-superior and middletemporal gyrus in the semantic experiment than in the syntactic experiment; and (3) no regions activated to a greater degree in the syntactic experiment than in the semantic experiment. These data show that, while left- and right-superior-temporal regions may be differentially involved in processing pragmatic and lexico-semantic information within sentences, the left-inferior-temporal/fusiform gyrus is involved in processing all three types of linguistic information. We suggest that this region may play a key role in using pragmatic, semantic (selection restriction), and subcategorical information to construct a higher representation of meaning of sentences.
fMRI Evidence for Dual Routes to the Mental Lexicon in Visual Word Recognition
Authors: Fiebach Christian J. , Friederici Angela D. , Müller Karsten , Cramon D. Yves von
Published: July 2002

Event-related fMRI was used to investigate lexical decisions to words of high and low frequency of occurrence and to pseudowords. The results obtained strongly support dual-route models of visual word processing. By contrasting words with pseudowords, bilateral occipito-temporal brain areas and posterior left middle temporal gyrus (MTG) were identified as contributing to the successful mapping of orthographic percepts onto visual word form representations. Low-frequency words and pseudowords elicited greater activations than high-frequency words in the superior pars opercularis [Brodmann's area (BA) 44] of the left inferior frontal gyrus (IFG), in the anterior insula, and in the thalamus and caudate nucleus. As processing of these stimuli during lexical search is known to rely on phonological information, it is concluded that these brain regions are involved in grapheme-to-phoneme conversion. Activation in the pars triangularis (BA 45) of the left IFG was observed only for low-frequency words. It is proposed that this region is involved in processes of lexical selection.
Domain-Specific Knowledge Systems in the Brain: The Animate-Inanimate Distinction
Authors: Caramazza Alfonso , Shelton Jennifer R.
Published: July 2002

We claim that the animate and inanimate conceptual categories represent evolutionarily adapted domain-specific knowledge systems that are subserved by distinct neural mechanisms, thereby allowing for their selective impairment in conditions of brain damage. On this view, (some of) the category-specific deficits that have recently been reported in the cognitive neuropsychological literature—for example, the selective damage or sparing of knowledge about animals—are truly categorical effects. Here, we articulate and defend this thesis against the dominant, reductionist theory of category-specific deficits, which holds that the categorical nature of the deficits is the result of selective damage to noncategorically organized visual or functional semantic subsystems. On the latter view, the sensory/functional dimension provides the fundamental organizing principle of the semantic system. Since, according to the latter theory, sensory and functional properties are differentially important in determining the meaning of the members of different semantic categories, selective damage to the visual or the functional semantic subsystem will result in a category-like deficit. A review of the literature and the results of a new case of category-specific deficit will show that the domain-specific knowledge framework provides a better account of category-specific deficits than the sensory/functional dichotomy theory.
Combined 5 × 2 cv F Test for Comparing Supervised Classification Learning Algorithms
Authors: Alpaydm Ethem
Published: July 2002

Dietterich (1998) reviews five statistical tests and proposes the 5 × 2 cvt test for determining whether there is a significant difference between the error rates of two classifiers. In our experiments, we noticed that the 5 × 2 cvt test result may vary depending on factors that should not affect the test, and we propose a variant, the combined 5 × 2 cv F test, that combines multiple statistics to get a more robust test. Simulation results show that this combined version of the test has lower type I error and higher power than 5 × 2 cv proper.
Small-Group Behavior in a Virtual and Real Environment: A Comparative Study
Authors: Slater Mel , Sadagic Amela , Usoh Martin , Schroeder Ralph
Published: July 2002

This paper describes an experiment that compares behavior in small groups when its members carry out a task in a virtual environment (VE) and then continue the same task in a similar, real-world environment. The purpose of the experiment was not to examine task performance, but to compare various aspects of the social relations among the group members in the two environments. Ten groups of three people each, who had never met before, met first in a shared VE and carried out a task that required the identification and solution of puzzles that were presented on pieces of paper displayed around the walls of a room. The puzzle involved identifying that the same-numbered words across all the pieces of paper formed a riddle or saying. The group continued this task for fifteen minutes, and then stopped to answer a questionnaire. The group then reconvened in the real world and continued the same task. The experiment also required one of the group members to continually monitor a particular one of the others in order to examine whether social discomfort could be generated within a VE. In each group, there was one immersed person with a head-mounted display and head-tracking and two non-immersed people who experienced the environment on a workstation display. The results suggest that the immersed person tended to emerge as the leader in the virtual group, but not in the real meeting. Group accord tended to be higher in the real meeting than in the virtual meeting. Socially conditioned responses such as embarrassment could be generated in the virtual meeting, even though the individuals were presented to one another by very simple avatars. The study also found a positive relationship between presence of being in a place and copresence—the sense of being with the other people. Accord in the group increased with presence, the performance of the group, and the presence of women in the group. The study is seen as part of a much larger planned study, for which this experiment was used to begin to understand the issues involved in comparing real and virtual meetings.
Using the “VREye” System for the Assessment of Unilateral Visual Neglect: Two Case Reports
Authors: Gupta Vineet , Knott Benjamin A. , Kodgi Santosh , Lathan Corinna E.
Published: July 2002

Unilateral visual neglect (UVN) is the inability of patients, with damage to their left or right cerebral hemisphere, to respond to stimuli presented on the side opposite the lesion. We present a preliminary study on using a HMD-based-eye-tracking system for the assessment of UVN. Normal subjects and patients with UVN were shown two virtual environment (VE) scenes. The subjects were required to identify and count the objects in scene 1, and to identify a clock and tell the time in scene 2. Eye movements of these subjects were recorded during the task. There were differences in the amount of visual field scanned by the subjects and patients. The normal subjects scanned the entire scene and identified all the objects. Patients with left UVN did not scan the left side of the scene and did not report objects on that side. Patients with right UVN scanned only the left side of the scene and did not report objects on the right side of the scene. This study demonstrates the feasibility of using the HMD-based eye-tracking system in a virtual environment for characterizing UVN.
A Virtual Presence Counter
Authors: Slater Mel , Steed Anthony
Published: July 2002

This paper describes a new measure for presence in immersive virtual environments (VEs) that is based on data that can be unobtrusively obtained during the course of a VE experience. At different times during an experience, a participant will occasionally switch between interpreting the totality of sensory inputs as forming the VE or the real world. The number of transitions from virtual to real is counted, and, using some simplifying assumptions, a probabilistic Markov chain model can be constructed to model these transitions. This model can be used to estimate the equilibrium probability of being “present” in the VE. This technique was applied in the context of an experiment to assess the relationship between presence and body movement in an immersive VE. The movement was that required by subjects to reach out and touch successive pieces on a three-dimensional chess board. The experiment included twenty subjects, ten of whom had to reach out to touch the chess pieces (the active group) and ten of whom only had to click a handheld mouse button (the control group). The results revealed a significant positive association in the active group between body movement and presence. The results lend support to interaction paradigms that are based on maximizing the match between sensory data and proprioception.
An Introduction to 3-D User Interface Design
Authors: Bowman Doug A. , Kruijff Ernst , LaViola Joseph J. , Poupyrev Ivan
Published: July 2002

Three-dimensional user interface design is a critical component of any virtual environment (VE) application. In this paper, we present a broad overview of 3-D interaction and user interfaces. We discuss the effect of common VE hardware devices on user interaction, as well as interaction techniques for generic 3-D tasks and the use of traditional 2-D interaction styles in 3-D environments. We divide most user-interaction tasks into three categories: navigation, selection/manipulation, and system control. Throughout the paper, our focus is on presenting not only the available techniques but also practical guidelines for 3-D interaction design and widely held myths. Finally, we briefly discuss two approaches to 3-D interaction design and some example applications with complex 3-D interaction requirements. We also present an annotated online bibliography as a reference companion to this article.
Identification of Meloidogyne incognita, M. javanica and M. arenaria using sequence characterised amplified region (SCAR) based PCR assays
Authors: Donkers-Venne Dorine T.H.M. , Fargette Mireille , Zijlstra Carolien
Published: July 2002

Three randomly amplified polymorphic DNA (RAPD) markers, OPA-12420, OPB-061200 and OPA-01700, species specific to the root-knot nematode species Meloidogyne arenaria, M. incognita and M. javanica respectively, were identified. After sequencing these RAPD-PCR products, longer primers of 18 to 23 nucleotides were designed to complement the terminal DNA sequences of the DNA fragments. This resulted in three pairs of species specific primers that were used to amplify the sequence characterised amplified regions (SCARs). The developed sets of SCAR primers were successfully used in straightforward, fast and reliable PCR assays to identify M. incognita, M. javanica and M. arenaria. The length variant SCAR markers can be amplified from DNA from egg masses, second stage juveniles and females. This species identification technique is therefore independent of the nematode's life cycle stage. Moreover the SCAR-PCR assay was successfully applied using DNA extracts from infested plant material. The method has potential to be optimised for routine practical diagnostic tests facilitating the control of these economically important pest organisms. Identification de Meloigyne incognita, M. javanica et M. arenaria au moyen de l'amplification de régions de séquences caractéristiques (SCAR) par une technique PCR - Trois marqueurs d'ADN polymorphique amplifiée au hasard (RAPD) OPA-12420, OPB-O61200 et OPA-OI700, respectivement spécifiques des espèces de nématodes Meloidogyne arenaria, M. incognita et M. javanica, ont été identifiés. Après le séquençage de ces produits RAPD-PCR, les amorces les plus longues de 18 à 23 nucléotides ont été choisies pour compléter les séquences terminales d'ADN des fragments d'ADN. Cela a conduit à trois paires d'amorces spécifiques de l'espèce, utilisées pour amplifier les régions des séquences caractéristiques (SCAR). Les lots d'amorces SCAR mis au point ont été utilisés avec succès lors d'essais directs, rapides et surs pour identifier M. incognita, M. javanica et M. arenia. Les marqueurs peuvent être amplifiés à partir de l'ADN des masses d'oeufs, des juvéniles de deuxième stade ou des femelles. Cette technique d'identification spécifique est donc indépendante des différents états de développement du nématode. De plus la technique SCAR-PCR a été appliquée avec succès à l'ADN extrait du matériel végétal infesté. Cette méthode présente des potentialités d'amélioration permettant d'envisager des tests pratiques d'identification de routine, facilitant ainsi le contrôle de ces parasites économiquement importants.
Occurrence and distribution of entomopathogenic nematodes in the Slovak Republic
Authors: Sturhan Dieter , Liskova Marta
Published: July 2002

Infective-stage juveniles of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis were recovered by direct extraction from 36% of a total of 111 soil samples collected in various biotopes from different regions of Slovakia. The rate of prevalence was highest in forest soil (58%). On the basis of morphological characters of the infective juveniles eight Steinernema and one Heterorhabditis species were distinguished. Steinernema affine, S. intermedium and S. feltiae were most prevalent (together 74% of all records). The other species of Steinernema encountered were S. kraussei, S. carpocapsae, S. bicornutum, a species of the S. glaseri group and an undescribed species earlier recorded from Germany. In 11 of the 40 soil samples positive for entomopathogenic nematodes mixtures of two to four species were present. Several species showed a distinct habitat preference, e.g., S. affine for arable soil and S. intermedium for woodland and river bank vegetation with trees. A preference for certain soil types was less apparent. Untersuchungen uber Vorkommen und Verbreitung entomopathogener Nematoden in der Slowakischen Republik - Insgesamt 111 Bodenproben, die in unterschiedlichen Biotopen aus verschiedenen Regionen der Slowakei entnommen worden waren, wurden auf entomopathogene Nematoden untersucht. Infektionsjuvenile der Gattungen Steinernema und Heterorhabditis waren uber eine direkte Extraktion der Nematoden aus dem Boden in 36% aller Proben nachweisbar. Der hochste Anteil "positiver" Proben fand sich bei Proben aus Waldern (58%). Anhand morphologischer Merkmale der Infektionsjuvenilen waren acht Steinernema Arten und eine Heterorhabditis-Art differenzierbar. Steinernema affine, S. intermedium und S. feltiae waren die haufigsten Arten (insgesamt 74% aller Nachweise). S. kraussei, S. carpocapsae, S. bicornutum, eine Steinernema-Art der S. glaseri-Gruppe und eine noch unbeschriebene Steinernema-Art (bereits aus Deutschland bekannt) und Heterorhabditis sp. wurden seltener gefunden. In 11 aller 40 "positiven" Proben kamen zwei bis vier Arten nebeneinander vor. Einige der Arten zeigten eine deutliche Bevorzugung bestimmter Biotoptypen, so S. affine von Acker- und Gartenboden und S. intermedium von Waldern und Ufervegetation mit Baumen. Eine Bevorzugung bestimmter Bodenarten war dagegen kaum erkennbar.
Age, origin and climatic signal of English Mesozoic clays based on K/Ar signatures
Authors: Jeans C. V. , Mitchell J. G. , Fisher M. J. , Wray D. S. , Hall I. R.
Published: July 2002

The K/Ar characteristics of 53 clay assemblages (Triassic–Cretaceous), representing the detrital, volcanogenic and arid-facies clay mineral associations, are interpreted in relation to their mineralogy, chronostratic age and geological origins. The K-bearing mineral components of the 1–2 μm, 0.2–1 μm and <0.2 μm fractions of each clay assemblage together display one of two characteristic patterns of K2O and 40Ar values (the K/Ar signature of the assemblage) on a 40Ar/K2O correlation diagram. Interpretation of the K/Ar signatures indicates that: (1) all of these clay assemblages are apparently unaffected by burial diagenetic illitization; (2) the Jurassic and Cretaceous detrital clay assemblages are derived from the reworking of weathered Caledonian metasediments (420 500 Ma) and weathered kaolin-bearing sediments of Upper Devonian/ Carboniferous age; and (3) the role played by palaeoclimate in developing the pattern of clay minerals in the Mesozoic sediments of England is much less significant than previously believed.
Pseudomorphous transformation of goethite needles into hematite in sediments of the Triassic Skagerrak Formation, Denmark
Authors: Weibel R. , Grobety B.
Published: July 2002

Van Houten (1973), Walker (1976) and Turner (1980) have documented the authigenic origin of red coatings in continental red beds. Pigmentary hematite, ferrihydrite, goethite and clay-associated Fe-oxide crystallites have been suggested as the principal colouring agents of continental red beds (Walker, 1968, 1976; Walker & Honea, 1969; Larson & Walker, 1975; Turner, 1980; Fine, 1986, Besly et al., 1993). The red pigment in most Mesozoic red beds consists of hematite, whereas ferrihydrite and goethite are more common in younger sediments (van Houten, 1973). This has led several authors to the assumption that poorly crystalline Fe-oxides/hydroxides age into hematite (Walker, 1968, 1976; Walker & Honea, 1969; Larson & Walker, 1975; Turner, 1980).
Interpretations of SHRIMP and isotope dilution zircon ages for the geological time-scale: I. The early Ordovician and late Cambrian
Authors: Compston W.
Published: July 2002

Ion probe data for zircons from tuffs within the Llfynant flags (Arenig) and the Serw Formation (lower Llanvirn) of north Wales have been revised using better statistical methods for separating detrital ages, making allowance for recently-found variability in radiogenic 206Pb/238U in the reference zircon SL13, and testing the sensitivity of the ages to the secondary ion discrimination slope. The revised ages are options of 469.2 ± 2.1 (σ) or 472.9 ± 2.9 Ma for the Llfynant flags dependent on mixture modelling, and 465.3 ± 1.4 Ma for the Serw Formation. All ages are within error of previous SHRIMP results and the Serw age now has the same numerical value as a previous MSID age for the same sample. It is shown that an MSID age of 483 ± 0.5 Ma with interpreted Pb loss for a late Tremadoc bentonite is dependent on the correction for common Pb, and that a slightly more radiogenic choice for the common Pb composition places nearly all data on Concordia. The latter would indicate that the bentonite might contain two zircon populations: inherited grains at 482 Ma and tuff magmatic grains at 473 Ma, which is more compatible with the SHRIMP Arenig result. Interpretations of other MSID zircon ages from the Ordovician are also sensitive to choice of common Pb, and raise the likelihood that many multigrain ages might be too old owing to admixture with slightly older inherited zircon. A supposed 1–2% technical bias of SHRIMP 206Pb/238U ages relative to MSID is refuted.
Cathodoluminescence (CL) behaviour and crystal chemistry of apatite from rare-metal deposits
Authors: Kempe U. , Götze J.
Published: July 2002

Apatite samples from rare-metal mineralization were investigated by a combination of cathodoluminescence (CL) microscopy and spectroscopy, microchemical analysis and trace element analysis. Internal structures revealed by CL can be related to variations in the crystal chemistry and may sometimes reflect changes in the composition of the mineralizing fluids.

Apatite from mineralization related to alkaline rocks and carbonatites (Type 1) typically exhibits relatively homogeneous blue and lilac/violet CL colours due to activation by trace quantities of rare earth element ions (Ce3+, Eu2+, Sm3+, Dy3+ and Nd3+). These results correlate with determined trace element abundances, which show strong light rare earth element (LREE) enrichment for this type of apatite. However, a simple quantitative correlation between emission intensities of REE3+/2+ and analysed element concentrations was not found.

Apatite from P-rich altered granites, greisens, pegmatites and veins from Sn-W deposits (Type 2) shows strong Mn2+-activated yellow-greenish CL, partially with distinct oscillatory zoning. Variations in the intensity of the Mn2+-activated CL emission can be related either to varying Mn/Fe ratios (quenching of Mn activated CL by Fe) or to self-quenching effects in zones with high Mn contents (>2.0 wt.%). The REE distribution patterns of apatite reflect the specific geological position of each sample and may serve as a “tracer” for the REE behaviour within the ore system. Although the REE contents are sometimes as high as several hundred parts per million, the spectral CL measurements do not exhibit typical REE emission lines because of dominance of the Mn emission. In these samples, REE-activated luminescence is only detectable by time-resolved laser-induced luminescence spectroscopy.

Both types of apatite (Type 1 in the core and Type 2 in the rim) were found in single crystals from the Be deposit Ermakovka (Transbaikalia). This finding proves the existence of two stages of mineralization within this deposit.
Highly efficient gene delivery by mRNA electroporation in human hematopoietic cells: superiority to lipofection and passive pulsing of mRNA and to electroporation of plasmid cDNA for tumor antigen loading of dendritic cells
Authors: Van Tendeloo Viggo F. I. , Ponsaerts Peter , Lardon Filip , Nijs Griet , Lenjou Marc , Van Broeckhoven Christine , Van Bockstaele Dirk R. , Berneman Zwi N.
Published: July 2002

Designing effective strategies to load human dendritic cells (DCs) with tumor antigens is a challenging approach for DC-based tumor vaccines. Here, a cytoplasmic expression system based on mRNA electroporation to efficiently introduce tumor antigens into DCs is described. Preliminary experiments in K562 cells using an enhanced green fluorescent protein (EGFP) reporter gene revealed that mRNA electroporation as compared with plasmid DNA electroporation showed a markedly improved transfection efficiency (89% versus 40% EGFP+ cells, respectively) and induced a strikingly lower cell toxicity (15% death rate with mRNA versus 51% with plasmid DNA). Next, mRNA electroporation was applied for nonviral transfection of different types of human DCs, including monocyte-derived DCs (Mo-DCs), CD34+ progenitor-derived DCs (34-DCs) and Langerhans cells (34-LCs). High-level transgene expression by mRNA electroporation was obtained in more than 50% of all DC types. mRNA-electroporated DCs retained their phenotype and maturational potential. Importantly, DCs electroporated with mRNA-encoding Melan-A strongly activated a Melan-A–specific cytotoxic T lymphocyte (CTL) clone in an HLA-restricted manner and were superior to mRNA-lipofected or -pulsed DCs. Optimal stimulation of the CTL occurred when Mo-DCs underwent maturation following mRNA transfection. Strikingly, a nonspecific stimulation of CTL was observed when DCs were transfected with plasmid DNA. The data clearly demonstrate that Mo-DCs electroporated with mRNA efficiently present functional antigenic peptides to cytotoxic T cells. Therefore, electroporation of mRNA-encoding tumor antigens is a powerful technique to charge human dendritic cells with tumor antigens and could serve applications in future DC-based tumor vaccines.
Recurrent inversion breaking intron 1 of the factor VIII gene is a frequent cause of severe hemophilia A
Authors: Bagnall Richard D. , Waseem Naushin , Green Peter M. , Giannelli Francesco
Published: July 2002

The messenger RNA (mRNA) from 5 of 69 patients with severe hemophilia A did not support amplification of complementary DNA containing the first few exons of the factor VIII (F8) gene but supported amplification of mRNA containing exon 1 ofF8 plus exons of the VBP1 gene. This chimeric mRNA signals an inversion breaking intron 1 of the F8 gene. Using an inversion patient, one deleted for F8 exons 1 to 6, and cosmids mapped 70 to 100 kb telomeric of the F8gene, this study shows that this break strictly affects a sequence (int1h-1) repeated (int1h-2) about 140 kb more telomerically, between the C6.1A andVBP1 genes. The 1041-base pair repeats differ at a single nucleotide (although int1h-2 also showed one polymorphism) and are in opposite orientation. The results demonstrate that they cause inversions by intrachromosome or intrachromatid homologous recombination. The genomic structure of the inversion region shows that transcription traverses intergenic spaces to produce the 2 chimeric mRNAs containing the F8 sequences and characteristic of the inversion. This observation prompts the suggestion that nature may use such extended transcription to test whether the addition of novel domains from neighboring genes creates desirable new genes. A rapid polymerase chain reaction test was developed for the inversion in both patients and carriers. This has identified 10 inversions, affectingF8 genes with 5 different haplotypes for the BclI, introns 13 and 22 VNTR polymorphism, among 209 unrelated families with severe hemophilia A. This indicates a prevalence of 4.8% and frequent recurrence of the inversion. This should result in absence ofF8, and one inversion patient is known to have inhibitors.
Cell surface proteoglycan syndecan-1 mediates hepatocyte growth factor binding and promotes Met signaling in multiple myeloma
Authors: Derksen Patrick W. B. , Keehnen Robert M. J. , Evers Ludo M. , van Oers Marinus H. J. , Spaargaren Marcel , Pals Steven T.
Published: July 2002

Heparan sulfate proteoglycans (HSPGs) play a crucial role in growth regulation by assembling signaling complexes and presenting growth factors to their cognate receptors. Within the immune system, expression of the HSPG syndecan-1 (CD138) is characteristic of terminally differentiated B cells, ie, plasma cells, and their malignant counterpart, multiple myeloma (MM). This study explored the hypothesis that syndecan-1 might promote growth factor signaling and tumor growth in MM. For this purpose, the interaction was studied between syndecan-1 and hepatocyte growth factor (HGF), a putative paracrine and autocrine regulator of MM growth. The study demonstrates that syndecan-1 is capable of binding HGF and that this growth factor is indeed a potent stimulator of MM survival and proliferation. Importantly, the interaction of HGF with heparan sulfate moieties on syndecan-1 strongly promotes HGF-mediated signaling, resulting in enhanced activation of Met, the receptor tyrosine kinase for HGF. Moreover, HGF binding to syndecan-1 promotes activation of the phosphatidylinositol 3-kinase/protein kinase B and RAS/mitogen-activated protein kinase pathways, signaling routes that have been implicated in the regulation of cell survival and proliferation, respectively. These results identify syndecan-1 as a functional coreceptor for HGF that promotes HGF/Met signaling in MM cells, thus suggesting a novel function for syndecan-1 in MM tumorigenesis.
Structural uncertainties: Determination, management, and applications
Authors: Thore Pierre , Shtuka Arben , Lecour Magali , Ait‐Ettajer Taoufik , Cognot Richard
Published: July 2002

Structural uncertainties have a direct impact in exploration, development, and production, and in drilling decisions. In this paper, we present an approach for determining and handling structural uncertainties. We first examine the magnitude of the different sources of uncertainty, and explain how to estimate their direction and correlation length. This task requires a huge geophysical input. This information is then used in a general scheme to generate multiple realizations of the structural model consistent with structural uncertainties. The technique is based on geostatistical concepts. Finally, we illustrate the application of this scheme in examples relevant for exploration, development and production, and drilling.

The structural model is described as a set of horizons represented by triangulated surfaces cut by faults. The relationships between horizons and faults are expressed as a set of constraints. On a horizon, each source of uncertainty (typically migration, picking, and time‐to‐depth conversion) is described as a field of vectors with its magnitude, direction, and correlation length expressed in terms of a variogram. A special fault object has been developed to aid in discribing the faults as probabilistic objects in a very simple way. Once all sources of uncertainty have been quantified many equiprobable realizations of the structural model are generated. For this, we use a special implementation of the probability field technique adapted to triangulated surfaces that handles correlation between horizons. At each realization, faults and horizons are moved in three dimensions according to uncertainties. Links between faults and horizons are maintained. Such complex 3‐D modeling can only be achieved in the frame of a geomodeler. Finally, we propose three types of applications requiring structural uncertainty determination:rock volume distribution, well trajectory optimization and risk analysis, and the use of structural uncertainty as a parameter for history matching.

Our scheme generates many equiprobable realizations of the structural model provided that each source of uncertainty has been described in terms of magnitude direction and correlation length. These realizations may then be used to quantify risk in exploration development and drilling.
Randomized Controlled Trial of Azacitidine in Patients With the Myelodysplastic Syndrome: A Study of the Cancer and Leukemia Group B
Authors: Silverman Lewis R. , Demakos Erin P. , Peterson Bercedis L. , Kornblith Alice B. , Holland Jimmie C. , Odchimar-Reissig Rosalie , Stone Richard M. , Nelson Douglas , Powell Bayard L. , DeCastro Carlos M. , Ellerton John , Larson Richard A. , Schiffer Charles A. , Holland James F.
Published: July 2002

PURPOSE: Patients with high-risk myelodysplastic syndrome (MDS) have high mortality from bone marrow failure or transformation to acute leukemia. Supportive care is standard therapy. We previously reported that azacitidine (Aza C) was active in patients with high-risk MDS.

PATIENTS AND METHODS: A randomized controlled trial was undertaken in 191 patients with MDS to compare Aza C (75 mg/m2/d subcutaneously for 7 days every 28 days) with supportive care. MDS was defined by French-American-British criteria. New rigorous response criteria were applied. Both arms received transfusions and antibiotics as required. Patients in the supportive care arm whose disease worsened were permitted to cross over to Aza C.

RESULTS: Responses occurred in 60% of patients on the Aza C arm (7% complete response, 16% partial response, 37% improved) compared with 5% (improved) receiving supportive care (P < .001). Median time to leukemic transformation or death was 21 months for Aza C versus 13 months for supportive care (P = .007). Transformation to acute myelogenous leukemia occurred as the first event in 15% of patients on the Aza C arm and in 38% receiving supportive care (P = .001). Eliminating the confounding effect of early cross-over to Aza C, a landmark analysis after 6 months showed median survival of an additional 18 months for Aza C and 11 months for supportive care (P = .03). Quality-of-life assessment found significant major advantages in physical function, symptoms, and psychological state for patients initially randomized to Aza C.

CONCLUSION: Aza C treatment results in significantly higher response rates, improved quality of life, reduced risk of leukemic transformation, and improved survival compared with supportive care. Aza C provides a new treatment option that is superior to supportive care for patients with the MDS subtypes and specific entry criteria treated in this study.
Modifications du renouvellement de l'amp final du tRNA dans le foie de rat sous l'influence de divers inhibiteurs de synthese
Authors: Moulé Y. , Landin R.M.
Published: July 2002

The turnover of terminal AMP of rat liver tRNA relative to that of internal AMP was studied in presence of various inhibitors. Actinomycin D and aflatoxin B1, which strongly depress transcription in liver, lead to an increase of the specific radioactivity of external AMP/specific radioactivity of internal AMP ratio. On the contrary, drugs which inhibit the in vivo incorporation of aminoacids determine a significant decrease of this ratio.
Solubilization of the membrane bound lactose specific component of the staphylococcal PEP dependant phosphotransferase system
Authors: Hengstenberg W.
Published: July 2002

The membrane bound lactose specific component of the PEP dependant phosphotransferase system of Staphylococcus aureus has been solubilized using the non ionic detergent Triton X‐100. Some properties of the crude soluble enzyme are reported.
Presence d'enzymes marqueurs des membranes plasmiques, de l'appareil de golgi et du reticulum endoplasmique dans les membranes des globules lipidiques de lait maternel
Authors: Martel-Pradal M.B. , Got R.
Published: July 2002

We report here the presence in human milk fat globules membranes of 5′‐nucleotidase, Na+‐K+ and Mg2+ ATPases, and phosphodiesterase which are marker enzymes for the plasma membrane. Thiamine‐pyrophosphatase, lactose and lactosamine synthetase were also found, which are usually considered as Golgi apparatus marker enzymes. Lastly, glucose‐6‐phosphatase, NADH‐cytochromec reductase and RNase, characteristic enzymes of the endoplasmic membrane, were also present.
Activation of phosphodiesterase by chicken iodopsin
Authors: Fukada Yoshitaka , Yoshizawa Tôru
Published: July 2002

Activation of guanosine 3′,5′‐cyclic monophosphate phosphodiesterase in outer‐segment membrane of chicken retina was investigated. Irradiation of dark‐adapted chicken outer segment membrane for bleaching of iodopsin increased the enzyme activity twice as much as that in the dark in the presence of GTP. Further irradiation of the sample for bleaching of rhodopsin in the membrane induced some additional activation of the enzyme. However, chicken iodopsin activated the enzyme in frog rod outer segment membrane without irradiation, while chicken rhodopsin did not. Irradiation of chicken iodopsin increased the enzyme activity twice as much as that in the dark.
Hb F Kingston (Gγ55 [D6] Met→Arg)
Authors: Serjeant G.R. , Serjeant Beryl E. , Lehmann H. , Dukes Monica , Robb Laurene
Published: July 2002

A fetal haemoglobin variant was noted in a healthy Jamaican infant of mixed African/Chinese extraction. A two‐dimensional chromatogram of the soluble tryptic peptides (Tp) showed 2 ‘new’ ones/ One was composed of the last 4 residues of the usually insoluble Tpγ41–59. To permit a tryptic split this required a change of residue γ55 Met to Lys or Arg. The other new Tp contained arginine and was in the position expected for a Tpγ41–55 (55 Arg). As the material was limited it could not be analysed. When after more than 6 years no example of Hb F Kingston had become available it was decided to describe the variant on the basis of the present evidence.
Demonstration of a main immunogenic region on acetylcholine receptors from human muscle using monoclonal antibodies to human receptor
Authors: Tzartos Socrates , Langeberg Lorene , Hochschwender Susan , Lindstrom Jon
Published: July 2002

Eleven cloned hybridomas which secrete antibodies to acetylcholine receptors from human muscle have been prepared. All of these monoclonal antibodies to have the same basic specificity as shown by competition for binding to the main immunogenic region on the receptor, but these antibodies differ in fine specificity as shown by reaction with denatured receptor subunits and interspecies cross‐reaction.
[125I]Iodonaphtylazide labeling selectively a cysteine residue in the F0 of the ATP‐synthase from E. coli is unsuitable for topographic studies of membrane proteins
Authors: Hoppe J. , Friedl P. , Jørgensen B.B
Published: July 2002

The ATP synthase from E. coli was reacted with the hydrophobic photolabel [125I]iodonaphtylazide. Subunit b in the F0‐part was selectively labelled. Label was traced back to the single cysteine21 in subunit b. Thus the reactive intermediate of INA generated by photolysis had a high preference for nucleophiles. Due to this high selectivity the detection of membrane spanning peptide segments by labelling with INA is not reliable.
A molecular model for the bilayer helices of the acetylcholine receptor including an acetylcholine binding site
Authors: Kosower Edward M.
Published: July 2002

A molecular model for the bilayer helices of the acetylcholine receptor is constructed from the 7 channel elements and the 17 hydrophobic helices of the 5 protein subunits. The acetylcholine binding site and the opening to the ion channel are included.
The complete amino‐acid sequence of anglerfish somatostatin‐28 II
Authors: Morel Alain , Chang Jui-Yoa , Cohen Paul
Published: July 2002

A new somatostatin‐28 has been isolated from the Teleostean fish (Lophius piscatorius) Brockmann organs. Determination of its aminoacid sequence indicates that it corresponds to an octacosapeptide containing in its C‐terminal end the Tyr‐7 Gly‐10 derivative of somatostatin‐14 I. This structure is in agreement with the one predicted by Hobart et al. (Nature (1980) 288, 137‐141) from a cDNA nucleotide sequence. It demonstrates that, since the corresponding somatostatin‐14 II cannot be detected in this organ, S‐28 II is a terminal product of prosomatostatin II processing in anglerfish pancreatic islets.
Human serum contains a lectin which inhibits hepatic uptake of glycoproteins
Authors: Taylor Maureen E. , Summerfield John A.
Published: July 2002

Human serum will inhibit the specific uptake of N‐acetylglucosamine‐terminated glycoproteins by isolated rat hepatic sinusoidal cells. The serum inhibitors are not glycoproteins that bind to the hepatic mannose/N‐acetylglucosamine receptor but have the properties of lectins which bind to mannose/N‐acetylglucosamine‐terminated glycoproteins. They can be isolated from serum by affinity chromatography. The predominant lectin, with a molecular mass of less than 35 kDa, will inhibit the sinusoidal cell uptake of glycoproteins in vitro.
40 S subunits from rat liver ribosomes contain two codon‐dependent sites for transfer RNA
Authors: Semenkov Yu.P. , Kirillov S.V. , Stahl J.
Published: July 2002

40 S subunits from rat liver ribosomes are able to bind, after heat activation, two molecules of either Phe‐tRNAphe, Ac‐Phe‐tRNAphe or deacylated tRNAphe. Addition of 60 S subunits to the quaternary complex 40 S·poly(U)·(Phe‐tRNAphe)2 results in quantitative formation of (Phe)2‐tRNAphe. This indicates that the two binding sites for tRNA on 40 S subunits should be considered as the constituent of P and A sites of 80 S ribosomes.
The specificity and kinetic properties of trypsin ethylated at the binding site
Authors: Ben Avraham Ruth , Shalitin Yechiel
Published: July 2002

Treatment of trypsin with triethyloxonium tetrafluoroborate at pH 8, 25 °C, results in abolition of binding to the enzyme of specific cationic substrates and inhibitors. The binding constant of soybean trypsin inhibitor to ethylated trypsin is 10000‐fold smaller than to intact trypsin. However, the intrinsic ability of trypsin to recognize and react with nonspecific neutral substrates and inhibitors is not lost, and in several cases even considerably enhanced. Thus ethylated trypsin (Tret) resembles chymotrypsin in its behavior. Trypsin‐like enzymes are also affected in a similar manner.
Effect of drugs, peptide hormones and lipogenic precursors on the relative incorporation of [3H]H2O and carbon into hepatic cholesterol
Authors: Björnsson O.G. , Pullinger C.R. , Gibbons G.F.
Published: July 2002

Measurement of the weight of desmosterol produced during its biosynthesis in the presence of tritiated water and triparanol has permitted a direct determination of the relative flux of carbon and tritium (the H/C ratio) into sterol in hepatocytes. The H/C ratio increased with time of incubation irrespective of the nutritional state of the donor animals. This increase was more marked in hepatocytes from starved animals. Pyruvate and lactate increased, and glucagon decreased, the sterol H/C ratio. Addition of pyruvate to incubations containing glucagon resulted in a 32–67% increase in the H/C ratio depending upon nutritional status. Insulin had no effect whilst (−)‐hydroxycitrate decreased the ratio by 25%.