bluuebunny/crossref_metadata_2025 huggingface dataset:
An approach to electrical modeling of single and multiple cells
Authors: Gowrishankar Thiruvallur R. , Weaver James C.
Published: March 2003

Previous theoretical approaches to understanding effects of electric fields on cells have used partial differential equations such as Laplace's equation and cell models with simple shapes. Here we describe a transport lattice method illustrated by a didactic multicellular system model with irregular shapes. Each elementary membrane region includes local models for passive membrane resistance and capacitance, nonlinear active sources of the resting potential, and a hysteretic model of electroporation. Field amplification through current or voltage concentration changes with frequency, exhibiting significant spatial heterogeneity until the microwave range is reached, where cellular structure becomes almost “electrically invisible.” In the time domain, membrane electroporation exhibits significant heterogeneity but occurs mostly at invaginations and cell layers with tight junctions. Such results involve emergent behavior and emphasize the importance of using multicellular models for understanding tissue-level electric field effects in higher organisms.
The topoisomerase IIβ circular clamp arrests transcription and signals a 26S proteasome pathway
Authors: Xiao Hai , Mao Yong , Desai Shyamal D. , Zhou Nai , Ting Chun-Yuan , Hwang Jaulang , Liu Leroy F.
Published: March 2003

It has been proposed that the topoisomerase II (TOP2)β–DNA covalent complex arrests transcription and triggers 26S proteasome-mediated degradation of TOP2β. It is unclear whether the initial trigger for proteasomal degradation is due to DNA damage or transcriptional arrest. In the current study we show that the TOP2 catalytic inhibitor 4,4-(2,3-butanediyl)-bis(2,6-piperazinedione) (ICRF-193), which traps TOP2 into a circular clamp rather than the TOP2–DNA covalent complex, can also arrest transcription. Arrest of transcription, which is TOP2β-dependent, is accompanied by proteasomal degradation of TOP2β. Different from TOP2 poisons and other DNA-damaging agents, ICRF-193 did not induce proteasomal degradation of the large subunit of RNA polymerase II. These results suggest that proteasomal degradation of TOP2β induced by the TOP2–DNA covalent complex or the TOP2 circular clamp is due to transcriptional arrest but not DNA damage. By contrast, degradation of the large subunit of RNA polymerase II is due to a DNA-damage signal.
Designing surgical clothing and drapes according to the new technical standards
Authors: Abreu M.J. , Silva M.E. , Schacher L. , Adolphe D.
Published: March 2003

Hospitals will continue to be the largest consumers of disposables, because of the diverse range of procedures they provide. Favourable growth is forecast for non‐wovens. Increasing concern over contamination and nosocomial infections will boost the demand for consumable and disposable surgical gowns and drapes. But, until now neither the manufacturers nor the end users of surgical gowns and drapes could agree on standards. So, a mandatory European standard is being developed to establish basic requirements and test methods for disposable and reusable materials used for surgical gowns and drapes. Once this standard has been adopted, the continued use of cotton textiles and conventional cotton‐polyester mixed textiles will become questionable.
STABILITY OF SPATIALLY PERIODIC SOLUTIONS IN COUPLED MAP LATTICES
Authors: DUBCOVÁ M. , KLÍČ A. , POKORNÝ P. , TURZÍK D.
Published: March 2003

Stability of steady-state solutions of 1-dim coupled map lattices is studied. The stability is determined by the spectrum of linear operators on two-sided sequences of vectors in [Formula: see text] arising as a linearization of the corresponding nonlinear evolution operators. Theoretical results are applied to several examples.
SYMMETRY BREAKING EFFECTS ON EQUILIBRIA AND TIME DEPENDENT REGIMES IN ADAPTIVE LOTKA–VOLTERRA SYSTEMS
Authors: LACITIGNOLA DEBORAH , TEBALDI CLAUDIO
Published: March 2003

We study the properties of a n2-dimensional Lotka–Volterra system describing competition among n different species with adaptive skills, i.e. whose interaction coefficients are time averages of the species level of interaction over their past.

Starting by the case of adaptive competition among species all having the same carrying capacities, we focus our attention on the model obtained on perturbing the carrying capacity of a fixed species, which is made more or less disadvantaged.

We prove the existence of a certain class of invariant subspaces and introduce a seven-dimensional reduced model, where n appears as a parameter, which gives full account of existence and stability of equilibria in the system. The relevance of this reduced model to the complete one has also been found when the time dependent regimes have been investigated.

Ecologically relevant questions, i.e. species survival and the time dependent behavior of the system have also been analyzed focusing on the role of behavioral adaptation. In particular, we have found that competitive exclusion cannot occur but coexistence is possible in various forms (i.e. competitive stable equilibria and different periodic oscillations).
FURTHER INVESTIGATION ON CHAOS OF REAL DIGITAL FILTERS
Authors: LING B. W. K. , LUK F. C. K. , TAM P. K. S.
Published: March 2003

This Letter displays, via the numerical simulation of a real digital filter, that a finite-state machine may behave in a near-chaotic way even when its corresponding infinite-state machine does not exhibit chaotic behavior.
THE INVARIANT TORI FOR THE 2-MODE DAMPED, DRIVEN SINE-GORDON ODE
Authors: YU CHI-JER , LEE JONG-EAO
Published: March 2003

In this paper, we perform our algorithm developed in [Yu & Lee, 2001] to present the entire branches of quasiperiodic solutions starting from the bifurcation points in the branches of periodic solutions in an interval of parameters for the 2-mode damped, driven sine-Gordon ODE.
ATUCG — AN AGENT–BASED ENVIRONMENT FOR AUTOMATIC ANNOTATION OF GENOMES
Authors: BAZZAN ANA L. C. , DUARTE ROGÉRIO , PITINGA ABNER N. , SCHROEDER LUCIANA F. , DE A. SOUTO FARLON , DA SILVA SÉRGIO CERONI
Published: March 2003

This work reports on the ATUCG environment (Agent-based environmenT for aUtomatiC annotation of Genomes). It consists of three layers, each having several agents in charge of performing repetitive and time-consuming tasks. Layer I aims at automating the tasks behind the process of finding ORFs (Open Reading Frames). Layer II (the core of our approach) is associated with three main tasks: extraction and formatting of data, automatic annotation of data regarding profiles or families of proteins, and generation and validation of rules to automatically annotate the Keywords field in the SWISS-PROT database. Layer III permits the user to check the correctness of the automatic annotation. This environment is being designed having the sequencing of the Mycoplasma hyopneumoniae in mind. Thus examples are presented using data of organisms of the Mycoplasmataceae family. We have concentrated the developments in layer II because this is the most general one and because it focusses on machine learning algorithms, a characteristic which is not usual in annotation systems. Results regarding this layer show that with learning (individual or colaborative), agents are able to generate rules for annotation which achieve better results than those reported in the literature.
THEORETICAL PREDICTION OF POTENTIAL ENERGY SURFACE FOR N14 CLUSTER
Authors: GUAN JUN , CHENG LI PING , XU WEN GUO , LI QIAN SHU , LI SE , ZHANG ZHI PEI
Published: March 2003

In addition to four isomers of N 14 cluster previously reported, one new isomer was investigated. The decomposition and isomerization pathways of these five N 14 isomers were studied using the density functional theory (DFT) method. Relative energies were refined at the B3LYP/6-311+G(3df, 2p)//B3LYP/6-31G* level of theory. The present study shows that the decomposition barrier heights for the isomers 1, 2, and 3 are all much lower than 20 kcal/mol, which hints the fact that it may be possible to observe these three isomers only as short-lived species at room temperature. The barrier height for the cis-trans isomerization reaction of the isomers 4 and 5 is about 43.3 kcal/mol at the B3LYP/6-113+G(3df, 2p)//B3LYP/6-31G* level of theory. Unfortunately, however, the decomposition barrier height for the isomer 4 is about 17.9 kcal/mol. For the isomer 5, one barrier height corresponding to the - N 4 side chain breaking to lose the N 2 molecules is about 32.9 kcal/mol, however, the other barrier height corresponding to the - N 5 side chain breaking to lose a N 2 molecule is about 17.1 kcal/mol. From the study presented here, it seems that these five N 14 isomers are not kinetically stable enough to serve as high energy density materials (HEDMs).
HIGH-TEMPERATURE SERIES FOR THERMODYNAMIC FUNCTIONS
Authors: FERNÁNDEZ FRANCISCO M.
Published: March 2003

We propose a high-temperature expansion for thermodynamic functions. As an example we calculate the free energy for a restricted plane rigid rotor and compare present approach with perturbation theory.
Human Protease-Activated Receptor 1 Expression in Malignant Epithelia
Authors: Yin Yong-Jun , Salah Zaidoun , Grisaru-Granovsky Sorina , Cohen Irit , Even-Ram Sharona Cohen , Maoz Myriam , Uziely Beatrice , Peretz Tamar , Bar-Shavit Rachel
Published: March 2003

While protease-activated receptors (PARs) play a traditional role in vascular biology, they emerge with surprisingly new assignments in tumor biology. PAR1 expression correlates with the invasion properties of breast carcinoma, whereas human PAR1 antisense reduces their ability to migrate through Matrigel. Part of the molecular mechanism of PAR1 invasion involves the formation of focal contact complexes on PAR1 activation. PAR1 induces angiogenesis in animal models in vivo and exhibits an oncogenic phenotype of enhanced ductal complexity when overexpressed in mouse mammary glands.
Oxidative Stress Mediates Tumor Necrosis Factor-α–Induced Mitochondrial DNA Damage and Dysfunction in Cardiac Myocytes
Authors: Suematsu Nobuhiro , Tsutsui Hiroyuki , Wen Jing , Kang Dongchon , Ikeuchi Masaki , Ide Tomomi , Hayashidani Shunji , Shiomi Tetsuya , Kubota Toru , Hamasaki Naotaka , Takeshita Akira
Published: March 2003

Background—

Tumor necrosis factor-α (TNF-α) and angiotensin II (Ang II) are implicated in the development and further progression of heart failure, which might be, at least in part, mediated by the production of reactive oxygen species (ROS). However, the cause and consequences of this agonist-mediated ROS production in cardiac myocytes have not been well defined. Recently, we demonstrated that increased ROS production was associated with mitochondrial DNA (mtDNA) damage and dysfunction in failing hearts. We thus investigated whether the direct exposure of cardiac myocytes to TNF-α and Ang II in vitro could induce mtDNA damage via production of ROS.

Methods and Results—

TNF-α increased ROS production within cultured neonatal rat ventricular myocytes after 1 hour, as assessed by 2′,7′-dichlorofluorescin diacetate fluorescence microscopy. TNF-α also decreased mtDNA copy number by Southern blot analysis in association with complex III activity, which was prevented in the presence of the antioxidant α-tocopherol. A direct exposure of myocytes to H
2
O
2
caused a similar decrease in mtDNA copy number. In contrast, Ang II did not affect mtDNA copy number, despite the similar increase in ROS production. TNF-α–mediated ROS production and a decrease in mtDNA copy number were inhibited by the sphingomyelinase inhibitor D609. Furthermore,
N
-acetylsphingosine (C2-ceramide), a synthetic cell-permeable ceramide analogue, increased myocyte ROS production, suggesting that TNF-α–mediated ROS production and subsequent mtDNA damage were mediated by the sphingomyelin-ceramide signaling pathway.

Conclusions—

The intimate link between TNF-α, ROS, and mtDNA damage might play an important role in myocardial remodeling and failure.
Telecommunications and Travel: The Case for Complementarity
Authors: Mokhtarian Patricia L.
Published: March 2003

This article examines the conceptual, theoretical, and empirical evidence with respect to the impact of telecommunications on travel. The primary focus is on passenger travel, but goods movement is addressed briefly. I argue that although direct, short‐term studies focusing on a single application (such as telecommuting) have often found substitution effects, such studies are likely to miss the more subtle, indirect, and longer‐term complementarity effects that are typically observed in more comprehensive analyses. Overall, substitution, complementarity, modification, and neutrality within and across communication modes are all happening simultaneously. The net outcome of these partially counteracting effects, if current trends continue, is likely to be faster growth in telecommunications than in travel, resulting in an increasing share of interactions falling to telecommunications, but with continued growth in travel in absolute terms. The empirical evidence to date is quite limited in its ability to assess the extent of true causality between telecommunications and travel, and more research is needed in that area. At this point, what we can say with confidence is that the empirical evidence for net complementarity is substantial, although not definitive, and the empirical evidence for net substitution appears to be virtually nonexistent.
Effects of E‐Commerce on Greenhouse Gas Emissions: A Case Study of Grocery Home Delivery in Finland
Authors: Siikavirta Hanne , Punakivi Mikko , Kärkkäinen Mikko , Linnanen Lassi
Published: March 2003

In this article, we present a literature review of the general and environmental effects of e‐commerce in various parts of the demand‐supply chain. These are further translated into effects on greenhouse gas (GHG) emissions in the food production and consumption system. The literature study revealed many opportunities for e‐commerce to reduce GHG emissions in the food production and consumption system. Some possibly negative effects were also identified. Electronic grocery shopping (e‐grocery) home delivery service was chosen as the subject of a case study because of its direct and indirect potential for reducing the GHG emissions in the food production and consumption system.

GHG emission reduction potential through the implementation of various e‐grocery home delivery strategies was quantified. Depending on the home delivery model used, it is possible to reduce the GHG emissions generated by grocery shopping by 18% to 87% compared with the situation in which household members go to the store themselves. We estimate that the maximum theoretical potential of e‐grocery home delivery service for reducing the GHG emissions of Finland is roughly 0.3% to 1.3%; however, the current and estimated future market potential is much smaller, because the estimated market share of e‐grocery services is only 10% by 2005. Narrowing the gap between the theoretical and the actual potential requires a model that would simultaneously provide additional value to the consumer and be profitable to companies. To be able to achieve significant reductions in GHG emissions, system‐level innovations and changes are required. Further research is needed before conclusions can be reached as to whether e‐commerce and e‐grocery are useful tools in that respect.
Human reconstituting hematopoietic stem cells up-regulate Fas expression upon active cell cycling but remain resistant to Fas-induced suppression
Authors: Dybedal Ingunn , Yang Liping , Bryder David , Aastrand-Grundstrom Ingbritt , Leandersson Karin , Jacobsen Sten Eirik W.
Published: March 2003

The Fas receptor and its ligand have been implicated in mediating the bone marrow (BM) suppression observed in graft-versus-host disease and a number of other BM-failure syndromes. However, previous studies have suggested that Fas is probably not expressed on human hematopoietic stem cells (HSCs), but up-regulated as a consequence of their commitment and differentiation, suggesting that progenitors or differentiated blood cells, rather than HSCs, are the targets of Fas-mediated suppression. The present studies confirm that candidate HSCs in human cord blood and BM lack constitutive expression of Fas, but demonstrate that Fas expression on CD34+ progenitor and stem cells is correlated to their cell cycle and activation status. With the use of recently developed in vitro conditions promoting HSC self-renewing divisions, Fas was up-regulated on virtually all HSCs capable of multilineage reconstituting nonobese diabetic/severe combined immunodeficiency (NOD-SCID) mice in vivo, as well as on long-term culture-initiating cells (LTC-ICs). Similarly, in vivo cycling of NOD-SCID repopulating cells upon transplantation, resulted in up-regulation of Fas expression. However, repopulating HSCs expressing high levels of Fas remained highly resistant to Fas-mediated suppression, and HSC function was compromised only upon coactivation with tumor necrosis factor. Thus, reconstituting human HSCs up-regulate Fas expression upon active cycling, demonstrating that HSCs could be targets for Fas-mediated BM suppression. (Blood. 2003;102: 118-126)
Gene expression analysis of purified hematopoietic stem cells and committed progenitors
Authors: Terskikh Alexey V. , Miyamoto Toshihiro , Chang Cynthia , Diatchenko Luda , Weissman Irving L.
Published: March 2003

Lifelong self-renewal is a unique property of somatic stem cells. Recently, several primitive multipotent yet committed (non—self-renewing) hematopoietic progenitor populations were identified in mouse bone marrow. We have characterized the expression of 1200 selected mouse genes using the Atlas cDNA array in highly purified hematopoietic stem cells (HSCs) and 6 closely related progenitor populations: common myeloid progenitors (CMPs), granulocyte-macrophage progenitors (GMPs), megakaryocyte-erythrocyte progenitors (MEPs), common lymphoid progenitors (CLPs), and pro-T and pro-B cells. Cluster analysis revealed that nearly half of all differentially expressed transcripts are associated with HSCs, supporting the notion of an active transcriptional status of HSCs. Genes found enriched in the HSC cluster encompass many developmentally regulated genes, some previously associated with HSC self-renewal. In contrast, genes that are enriched in committed progenitors are mostly associated with hematopoietic differentiation, immune regulation, and metabolism. Thus, the transition from HSCs toward committed progenitors correlates with the down-regulation of a large number of HSC-associated genes and progressive up-regulation of a limited number of lineage-specific genes. These genetic analyses revealed both quantitative and qualitative differences between the transcripts associated with HSCs versus downstream progenitors and produced a list of the candidate genes, potentially involved in HSC self-renewal. (Blood. 2003;102:94-101)
Sex significantly influences transduction of murine liver by recombinant adeno-associated viral vectors through an androgen-dependent pathway
Authors: Davidoff Andrew M. , Ng Catherine Y. C. , Zhou Junfang , Spence Yunyu , Nathwani Amit C.
Published: March 2003

A systematic evaluation of the influence of sex on transduction by recombinant adeno-associated viral vector (rAAV) indicated that transgene expression after liver-targeted delivery of vector particles was between 5- to 13-fold higher in male mice compared with female mice, irrespective of the proviral promoter or cDNA and mouse strain. Molecular analysis revealed that the rAAV genome was stably retained in male liver at levels that were 7-fold higher than those observed in females. Further, the sex difference in transduction was observed with AAV-2– and AAV-5–based vectors, which use distinct receptor complexes for infection. In concordance with the differences in AAV transduction, gel shift analysis with nuclear extracts derived from the liver of mice and humans revealed substantially higher binding of host nuclear protein to the rep-binding site (RBS) of AAV inverted terminal repeat (ITR) in males compared with females. Transduction efficiency and binding of nuclear protein to RBS was dramatically reduced in male mice by castration. In contrast, although oophorectomy did not significantly influence rAAV transduction, administration of 5α dihydrotestosterone, prior to gene transfer, increased stable hepatocyte gene transfer in females to levels observed in male mice, implying that androgens significantly influence hepatocyte gene transfer. Interestingly, sex did not have a significant effect on AAV gene transfer into nonhepatic tissue, indicating that there are distinct tissue- and sex-specific differences in the mechanisms responsible for efficient transduction with this vector. These results have significant implications for gene therapy of autosomal and acquired disorders affecting the liver.
Membrane cholesterol regulates LFA-1 function and lipid raft heterogeneity
Authors: Marwali Muhammad Reza , Rey-Ladino Jose , Dreolini Lisa , Shaw Douglas , Takei Fumio
Published: March 2003

Many surface receptors and signaling molecules are thought to associate with unique membrane microdomains termed lipid rafts. We examined the involvement of lipid rafts in the activation of leukocyte function–associated antigen-1 (LFA-1). Depletion or sequestration of cholesterol with methyl-β-cyclodextrin (MCD) or filipin, respectively, strongly inhibited LFA-1–mediated adhesion of T-cell lines and primary T cells. This inhibition was reversed by cholesterol reconstitution. LFA-1 on T-cell lines was detected in cold Triton X-100–insoluble lipid rafts, which were disrupted by MCD or filipin treatment. However, no LFA-1 on primary T cells was detected in lipid rafts isolated by the same procedures, and these rafts were resistant to cholesterol depletion or sequestration. Association of LFA-1 with lipid rafts of primary T cells could be detected only when they were isolated with another nonionic detergent, Brij 35. Upon treatment with MCD, LFA-1 in Brij 35–insoluble lipid rafts partially shifted to nonraft fractions. T-cell lines were found to have a high level of cholesterol and a low level of ganglioside GM1, a common marker for lipid rafts, whereas primary T cells have a much lower level of cholesterol and a very high amount of GM1. Cross-linking of LFA-1 on primary T cells induced cocapping of cholesterol but not GM1. These results suggest that lipid rafts of T cells are heterogenous, and LFA-1 associates with a subset of lipid rafts containing a high level of cholesterol. This association seems to regulate LFA-1 functions, possibly by facilitating LFA-1 clustering. (Blood. 2003;102: 215-222)
Gene expression signatures in MLL-rearranged T-lineage and B-precursor acute leukemias: dominance of HOX dysregulation
Authors: Ferrando Adolfo A. , Armstrong Scott A. , Neuberg Donna S. , Sallan Stephen E. , Silverman Lewis B. , Korsmeyer Stanley J. , Look A. Thomas
Published: March 2003

Rearrangements of the MLL locus, located on human chromosome 11q23, are frequent in both infant and therapy-related leukemias. Gene expression analysis of MLL-rearranged B-precursor acute lymphoblastic leukemias (MLL B-ALLs) has identified these cases as a unique subtype of leukemia, characterized by the expression of genes associated with both lymphoid and myeloid hematopoietic lineages. Here we show that MLL fusions also generate a distinct genetic subtype of T-lineage ALL (MLL T-ALL), in which leukemic cells are characterized by an early arrest in thymocyte differentiation, with suggestive evidence of commitment to the γδ lineage. Interestingly, multiple genes linked to cell proliferation (eg, PCNA, MYC, CDK2, and POLA) were down-regulated in MLL-fusion samples, relative to those transformed by other T-ALL oncogenes (P < .000 001, Fisher exact test). Overall, MLL T-ALL cases consistently demonstrated increased levels of expression of a subset of major HOX genes—HOXA9, HOXA10, and HOXC6—and the MEIS1 HOX coregulator (P < .008, one-sided Wilcoxon test), a pattern of gene expression that was reiterated in MLL B-ALLs. However, expression of myeloid lineage genes, previously reported in MLL B-ALLs, was not identified in T-lineage cases with this abnormality, suggesting that myeloid gene dysregulation is dispensable in leukemic transformation mediated by MLL fusion proteins. Our findings implicate dysregulation of HOX gene family members as a dominant mechanism of leukemic transformation induced by chimeric MLL oncogenes. (Blood. 2003;102:262-268)
p190-B RhoGAP Regulates Mammary Ductal Morphogenesis
Authors: Chakravarty Geetika , Hadsell Darryl , Buitrago William , Settleman Jeffrey , Rosen Jeffrey M.
Published: March 2003

Previous studies from our laboratory have demonstrated that p190-B RhoGAP (p190-B) is differentially expressed in the Cap cells of terminal end buds (TEBs) and poorly differentiated rodent mammary tumors. Based on these observations we hypothesized that p190-B might play an essential role in invasion of the TEBs into the surrounding fat pad during ductal morphogenesis. To test this hypothesis, mammary development was studied in p190-B-deficient mice. A haploinsufficiency phenotype was observed in p190-B heterozygous mice as indicated by decreased number and rate of ductal outgrowth(s) at 3, 4, and 5 wk of age when compared with their wild-type littermates. This appeared to result from decreased proliferation in the Cap cells of the TEBs, a phenotype remarkably similar to that observed previously in IGF-I receptor null mammary epithelium. Furthermore, decreased expression of insulin receptor substrates 1 and 2 were observed in TEBs of p190-B heterozygous mice. These findings are consistent with decreased IGF signaling observed previously in p190-B−/− mouse embryo fibroblasts. To further assess if this defect was cell autonomous or due to systemic endocrine effects, the mammary anlagen from p190-B+/+, p190-B+/−, and p190-B−/− mice was rescued by transplantation into the cleared fat pad of recipient Rag1−/− mice. Surprisingly, as opposed to 75–80% outgrowths observed using wild-type donor epithelium, only 40% of the heterozygous and none of the p190-B−/− epithelial transplants displayed any outgrowths. Together, these results suggest that p190-B regulates ductal morphogenesis, at least in part, by modulating the IGF signaling axis.
Early patterning of the spider embryo: a cluster of mesenchymal cells at the cumulus produces Dpp signals received by germ disc epithelial cells
Authors: Akiyama-Oda Yasuko , Oda Hiroki
Published: March 2003

In early embryogenesis of spiders, the cumulus is characteristically observed as a cellular thickening that arises from the center of the germ disc and moves centrifugally. This cumulus movement breaks the radial symmetry of the germ disc morphology, correlating with the development of the dorsal region of the embryo. Classical experiments on spider embryos have shown that a cumulus has the capacity to induce a secondary axis when transplanted ectopically. In this study, we have examined the house spider, Achaearanea tepidariorum, on the basis of knowledge from Drosophila to characterize the cumulus at the cellular and molecular level. In the cumulus,a cluster of about 10 mesenchymal cells, designated the cumulus mesenchymal(CM) cells, is situated beneath the epithelium, where the CM cells migrate to the rim of the germ disc. Germ disc epithelial cells near the migrating CM cells extend cytoneme-like projections from their basal side onto the surface of the CM cells. Molecular cloning and whole-mount in situ hybridization showed that the CM cells expressed a spider homolog of Drosophila decapentaplegic (dpp), which encodes a secreted protein that functions as a dorsal morphogen in the Drosophila embryo. Furthermore, the spider Dpp signal appeared to induce graded levels of the phosphorylated Mothers against dpp (Mad) protein in the nuclei of germ disc epithelial cells. Adding data from spider homologs of fork head,orthodenticle and caudal, we suggest that, in contrast to theDrosophila embryo, the progressive mesenchymal-epithelial cell interactions involving the Dpp-Mad signaling cascade generate dorsoventral polarity in accordance with the anteroposterior axis formation in the spider embryo. Our findings support the idea that the cumulus plays a central role in the axial pattern formation of the spider embryo.
Nodal signaling induces the midline barrier by activatingNodalexpression in the lateral plate
Authors: Yamamoto Masamichi , Mine Naoki , Mochida Kyoko , Sakai Yasuo , Saijoh Yukio , Meno Chikara , Hamada Hiroshi
Published: March 2003

The transcription factor Foxh1 mediates Nodal signaling. The role of Foxh1 in left-right (LR) patterning was examined with mutant mice that lack this protein in lateral plate mesoderm (LPM). The mutant mice failed to expressNodal, Lefty2 and Pitx2 on the left side during embryogenesis and exhibited right isomerism. Ectopic introduction of Nodal into right LPM, by transplantation of left LPM or by electroporation of aNodal vector, induced Nodal expression in wild-type embryos but not in the mutant. Ectopic Nodal expression in right LPM also induced Lefty1 expression in the floor plate. Nodal signaling thus initiates asymmetric Nodal expression in LPM and inducesLefty1 at the midline. Monitoring of Nodal activity in wild-type andFoxh1 mutant embryos suggested that Nodal activity travels from the node to left LPM, and from left LPM to the midline.
A homeobox gene,pnx, is involved in the formation of posterior neurons in zebrafish
Authors: Bae Young-Ki , Shimizu Takashi , Yabe Taijiro , Kim Cheol-Hee , Hirata Tsutomu , Nojima Hideaki , Muraoka Osamu , Hirano Toshio , Hibi Masahiko
Published: March 2003

A homeobox gene, pnx, is expressed in prospective posterior neurogenic regions and later in primary neurons. pnx expression was regulated by a signal from the non-axial mesendoderm and by Notch signaling. Pnx contains an Eh1 repressor domain, which interacted with Groucho and acted as a transcriptional repressor. Misexpression of pnx increased neural precursor cells and postmitotic neurons, which express neurogenin1and elavl3/HuC, respectively. Expression of an antimorphic Pnx(VP16Pnx) or inhibition of Pnx by antisense morpholino oligonucleotide led to the reduction in the number of a subset of primary neurons. Misexpression ofpnx promoted neurogenesis independent of Notch signaling. Epistatic analyses showed that Pnx also functions downstream of the Notch signal. These data indicate that pnx is a novel repressor-type homeobox gene that regulates posterior neurogenesis.
Negotiating Cross-Cultural Issues at the End of Life
Authors: Kagawa-Singer Marjorie , Blackhall Leslie J.
Published: March 2003

Culture fundamentally shapes how individuals make meaning out of illness, suffering, and dying. With increasing diversity in the United States, encounters between patients and physicians of different backgrounds are becoming more common. Thus the risk for cross-cultural misunderstandings surrounding care at the end of life is also increasing. Studies have shown cultural differences in attitudes toward truth telling, life-prolonging technology, and decision-making styles at the end of life. Using 2 case studies of patients, one of an African American couple in the southern United States and the other of a Chinese-American family in Hawaii, we outline some of the major issues involved in cross-cultural care and indicate how the patient, family, and clinician can navigate among differing cultural beliefs, values, and practices. Skilled use of cross-cultural understanding and communication techniques increases the likelihood that both the process and outcomes of care are satisfactory for all involved.
Enrollee Appeals of Preservice Coverage Denials at 2 Health Maintenance Organizations
Authors: Studdert David M. , Gresenz Carole Roan
Published: March 2003

Context

Congress and state legislatures are considering patient bills of rights that seek to strengthen opportunities for patients to have denials of coverage reconsidered by their health plans. Little is publicly known about such appeals systems.

Objective

To improve understanding of the sources, types, and outcomes of conflicts between patients and managed care organizations over coverage of services.

Design and Setting

Descriptive study of information abstracted from 1774 preservice appeals out of a larger stratified random sample of 3519 appeals lodged between January 1998 and June 2000 at 2 large US health maintenance organizations.

Main Outcome Measures

Classification of preservice appeals according to whether they contested access to out-of-network care, the contractual limits of coverage, or the medical necessity of services; analysis of contractual coverage and medical necessity appeals by the services in dispute and out-of-network appeals by enrollees' reasons for seeking care; and comparison of the proportions of appeals won by enrollees across types of appeals and services.

Results

Approximately one third (36.9%) of preservice appeals involved medical necessity determinations, another third (36.6%) centered on the scope of contractually covered benefits, and most of the remainder (19.7%) involved out-of-network care. Enrollee wins were significantly more frequent among medical necessity appeals than out-of-network or contractual coverage appeals (52.2% vs 35.4% and 33.2%, respectively; P<.001). Appeals were concentrated among relatively few services and among therapies that are generally regarded as nonessential.

Conclusions

A majority of preservice appeals disputed choice of provider or contractual coverage issues, rather than medical necessity. Medical necessity disputes proliferate not around life-saving treatments but in areas of societal uncertainty about the legitimate boundaries of insurance coverage. Greater transparency about the coverage status of specific services, through more precise contractual language and consumer education about benefits limitations, may help to avoid a large proportion of disputes in managed care.
Medical Monitoring for Pharmaceutical Injuries
Authors: Studdert David M. , Mello Michelle M. , Brennan Troyen A.
Published: March 2003

A remarkable development in personal injury litigation in recent years involves attempts to expand legal claims beyond existing injuries to anticipated future harms. Attorneys have begun to sue on behalf of individuals exposed to defective pharmaceutical products who have no current injury, but who may be at risk for developing one after a latency period. This strategy seeks to make drug manufacturers pay formedical monitoring, a court-ordered program that provides diagnostic tests to exposed individuals to facilitate early detection of adverse health effects. Because medical monitoring does not depend on the existence of an actual injury and large populations may be exposed, some commentators have warned that it has the potential to spiral out of control. We examine medical monitoring in the context of 2 major cases involving diet drugs and an oral hypoglycemic drug. We conclude that this expansion of tort law should be applied sparingly, but that the performance of courts to date in these cases gives cause for optimism. Judges appear to be paying close attention to sophisticated epidemiological, clinical, and cost-effectiveness considerations. Medical monitoring arms the courts with a new mechanism for addressing harms proactively rather than reactively, which could yield new victories for public health.
Sex differences in genetic and environmental effects on aggression
Authors: Vierikko Elina , Pulkkinen Lea , Kaprio Jaakko , Viken Richard , Rose Richard J.
Published: March 2003

The aim of the present study was to investigate the genetic and environmental factors influencing teacher and parental rated aggression in boys and girls, asking whether the magnitude of these effects is similar across rater and sex. The study is part of an ongoing nationwide twin‐family study of behavioral development and health habits carried out in Finland. The sample consisted of 1651 twin pairs (264 monozygotic male, 300 monozygotic female, 292 dizygotic male, 278 dizygotic female, and 517 dizygotic opposite‐sex twin pairs), representing subsets of five 11‐ to 12‐year‐old twin cohorts (b. 1983–1987). The data were collected using the teacher and parental rating forms of the Multidimensional Peer Nomination Inventory. Structural equation models of sex‐limitation assessed sex differences in genetic and environmental influences on aggression. The results suggested significant genetic, common environmental, and specific environmental effects on aggression in both boys and girls, but the best fitting model differed depending on the informant. For both ratings, boys showed lower levels of heritability and higher levels of common environment than girls. In addition, the teacher rating data also suggested the presence of either sex‐specific common environmental effects or sex‐specific genetic effects. Support is provided also for sibling contrast effects, either at the behavioral level or as a rater bias. Aggr. Behav. 29:55–68, 2003. © 2003 Wiley‐Liss, Inc.
Assessment in accelerated learning programs: A practical guide
Authors: Walvoord Barbara E.
Published: March 2003

Assessment can be used to improve student learning in accelerated programs.
A critical theory perspective on accelerated learning
Authors: Brookfield Stephen D.
Published: March 2003

This chapter situates accelerated learning programs, and in particular cohort‐based programs, within a critical analysis using concepts from Herbert Marcuse and Erich Fromm.
Action/inaction regret as a function of severity of loss
Authors: Avni‐Babad Dinah
Published: March 2003

Two studies were conducted to examine whether people who experience severe losses tend to regret their failures to act more than people that experience less severe losses. Two time points were considered, after the event (short term), and a year later (long term). In Study 1, participants responded to scenarios depicting losses varying in degree of severity. As hypothesized, protagonists in the heavy loss cases were attributed with more regrets of omission (inaction) both in the short and in the long term. In the less severe loss scenarios, action regrets decreased significantly in the long term. In Study 2, one of the severe loss scenarios from Study 1 was presented with a less severe outcome. As expected, participants generated more inaction regrets in the severe loss version. Severity of loss influenced the preference for omission regrets in both studies for the short term and the long term. Copyright © 2002 John Wiley & Sons, Ltd.
The everyday production of knowledge: individual differences in epistemological understanding and juror‐reasoning skill
Authors: Weinstock Michael , Cronin Matthew A.
Published: March 2003

This study investigated the untested assumption that people's everyday reasoning reflects different understandings of the nature of knowledge and knowing. The epistemological stances of 180 prospective jurors were assessed with an interview that probed the nature and source of the discrepant knowledge claims of two historical accounts. The researchers derived global epistemological levels from these interviews. The jurors also heard trials and offered justifications for their verdict choices. The researchers assessed these justifications for whether subjects could use various reasoning skills successfully. Epistemological level, but not educational level, age, or gender, predicted juror‐reasoning skills and degree of certainty about verdict choice. Epistemological level, mediated by the juror‐reasoning skills, was a better predictor of general argument skill than certainty about verdict choice and the amount of evidence used in arguing for a verdict. The results indicate that epistemological understandings underlie specific juror‐reasoning skills and overall argument ability. Copyright © 2002 John Wiley & Sons, Ltd.
Children's memory of recurring events: is the first event always the best remembered?
Authors: Powell Martine B. , Thomson Donald M. , Ceci Stephen J.
Published: March 2003

Three experiments were conducted to examine the effect of age (4–5 and 6–8 years) and retention interval on children's ability to remember separate occurrences of a repeated event that varied in terms of content (items, dialog, etc.) Experiment 1 explored children's ability to recall the first versus last occurrence of a series of six events, at either one week or six weeks delay. Experiments 2 and 3 explored children's ability to identify the position of items in terms of their order of presentation within the series across two retention intervals. Overall, the results revealed clear age differences in children's performance. In general, the 6‐ to 8‐year‐old children performed better on all tasks than the 4‐ to 5‐year‐old children. Further, the older children showed relatively good memory of the first and last items compared to the middle items, although the last items were more likely to be forgotten or misplaced in the sequencing tasks over time than the first items. For the younger children, the patterns of results were sometimes but not always consistent with that of the older children. The relevance and generalisability of these findings to the legal setting are discussed as well as directions for future research. Copyright © 2002 John Wiley & Sons, Ltd.
Whose life is it anyway? Adoption of each other's autobiographical memories by twins
Authors: Ikier Simay , Tekcan Ali İ. , Gülgöz Sami , Küntay Aylin C.
Published: March 2003

Anecdotal evidence suggests that twins may dispute ownership of autobiographical experiences. We investigated the frequency and characteristics of such disputed memories in comparison to memories with undisputed ownership. In the present study, monozygotic twins (MZ), dizygotic twins (DZ), and siblings were asked to remember disputed and non‐disputed memories. They also dated each memory and provided a rating on the following variables: level of imagery, detail, rehearsal, and importance. Results showed that disputed memories were more common among MZ twins than in DZ twins and siblings. The frequencies of undisputed memories were not different among the three groups. When compared to non‐disputed memories, disputed memories were more likely to come from events experienced during preschool years. We consider disputed memories as instances of false memories, at least partly influenced by social interactional processes, and event characteristics. Copyright © 2003 John Wiley & Sons, Ltd.
Artificial Muscles with Tactile Sensitivity
Authors: Otero T.F. , Cortés M.T.
Published: March 2003

All‐polymeric triple‐layer artificial musclescapable of pushing obstacles that they meet during their angular movement are presented (see Figure). Upon contact of the muscle with an obstacle, a potential step proportional to the weight of the object evolves. Thus the muscle works simultaneously as an actuator and a tactile sensor.
Cholesteric Mixtures with Photochemically Tunable, Circularly Polarized Fluorescence
Authors: Bobrovsky A.Yu. , Boiko N.I. , Shibaev V.P. , Wendorff J.H.
Published: March 2003

Photo‐patternable cholesteric materials that combine fluorescence and a photochemically variable helical pitch have been investigated. Two cholesteric mixtures containing chiral photochromic (see Figure) as well as fluorescent dopants are examined. It is shown that photoregulation of both the fluorescence intensity and the polarization state of the emitted light can be realized.
Long‐Lived Photoinduced Charge Separation in (Zinc, Lead) Phosphate Glass–C60 Composites
Authors: Sahoo R. , Debnath R.
Published: March 2003

A group of (zinc, lead) phosphate glass–C60 composites that display long‐lived photoinduced electron transfer from the Pb2+ center to the fullerene upon 230–400 nm UV irradiation has been developed. Both the steady state photoinduced absorption and photoinduced electron spin resonance spectra of the irradiated system support this view. Analysis of the carrier dynamics suggests that the electrons migrate from the hole sites to the fullerene sites in a tunneling mode.
A New Soluble 1,10‐Phenanthroline‐Containing π‐Conjugated Polymer: Synthesis and Effect of Metal Complexation on Optical Properties
Authors: Yasuda T. , Yamaguchi I. , Yamamoto T.
Published: March 2003

A new 1,10‐phenanthroline‐containing π‐conjugated polymer, the color of which can be tuned from blue to red by metal complexation, has been synthesized. The polymer responds sensitively to various metal ions due to its high coordinating ability, and the Figure shows emission from the polymer–metal complexes under 365 nm irradiation. The complexes are expected to serve as materials for light‐emitting diodes.
One‐Dimensional Nanostructures: Synthesis, Characterization, and Applications
Authors: Xia Y. , Yang P. , Sun Y. , Wu Y. , Mayers B. , Gates B. , Yin Y. , Kim F. , Yan H.
Published: March 2003

This article provides a comprehensive review of current research activities that concentrate on one‐dimensional (1D) nanostructures—wires, rods, belts, and tubes—whose lateral dimensions fall anywhere in the range of 1 to 100 nm. We devote the most attention to 1D nanostructures that have been synthesized in relatively copious quantities using chemical methods. We begin this article with an overview of synthetic strategies that have been exploited to achieve 1D growth. We then elaborate on these approaches in the following four sections: i) anisotropic growth dictated by the crystallographic structure of a solid material; ii) anisotropic growth confined and directed by various templates; iii) anisotropic growth kinetically controlled by supersaturation or through the use of an appropriate capping reagent; and iv) new concepts not yet fully demonstrated, but with long‐term potential in generating 1D nanostructures. Following is a discussion of techniques for generating various types of important heterostructured nanowires. By the end of this article, we highlight a range of unique properties (e.g., thermal, mechanical, electronic, optoelectronic, optical, nonlinear optical, and field emission) associated with different types of 1D nanostructures. We also briefly discuss a number of methods potentially useful for assembling 1D nanostructures into functional devices based on crossbar junctions, and complex architectures such as 2D and 3D periodic lattices. We conclude this review with personal perspectives on the directions towards which future research on this new class of nanostructured materials might be directed.
“Beaded” Bimetallic Nanowires: Wiring Nanoparticles of Metal 1 Using Nanowires of Metal 2
Authors: Walter E.C. , Murray B.J. , Favier F. , Penner R.M.
Published: March 2003

Aligned metal nanoparticles are connected using a second metal to produce bimetallic wires. The nanoparticles are electrodeposited along the step edges of a highly oriented graphite surface and, after being given a protective coating, joined by long nanowires which are also electrodeposited. Beaded structures are produced, such as the nickel/molybdenum oxide wire shown the Figure.
Diffusion of Gold Nanorods on Chemically Functionalized Surfaces
Authors: Angelo S.K.St. , Waraksa C.C. , Mallouk T.E.
Published: March 2003

Surface diffusion coefficients (D) have been measured for gold nanorods suspended in water on planar gold substrates. The Figure shows the composite image of sequential optical micrographs at 15 s intervals. The variation of D is more dependent on rod length than predicted by the Stokes–Einstein equation, consistent with a frictional interaction between the rod and the surface.
Morphogenesis of One‐Dimensional ZnO Nano‐ and Microcrystals
Authors: Yan H. , He R. , Pham J. , Yang P.
Published: March 2003

The deterministic growth of different shapes of ZnO crystals from nanometer to micrometer scale is reported. Tetrapods (see Figure) and dendrites have been synthesized by simply adjusting the reaction temperature and the partial pressure of oxygen within the system. Size control of these structures can be achieved. ZnO nanoribbons are also easily accessible.