bluuebunny/crossref_metadata_2025 huggingface dataset:
Rheological Characterization of Computationally Synthesized Reactor Populations of Hyperbranched Macromolecules: Bivariate Seniority‐Priority Distribution of ldPE
Authors: Iedema Piet D. , Slot Johan J. M. , Kim Dong‐Min , Hoefsloot Huub C. J.
Published: May 2004

Summary: Hyperbranched molecules like low‐density polyethylene (ldPE) adopt a huge variety of molecular architectures. Previous work has shown that it is possible to computationally synthesize these architectures and to characterize them according to radius of gyration. Here, a method is presented and applied on ldPE to characterize populations using rheological quantities in terms of comb‐shaped and Cayley tree structures. Interbranch segments are assigned seniority and priority values that quantify their behavior in relaxation and elastic deformation processes. New general‐purpose algorithms have been developed to derive the full bivariate seniority/priority distribution using a representation from the graph theory of branched architectures. This paper describes the computation of bivariate chain length/degree of branching distributions (CLD/DBD) using a Galerkin finite element method for two scission mechanisms: linear and topological scission. The DBD is calculated using pseudo‐distributions. Random scission is treated with fragment length and branch point redistribution functions as obtained from scission statistics of branched molecules, preferentially yielding short and long fragments. Reactor populations of ldPE architectures are then obtained using computational synthesis. The seniority and priority distributions calculated indeed prove to be an adequate characterization method. They show good comparison, although not a complete overlap, with size characterization using a variant of the radius of gyration. It was possible to calculate a full bivariate seniority/priority fraction distribution, but due to the limited sample size its surface was not smooth. Subsequent work has shown the consequences for the prediction of rheological properties.

Seniority/priority values for segments of molecules for one chain length/number of branch points combination.

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Seniority/priority values for segments of molecules for one chain length/number of branch points combination.
Negative growth control of renal cell carcinoma cell by connexin 32: Possible involvement of Her‐2
Authors: Fujimoto Eriko , Satoh Haruna , Negishi Etsuko , Ueno Koichi , Nagashima Yoji , Hagiwara Kiyokazu , Yamasaki Hiroshi , Yano Tomohiro
Published: May 2004

Connexin (Cx) genes have negative growth effects on tumor cells with certain cell specificity. We have previously reported that Cx32 is specifically downregulated in human renal cell carcinoma cell (RCC) lines as well as cancerous regions of kidneys and that the Cx is expressed in the progenitor cells of the carcinoma. However, the precise role of Cx32 in growth control of RCC cells remains unknown. In this study, we examined whether Cx32 could act in growth control against a human RCC cell, Caki‐2 cell. In order to estimate the cell growth control, we established Caki‐2 cells that have stable expression of Cx32 genes. Cx32 expression in Caki‐2 cells induced contact inhibition of growth and reduced anchorage‐independent growth ability, but did not significantly affect lag phase growth rates. This growth control by Cx32 was dependent on the inhibition of the cell‐cycle transition from G1 to S phase at high cell density, and the inhibition of the cell‐cycle transition related to the suppression of Her‐2 activation. Furthermore, the suppression of Cx32 expression in Caki‐2 cells by short interfering RNA induced the activation of Her‐2. These data suggest that Cx32 has negative growth control of Caki‐2 cells, partly due to the inhibition of the Her‐2 activation. © 2004 Wiley‐Liss, Inc.
Generation and adaptation of computational surface meshes from discrete anatomical data
Authors: Frey Pascal J.
Published: May 2004

Fast and accurate scanning devices are nowadays widely used in many engineering and biomedical fields. The resulting discrete data is usually directly converted into polygonal surface meshes, using ‘brute‐force’ algorithms, often resulting in meshes that may contain several millions of polygons. Simplification is therefore required in order to make storage, computation and display possible if not efficient. In this paper, we present a general scheme for mesh simplification and optimization that allows to control the geometric approximation as well as the element shape and size quality (required for numerical simulations). Several examples ranging from academic to complex biomedical geometries (organs) are presented to illustrate the efficiency and the utility of the proposed approach. Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of viscoelastic behavior and dynamic mechanical relaxation of copolyester based layered silicate nanocomposites using Havriliak–Negami model
Authors: Kalgaonkar Rajendra A. , Nandi Somnath , Tambe Sanjeev S. , Jog Jyoti P.
Published: May 2004

The solid‐state viscoelastic properties are examined for intercalated nanocomposites based on a copolyester and (2‐ethyl‐hexyl)dimethyl hydrogenated‐tallow ammonium montmorillonite. The nanocomposites are prepared via the direct melt intercalation technique using a conventional twin‐screw extruder. Dynamic mechanical thermal analysis of the nanocomposites is conducted using two different test setups. The dynamic mechanical relaxation spectra show an increase in the storage modulus of the nanocomposite over the entire temperature range under study as compared to the pristine polymer (except in the transition region from 70 to 80 °C). These results are analyzed using the empirical Havriliak–Negami (HN) equation. The four temperature independent HN parameters (α, β, E0, and E∞) and one temperature dependent parameter (τ, the relaxation time) are determined by solving the HN equation for each temperature over the range of temperatures. The calculated moduli results fit well with the experimental values of the relaxation spectra for the nanocomposites. This study shows that the HN model can be applied to polymer layered silicate nanocomposites, and it can be used to predict their dynamic mechanical properties over a wide range of temperatures and frequencies a priori. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2657–2666, 2004
Curing kinetics of epoxy resins with hyperbranched polyesters as toughening agents
Authors: Xu Gang , Shi Wenfang , Shen Shijun
Published: May 2004

The effects of hyperbranched polyesters on the cure kinetics of diglycidyl ether of bisphenol A (DGEBA) in the presence of m‐phenylene diamine were investigated with nonisothermal differential scanning calorimetry. The results showed that the addition of hyperbranched polyesters enhanced the cure reaction of DGEBA with m‐phenylene diamine, and this resulted in a reduction of the peak temperature of the curing curve and the activation energy because of the low viscosity and large number of terminal hydroxyl groups. However, when linear poly(ethylene glycol) was added, the activation energy of the blends also slightly decreased, whereas the peak temperature of the curing curve increased. The curing kinetics of the blends were calculated by the isoconversional method of Málek. The two‐parameter autocatalytic model (i.e., the Šesták–Berggren equation) was found to be the most adequate for describing the cure kinetics of the studied systems. The obtained nonisothermal differential scanning calorimetry curves showed results in agreement with those theoretically calculated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2649–2656, 2004
Effect of Dry Cassava Chip Storage on Yield and Functional Properties of Extracted Starch
Authors: Abera Solomon , Rakshit Sudip Kumar
Published: May 2004

Dry cassava chips of variety CMR35‐22‐196 and KU50 were stored at 5 and 30°C up to a period of 8 months. The yield and functional properties of the starches extracted from the chips after 2 months of storage were compared with those of starches extracted from fresh roots and freshly dried chips. Starch yield from dry chips was reduced by up to 5% after 8 months of storage. Functional properties of the starches exhibited a declining trend with increasing storage period of the chips. Peak viscosity and swelling power decreased by up to 30% and 5 g/g, respectively. Paste clarity dropped by up to 30% and syneresis of the gels increased by up to 10% after 8 months storage. A high storage temperature (30°C) was found to increase the changes in functional properties of the starches. The changes in the functional properties, however, were not so severe to negatively affect the application of the dry‐chip starches. All the properties remained within the generally recognized ranges of cassava starches. The use of dry chips for extraction of starch could thus overcome the problems of seasonal glut and closure of factories in low season.
Free radicals in the European periphery: ‘translating’ organic chemistry from Zurich to Barcelona in the early twentieth century
Authors: NIETO-GALAN AGUSTÍ
Published: May 2004

In 1915, after acquiring first-hand knowledge of the new free radical chemistry at the Swiss Federal Institute of Technology (ETH) in Zurich, Antonio García Banús (1888–1955) became professor of organic chemistry at the University of Barcelona and created his own research group, which was to last from 1915 until 1936. He was a gifted teacher and a prolific writer who attempted to introduce international scientific standards into his local environment. This paper analyses the bridges that Banús built between the experimental culture of organic chemistry at the ETH and the University of Barcelona. It presents a case study which aims to provide new historical data for the general analysis of groups who conducted their work in the European periphery.
Impact of spatial aggregation of inputs and parameters on the efficiency of rainfall‐runoff models: A theoretical study using chimera watersheds
Authors: Andréassian Vazken , Oddos Audrey , Michel Claude , Anctil François , Perrin Charles , Loumagne Cécile
Published: May 2004

This paper examines the respective merits of aggregative and disaggregative approaches in hydrological modeling and aims at determining how to identify the most appropriate level of spatial distribution in rainfall‐runoff modeling. The lumped approach is compared with two types of semidistributed approaches to assess the relative importance of rainfall and parameter distribution on modeling results. In order to base these comparisons on a large number of definitely heterogeneous basins, we introduce chimera watersheds. Chimera watersheds associate two actual watersheds of similar size to constitute a third, highly heterogeneous virtual basin, where the knowledge of spatialized flows makes it possible to test disaggregated approaches and to compare them to the lumped approach. We show that the greatest portion (two thirds) of improvement contributed by spatial distribution comes from accounting for rainfall variability. If spatial distribution is considered to be a useful direction leading to improving the reliability of hydrological models, we believe that efforts should be directed first and foremost toward the use of spatially distributed rainfall data and only secondary to the disaggregation of watershed (land‐surface) parameters.
Orientation and motion of a discontinuity from Cluster curlometer capability: Minimum variance of current density
Authors: Haaland S. , Sonnerup B. U. Ö. , Dunlop M. W. , Georgescu E. , Paschmann G. , Klecker B. , Vaivads A.
Published: May 2004

A new technique to derive magnetopause key parameters such as orientation, velocity and thickness from multi‐spacecraft observations is presented. The method is based on four‐spacecraft determination of the current density, variance analysis to estimate the orientation and thereafter integration of the current density across the magnetopause to find the velocity. In cases where the spacecraft separation distance is small compared to the magnetopause thickness, the method can have advantages compared to other multi‐spacecraft techniques. We show an application to Cluster data and compare the results with those from other multi‐spacecraft methods as well as single‐spacecraft methods such as minimum variance of the magnetic field combined with deHoff‐mann‐Teller analysis and the minimum Faraday residue method. Our results indicate that under favorable conditions, the use of Cluster as a curlometer can be very successful.
The cholesterol membrane anchor of the Hedgehog protein confers stable membrane association to lipid-modified proteins
Authors: Peters Carsten , Wolf Alexander , Wagner Melanie , Kuhlmann Jürgen , Waldmann Herbert
Published: May 2004

The Hedgehog proteins are potent organizers of animal development. They carry a cholesterol ester at the C terminus of their signaling domain. The membrane anchoring mediated by this lipophilic modification was studied by means of an approach integrating cell biology, biochemistry, biophysics, and organic chemistry techniques. Sterol-modified and fluorescent-labeled Hedgehog-derived peptides and proteins were synthesized and investigated in biophysical and cell-biological assays. These experiments revealed that cholesterol alone anchors proteins to membranes with significant strength and half-times for spontaneous desorption of several hours. Its membrane anchoring ability is comparable to dual lipidation motifs such as double geranylgeranylation or S-palmitoylation plus S-farnesylation found in other lipidated proteins. The experiments also demonstrate that membrane binding changes dramatically if short lipidated peptides are equipped with a large protein. These data suggest that for Hedgehog release and subsequent signaling an interaction partner such as the Dispatched protein is necessary. In addition to these findings the described approach allows one to correlate biophysical data obtained with model peptides with data determined with fully functional proteins and to combine results from
in vitro
and
in vivo
experiments. It should be generally applicable to other membrane anchors and proteins.
Improving Access to Early Stage Venture Capital in Regional Economies: A New Approach to Investment Readiness
Authors: Mason Colin M. , Harrison Richard T.
Published: May 2004

It is now recognised that many businesses are unsuccessful in raising equity finance because they are not investment ready. This has prompted enterprise support organisations in various countries to develop investment ready programmes. In the UK, the emphasis of these programmes is on providing information on sources of finance and how to access them, and on presentational skills. These are necessary but not sufficient conditions to get a business investment ready because they do not address business development issues which discourage potential investors. These issues are generally company specific and often require the input of significant expertise in order to make a company investable. This paper reviews LINC Scotland's approach, which is based on investment facilitation. It suggests that this approach does effectively address the business development support component of investment readiness at limited public cost and provides useful lessons for the design of investment ready programmes.
Prosodic problems in Swedish children with language impairment: towards a classification of subgroups
Authors: Samuelsson Christina , Nettelbladt Ulrika
Published: May 2004

Background: Symptoms of prosodic problems have been found in Swedish children with language impairment at word and phrase level and possibly also at discourse level.

Aims: The aim was twofold. First, to characterize a group of children with prosodic problems compared with children with normal language development. Second, to investigate the possibilities to classify subgroups of prosodic problems.

Methods & Procedures: A new Swedish assessment procedure for prosody that captures prosodic features at word, phrase and discourse level was used. Twenty‐five children with prosodic problems and 25 children with typically developing language matched by age, gender and regional dialect participated in the study. Pretesting included tests of language comprehension, grammatical skills and oral motor skills.

Outcomes & Results: The difference between the experimental and control groups was highly significant in all parts of the procedure. The total score of the procedure significantly correlated with grammatical abilities measured in the pretesting procedure, but there was no correlation with the other linguistic abilities measured in the pretesting procedure.

Conclusions: The results indicate a possible differentiation into two different subgroups, one with primarily phonetic and/or linguistic problems, the other with prosodic problems at discourse level possibly related to pragmatic problems.
Ask a silly question: two decades of troublesome trials
Authors: Pring Tim
Published: May 2004

Background: Randomized control trials and the use of meta‐analysis in systematic reviews are the basis of evidence‐based practice. The paper reviews their use in the development of evidence‐based practice in speech and language therapy.

Aims: It is accepted that clinical outcome research should develop in a sequence of phases. A model of this process is described. Examples of outcome research in speech and language therapy are used to illustrate the use of the model and the problems that result when it is not followed.

Main Contribution: Existing research has largely ignored the agreed procedures for outcome research. Particular problems have arisen when randomized control trials are used to examine therapy provision for a client group. Clients are often a heterogeneous group and receive different therapies. Consequently, it is unlikely that trials can obtain significant results, nor, if they do, can they provide clinicians with useful information about the choice of treatment. Systematic reviews are equally uninformative. Many of the studies on which they are based have methodological problems and their frequent failure adequately to describe the therapies used mean that reviews cannot evaluate or compare different types of therapy.

Conclusions: Researchers in speech and language therapy have given too little attention to the basics of clinical outcome research. This requires that clinical and theoretical insights are used to identify specific therapies for well‐defined groups of clients. These therapies must be tested first in efficacy, then in effectiveness studies, and their results should be disseminated to clinicians. Only then is it meaningful to carry out large‐scale trials of the effectiveness of therapy provision for a client group or to conduct systematic reviews of existing research.
Validity and completeness of death reporting and registration in a rural district of Vietnam
Authors: Tran Quang Huy  , Nguyen Hoang Long  , Dinh Phuong Hoa  , Byass Peter , Eriksson Bo
Published: May 2004

Aims: Assessment was made of the validity of mortality estimates based on data collected during 1999 - 2000 by quarterly follow-up visits and compared with other methods (re-census, communal death registration, and neighbourhood survey). Methods: This study was carried out within a longitudinal epidemiological laboratory in Bavi District, Vietnam (called FilaBavi), covering a sample of 11,089 households with 51,024 inhabitants. Deaths within FilaBavi during 1999 - 2000 were collected by four methods and compared: quarterly household follow-ups, the re-census carried out in 2001, the Commune Population Registration System (CPRS), and a neighbourhood survey. Results: Within these four methods, a total of 471 deaths were detected in the FilaBavi sample. Quarterly household follow-ups detected 470 deaths (99.8%). The re-census missed 19 deaths, of which eight were infants, and two-thirds of the missed deaths fell in 1999. The CPRS missed 89 cases (19%), the majority being infant and elderly deaths. The neighbourhood survey over-reported deaths. Conclusions: Quarterly follow-ups were the best method for death registration. The re-census approach was less complete, with problems of recall bias. The completeness and quality of death registration by CPRS was low, especially for infant and elderly mortality.
Mortality from cardiovascular diseases in Bavi District, Vietnam
Authors: Van Minh Hoang , Byass Peter , Wall Stig
Published: May 2004

Aims: Like other developing countries, Vietnam is undergoing epidemiological transition, which is characterized by many changes in terms of morbidity and mortality patterns. The fact that cardiovascular diseases (CVD) are leading causes of death in hospitals in the whole country was ascertained from annual statistics. However, the magnitude of the burden of mortality from CVD at the community level remained unknown. The aims of the study were to outline CVD mortality during health transition in a rural community in the north of Vietnam and to examine associations between CVD mortality and the socioeconomic status of the population. Methods: Within an established demographic surveillance system (DSS), verbal autopsy (VA) was used to identify the burden of mortality from CVD. Cohort analysis was used in this study to measure associations between CVD mortality and socioeconomic determinants. Results: CVD emerged as a leading cause of death in the study area, accounting for more than infectious and parasitic diseases combined. CVD killed many people among the most economically productive age group, both men and women, in all socioeconomic groups. Occupational status was shown to be significantly associated with CVD mortality. Discussion: Already at this point in the epidemiological transition, there is evidence of a substantial burden of CVD in rural Vietnam. Although this study was not able to show trends, the current situation is a cause for concern in health policy and planning. Verbal autopsy methods and CVD risk factor evaluations will form important parts of future research agendas.
The economic burden of unintentional injuries: a community-based cost analysis in Bavi, Vietnam
Authors: Nguyen Xuan Thanh  , Hoang Minh Hang  , Nguyen Thi Kim Chuc  , Lindholm Lars
Published: May 2004

Aims: Relatively little is known about patterns of injury at the community level in Vietnam and their economic consequences. This study sought to estimate the costs of various unintentional injuries in Bavi District during one year; to describe how costs depended on gender, age, circumstances, and severity of injury; and to describe how the economic burden of unintentional injuries was distributed between households, government, and the health insurance agency. Methods: A cohort study was undertaken, which involved four cross-sectional household surveys among sampled communities in the Bavi District during the year 2000, each asking about injuries in the preceding three months. The costing system in public healthcare in Vietnam was applied as well as information from the victims. Results: The total cost of injuries over one year in Bavi District was estimated to be D3,412,539,000 (Vietnamese dong) (US$235,347), equivalent to the annual income of 1,800 people. In total, 90% of this economic burden fell on households, only 8% on government, and 2% on the health insurance agency. The cost of a severe injury to the victim corresponded to approximately seven months of earned income. Home and traffic injuries together accounted for more than 80% of the total cost, 45% and 38% respectively. The highest unit cost was related to traffic injuries, followed by home, ``other'', work-related, and school injuries in descending order. Discussion: The results can be considered as an economic baseline that can be used in evaluations of future interventions aimed at preventing injuries.
Self-reported illness and use of health services in a rural district of Vietnam: findings from an epidemiological field laboratory
Authors: Kim Bao Giang  , Allebeck Peter
Published: May 2004

Aims: The aims of the study were to assess the pattern of self-reported illness as well as use of health services in a rural district in Vietnam, and to analyse these in relation to gender, age, educational level, occupation, and economic status. Methods: A population-based survey of 11,089 households was conducted in 1999. Through household interviews, data were collected on self-reported health, use of health services during four weeks prior to the interview, and other background factors. Results: The prevalence of self-reported illness was 48%. Cough, fever, and headache were the most commonly reported symptoms (20%) while cardiovascular disorders were least reported (0.6%). Occurrence of illness was significantly lower in groups with higher education, especially among men, but there was no difference between occupational and economic groups. Self-treatment was very common (69%). Private health facilities were used to a large extent, while community health stations played a less important role. Use of district hospitals was significantly higher among employed people. Discussion: An epidemiological field laboratory enabled analysis of self-reported illness and use of health services, which is important for planning of health services. We found a high level of reported illness but a very low utilization of community health services. Better knowledge about illness patterns could be important for improving quality of and access to community health services.
Knowledge of tuberculosis and associated health-seeking behaviour among rural Vietnamese adults with a cough for at least three weeks
Authors: Nguyen Phuong Hoa  , Thorson Anna E. K. , Nguyen Hoang Long  , Diwan Vinod K.
Published: May 2004

Aims: Good general lay knowledge of tuberculosis (TB), its cause and treatment is considered important for both prompt healthcare seeking and adherence to treatment. The main aim of this study was to describe the knowledge of TB among men and women with a cough for more than three weeks and to see how their health seeking related to TB knowledge. Methods: A population-based survey was carried out within a demographic surveillance site in Vietnam. The study population included 35,832 adults aged 15 years or over. Cough cases were identified at household level and structured interviews were carried out with all cases of cough in person. Results: A total of 559 people (1.6%) reported coughing with a duration of three weeks or longer (259 men and 300 women). A large proportion of individuals with a cough for more than three weeks had limited knowledge of the causes, transmission modes, symptoms, and curability of TB. Men had a significantly higher knowledge score than women (3.04 vs 2.55). Better knowledge was significantly related to seeking healthcare and seeking hospital care. More men than women did not take any health care action at all. Discussion: Health education for TB thus seems to be useful, but efforts must be made to ensure that both men and women in different socioeconomic contexts can access the information.
Faces of poverty: sensitivity and specificity of economic classifications in rural Vietnam
Authors: Nguyen Duy Khe  , Eriksson Bo , Do Nguyen Phuong  , Höjer Bengt , Diwan Vinod K
Published: May 2004

Aims: Poverty concepts and measurements have occupied philosophers for centuries and are subject to debate by researchers. A wide range of possible measures have been developed and used. Most research is country specific and different methods produce different pictures of poverty. This study aimed to compare measures of poverty within an epidemiological field laboratory in Bavi District, northern Vietnam (FilaBavi) and specifically to find out whether the official economic classification made by the local authority matched other measurements of socioeconomic status. Methods: Structured questionnaires were used to collect socioeconomic information in 11,547 households. In addition, the official classification for individual households was recorded. Five economic indicators were constructed: income, expenditure, household assets, housing conditions, and local authority's estimation. Results: Official economic classification and housing score were symmetrically distributed, while assets score and particularly income were highly skewed. Design effects were high because of high intra-cluster correlations. No indicator was closely correlated with any other. Sensitivity and positive predictive value for poverty were generally low for all indicators. Discussion: The authors' findings do not suggest that any of the indicators used is substantially better than the other or better than the Official Economic Classification made by local authority. The results also show that no indicator is particularly useful to predict the values of any other indicator and different poverty indicators may classify different socioeconomic groups as poor.
Characterization of a mobilization-competent simian immunodeficiency virus (SIV) vector containing a ribozyme against SIV polymerase
Authors: Morris Kevin V. , Grahn Robert A. , Looney David J. , Pedersen Niels C.
Published: May 2004

Exploitation of the intracellular virus machinery within infected cells to drive an anti-viral gene therapy vector may prove to be a feasible alternative to reducing viral loads or overall virus infectivity while propagating the spread of a therapeutic vector. Using a simian immunodeficiency virus (SIV)-based system, it was shown that the pre-existing retroviral biological machinery within SIV-infected cells can drive the expression of an anti-SIV pol ribozyme and mobilize the vector to transduce neighbouring cells. The anti-SIV pol ribozyme vector was derived from the SIV backbone and contained the 5′- and 3′LTR including transactivation-response, Ψ and Rev-responsive elements, thus requiring Tat and Rev and therefore limiting expression to SIV-infected cells. The data presented here show an early reduction in SIV p27 levels in the presence of the anti-SIV pol ribozyme, as well as successful mobilization (vector RNA constituted ∼17 % of the total virus pool) and spread of the vector containing this ribozyme. These findings provide direct evidence that mobilization of an anti-retroviral SIV gene therapy vector is feasible in the SIV/macaque model.
Interaction of classical swine fever virus with dendritic cells
Authors: Carrasco C. P. , Rigden R. C. , Vincent I. E. , Balmelli C. , Ceppi M. , Bauhofer O. , Tâche V. , Hjertner B. , McNeilly F. , van Gennip H. G. , McCullough K. C. , Summerfield A.
Published: May 2004

Functional disruption of dendritic cells (DCs) is an important strategy for viral pathogens to evade host defences. Monocytotropic viruses such as classical swine fever virus (CSFV) could employ such a mechanism, since the virus can suppress immune responses and induce apoptosis without infecting lymphocytes. Here, CSFV was shown to infect and efficiently replicate in monocyte- and in bone marrow-derived DCs. Interestingly, the infected DCs displayed neither modulated MHC nor CD80/86 expression. Stimulation of DCs with IFN-α/TNF-αor polyinosinic–polycytidylic acid (pIC) induced phenotypic maturation with increased MHC and CD80/86 expression, both with mock-treated and infected DCs. In addition, the T cell stimulatory capacity of CSFV-infected DCs was maintained both in a polyclonal T cell stimulation and in specific antigen-presentation assays, requiring antigen uptake and processing. Interestingly, similar to macrophages, CSFV did not induce IFN-αresponses in these DCs and even suppressed pIC-induced IFN-αinduction. Other cytokines including interleukin (IL)-6, IL-10, IL-12 and TNF-αwere not modulated. Taken together, these results demonstrated that CSFV can replicate in DCs and control IFN type I responses, without interfering with the immune reactivity. These results are interesting considering that DC infection with RNA viruses usually results in DC activation.
Unusually long target site duplications flanking some of the long terminal repeats of human endogenous retrovirus K in the human genome
Authors: Mamedov Ilgar Z. , Lebedev Yuri B. , Sverdlov Eugene D.
Published: May 2004

Human endogenous retroviruses (HERVs) make up a substantial part of the human genome. HERVs and solitary long terminal repeats (solo LTRs) are usually flanked by 4–6 nt short direct repeats through the well-known mechanism of their integration. A number of solo LTRs flanked by unusually long direct repeats were detected in the human genome. These unusual structures might be a product of an alternative virus insertion mechanism.
Cationic phosphorus-containing dendrimers reduce prion replication both in cell culture and in mice infected with scrapie
Authors: Solassol Jérôme , Crozet Carole , Perrier Véronique , Leclaire Julien , Béranger Florence , Caminade Anne-Marie , Meunier Bernard , Dormont Dominique , Majoral Jean-Pierre , Lehmann Sylvain
Published: May 2004

Over the last 30 years, many drugs have been tested both in cell culture and in vivo for their ability to prevent the generation of prions and the development of transmissible spongiform encephalopathies. Among the compounds tested, dendrimers are defined by their branched and repeating molecular structure. The anti-prion activity of new cationic phosphorus-containing dendrimers (P-dendrimers) with tertiary amine end-groups was tested. These molecules had a strong anti-prion activity, decreasing both PrPSc and infectivity in scrapie-infected cells at non-cytotoxic doses. They can bind PrP and decrease the amount of pre-existing PrPSc from several prion strains, including the BSE strain. More importantly, when tested in a murine scrapie model, the dendrimers were able to decrease PrPSc accumulation in the spleen by more than 80 %. These molecules have a high bio-availability and therefore exhibit relevant potential for prion therapeutics for at least post-exposure prophylaxis.
Molecular determinants of antigenicity of two subtypes of the tick-borne flavivirus Omsk haemorrhagic fever virus
Authors: Li Li , Rollin Pierre E. , Nichol Stuart T. , Shope Robert E. , Barrett Alan D. T. , Holbrook Michael R.
Published: May 2004

In 1964, D. H. Clarke defined two antigenic subtypes of Omsk haemorrhagic fever virus (OHFV) based on polyclonal antibody absorption and haemagglutination assays. The current report defines the molecular basis for these antigenic subtypes by comparison of the complete genomes of OHFV strains Kubrin (subtype I) and Bogoluvovska (subtype II). There were six nucleotide differences between these two strains throughout the entire genome and they encoded four amino acid changes including three in the viral envelope (E) protein. Two of these changes were in solvent-exposed regions of domain 3 of the E protein, one of which lies in a region that could easily function in virus–host cell or virus–antibody interactions. These results demonstrate the minimal changes that are required to significantly alter the antigenicity of flaviviruses and also demonstrate the tremendous genetic stability of the tick-borne flaviviruses.
Identification of small-animal and primate models for evaluation of vaccine candidates for human metapneumovirus (hMPV) and implications for hMPV vaccine design
Authors: MacPhail Mia , Schickli Jeanne H. , Tang Roderick S. , Kaur Jasmine , Robinson Christopher , Fouchier Ron A. M. , Osterhaus Albert D. M. E. , Spaete Richard R. , Haller Aurelia A.
Published: May 2004

Human metapneumovirus (hMPV), a recently identified paramyxovirus, is the causative agent of respiratory tract disease in young children. Epidemiological studies have established the presence of hMPV in retrospective as well as current clinical samples in Europe, USA, Canada, Hong Kong and Australia. The hMPV disease incidence rate varied from 7 to 12 %. This rate of disease attack places hMPV in severity between respiratory syncytial virus and human parainfluenza virus type 3, two common respiratory pathogens of young children, the elderly and immunosuppressed individuals. To evaluate the effectiveness and safety of future hMPV antiviral drugs, therapeutic and prophylactic monoclonal antibodies (mAbs), and vaccine candidates, it was necessary to identify small-animal and primate models that efficiently supported hMPV replication in the respiratory tract and produced neutralizing serum antibodies, commonly a clinical correlate of protection in humans. In this study, various rodents (mice, cotton rats, hamsters and ferrets) and two primate species, rhesus macaques and African green monkeys (AGMs), were evaluated for hMPV replication in the respiratory tract. The results showed that hamsters, ferrets and AGMs supported hMPV replication efficiently and produced high levels of hMPV-neutralizing antibody titres. Hamsters vaccinated with subgroup A hMPV were protected from challenge with subgroup A or subgroup B hMPV, which has implications for hMPV vaccine design. Although these animal models do not mimic human hMPV disease signs, they will nevertheless be invaluable for the future evaluation of hMPV antivirals, mAbs and vaccines.
Priming with CpG-enriched plasmid and boosting with protein formulated with CpG oligodeoxynucleotides and Quil A induces strong cellular and humoral immune responses to hepatitis C virus NS3
Authors: Yu Hong , Babiuk Lorne A. , van Drunen Littel-van den Hurk Sylvia
Published: May 2004

Cell-mediated immune responses to hepatitis C virus (HCV) proteins play a key role in recovery from infection. The NS3 protein of HCV is of special interest, since it is one of the most conserved proteins and NS3-specific immune responses are stronger and more frequently observed in patients resolving the infection than in chronically infected patients. Since these characteristics make NS3 an attractive vaccine candidate, the objective of this study was to optimize NS3-specific immune responses. Results from this group first demonstrated that a plasmid enriched with 24 CpG motifs (pBISIA24-NS3) tends to induce the strongest and most consistent Th1-biased immune response. Subsequently, it was shown that NS3 formulated with CpG oligodeoxynucleotide and Quil A (rNS3+CpG+Quil A) adjuvants induces a balanced immune response in mice, whereas rNS3 combined with either CpG or Quil A elicits a Th2-biased response. To further enhance NS3-specific cell-mediated immune responses, a vaccination regime consisting of priming with pBISIA24-NS3, followed by boosting with rNS3+CpG+Quil A, was explored in mice and pigs. When compared to immunization with rNS3+CpG+Quil A, this regime shifted the immune response to a Th1-type response and, accordingly, enhanced MHC I-restricted killing by cytotoxic T lymphocytes in mice. Although immunization with pBISIA24-NS3 also induced a Th1-biased response, including cytotoxicity in the mice, the humoral response was significantly lower than that induced by the DNA prime–protein boost regime. These results demonstrate the advantage of a DNA prime–protein boost approach in inducing a strong NS3-specific cell-mediated, as well as humoral, immune response, in both inbred laboratory and outbred large animal species.
Characterization of regulatory elements within the coat protein (CP) coding region of Tobacco mosaic virus affecting subgenomic transcription and green fluorescent protein expression from the CP subgenomic RNA promoter
Authors: Man Michal , Epel Bernard L.
Published: May 2004

A replicon based on Tobacco mosaic virus that was engineered to express the open reading frame (ORF) of the green fluorescent protein (GFP) gene in place of the native coat protein (CP) gene from a minimal CP subgenomic (sg) RNA promoter was found to accumulate very low levels of GFP. Regulatory regions within the CP ORF were identified that, when presented as untranslated regions flanking the GFP ORF, enhanced or inhibited sg transcription and GFP expression. Full GFP expression from the CP sgRNA promoter required more than the first 20 nt of the CP ORF but not beyond the first 56 nt. Further analysis indicated the presence of an enhancer element between nt +25 and +55 with respect to the CP translation start site. The inclusion of this enhancer sequence upstream of the GFP ORF led to elevated sg transcription and to a 50-fold increase in GFP accumulation in comparison with a minimal CP promoter in which the entire CP ORF was displaced by the GFP ORF. Inclusion of the 3′-terminal 22 nt had a minor positive effect on GFP accumulation, but the addition of extended untranslated sequences from the 3′ terminus of the CP ORF downstream of the GFP ORF was basically found to inhibit sg transcription. Secondary structure analysis programs predicted the CP sgRNA promoter to reside within two stable stem–loop structures, which are followed by an enhancer region.
Evidence of rotavirus intragenic recombination between two sublineages of the same genotype
Authors: Parra Gabriel I. , Bok Karin , Martínez Magaly , Gomez Jorge A.
Published: May 2004

Rotavirus G4 prevalence increased during the past decade, with one of the highest prevalences reported during rotavirus surveillance in Argentina. Intragenotype diversity analysis has led to its subdivision into lineages (I and II) and sublineages (Ia–Id). On analysis of Argentine and G4 VP7 sequences from other locations, one Argentine strain (ArgRes1723) appeared to be an intermediate between G4 sublineages Ib and Ic. Similarity and bootscanning analyses and Sawyer's test were carried out to demonstrate the recombinant nature of this strain. It was concluded that intragenic recombination occurred between sequences of sublineages Ib and Ic, with a crossover point between nucleotide positions 336 and 387. This study constitutes the first report of a mechanism of evolution in rotaviruses that is currently considered unusual – a recombination event between two strains of the same rotavirus genotype. These results will help increase current knowledge about rotavirus evolution and divergence, improving our understanding of the adaptation mechanisms used by these viruses.
Significance of the 3′-terminal region in minus-strand RNA synthesis of Hibiscus chlorotic ringspot virus
Authors: Wang Hai-He , Wong Sek-Man
Published: May 2004

RNA-dependent RNA polymerase (RdRp) was solubilized from crude extracts of Hibiscus cannabinus infected by Hibiscus chlorotic ringspot virus (HCRSV), a member of the Carmoviridae. After treatment of the extracts with micrococcal nuclease to remove the endogenous templates, the full-length genomic RNA and the two subgenomic RNAs were efficiently synthesized by the partially purified RdRp complex in vitro. When the full-length RNAs of Potato virus X, Tobacco mosaic virus, Odontoglossum ringspot virus and Cucumber mosaic virus were used as templates, no detectable RNA was synthesized. Synthesis of HCRSV minus-strand RNA was shown to initiate opposite the 3′-terminal two C residues at the 3′ end in vitro and in vivo. The CCC-3′ terminal nucleotide sequence was optimal and nucleotide variations from CCC-3′ diminished minus-strand synthesis. In addition, two putative stem–loops (SLs) located within the 3′-terminal 87 nt of HCRSV plus-strand RNA were also essential for minus-strand RNA synthesis. Deletion or disruption of the structure of these two SLs severely reduced or abolished RNA synthesis. HCRSV RNA in which the two SLs were replaced with the SLs of Turnip crinkle virus could replicate in kenaf protoplasts, indicating that functionally conserved structure, rather than nucleotide sequence, plays an important role in the minus-strand synthesis of HCRSV. Taken together, the specific sequence CCC at the 3′ terminus and the two SLs structures located in the 3′UTR are essential for efficient minus-strand synthesis of HCRSV.
Inhibition of the Epstein–Barr virus lytic cycle by Zta-targeted RNA interference
Authors: Chang Yao , Chang Shih-Shin , Lee Heng-Huan , Doong Shin-Lian , Takada Kenzo , Tsai Ching-Hwa
Published: May 2004

Epstein–Barr virus (EBV) reactivation into the lytic cycle plays certain roles in the development of EBV-associated diseases, so an effective strategy to block the viral lytic cycle may be of value to reduce the disease risk or to improve the clinical outcome. This study examined whether the EBV lytic cycle could be inhibited using RNA interference (RNAi) directed against the essential viral gene Zta. In cases of EBV reactivation triggered by chemicals or by exogenous Rta, Zta-targeted RNAi prevented the induction of Zta and its downstream genes and further blocked the lytic replication of viral genomes. This antiviral effect of RNAi was not likely to be mediated by activation of the interferon pathway, as phosphorylation of STAT1 was not induced. In addition, novel EBV-infected epithelial cells showing constitutive activation of the lytic cycle were cloned; such established lytic infection was also suppressed by Zta-targeted RNAi. These results indicate that RNAi can be used to inhibit the EBV lytic cycle effectively in vitro and could also be of potential use to develop anti-EBV treatments.
Enhanced hepatitis C virus NS3 specific Th1 immune responses induced by co-delivery of protein antigen and CpG with cationic liposomes
Authors: Jiao Xuanmao , Wang Richard Yan-Hui , Qiu Qi , Alter Harvey J. , Shih J. Wai-Kuo
Published: May 2004

Mice were immunized intramuscularly with free recombinant hepatitis C virus (HCV) NS3 (non-structural protein 3) protein, liposomes encapsulating rNS3 or rNS3 and CpG mixture, liposomes co-encapsulating rNS3 and CpG or liposomes co-encapsulating rNS3 and GpC. Liposomes co-encapsulating rNS3 and CpG induced a much higher titre of anti-HCV NS3 IgG and the dominant IgG subtype was IgG2a. Liposomes co-encapsulating rNS3 and GpC also induced high levels of anti-HCV NS3 IgG antibody, but the dominant IgG subtype was still IgG1, the same as in free HCV/NS3 immunized mice. Liposomes encapsulating rHCV NS3 and the mixture of rHCV NS3 and CpG did not increase the antibody response but switched the IgG subtype. A cytokine profile analysis revealed that the levels of Th1 cytokines in the mice immunized with liposomes co-encapsulating rHCV NS3 and CpG were significantly higher than in other mice while the levels of Th2 cytokine were significantly lower than in the mice immunized with naked rNS3. IL-12 in the mice immunized with liposome-NS3-CpG was significantly higher than in other mice. In conclusion, liposomes co-encapsulating HCV NS3 and CpG are a good candidate vaccine to induce strong Th1 immune responses against hepatitis C viruses.
Identification of a region of the virus genome involved in murine gammaherpesvirus 68-induced splenic pathology
Authors: Dutia Bernadette M. , Roy Douglas J. , Ebrahimi Bahram , Gangadharan Babunilayam , Efstathiou Stacey , Stewart James P. , Nash Anthony A.
Published: May 2004

Infection with the murine gammaherpesvirus MHV-68 has profound effects on splenic and mediastinal lymph node pathology in mice which lack the interferon-γ receptor (IFN-γ R−/−). In these mice MHV-68 infection causes fibrosis and loss of lymphocytes in the spleen and the mediastinal lymph node as well as interstitial pulmonary fibrosis and fibrotic changes in the liver. The changes are associated with transient elevated latent virus loads in the spleen. Four independent virus mutants with insertions and/or deletions in the left end of the genome fail to induce the pathological changes and establish latency at normal levels in the spleen. The data indicate that the pathology does not correlate with any of the known genes encoded within this region of the genome, genes M1–M4 and the eight vtRNAs. Northern analysis of mRNAs transcribed by wild-type and mutant viruses shows that at least two uncharacterized transcripts are encoded within this region. These transcripts are absent in the mutant viruses and are candidates for the virus genes responsible for the aberrant pathology in IFN-γ R−/− mice.