bluuebunny/crossref_metadata_2025 huggingface dataset:
Delayed visual P3 in unilateral thalamic stroke
Authors: Trinka E. , Unterrainer J. , Staffen W. , Löscher N. W. , Ladurner G.
Published: November 2003

The P3 potential is accepted as a neurophysiological correlate of memory and attention. Delayed latencies were reported in different forms of dementias. Although the generator sites are still under debate, the thalamus may play a crucial role. The aim of this study was to investigate the influence of an unilateral thalamic ischaemic infarction on P3 generation.

The event‐related P3 component of six patients (2 male, four female; mean age 47 years, range 22–63 years) with unilateral thalamic ischaemic infarction was studied and compared to age‐matched controls (five male, nine female; mean age 45.8 years; range 22–69 years). All patients underwent full clinical examination, CCT, and MRI scan. P3 potentials were recorded with a visual three stimulus discrimination paradigm. The mean P3 latency of the patient group to the target stimulus was delayed (469.7 ms, SD = 36.8) compared with the controls (378.8 ms, SD = 51.5; P < 0.05). The mean P3 latency to the unexpected stimulus was delayed in patients with thalamic infarction compared with controls [477 ms (SD = 46.6) vs. 381.2 ms (SD = 48.5); P < 0.001). Delayed P3 components of the event‐related potential (ERP) were recorded in six patients with unilateral thalamic infarction, suggesting an important role of the thalamus in the generation of the P3 potential.
Granulocyte and Monocyte Adsorptive Apheresis for Patients with Chronic Hepatitis C Virus Infection: A Report on Six Cases with High Plasma Viremia
Authors: Sawada Koji , Ohnishi Kunio , Fukunaga Ken , Kusaka Tsuyoshi , Ohdo Maiko , Nagase Kazuko , Shimoyama Takashi , Hada Toshikazu
Published: November 2003

Abstract:  Granulocytes and monocytes/macrophages (GM) are known to constitute extra‐hepatic sites for hepatitis C virus (HCV) replication and dissemination. Accordingly, we thought that selective GM adsorptive apheresis (GMA) might contribute to the treatment of HCV in patients with high viremia (HCV‐RNA > 100 kIU/mL). Of six patients (three males and three females), mean age 62.2 years, five had not responded to interferon‐α (INF‐α) and one was INF‐α naïve. Each patient received five GMA sessions, once a week for 5 weeks. The two antecubital veins were used as blood access and return lines and the apheresis was performed at 30 mL/min for 60 min. Treatment efficacy was assessed by monitoring changes in plasma HCV‐RNA and aminotransferase. Granulocyte and monocyte/macrophage adsorptive apheresis was well tolerated. During each GMA, there was on average a 52.9% fall in plasma HCV‐RNA, but HCV‐RNA increased again during the time before the next GMA. There was no marked change in either aminotransferase during GMA. Furthermore, beyond the last GMA, HCV‐RNA increased together with worsening aminotransferase in three of six patients. In conclusion, it would appear that GMA can partially reduce plasma HCV and GMA at a frequency of one session/week for 5 consecutive weeks but that this was inadequate to induce a sustained decrease in plasma HCV‐RNA in patients with high viremia without simultaneous administration of antiviral medications. The most effective frequency of GMA needs to be determined in future clinical studies.
Silver Coating of Dialysis Catheters to Reduce Bacterial Colonization and Infection
Authors: Tobin Eric J. , Bambauer Rolf
Published: November 2003

Abstract:  Complications resulting from infection remain a major problem for hemodialysis catheters, with significant numbers of catheters being removed due to catheter‐related sepsis. Numerous strategies have been employed to reduce the occurrence of infection and improve long‐term outcomes, with varying degrees of success. One promising approach is coating the external surface of catheters with silver using physical vapor deposition processes. This article reviews results of animal and clinical experiments conducted to assess efficacy and biocompatibility of silver‐coated dialysis catheters. It is concluded that silver coatings can reduce bacterial colonization and occurrence of infection associated with these devices.
Microsurgery in Children for Creation of Arteriovenous Fistulas in Renal and Non‐renal Diseases
Authors: Bourquelot Pierre , Raynaud Fabien , Pirozzi Nicola
Published: November 2003

Abstract:  Microsurgery for angioaccess in children includes the use of a surgical microscope, microsurgical instruments, prophylactic tourniquet‐induced hemostasis and no‐touch surgery. In the recent publications concerning angioaccess in children, the percentages of grafts versus arteriovenous fistulas (AVF) varied from 54 to 76% without microsurgery, and from 0 to 14% with microsurgery. Similarly, the percentages of AVF which failed to mature varied from 30 to 33% without microsurgery, and from 5 to 10% with microsurgery. In a personal series of 380 children receiving hemodialysis, 434 microsurgical angioaccesses were created, 78% being distal autologous AVF. Eighty‐five percent of the distal radial‐cephalic AVF were patent after 2 years and 60% after 4 years. These results of microsurgically created AVF are probably responsible, at least in part, for the high percentage of end‐stage renal disease (ESRD) children treated by hemodialysis on 1 February 2003 in Paris using an autologous fistula (70% of 33 children), while only 24% were hemodialyzed via a central venous catheter and 6% were on peritoneal dialysis. This compares favorably with the annual publication of the North American Pediatric Renal Transplant Cooperative Study in 1996 reporting that two‐thirds of the dialysis population were maintained on peritoneal dialysis and that the majority of hemodialysis accesses were external percutaneous catheters. Microsurgical AVF are also created successfully in non‐ESRD children requiring frequent blood access for various chronic diseases. It has been possible to create a distal AVF in 68% of cases and the long‐term patency rate was just below 60% after 10 years. Microsurgery is mandatory for creation of arteriovenous fistulas, the best form of angioaccess for children treated by hemodialysis or requiring repeated access to blood in various non‐renal diseases.
Plasmapheresis in C4d‐positive Acute Humoral Rejection Following Kidney Transplantation: A Review of 4 Cases
Authors: Lennertz Andrea , Fertmann Jan , Thomae Robert , Illner Wolf‐Dieter , Hillebrand Günther F. , Feucht Helmut E. , Land Walter , Samtleben Walter , Bosch Thomas
Published: November 2003

Abstract:  Acute and chronic rejection after kidney transplantation has long been exclusively attributed to cellular and vascular mechanisms. Modern immunosuppressive therapy, therefore, addresses the cellular immune system. Rising experiences in kidney transplantation in the last few decades have revealed that some types of rejection are refractory to the conventional immunosuppressive treatment. Humoral rejection, which has previously been reported as a crucial factor in hyperacute rejection, is now suspected to play also an important role in acute and chronic rejection. Acute humoral rejection (AHR) is characterized by immunohistochemical detection of C4d deposits in peritubular capillaries. As shown for other antibody‐mediated diseases, such as some autoimmune diseases, plasmapheresis has been suggested to be an efficient therapeutic approach in AHR. We present four patients with C4d‐positive AHR in the early phase after kidney transplantation. In three of the four patients, humoral graft rejection was successfully treated by plasmapheresis. Graft function was significantly improved with a stable long‐term outcome. One patient lost the graft. Although the number of patients with C4d‐positive AHR treated by plasmapheresis is limited, plasma exchange appears to be an efficient and powerful therapeutic approach to control humoral rejection.
Accelerated Gene Counting for Haplotype Frequency Estimation
Authors: Thomas Alun
Published: November 2003

Current implementations of the EM algorithm for estimating haplotype frequencies from genotypes on proximal loci require computational resources that grow asnh2k, where n is the number of individuals genotyped andhis the number of haplotypes possible onkloci. For diallelic locihk= 2k. We present an approach whose computational requirement grows asn2twheretis the largest number of loci at which an individual in the sample is heterozygous. The method is illustrated by haplotype frequency estimation from a sample of 45 individuals genotyped at 26 single nucleotide polymorphisms in the PIK3R1 gene.
An adaptive way for improving noise reduction using local geometric projection
Authors: Leontitsis Alexandros , Bountis Tassos , Pagge Jenny
Published: November 2003

We propose an adaptive way to improve noise reduction by local geometric projection. From the neighborhood of each candidate point in phase space, we identify the best subspace that the point will be orthogonally projected to. The signal subspace is formed by the most significant eigendirections of the neighborhood, while the less significant ones define the noise subspace. We provide a simple criterion to separate the most significant eigendirections from the less significant ones. This criterion is based on the maximum logarithmic difference between the neighborhood eigendirection lengths, and the assumption that there is at least one eigendirection that corresponds to the noise subspace. In this way, we take into account the special characteristics of each neighborhood and introduce a more successful noise reduction technique. Results are presented for a chaotic time series of the Hénon map and Ikeda map, as well as on the Nasdaq Composite index.
Stability and the maintenance of balance following a perturbation from quiet stance
Authors: Stirling J. R. , Zakynthinaki M. S.
Published: November 2003

We investigate stability and the maintenance of balance with the use of tools from dynamical systems. In particular we investigate the application of such tools to the study of the ground reaction forces resulting from an athlete being perturbed from quiet stance. We develop a nonlinear model consisting of a set of coupled vector fields for the derivative with respect to time of the angles between the resultant ground reaction forces and the vertical in the anteroposterior and mediolateral directions. This model contains a basin of attraction bound by a closed curve which we call the critical curve. It is only inside this curve that perturbations can be corrected, with the orbit spiraling onto an attractor corresponding to quiet stance. We show how the critical curve and also the strength of the attractor found in the basin of attraction can be fit to model the experimental data (time series) for an individual athlete. We also discuss how our model can be used to identify nonsymmetric behavior caused by muscle imbalances and differences in the ranges of motion on either side of the body.
Chaotic attitude oscillations of a satellite filled with a rotating ellipsoidal mass of liquid subject to gravity-gradient torques
Authors: Kuang Jinlu , Leung A. Y. T. , Tan Soonhie
Published: November 2003

The Hamiltonian equations of a liquid-filled satellite subject to gravity-gradient torques in terms of the generalized Deprit variables are established for applying the Melnikov theory formally. The heteroclinic orbits of the torque-free symmetric liquid-filled satellite are found. A criterion for the heteroclinic transversal intersections at the onset of chaotic attitude is formulated using Melnikov’s integral. The results from the Melnikov theory are crosschecked with simulation.
Valence-Bond and Hückel Molecular Orbital Diradicals—Alternant versus Nonalternant Effects
Authors: Dias Jerry Ray
Published: November 2003

Two distinct classes of diradicals are examined and compared. Valence-bond diradicals are topologically enforced, whereas Hückel molecular orbital diradicals can undergo skeletal distortions and transform to a nonradical form and tend to gain or lose electrons to form stable polyions. Alternant hydrocarbon diradicals are nonpolar species and nonalternant hydrocarbon diradicals tend to be polar species and less prevalent.
‘Neutralmolekülcomplexe’—Structural Characterization of Some Adducts of Urea and Thiourea with N,N′-Bidentate Aromatic Bases
Authors: Donnelly Paul S. , Skelton Brian W. , White Allan H.
Published: November 2003

Oepen and Vögtle in 1979 recorded the formation of a number of ‘neutral molecule complexes’ between urea (ur) and/or thiourea (tu) and a number of N,N′-aromatic chelate bases derivative of 2,2′-bipyridine (bpy), motifs now widely utilized in essays in studies of molecular/crystal architecture. The structures are recorded of a number of their adducts, namely (a) bpy/ur (1 : 1), (b) phen/ur (1 : 1), (c) phen/tu (1 : 1), (d) dmp/ur (1 : 1), together with (e) bpy/tu (1 : 1) and (f) a dmp/tu adduct of 1 : 2 stoichiometry (phen = 1,10-phenanthroline; dmp = 2,9-dimethyl-1,10-phenanthroline). Association takes places in all cases by way of hydrogen-bonding interactions between alternating (thio-)urea NH2 groups which form an infinite band with the nitrogen atoms of the aromatic base at the periphery, the base planes quasi-normal to that of the band, as in the archetypical 2,6-lutidine/urea (1 : 1) array, described long ago.
Tetracycle Formation from the Reaction of Acetophenones with 1-Aminoanthraquinone, and Further Annulation of Pyridine and Diazepine Rings
Authors: Deady Leslie W. , Smith Clare L.
Published: November 2003

Acetophenones (H, o-, m-, p-Cl, o-aza) react with aminoanthraquinone in pyridine containing solid sodium hydroxide to form 6-(arylcarbonyl)methyl-2-aryl-7H-naphtho[1,2,3-de]quinolin-7-ones (with the 4-(arylcarbonyl)methyl isomer as minor product). Preformed 7H-benzo[e]perimidin-7-one with acetophenone underwent the second part of this process, i.e. nucleophilic substitution to form 6-phenacyl-7H-benzo-[e]perimidin-7-one. Further reactions are described, including cyclization with ammonium acetate/acetic acid to 2,7-diphenyl-1,6-diazabenzo[e]pyrene and 7-phenyl-1,3,8-triazabenzo[e]pyrene, respectively, and with hydrazine hydrate to 3,8-diphenyl-4H-[1,2]diazepino[3,4-4′,3′ : 4,5-f]naphtho[1,2,3-de]quinoline and 3-phenyl-4H-benzo[e][1,2]diazepino[3,4,5-gh]perimidine.
Amino Acid Binding to Copper(II) in (1,4,7-Triazacyclononane) (L-histidine)copper(II) Hexafluorophosphate Monohydrate
Authors: Graham Bim , Hearn Milton T. W. , Spiccia Leone , Skelton Brian W. , White Allan H.
Published: November 2003

The synthesis, characterization, and single-crystal X-ray structure determination of [Cu(tacn)(L-His)](PF6)2 . H2O (tacn = 1,4,7-triazacyclononane, L-His = L-histidine) are reported. Spectroscopic studies indicated the formation of the square pyramidal copper(II) complex [Cu(tacn)(L-His)]2+. This was confirmed through structure determination, which also revealed that the distorted square-pyramidal copper(II) coordination sphere is comprised of three nitrogen donors from the tacn macrocycle plus one carboxylate oxygen atom and the primary nitrogen atom from L-histidine. The L-histidine ligand is zwitterionic, with the negative charge on the carboxylate balanced by protonation at one nitrogen atom on the imidazole ring. It binds to the copper centre, forming a five-membered chelate ring, common in amino acid coordination.
The farmer as conservationist
Authors: Badgley Catherine
Published: December 2003

Agricultural landscapes are essential for preserving biodiversity, even though agricultural activities are the leading cause of habitat degradation worldwide. About half of the Earth's productive land area is farmed or grazed, whereas only about 6% of the total land area is protected for native species and ecosystems. The ecological services of healthy ecosystems are fundamental to agriculture, and these services depend upon a large number of species interacting with each other and with inorganic nutrient cycles. Likewise, the quality of ecosystems between reserves is critical to the persistence of species and ecological processes within reserves. Thus, conservation-oriented farming methods are critically important for both agriculture and biodiversity. Three examples illustrate agricultural practices that benefit the farmers, the local ecosystem and the landscape: (1) In Minnesota, rotational grazing, evaluated by the collaborative research of farmers and scientists, improved soil, pasture and stream quality, and boosted the confidence of the farmers in developing more sustainable grazing practices. (2) Predator-friendly ranching in Montana, in which nonlethal methods are used to protect livestock from depredation by native predators, benefited the ranchers with premium prices for wool and meat. The persistence of native predators, many of which have been on endangered species lists for years, benefited the regional ecosystem. (3) Shade-grown coffee in Latin America, in which coffee shrubs grow under an intact forest canopy, often looks and behaves ecologically like native forest and may house high levels of native biodiversity. This system benefited farmers, as long as they received a price premium for shade-grown coffee. The economic viability of these conservation-oriented practices depends upon farmers receiving price premiums for their products and by society rewarding fanners for their practices. A vision of ecological farming as the dominant form of agriculture is presented, with benefits at the scale of the farm, the landscape and society.
GDNF-deprived sympathetic neurons die via a novel nonmitochondrial pathway
Authors: Yu Li-Ying , Jokitalo Eija , Sun Yun-Fu , Mehlen Patrick , Lindholm Dan , Saarma Mart , Arumäe Urmas
Published: December 2003

The mitochondrial death pathway is triggered in cultured sympathetic neurons by deprivation of nerve growth factor (NGF), but the death mechanisms activated by deprivation of other neurotrophic factors are poorly studied. We compared sympathetic neurons deprived of NGF to those deprived of glial cell line–derived neurotrophic factor (GDNF). In contrast to NGF-deprived neurons, GDNF-deprived neurons did not die via the mitochondrial pathway. Indeed, cytochrome c was not released to the cytosol; Bax and caspase-9 and -3 were not involved; overexpressed Bcl-xL did not block the death; and the mitochondrial ultrastructure was not changed. Similarly to NGF-deprived neurons, the death induced by GDNF removal is associated with increased autophagy and requires multiple lineage kinases, c-Jun and caspase-2 and -7. Serine 73 of c-Jun was phosphorylated in both NGF- and GDNF-deprived neurons, whereas serine 63 was phosphorylated only in NGF-deprived neurons. In many NGF-deprived neurons, the ultrastructure of the mitochondria was changed. Thus, a novel nonmitochondrial caspase-dependent death pathway is activated in GDNF-deprived sympathetic neurons.
Aberrant myofibril assembly in tropomodulin1 null mice leads to aborted heart development and embryonic lethality
Authors: Fritz-Six Kimberly L. , Cox Patrick R. , Fischer Robert S. , Xu Bisong , Gregorio Carol C. , Zoghbi Huda Y. , Fowler Velia M.
Published: December 2003

Tropomodulin1 (Tmod1) caps thin filament pointed ends in striated muscle, where it controls filament lengths by regulating actin dynamics. Here, we investigated myofibril assembly and heart development in a Tmod1 knockout mouse. In the absence of Tmod1, embryonic development appeared normal up to embryonic day (E) 8.5. By E9.5, heart defects were evident, including aborted development of the myocardium and inability to pump, leading to embryonic lethality by E10.5. Confocal microscopy of hearts of E8–8.5 Tmod1 null embryos revealed structures resembling nascent myofibrils with continuous F-actin staining and periodic dots of α-actinin, indicating that I-Z-I complexes assembled in the absence of Tmod1. Myomesin, a thick filament component, was also assembled normally along these structures, indicating that thick filament assembly is independent of Tmod1. However, myofibrils did not become striated, and gaps in F-actin staining (H zones) were never observed. We conclude that Tmod1 is required for regulation of actin filament lengths and myofibril maturation; this is critical for heart morphogenesis during embryonic development.
Espin cross-links cause the elongation of microvillus-type parallel actin bundles in vivo
Authors: Loomis Patricia A. , Zheng Lili , Sekerková Gabriella , Changyaleket Benjarat , Mugnaini Enrico , Bartles James R.
Published: December 2003

The espin actin-bundling proteins, which are the target of the jerker deafness mutation, caused a dramatic, concentration-dependent lengthening of LLC-PK1-CL4 cell microvilli and their parallel actin bundles. Espin level was also positively correlated with stereocilium length in hair cells. Villin, but not fascin or fimbrin, also produced noticeable lengthening. The espin COOH-terminal peptide, which contains the actin-bundling module, was necessary and sufficient for lengthening. Lengthening was blocked by 100 nM cytochalasin D. Espin cross-links slowed actin depolymerization in vitro less than twofold. Elimination of an actin monomer-binding WASP homology 2 domain and a profilin-binding proline-rich domain from espin did not decrease lengthening, but made it possible to demonstrate that actin incorporation was restricted to the microvillar tip and that bundles continued to undergo actin treadmilling at ∼1.5 s−1 during and after lengthening. Thus, through relatively subtle effects on actin polymerization/depolymerization reactions in a treadmilling parallel actin bundle, espin cross-links cause pronounced barbed-end elongation and, thereby, make a longer bundle without joining shorter modules.
Dendritic Cells Initiate Immune Control of Epstein-Barr Virus Transformation of B Lymphocytes In Vitro
Authors: Bickham Kara , Goodman Kiera , Paludan Casper , Nikiforow Sarah , Tsang Ming Li , Steinman Ralph M. , Münz Christian
Published: December 2003

The initiation of cell-mediated immunity to Epstein-Barr virus (EBV) has been analyzed with cells from EBV-seronegative blood donors in culture. The addition of dendritic cells (DCs) is essential to prime naive T cells that recognize EBV-latent antigens in enzyme-linked immunospot assays for interferon γ secretion and eradicate transformed B cells in regression assays. In contrast, DCs are not required to control the outgrowth of EBV-transformed B lymphocytes from seropositive donors. Enriched CD4+ and CD8+ T cells mediate regression of EBV-transformed cells in seronegative and seropositive donors, but the kinetics of T-dependent regression occurs with much greater speed with seropositives. EBV infection of DCs cannot be detected by reverse transcription–polymerase chain reaction with primers specific for mRNA for the EBNA1 U and K exons. Instead, DCs capture B cell debris and generate T cells specific for EBV latency antigens. We suggest that the cross-presentation of EBV-latent antigens from infected B cells by DCs is required for the initiation of EBV-specific immune control in vivo and that future EBV vaccine strategies should target viral antigens to DCs.
Alveolar Macrophage–mediated Killing of Pneumocystis carinii f. sp. muris Involves Molecular Recognition by the Dectin-1 β-Glucan Receptor
Authors: Steele Chad , Marrero Luis , Swain Steve , Harmsen Allen G. , Zheng Mingquan , Brown Gordon D. , Gordon Siamon , Shellito Judd E. , Kolls Jay K.
Published: December 2003

Innate immune mechanisms against Pneumocystis carinii, a frequent cause of pneumonia in immunocompromised individuals, are not well understood. Using both real time polymerase chain reaction as a measure of organism viability and fluorescent deconvolution microscopy, we show that nonopsonic phagocytosis of P. carinii by alveolar macrophages is mediated by the Dectin-1 β-glucan receptor and that the subsequent generation of hydrogen peroxide is involved in alveolar macrophage–mediated killing of P. carinii. The macrophage Dectin-1 β-glucan receptor colocalized with the P. carinii cyst wall. However, blockage of Dectin-1 with high concentrations of anti–Dectin-1 antibody inhibited binding and concomitant killing of P. carinii by alveolar macrophages. Furthermore, RAW 264.7 macrophages overexpressing Dectin-1 bound P. carinii at a higher level than control RAW cells. In the presence of Dectin-1 blockage, killing of opsonized P. carinii could be restored through FcγRII/III receptors. Opsonized P. carinii could also be efficiently killed in the presence of FcγRII/III receptor blockage through Dectin-1–mediated phagocytosis. We further show that Dectin-1 is required for P. carinii–induced macrophage inflammatory protein 2 production by alveolar macrophages. Taken together, these results show that nonopsonic phagocytosis and subsequent killing of P. carinii by alveolar macrophages is dependent upon recognition by the Dectin-1 β-glucan receptor.
Ask Prices, Offers, and Time to Sale in an Online Exchange
Authors: Farmer Amy , Stango Victor
Published: December 2003

By examining an online computer exchange, we find that sellers who place higher nonbinding ask prices have higher outstanding offers and remain on the exchange longer, suggesting a willingness to hold out for higher offers. Additionally, higher ask prices deter buyers from making offers. The results are stronger in thinner market segments, suggesting that gains from waiting for a high price are greater when buyers' tastes are idiosyncratic. These relationships are consistent with models in which buyers engage in costly search and suggest that online exchanges may not eliminate the frictions related to bilateral transactions.
Convergence in the OECD: Transitional Dynamics or Narrowing Steady‐State Differences?
Authors: Andrés Javier , Boscá José E. , Doménech Rafael
Published: December 2003

In this article we show that the picture emerging from models that allow for generalized parameter heterogeneity in convergence equations changes our view of the convergence process within the OECD. Estimation methods that allow for non‐ or partial heterogeneity stress the importance of transitional dynamics. Thus the observed reduction in the dispersion of per capita income is mostly explained by transitional dynamics. When generalized parameter heterogeneity is allowed for, we find that the observed narrowing of incomes has little bearing on transitional dynamics. Convergence in this case happens because the long‐run features of these countries are becoming increasingly similar.
Endangered Species and Timber Harvesting: The Case of Red‐Cockaded Woodpeckers
Authors: Zhang Daowei
Published: December 2003

This article presents a theoretical framework and empirical evidence on the relationship between regulatory uncertainty induced by the possible invasion of an endangered species—the red‐cockaded woodpecker (RCW)—and timber harvesting. The results indicate that landowners whose forests are close to a known or perceived RCW habitat have a high propensity to cut timber and use a clear‐cut method. These preemptive actions are apparently aimed at destroying potential RCW habitat so that the existing values of their property could be protected from the Endangered Species Act (ESA)–related land use limitations.
Posterior midgut and hindgut are both sites of acquisition of Cucurbit aphid-borne yellows virus in Myzus persicae and Aphis gossypii
Authors: Reinbold C. , Herrbach E. , Brault V.
Published: November 2003

Members of the family Luteoviridae (‘luteovirids’) rely strictly on aphid vectors for plant-to-plant transmission. This interaction operates according to a persistent and circulative manner, which implies that the virions are being endocytosed and exocytosed across two epithelial barriers (alimentary tract and accessory salivary glands) in the vector's body. In several luteovirid–aphid vector species combinations, the route of virions in the insect has been investigated ultrastructurally by transmission electron microscopy (TEM). Here, we used TEM to follow the route of Cucurbit aphid-borne yellows virus (CABYV; genus Polerovirus) in its two efficient vector species, Myzus persicae and Aphis gossypii. We demonstrated that CABYV particles are acquired from the gut lumen to the haemocoel through two different sites in both aphid species, i.e. the posterior midgut (as for Beet western yellows virus in M. persicae) and the hindgut (as for Barley yellow dwarf virus complex in cereal aphids). This ‘dual’ tissue specificity of CABYV represents an original situation among viruses in the family Luteoviridae examined so far by TEM. A variety of virion-containing structures (e.g. clathrin-coated and tubular vesicles, endosome-like bodies) are found in intestinal cells of both types in both aphids. Release of virus particles from midgut and hindgut cells into the haemolymph was confirmed by immunotrapping using CABYV-specific antibodies. In accessory salivary glands, transport of CABYV virions across the cells was similar in each aphid species, and occurred by a transcytosis mechanism involving formation of tubular and coated vesicles before release of free virions in the salivary canal.
The mechanism of cell death during West Nile virus infection is dependent on initial infectious dose
Authors: Chu J. J. H. , Ng M. L.
Published: November 2003

The mechanism of West Nile (WN) virus-induced cell death is determined by the initial infectious dose. In Vero cells infected with WN virus at an m.o.i. of 10 or greater, morphological changes characteristic of necrosis were observed as early as 8 h post-infection (p.i.). Pathological changes included extensive cell swelling and loss of plasma membrane integrity, as revealed by optical and electron microscopy. High extracellular lactate dehydrogenase (LDH) activity was observed together with leakage of the high mobility group 1 (HMGB1) protein into the extracellular space. When cells undergo necrosis, they release the HMGB1 protein, a pro-inflammatory mediator cytokine. At high infectious doses, loss of cell plasma membrane integrity was due to the profuse budding of WN progeny virus particles during maturation. When this profuse budding process was disrupted using cytochalasin B, LDH activity was reduced dramatically. In contrast, WN virus-induced cell killing occurred predominantly by apoptosis when cells were infected with an m.o.i. of ⩽1; the process of apoptosis observed was much later after infection (32 h p.i.). Fragmentation of DNA, chromatin condensation and formation of apoptotic bodies were all observed. This WN virus-induced apoptosis pathway was initiated by the release of cytochrome c from the mitochondria and was accompanied by the formation of apoptosomes. In turn, this led to the activation of caspase-9 and –3, and to the cleavage of the poly(ADP-ribose) polymerase.
Proliferative growth of SARS coronavirus in Vero E6 cells
Authors: Ng M.-L. , Tan S.-H. , See E.-E. , Ooi E.-E. , Ling A.-E.
Published: November 2003

An isolate of SARS coronavirus (strain 2003VA2774) was obtained from a patient and used to infect Vero E6 cells. The replication cycle of the virus was followed from 1 to 30 h post-infection (p.i.). It was surprising to observe the swift growth of this human virus in Vero cells. Within the first hour of infection, the most obvious ultrastructural change was the proliferation of the Golgi complexes and related vesicles accompanied by swelling of some of the trans-Golgi sacs. Extracellular virus particles were present by 5 h p.i. in about 5 % of the cells and this increased dramatically to about 30 % of the cell population within an hour (6 h p.i.). Swollen Golgi sacs contained virus nucleocapsids at different stages of maturation. These virus precursors were also in large vacuoles and in close association with membrane whorls. The membrane whorls could be the replication complexes, since they appeared rather early in the replication cycle. As infection progressed from 12 to 21 h p.i., the cytoplasm of the infected cells was filled with numerous large, smooth-membraned vacuoles containing a mixture of mature virus and spherical cores. Several of these vacuoles were close to the cell periphery, ready to export out the mature progeny virus particles via exocytosis. By 24 to 30 h p.i., crystalline arrays of the extracellular virus particles were seen commonly at the cell surface.
Evaluation of attenuation, immunogenicity and efficacy of a bovine parainfluenza virus type 3 (PIV-3) vaccine and a recombinant chimeric bovine/human PIV-3 vaccine vector in rhesus monkeys
Authors: Pennathur Sridhar , Haller Aurelia A. , MacPhail Mia , Rizzi Tom , Kaderi Sepideh , Fernandes Fiona , Bicha Leenas , Schickli Jeanne H. , Tang Roderick S. , Chen Wendy , Nguyen Nick , Mathie Sharon , Mehta Hersh , Coelingh Kathleen L.
Published: November 2003

Restricted replication in the respiratory tract of rhesus monkeys is an intrinsic property of bovine parainfluenza virus type 3 (bPIV-3) strains. This host range phenotype of bPIV-3 has been utilized as a marker to evaluate the attenuation of bPIV-3 vaccines for human use. Two safety, immunogenicity and efficacy studies in primates evaluated and compared three human parainfluenza virus type 3 (hPIV-3) vaccine candidates: biologically derived bPIV-3, a plasmid-derived bPIV-3 (r-bPIV-3) and a chimeric bovine/human PIV-3 (b/hPIV-3). These studies also examined the feasibility of substituting Vero cells, cultured in the presence or absence of foetal bovine serum, for foetal rhesus lung-2 (FRhL-2) cells as the tissue culture substrate for the production of bPIV-3 vaccine. The results demonstrated that (i) Vero cell-produced bPIV-3 was as attenuated, immunogenic and efficacious as bPIV-3 vaccine grown in FRhL-2 cells, (ii) plasmid-derived bPIV-3 was as attenuated, immunogenic and efficacious as the biologically derived bPIV-3 and (iii) the b/hPIV-3 chimera displayed an intermediate attenuation phenotype and protected animals completely from hPIV-3 challenge. These results support the use of bPIV-3 vaccines propagated in Vero cells in human clinical trials and the use of b/hPIV-3 as a virus vaccine vector to express foreign viral antigens.
Facility Location Under Zone Pricing
Authors: Hansen Pierre , Peeters Dominique , Thisse Jacques‐François
Published: December 2003

Zone pricing consists in determining simultaneously several delivered prices together with the zones where these prices apply. A model and algorithm are proposed to determine optimal facility locations, prices, tariff‐zones, and market areas in order to maximize the firm's profit under zone pricing. The resulting nonlinear mixed‐integer program is tackled by projecting the objective function on the price space, solving repeatedly uncapacitated facility location problems for fixed values of the prices. The implicit profit function so defined is optimized by branch‐and‐bound. Computational results are reported.
Competitive Tendering and Optimal Size in the Regional Bus Transportation Industry: An Example from Italy
Authors: Cambini C. , Filippini M.
Published: November 2003

When defining how to implement tendering procedures for the regional bus transportation industry, one of the main problems local authorities have to face is setting the area size to be assigned as franchised monopoly.

This paper's aim is to analyse the topic by combining some empirical results and evidence from recent developments in the Italian regional bus industry. The empirical results show that the bus transportation sector is characterized by the presence of economies of density and scale. These results imply that the best strategy for introducing competition in the bus industry is a competitive tendering approach for an area of given dimension and not necessarily a route‐by‐route tendering. However, it seems that the criterion applied by local authorities in Italy is much more related to political issues—such as jurisdictional boundaries of a municipal or provincial area—than a desire to promote the exploitation of economies of scale and density.
Anticipated Inflation, Liquidity Costs and the Tobin Effect
Authors: Petrucci Alberto
Published: December 2003

This paper analyses the steady‐state effects of inflation on capital accumulation within an optimizing monetary growth model with liquidity costs and an endogenous labour supply. It is assumed that consumption and leisure are perfect complements in the preferences of the representative agent. The particular environment considered, despite the results obtained by the growing literature on inflation and growth with endogenous labour effort, gives support to the Tobin effect, i.e. a positive effect of the money growth rate on capital, labour and output.

(J.E.L.: O42).
Institutional Design as a Commitment Device in Credit Markets with Asymmetric Information: Experimental Evidence
Authors: Di Cagno Daniela , Sciubba Emanuela
Published: December 2003

The aim of this experiment is to test the role of institutional design in credit markets as a commitment device against renegotiation: when there is asymmetric information does a lower degree of centralization enhance efficiency? Does decentralization alleviate the adverse selection problem in credit markets? We run a large‐scale computerized experiment involving 12 different data sets and 3 different uncertainty scenarios on a sample of 120 subjects. The results obtained confirm the superiority of a decentralized institutional framework: the number of poor projects undertaken in a decentralized market was significantly smaller than the number of poor projects undertaken in centralized markets in all the scenarios. This experimental evidence shows that the institutional design is crucial in seeking financial discipline and therefore can shed some light on the debate on ‘Anglo‐Saxon’ versus ‘German–Japanese’ credit practices.

(J.E.L.: C90, D82, G21, L10).
Capital Requirements in a Financially Driven Business Cycle Model
Authors: Mattesini Fabrizio
Published: December 2003

We consider a simple overlapping generations economy where, because of asymmetric information and limited liability both in the loan and the deposits markets, firms have the incentive to undertake less efficient investment projects, while intermediaries have the incentive to monitor a smaller number of firms. Because of the positive relationship between the deposit interest rate and the level of monitoring, the lending activity of intermediaries may cause endogenous fluctuations in the level of economic activity.

In this economy, a higher capital requirement, introduced to render deposit contracts incentive compatible, implies a higher steady state stock of capital, fewer bankruptcies among intermediaries and smaller fluctuations in the level of economic activity.

(J.E.L. E32, D82, G28)
Market Size and Investment Performance of Defaulted Bonds and Bank Loans: 1987–2001
Authors: Altman Edward I. , Pompeii Jason
Published: December 2003

The defaulted and distressed, public and private debt markets in the United States swelled to a record $680 billion (face value) at the end of 2001. The market value of this ‘niche’ segment was approximately $400 billion.

Defaulted security investors enjoyed an excellent year on average, as returns in 2001 were 17.5 per cent on bonds, 13.9 per cent on bank loans, and 15.6 per cent combined defaulted public bonds and private bank loans.

The Altman–New York University Salomon Center Index of Defaulted Bonds grew to over 200 individual issues and a face value of $56.2 billion; the market value was only $11.8 billion. The market–to–face value ratio of the Bond Index grew somewhat to 0.21 from 0.15 one year ago, but remained at a relatively low figure. The face value of our Defaulted Bank Loan Index also grew to $44.7 billion and the market–to–face value ratio remained quite low at 0.53.

The recovery rate on defaulted bonds (price just after default) was very low at 25 cents on the dollar; likewise, the bank loan recovery rate in 2001 was also relatively low at 55 cents on the dollar. With new defaulted bonds rising in 2001 to a record $63.6 billion (default rate of 9.80 per cent) and the default outlook for 2002 high investment opportunities should abound in the distressed debt market.

Indications are that distressed investors (both old and new) are successfully raising funds because investor expectations are buoyant.

(J.E.L.: G21, G33).
Credit Risk Models – Do They Deliver Their Promises? A Quantitative Assessment
Authors: Oderda Gianluca , Dacorogna Michel M. , Jung Tobias
Published: December 2003

We develop a framework to assess the statistical significance of expected default frequency calculated by credit risk models. This framework is then used to analyse the quality of two commercially available models that have become popular among practitioners: KMV Credit Monitor and RiskCalc from Moody’s.

Using a unique database of expected default probability from both vendors, we study both the consistency of the prediction and its timeliness. We introduce the concept of cumulative accuracy profile (CAP) that allows to see in one curve the percentage of defaulting companies captured by the models one year in advance. We also use the Miller's information test to see if the models add information to the S&P rating.

The result of the analysis indicates that these models indeed add relevant information not accounted for by rating alone. Moreover, with respect to rating agencies, the models predict defaults more than ten months in advance on average.

(J.E.L.: C52).
The Taylor Rule and Dynamic Stability in a Small Macroeconomic Model
Authors: Chappell David , Turner Paul
Published: December 2003

In this paper, we embed the Taylor interest rate rule in a simple macroeconomic model with Calvo contracts. We contrast this with the case in which the interest rate is determined by the conventional LM curve along with a fixed value for the monetary aggregate. We derive conditions under which the adjustment of the economy is characterized by a unique saddle–path and show that the conditions required for this to be the case are more stringent when the authorities adopt the Taylor rule. In both cases, the possible failure of the saddle–path condition arises when there are debt–deflation effects in the IS curve. If interest rates are set according to the Taylor rule, then debt–deflation is always enough to cause the failure of the saddle–path condition. However, when interest rates are determined by the LM curve then it is possible that the real balance effect from the LM curve may offset the debt–deflation effect and produce a saddle–path.

(J.E.L. E4, E5).
Reassessment of ‘Cladodus’neilsoni Traquair: a primitive shark from the Lower Carboniferous of East Kilbridge, Scotland
Authors: Sequeira S. E. K. , Coates M. I.
Published: November 2003

The partly articulated specimen of the Palaeozoic (Early Carboniferous) chondrichthyan ‘Cladodus’neilsoni Traquair from East Kilbride has been known since the late nineteenth century. As such, ‘C.’neilsoni Traquair has been cited in numerous publications, but it has become increasingly clear that its anatomy and systematic affinities are obscure. This comprehensive redescription of ‘C.’neilsoni reveals new details of the neurocranium (including presence of an otico‐occipital fissure), dentition, visceral arches (clarifying the condition of the basibranchial pattern plus elongate copula), and pectoral fin. These data refute previously suggested synonymies, such as between ‘C’neilsoni and the contemporaneous Bearsden Stethacanthus. Attribution of ‘C.’neilsoni to the taxonomically unsupportable genus ‘Cladodus’ is rejected, and the species is redesignated as Gutturensisneilsoni gen. nov. Preliminary cladistic analysis places Gutturensisneilsoni within a polytomy including Stethacanthus, the symmoriid Cobelodus, and the root of a monophyletic group of neoselachian‐like genera. ‘ Cladodont’ as a diagnostic term for early chondrichthyan teeth is found to be insufficiently precise, referring to an ill‐defined grade of tooth morphologies present in a wide variety of Palaeozoic genera.
A Review Of Two De Koninck Retzioid Brachiopod Species, And Description Of A New Genus From The Carboniferous Of Europe
Authors: Alvarez Fernando , Brunton C. Howard C.
Published: November 2003

A new neoretziid brachiopod genus, Coveenia, from the Lower Carboniferous of western Europe is erected; the type species is Coveenia ulothrix (de Koninck, 1843), and C. buchiana (de Koninck, 1843, sensu 1887) and C. tilsleia sp. nov. are included, diagnosed and described. Neotypes are selected and illustrated for C. ulothrixC. buchiana.
An Odontogriphid from the Upper Permian of Australia
Authors: Ritchie Alexander , Edgecombe Gregory D.
Published: November 2003

A problematic organism, Bowengriphus perphlegis gen. et sp. nov., is described based on two specimens from the Late Permian Rangal Coal Measures of eastern central Queensland. It displays a double‐looped feeding apparatus bearing small conical elements, considered homologous with that of the supposed lophophorate Odontogriphus omalus Conway Morris, 1976, from the Middle Cambrian Burgess Shale of British Columbia, Canada. Odontogriphids are thus interpreted as a group that survived through the Palaeozoic and made the transition from marine to freshwater environments. Recent proposals that odontogriphids are stem‐group chordates are not well established.
Middle and Upper Cambrian Protoconodonts and Paraconodonts from Hunan, South China
Authors: Xi‐Ping Dong , Bergström Stig M.
Published: November 2003

More than 4200 kg of limestone, representing 980 productive samples, from the upper Middle Cambrian, Upper Cambrian, and lowermost Ordovician in western and north‐western Hunan were processed for paraconodonts, protoconodonts, and euconodonts. The focus of the present paper is on the upper Middle and lower Upper Cambrian interval as it is developed at two, apparently stratigraphically continuous, key sections. The collections studied, which include more than 20,000 specimens and are quite diverse taxonomically, prove that some protoconodonts and paraconodonts are useful biostratigraphically. Previously proposed protoconodont‐paraconodont biozones in Hunan are revised and correlated with recently revised trilobite biozones, as well as with protoconodont‐paraconodont and trilobite biozones in North China. Twenty‐six species and seven conditionally identified species belonging to 13 genera are described. Among these, two genera (Huayuanodontus and Yongshunella) and two species (Westergaardodina elegans and Yongshunella polymorpha) are new. This study has special interest for Cambrian biostratigraphy because the two studied sections are global stratotype candidates for the Middle‐Upper Cambrian series boundary. The level of the Upper‐Middle Cambrian Series boundary, as currently recognized in China (at the base of the Linguagnostus reconditus Trilobite Biozone) is well marked in the paraconodont succession and can be traced into the Swedish standard succession using these fossils. By contrast, another level recently proposed as a potential global Middle‐Upper Cambrian Series boundary level, the base of the Glyptagnostus reticulatus Trilobite Biozone, does not coincide with any marked change in the Hunan conodont species succession useful for local and regional correlation.