bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clink, a Nanovirus-Encoded Protein, Binds both pRB and SKP1
Authors: Aronson Marie N. , Meyer Alain D. , Györgyey Jànos , Katul Lina , Vetten H. Josef , Gronenborn Bruno , Timchenko Tatiana 
Published: July 2002

ABSTRACT

Clink, a 20-kDa protein of faba bean necrotic yellows virus, a single-stranded DNA plant virus, interacts with pRB family members and a SKP1 homologue from
Medicago sativa
. An LxCxE motif and an F-box of Clink mediate the interactions with the respective proteins. The capacity of Clink to bind pRB correlates with its ability to stimulate viral replication. Interaction of a single protein with the cell cycle regulator pRB and SKP1, a constituent of the ubiquitin-protein turnover pathway, appears to be a novel feature. Hence, Clink may represent a new class of viral cell cycle modulators.
Biochemical Characterization of the Helper Component of
Cauliflower Mosaic Virus
Authors: Hebrard Eugenie , Drucker Martin , Leclerc Denis , Hohn Thomas , Uzest Marilyne , Froissart Remy , Strub Jean-Marc , Sanglier Sarah , van Dorsselaer Alain , Padilla Andre , Labesse Gilles , Blanc Stephane 
Published: July 2002

ABSTRACT

The helper component of
Cauliflower mosaic virus
is encoded by viral gene II. This protein (P2) is dispensable for virus replication but required for aphid transmission. The purification of P2 has never been reported, and hence its biochemical properties are largely unknown. We produced the P2 protein via a recombinant baculovirus with a His tag fused at the N terminus. The fusion protein was purified by affinity chromatography in a soluble and biologically active form. Matrix-assisted laser desorption time-of-flight mass spectrometry demonstrated that P2 is not posttranslationally modified. UV circular dichroism revealed the secondary structure of P2 to be 23% α-helical. Most α-helices are suggested to be located in the C-terminal domain. Using size exclusion chromatography and aphid transmission testing, we established that the active form of P2 assembles as a huge soluble oligomer containing 200 to 300 subunits. We further showed that P2 can also polymerize as long paracrystalline filaments. We mapped P2 domains involved in P2 self-interaction, presumably through coiled-coil structures, one of which is proposed to form a parallel trimer. These regions have previously been reported to also interact with viral P3, another protein involved in aphid transmission. Possible interference between the two types of interaction is discussed with regard to the biological activity of P2.
Ty1 Proteolytic Cleavage Sites Are Required for Transposition: All Sites Are Not Created Equal
Authors: Merkulov Gennady V. , Lawler Joseph F. , Eby Yolanda , Boeke Jef D. 
Published: July 2002

ABSTRACT

The retroviral protease is a key enzyme in a viral multienzyme complex that initiates an ordered sequence of events leading to virus assembly and propagation. Viral peptides are initially synthesized as polyprotein precursors; these precursors undergo a number of proteolytic cleavages executed by the protease in a specific and presumably ordered manner. To determine the role of individual protease cleavage sites in Ty1, a retrotransposon from
Saccharomyces cerevisiae
, the cleavage sites were systematically mutagenized. Altering the cleavage sites of the yeast Ty1 retrotransposon produces mutants with distinct retrotransposition phenotypes. Blocking the Gag/PR site also blocks cleavage at the other two cleavage sites, PR/IN and IN/RT. In contrast, mutational block of the PR/IN or IN/RT sites does not prevent cleavage at the other two sites. Retrotransposons with mutations in each of these sites have transposition defects. Mutations in the PR/IN and IN/RT sites, but not in the Gag/PR site, can be complemented in
trans
by endogenous Ty1 copies. Hence, the digestion of the Gag/PR site and release of the protease N terminus is a prerequisite for processing at the remaining sites; cleavage of PR/IN is not required for the cleavage of IN/RT, and vice versa. Of the three cleavage sites in the Gag-Pol precursor, the Gag/PR site is processed first. Thus, Ty1 Gag-Pol processing proceeds by an ordered pathway.
Neutralization of Hepatitis A Virus (HAV) by an Immunoadhesin Containing the Cysteine-Rich Region of HAV Cellular Receptor-1
Authors: Silberstein Erica , Dveksler Gabriela , Kaplan Gerardo G. 
Published: July 2002

ABSTRACT
Hepatitis A virus (HAV) infects African green monkey kidney (AGMK) cells via the HAV cellular receptor-1 (havcr-1), a mucin-like type 1 integral-membrane glycoprotein of unknown natural function. The ectodomain of havcr-1 contains an N-terminal immunoglobulin-like cysteine-rich region (D1), which binds protective monoclonal antibody (MAb) 190/4, followed by an O-glycosylated mucin-like threonine-serine-proline-rich region that extends D1 well above the cell surface. To study the interaction of HAV with havcr-1, we constructed immunoadhesins fusing the hinge and Fc portion of human IgG1 to D1 (D1-Fc) or the ectodomain of the poliovirus receptor (PVR-Fc) and expressed them in CHO cells. These immunoadhesins were secreted to the cell culture medium and purified through protein A-agarose columns. In a solid-phase assay, HAV bound to D1-Fc in a concentration-dependent manner whereas background levels of HAV bound to PVR-Fc. Binding of HAV to D1-Fc was blocked by treatment with MAb 190/4 but not with control MAb M2, which binds to a tag epitope introduced between the D1 and Fc portions of the immunoadhesin. D1-Fc neutralized approximately 1 log unit of the HAV infectivity in AGMK cells, whereas PVR-Fc had no effect in the HAV titers. A similarly poor reduction in HAV titers was observed after treating the same stock of HAV with murine neutralizing MAbs K2-4F2, K3-4C8, and VHA 813. Neutralization of poliovirus by PVR-Fc but not by D1-Fc indicated that the virus-receptor interactions were specific. These results show that D1 is sufficient for binding and neutralization of HAV and provide further evidence that havcr-1 is a functional cellular receptor for HAV.
Chromosomal Integration of Transduced Recombinant Baculovirus DNA in Mammalian Cells
Authors: Merrihew Raymond V. , Clay William C. , Condreay J. Patrick , Witherspoon Sam M. , Dallas Walter S. , Kost Thomas A. 
Published: July 2002

ABSTRACT
Our group and others have recently demonstrated the ability of recombinant baculoviruses to transduce mammalian cells at high frequency. To further characterize the use of baculovirus as a mammalian gene delivery system, we examined the status of transduced DNA stably maintained in Chinese hamster ovary (CHO) cells. Four independent clones carrying two introduced markers, the genes for neomycin resistance (Neo) and green fluorescent protein (GFP), were selected. PCR analysis, Southern blotting, and DNA sequencing showed that discrete portions of the 148-kb baculovirus DNA were present as single-copy fragments ranging in size from 5 to 18 kb. Integration into the CHO cell genome was confirmed by fluorescent in situ hybridization (FISH) analysis. For one clone, the left and right viral/chromosomal junctions were determined by DNA sequencing of inverse PCR products. Similarly, for a different clone, the left viral/chromosomal junction was determined; however, the right junction sequence revealed the joining to another viral fragment by a short homology (microhomology), a hallmark of illegitimate recombination. The random viral breakpoints and the lack of homology between the virus and flanking chromosomal sequences are also suggestive of an illegitimate integration mechanism. To examine the long-term stability of reporter gene expression, all four clones were grown continuously for 36 passages in either the presence or absence of selection for Neo. Periodic assays over a 5-month period showed no loss of GFP expression for at least two of the clones. This report represents the first detailed analysis of baculovirus integrants within mammalian cells. The potential advantages of the baculovirus system for the stable integration of genetic material into mammalian genomes are discussed.
Function of the Intercistronic Region of BRLF1-BZLF1 Bicistronic mRNA in Translating the Zta Protein of Epstein-Barr Virus
Authors: Chang Pey-Jium , Liu Shih-Tung 
Published: July 2002

ABSTRACT
Zta, a transcription factor encoded by Epstein-Barr virus, is efficiently translated from a BRLF1-BZLF1 bicistronic mRNA. In this study, we demonstrate that inserting a stem-loop structure, which is known to block ribosome scanning, in the 5′ region of the intercistronic region does not prevent the translation of a luciferase reporter protein from the bicistronic mRNA fused with the firefly luciferase gene, suggesting that the translation does not involve translation reinitiation. Mutational analyses reveal that the region between nucleotides 86 and 125 (region I) of the intercistronic region is essential for the translation. Meanwhile, the region between nucleotides 126 and 165 (region II) is also important since, without this region, the translation is inefficient. The region I sequence is partially complementary to the sequence between nucleotides 1489 and 1524 of 18S rRNA. This homology is significant, since disrupting the homology reduces the translation efficiency. Furthermore, luciferase is efficiently translated if the entire intercistronic region is replaced with a sequence complementary to the region between nucleotides 1401 and 1560 of the 18S rRNA. We hypothesize that Rta may assist 40S ribosome in recognizing the region I sequence to start a scanning process for Zta translation.
Furin Is Involved in Baculovirus Envelope Fusion Protein Activation
Authors: Westenberg Marcel , Wang Hualin , IJkel Wilfred F. J. , Goldbach Rob W. , Vlak Just M. , Zuidema Douwe 
Published: July 2002

ABSTRACT

The
Spodoptera exigua
multicapsid nucleopolyhedrovirus (Se
M
NPV)
Se8
gene was recently shown to encode the viral envelope fusion (F) protein. A 60-kDa C-terminal subunit (F
1
) of the 76-kDa primary translation product of this gene was found to be the major envelope protein of Se
M
NPV budded virus (BV) (W. F. J. IJkel, M. Westenberg, R. W. Goldbach, G. W. Blissard, J. M. Vlak, and D. Zuidema, Virology 275:30–41, 2000). A specific inhibitor was used to show that furin is involved in cleavage of the precursor envelope fusion (F
0
) protein. BV produced in the presence of the inhibitor possesses the uncleaved F
0
protein, while an F protein with a mutation in the furin cleavage site was translocated to the plasma membrane but lost its fusogenic activity. These results indicate that cleavage of F
0
is required to activate the Se
M
NPV F protein and is necessary for BV infectivity. Specific antibodies against F
1
and against the putative N terminus (F
2
) of the primary translation product were used to show that the F protein is BV specific and that BVs contain both the 60- (F
1
) and 21-kDa (F
2
) cleavage products. In nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis both subunits migrate as a single 80-kDa protein, indicating that the subunits remain associated by a disulfide linkage. In addition, the presence of the F protein predominately as a monomer suggests that disulfide links are not involved in oligomerization. Thus, the envelope fusion protein from group II nucleopolyhedroviruses of baculoviruses has properties similar to those of proteins from a number of vertebrate viruses.
Longitudinal Analysis of Feline Leukemia Virus-Specific Cytotoxic T Lymphocytes: Correlation with Recovery from Infection
Authors: Flynn J. Norman , Dunham Stephen P. , Watson Vivien , Jarrett Oswald 
Published: July 2002

ABSTRACTFeline leukemia virus (FeLV) is a common naturally occurring gammaretrovirus of domestic cats that is associated with degenerative diseases of the hematopoietic system, immunodeficiency, and neoplasia. Although the majority of cats exposed to FeLV develop a transient infection and recover, a proportion of cats become persistently viremic and many subsequently develop fatal diseases. To define the dominant host immune effector mechanisms responsible for the outcome of infection, we studied the longitudinal changes in FeLV-specific cytotoxic T lymphocytes (CTLs) in a group of na|$$|Ad|five cats following oronasal exposure to FeLV. Using51Cr release assays to measure ex vivo virus-specific cytotoxicity, the emerging virus-specific CTL response was correlated with modulations in viral burden as assessed by detection of infectious virus, FeLV p27 capsid antigen, and proviral DNA in the blood. High levels of circulating FeLV-specific effector CTLs appeared before virus neutralizing antibodies in cats that recovered from exposure to FeLV. In contrast, persistent viremia was associated with a silencing of virus-specific humoral and cell-mediated host immune effector mechanisms. A single transfer of between 2 × 107and 1 × 108autologous, antigen-activated lymphoblasts was associated with a downmodulation in viral burden in vivo. The results suggest an important role for FeLV-specific CTLs in retroviral immunity and demonstrate the potential to modulate disease outcome by the adoptive transfer of antigen-specific T cells in vivo.
Is glucose/amino acid supplementation after exercise an aid to strength training?
Authors: Williams A G , van den Oord M , Sharma A , Jones D A 
Published: July 2002

Background—The precise timing of carbohydrate and amino acid ingestion relative to a bout of resistance exercise may modulate the training effect of the resistance exercise.Objective—To assess whether regular glucose/amino acid supplementation immediately after resistance exercise could enhance the gain in muscle strength brought about by resistance training.Methods—Seven untrained participants with a median age of 23 years and mean (SD) body mass 68.9 (13.5) kg resistance trained on a leg extension machine for five days a week for 10 weeks, using four sets of 10 repetitions. Alternate legs were trained on successive days, one leg each day. Subjects ingested either a supplement including 0.8 g glucose/kg and 0.2 g amino acids/kg, or placebo, on alternate training days immediately after training. Therefore the supplement was always ingested after training the same leg (supplement leg). Isometric, isokinetic, and 1 repetition maximum (RM) strength were measured before, during, and after training. Blood samples were analysed to determine the acute responses of insulin and glucose to resistance exercise and supplementation or placebo.Results—Serum insulin concentration peaked 20 minutes after supplement ingestion at ninefold the placebo level, and remained significantly elevated for at least 80 minutes (p<0.01). Isometric, isokinetic, and 1 RM strength improved on both supplement and placebo legs (p<0.05). There were no significant differences in the gain in strength between the supplement leg and the placebo leg (p>0.05).Conclusion—Regular glucose/amino acid supplementation immediately after resistance exercise is unlikely to enhance the gain in muscle strength brought about by resistance training.
Decision analysis in the surgical treatment of patients with familial adenomatous polyposis: a Dutch-Scandinavian collaborative study including 659 patients
Authors: Vasen H F A , van Duijvendijk P , Buskens E , Bülow C , Björk J , Järvinen H J , Bülow S 
Published: July 2002

BACKGROUND AND AIMSThe choice of colorectal surgery in patients with familial adenomatous polyposis lies between the morbidity of proctocolectomy and ileum-pouch-anal anastomosis (IPAA) and the mortality from rectal cancer after total colectomy and ileorectal anastomosis (IRA). The aims of the present study were: (1) to assess the risk of dying from rectal cancer after IRA, (2) to compare the life expectancy between patients with an IRA and those with an IPAA, and (3) to investigate whether regular endoscopic examination of the rectum leads to detection of cancer at an earlier stage.METHODSClinical and pathological data on 659 patients who underwent colectomy and ileorectal anastomosis were collected from four national polyposis registries—that is, in Denmark, Finland, Sweden, and the Netherlands. Data were analysed using survival analysis methods. Decision analysis was used to compare the life expectancy between patients with an IRA and those with an IPAA.RESULTSA total of 47 patients developed rectal cancer after IRA. The risk of dying from rectal cancer was 12.5% (95% confidence interval 7.1–17.9%) by age 65. Compared with IRA, IPAA would lead to an increase in life expectancy of 1.8 years. Seventy five per cent of patients with rectal cancer had a negative rectoscopy within 12 months before the diagnosis.CONCLUSIONIRA is associated with substantial mortality due to rectal cancer. Follow up examinations of the rectum does not have sufficient preventive effect on morbidity and mortality of rectal cancer.
‘If you pay, we'll operate immediately’
Authors: Miller William L , Grødeland Åse B , Koshechkina Tatyana Y 
Published: July 2002

Objectives—To study the attitudes of health care staff in four postcommunist countries towards taking gifts from their clients—and their confessed experience of actually taking such gifts.Design—Survey questionnaire administered to officials including health care staff, supplemented by focus-group discussions with the general public.Setting – Ukraine, Bulgaria, Slovakia and the Czech Republic.Participants—A quota sample of 1,307 officials including 292 health care staff, supplemented by stratified national random samples of 4,778 ordinary members of the public and in-depth interviews or focus-group discussions involving another 323.Main measurements—Explicit justifications and willingness to accept offers, reported frequency of offers, and personal confessions to accepting “money and expensive presents” as well as smaller gifts.Results—Health care staff were far more inclined than the average official or public servant to accept “money or an expensive present” if offered, far more inclined to justify asking clients for “extra payments”, and far more inclined to confess that they had actually taken gifts from clients recently. Judged by their own confessions, hospital doctors were only rivalled by traffic police and customs officials for taking money or expensive gifts from their clients.Conclusions—Poor pay does not explain why doctors so often took large gifts from their clients. Moral self justification, opportunity, and bargaining power are much more effective explanations.
DERANDOMIZED LEARNING OF BOOLEAN FUNCTIONS OVER FINITE ABELIAN GROUPS
Authors: SITHARAM M. , STRANEY TIMOTHY 
Published: July 2002

We employ the Always Approximately Correct or AAC model defined in [35], to prove learnability results for classes of Boolean functions over arbitrary finite Abelian groups. This model is an extension of Angluin's Query model of exact learning. The Boolean functions we consider belong to approximation classes, i.e. functions that are approximable (in various norms) by few Fourier basis functions, or irreducible characters of the domain Abelian group. We contrast our learnability results to previous results for similar classes in the PAC model of learning with and without membership queries. In addition, we discuss new, natural issues and questions that arise when the AAC model is used. One such question is whether a uniform training set is available for learning any function in a given approximation class. No analogous question seems to have been studied in the context of Angluin's Query model. Another question is whether the training set can be found quickly if the approximation class of the function is completely unknown to the learner, or only partial information about the approximation class is given to the learner (in addition to the answers to membership queries). In order to prove the learnability results in this paper we require new techniques for efficiently sampling Boolean functions using the character theory of finite Abelian groups, as well as the development of algebraic algorithms. The techniques result in other natural applications closely related to learning, for example, query complexity of deterministic algorithms for testing linearity, efficient pseudorandom generators, and estimating VC dimensions for classes of Boolean functions over finite Abelian groups.
Evidence for Oxygen and Mercury Non-Stoichiometry in Hg-1201 HTC Superconductor
Authors: Costa G. A. , Carnasciali M. M. , Kaiser E. 
Published: July 2002

A review of the structural existing data on Hg-1201 shows evidence of non stoichiometry of the sample. In this compound not only oxygen but also Hg seems to be released or, perhaps, substituted. So, the production of bulk samples with optimal oxygen doping and homogeneus Hg content could be profitable for the study of the effect of the Hg solubility, allowing to confirm its existence till to room temperatures, and to test the effect of Hg impoverishment on other critical superconducting parameter different from Tc.
COMBING NILPOTENT AND POLYCYCLIC GROUPS
Authors: GILMAN ROBERT H. , HOLT DEREK F. , REES SARAH 
Published: July 2002

The notable exclusions from the family of automatic groups are those nilpotent groups which are not virtually abelian, and the fundamental groups of compact 3-manifolds based on the Nil or Sol geometries. Of these, the 3-manifold groups have been shown by Bridson and Gilman to lie in a family of groups defined by conditions slightly more general than those of the automatic groups, i.e. to have combings which lie in the formal language class of indexed languages. In fact, the combings constructed by Bridson and Gilman for these groups can also be seen to be real-time languages (i.e. recognized by real-time Turing machines). This article investigates the situation for nilpotent and polycyclic groups. It is shown that a finitely generated class 2 nilpotent group with cyclic commutator subgroup is real-time combable, as are all 2 or 3-generated class 2 nilpotent groups, and groups in specific families of nilpotent groups (the finitely generated Heisenberg groups, groups of unipotent matrices over Z and the free class 2 nilpotent groups). Further, it is shown that any polycyclic-by-finite group embeds in a real-time combable group. All the combings constructed in the article are boundedly asynchronous, and those for nilpotent-by-finite groups have polynomially bounded length functions, of a degree equal to the nilpotency class, c; this verifies a polynomial upper bound on the Dehn functions of those groups of degree c+1.
LINEAR ELLIPTIC PROBLEMS WITH MIXED BOUNDARY CONDITIONS RELATED TO RADIATION HEAT TRANSFER
Authors: PORZIO MARIA MICHAELA , LÓPEZ-POUSO ÓSCAR 
Published: July 2002

We prove the existence and uniqueness results for elliptic problems with L1 data and mixed boundary conditions which include as particular cases the Dirichlet and the Neumann problems. These elliptic equations are related to radiation heat trasfer.
AN UNUSUAL CASE OF HYPERPHALANGISM ASSOCIATED WITH FOREARM AND ELBOW ANOMALIES
Authors: Seradge H. , Wood V. E. 
Published: July 2002

Hyperphalangism is characterized by an extra phalanx between the phalanges of a finger, usually excluding the thumb. This abnormality is distinguished from polydactyly and polyphalangism in that the hand has more phalanges in the fingers and no extra fingers. Because the digits are small and short, a better term to describe this abnormality would be "brachyhyperphalangism",7 but the term is cumbersome and unpopular. We have reviewed the world literature up to the present time and have never seen reported elbow abnormalities associated with hyperphalangism.