bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcriptional Analysis of Marek's Disease Virus Glycoprotein D, I, and E Genes: gD Expression Is Undetectable in Cell Culture
Authors: Tan Xinyu , Brunovskis Peter , Velicer Leland F. 
Published: July 2002

ABSTRACT

The various alphaherpesviruses, including Marek's disease virus (MDV), have both common and unique features of gene content and expression. The entire MDV U
s
region has been sequenced in our laboratory (P. Brunovskis and L. F. Velicar, Virology 206:324–338, 1995). Genes encoding the MDV glycoprotein D (gD), glycoprotein I (gI), and glycoprotein E (gE) homologs have been found in this region, although no gG homolog was found. In this work, transcription of the tandem MDV gD, gI, and gE genes was studied and found to have both unique characteristics and also features in common with other alphaherpesviruses. MDV gD could not be immunoprecipitated from MDV GA-infected duck embryo fibroblast cells by antisera reactive to its TrpE fusion proteins, while gI and gE could be. When the gD gene was subjected to in vitro-coupled transcription-translation, the precursor polypeptide was produced and could be immunoprecipitated by anti-gD. Northern blot, reverse transcriptase PCR, and RNase protection analyses have shown that (i) no mRNA initiating directly from the gD gene could be detected; (ii) a large but low-abundance 7.5-kb transcript spanning five genes, including the one encoding gD, was seen on longer exposure; and (iii) transcription of the gI and gE genes formed an abundant bicistronic 3.5-kb mRNA, as well as an abundant 2.0-kb gE-specific mRNA. Therefore, the MDV gD gene expression is down-regulated at the transcription level in MDV-infected cell culture, which may be related to the cell-associated nature of MDV in fibroblast cells. Compared to the highly gD-dependent herpes simplex virus and the other extreme of the varicella-zoster virus which lacks the gD gene, MDV is an intermediate type of alphaherpesvirus.
RNA Replication from the Simian Virus 5 Antigenomic Promoter Requires Three Sequence-Dependent Elements Separated by Sequence-Independent Spacer Regions
Authors: Keller Michael A. , Murphy Susan K. , Parks Griffith D. 
Published: July 2002

ABSTRACT
We have previously shown for the paramyxovirus simian virus 5 (SV5) that a functional promoter for RNA replication requires proper spacing between two discontinuous elements: a 19-base segment at the 3′ terminus (conserved region I [CRI]) and an 18-base internal region (CRII) that is contained within the coding region of the L protein gene. In the work described here, we have used a reverse-genetics system to determine if the 53-base segment between CRI and CRII contains additional sequence-specific signals required for optimal replication or if this segment functions solely as a sequence-independent spacer region. A series of copyback defective interfering minigenome analogs were constructed to contain substitutions of nonviral sequences in place of bases 21 to 72 of the antigenomic promoter, and the relative level of RNA replication was measured by Northern blot analysis. The results from our mutational analysis indicate that in addition to CRI and CRII, optimal replication from the SV5 antigenomic promoter requires a third sequence-dependent element located 51 to 66 bases from the 3′ end of the RNA. Minigenome RNA replication was not affected by changes in the either the position of this element in relation to CRI and CRII or the predicted hexamer phase of NP encapsidation. Thus, optimal RNA replication from the SV5 antigenomic promoter requires three sequence-dependent elements, CRI, CRII and bases 51 to 66.
Construction and In Vitro Properties of a Series of Attenuated Simian Immunodeficiency Viruses with All Accessory Genes Deleted
Authors: Guan Yongjun , Whitney James B. , Detorio Mervi , Wainberg Mark A. 
Published: July 2002

ABSTRACT

We have generated simplified simian immunodeficiency virus (SIV) constructs lacking the
nef
,
vpr
,
vpx
,
vif
,
tat
, and
rev
genes (Δ6 viruses). To accomplish this, we began with an infectious molecular clone of SIV, i.e. SIVmac239, and replaced the deleted segments with three alternate elements: (i) a constitutive transport element (CTE) derived from simian retrovirus type 1 to replace the Rev/Rev-responsive element (RRE) posttranscriptional regulation system, (ii) a chimeric SIV long terminal repeat (LTR) containing a cytomegalovirus (CMV) promoter to augment transcription and virus production, and (iii) an internal ribosome entry site (IRES) upstream of the
env
gene to ensure expression of envelope proteins. This simplified construct (Δ6CCI) efficiently produced all viral structural proteins, and mature virions possessed morphology typical of wild-type virus. It was also observed that deletion of the six accessory genes dramatically affected both the specificity and efficiency of packaging of SIV genomic RNA into virions. However, the presence of both the CTE and the chimeric CMV promoter increased the specificity of viral genomic RNA packaging, while the presence of the IRES augmented packaging efficiency. The Δ6CCI virus was extremely attenuated in replication capacity yet retained infectiousness for CEMx174 and MT4 cells. We also generated constructs that retained either the
rev
gene or both the
rev
and
vif
genes and showed that these viruses, when complemented by the CMV promoter, i.e., Δ5-CMV and Δ4-CMV, were able to replicate in MT4 cells with moderate and high-level efficiency, respectively. Long-term culture of each of these constructs over 6 months revealed no potential for reversion. We hope to shortly evaluate these simplified constructs in rhesus macaques to determine their long-term safety as well as ability to induce protective immune responsiveness as proviral DNA vaccines.
Mutational Analysis of the v-Rel Dimerization Interface Reveals a Critical Role for v-Rel Homodimers in Transformation
Authors: Liss Andrew S. , Bose, Henry R. 
Published: July 2002

ABSTRACT

The v-
rel
oncogene encoded by reticuloendotheliosis virus strain T is the acutely transforming member of the Rel/NF-κB family of transcription factors. In v-Rel-transformed cells, v-Rel exists as homodimers or heterodimers with the endogenous Rel/NF-κB proteins c-Rel, NF-κB1, NF-κB2, and RelA. To examine the contribution of these complexes to v-Rel-mediated transformation, mutations were introduced into the dimerization interface of v-Rel to generate v-Rel mutants with selective dimerization properties. Nine mutants are described in this study that are defective in homodimer and/or heterodimer formation with specific Rel/NF-κB family members. Viruses expressing mutants that failed to homodimerize but were able to form heterodimeric complexes were unable to transform splenic lymphocytes in vitro, indicating that the dimerization of v-Rel with endogenously expressed Rel/NF-κB proteins is not in itself sufficient for transformation. In addition, two partially transforming mutants were identified that exhibited an impaired ability to form homodimers. Sequence analysis of the proviral DNA from cells transformed by these mutants revealed the presence of multiple secondary mutations in sequences responsible for dimerization and DNA binding. Two of these mutations either enhanced or restored the ability of these proteins to bind DNA as a homodimer. Viruses expressing these proteins transformed cells at levels comparable to or slightly less than v-Rel, suggesting that a threshold level of DNA binding by v-Rel homodimers is required for transformation.
Rhesus Macaque Resistance to Mucosal Simian Immunodeficiency Virus Infection Is Associated with a Postentry Block in Viral Replication
Authors: Peng Bo , Voltan Rebecca , Lim Lulu , Edghill-Smith Yvette , Phogat Sanjay , Dimitrov Dimiter S. , Arora Kamalpreet , Leno Michel , Than Soe , Woodward Ruth , Markham Phillip D. , Cranage Martin , Robert-Guroff Marjorie 
Published: July 2002

ABSTRACT

Elucidation of the host factors which influence susceptibility to human immunodeficiency virus or simian immunodeficiency virus (SIV) infection and disease progression has important theoretical and practical implications. Rhesus macaque 359, a vaccine control animal, resisted two successive intravaginal challenges with SIV
mac251
and failed to seroconvert. Here, after an additional intrarectal SIVmac32H challenge, macaque 359 remained highly resistant to infection. Viral RNA (10
6
copies/ml) was observed in plasma only at week 2 postchallenge. Virus isolation and proviral DNA were positive only once at week eight postchallenge. The animal remained seronegative and cleared SIV in vivo. Its blood and lymph node cells obtained at 49 weeks after intrarectal challenge did not transmit SIV to a naive macaque. We found that the resistance of macaque 359 to SIV infection was not due to a high level of CD8
+
suppressor activity but to an inherent resistance of its CD4
+
T cells. To elucidate the basis for the unusually strong resistance of macaque 359 to SIV infection in vivo and in vitro, we investigated early events of viral infection and replication in CD4
+
cells of macaque 359, including expression and mutation screening of SIV coreceptors and analysis of viral entry and reverse transcription. Mutation screening revealed no genetic alteration in SIV coreceptors. PCR analysis revealed a significant delay in production of early in vitro reverse transcription intermediates in macaque 359 cells compared to susceptible controls, but cell fusion assays showed that SIV entered the CD4
+
CCR5
+
cells of macaque 359 as readily as cells of macaques susceptible to SIV infection. Our results suggest that the resistance of macaque 359 to SIV infection is due to a postentry block in viral replication and implicate a cellular inhibitory mechanism in its CD4
+
T cells. Identification of this host mechanism will help further elucidate the biochemistry of reverse transcription and may suggest therapeutic strategies. Determining the prevalence of this host resistance mechanism among macaques may lead to better design of SIV pathogenesis and vaccine studies.
Cell Type-Specific Replication of Simian Virus 40 Conferred by Hormone Response Elements in the Late Promoter
Authors: Farrell Michael L. , Mertz Janet E. 
Published: July 2002

ABSTRACT
The late genes of SV40 are not expressed at significant levels until after the onset of viral DNA replication. We previously identified two hormone response elements (HREs) in the late promoter that contribute to this delay. Mutants defective in these HREs overexpress late RNA at early, but not late, times after transfection of CV-1PD cells. Overexpression of nuclear receptors (NRs) that recognize these HREs leads to repression of the late promoter in a sequence-specific and titratable manner, resulting in a delay in late gene expression. These observations led to a model in which the late promoter is repressed at early times after infection by NRs, with this repression being relieved by titration of these repressors through simian virus 40 (SV40) genome replication to high copy number. Here, we tested this model in the context of the viral life cycle. SV40 genomes containing mutations in either or both HREs that significantly reduce NR binding without altering the coding of any proteins were constructed. Competition for replication between mutant and wild-type viruses in low-multiplicity coinfections indicated that the +1 HRE offered a significant selective advantage to the virus within a few cycles of infection in African green monkey kidney cell lines CV-1, CV-1P, TC-7, MA-134, and Vero but not in CV-1PD′ cells. Interestingly, the +55 HRE offered a selective disadvantage in MA-134 cells but had no effect in CV-1, CV-1P, TC-7, Vero, and CV-1PD′ cells. Thus, we conclude that these HREs are biologically important to the virus, but in a cell type-specific manner.
Nef Enhances Human Immunodeficiency Virus Type 1 Infectivity in the Absence of Matrix
Authors: Dorfman Tatyana , Popova Elena , Pizzato Massimo , Göttlinger Heinrich G. 
Published: July 2002

ABSTRACT
Nef enhances the serine phosphorylation of the human immunodeficiency virus type 1 matrix (MA) protein, which suggests that MA may be a functional target of Nef. Using mutants that remain infectious despite the absence of most or all of MA, we show in the present study that the ability of Nef to enhance virus infectivity is not compromised even if MA is entirely replaced by a heterologous lipid anchor.
Rapid Construction of Adenoviral Vectors by Lambda Phage Genetics
Authors: McVey Duncan , Zuber Mohammed , Ettyreddy Damodar , Brough Douglas E. , Kovesdi Imre 
Published: July 2002

ABSTRACT

Continued improvements of adenoviral vectors require the investigation of novel genome configurations. Since adenovirus can be generated directly by transfecting packaging cell lines with viral genomes isolated from plasmid DNA, it is possible to separate genome construction from virus production. In this way failure to generate a virus is not associated with an inability to generate the desired genome. We have developed a novel lambda-based system that allows rapid modification of the viral genome by double homologous recombination in
Escherichia coli
. The recombination reaction and newly generated genome may reside in a recombination-deficient bacterial host for enhanced plasmid stability. Furthermore, the process is independent of any restriction endonucleases. The strategy relies on four main steps: (i) homologous recombination between an adenovirus cosmid and a donor plasmid (the donor plasmid carries the desired modification[s] and flanking regions of homology to direct its recombination into the viral genome); (ii) in vivo packaging of the recombinant adenoviral cosmids during a productive lambda infection; (iii) transducing a recombination-deficient
E. coli
lambda lysogen with the generated lysate (the lysogen inhibits the helper phage used to package the recombinant andenoviral cosmid from productively infecting and destroying the host bacteria); (iv) effectively selecting for the desired double-recombinant cosmid. Approximately 10,000 double-recombinant cosmids are recovered per reaction with essentially all of them being the correct double-recombinant molecule. This system was used to generate quickly and efficiently adenoviral genomes deficient in the E1/E3 and E1/E3/E4 regions. The basis of this technology allows any region of the viral genome to be readily modified for investigation of novel configurations.
Cesium and Cesium-Lithium Selenates
Authors: Havlíček David , Mička Zdeněk , Barbořák Václav , Šmejkal Petr 
Published: July 2002

The Cs2SeO4-H2SeO4-H2O and Cs2SeO4-Li2SeO4-H2O systems were studied at 30 °C as a basis for determining the conditions for formation of the compound Cs4LiH3(SeO4)4, which has been observed to undergo a ferroelectric phase transition. The results of a solubility study were used to construct a pseudo-ternary cross-section for CsLiSeO4-CsHSeO4-H2O in the quaternary system Cs2SeO4-Li2SeO4-H2SeO4-H2O, which demonstrated that, in the region of crystallization of the compound of interest, a substance with the composition Cs4LiH3(SeO4)4 is actually formed. Attention was further paid to the following newly prepared compounds: cesium-lithium selenate hemihydrate, CsLiSeO4·1/2 H2O, tricesium-lithium bis(selenate) hemihydrate, Cs3Li(SeO4)2·1/2 H2O and hydrogen tricesium bis(selenate) hemihydrate, Cs3H(SeO4)2·1/2 H2O, which were characterized by X-ray, spectral and thermoanalytical data.
Sickness absence and early retirement on health grounds in the construction industry in Ireland
Authors: Brenner Harold , Ahern William 
Published: July 2002

OBJECTIVETo establish a detailed pattern of the nature and extent of illnesses and injuries among construction workers in Ireland which cause temporary absence from work, and to identify diseases and disabilities which lead to premature retirement from the industry on health grounds.METHODSThe population base for the study consisted of construction workers who were members of the Construction Federation operatives pension and sick pay scheme. Records of sickness absence since 1981, stored on computer disks, and records of early retirement on health grounds since 1972, stored on microfiche film, were examined. Pertinent data were extracted and transferred to a database; after cleaning and the exclusion of unvalidated data, records of 28 792 absences and 3098 records of early retirement were available for analysis. Data were analysed with Access 97 and Epi Info.RESULTSOver the period of the study the mean annual absences were 7.8/100 workers. Three quarters of absences were among younger workers; however, the rate of absence increased with age, as did the mean duration of absence. Injury was the most frequent reason for absence, followed by infectious disease, then musculoskeletal disorders. The mean annual rate of early retirement on health grounds was 5.3/1000 workers. The median age at retirement was 58 years. Cardiovascular disease and musculoskeletal disorders each accounted for nearly one third of the conditions leading to permanent disability on the grounds of which early retirement was granted. During the period of the study, over 677 000 working days were lost due to sickness absence, and over 24 000 potential years of working lives were lost due to early retirement on health grounds.CONCLUSIONSThe study has shown patterns of sickness absence and early retirement on health grounds in the Irish construction industry which will contribute to the further development of health promotion strategies for construction workers.
Chemotherapy for upper gastrointestinal tumours
Authors: Thomas A L , O'Byrne K , Steward W P 
Published: July 2002

Abstract
The aim of this review is to identify current chemotherapy treatment for tumours of the oesophagus, stomach, pancreas, and liver. The role of both neoadjuvant, adjuvant, and palliative chemotherapy regimens will be discussed. This review will be of interest to oncologists in clarifying current issues regarding chemotherapy, and to physicians in other medical specialties, to increase their general understanding of benefits and drawbacks of chemotherapy in this patient group.
On the Right Hamiltonian for Singular Perturbations: General Theory
Authors: Neidhardt Hagen , Zagrebnov Valentin 
Published: July 2002

Let the pair of self-adjoint operators {A≥0,W≤0} be such that: (a) there is a dense domain [Formula: see text] such that [Formula: see text] is semibounded from below (stability domain), (b) the symmetric operator [Formula: see text] is not essentially self-adjoint (singularity of the perturbation), (c) the Friedrichs extension [Formula: see text] of [Formula: see text] is maximal with respect to W, i.e., [Formula: see text]. [Formula: see text]. Let [Formula: see text] be a regularizing sequence of bounded operators which tends in the strong resolvent sense to W. The abstract problem of the right Hamiltonian is: (i) to give conditions such that the limit H of self-adjoint regularized Hamiltonians [Formula: see text] exists and is unique for any self-adjoint extension [Formula: see text] of [Formula: see text], (ii) to describe the limit H. We show that under the conditions (a)–(c) there is a regularizing sequence [Formula: see text] such that [Formula: see text] tends in the strong resolvent sense to unique (right Hamiltonian) [Formula: see text], otherwise the limit is not unique.
SIGNATURE OF LOCAL STRUCTURE ANOMALY AT Tc IN THE Nb3Ge SUPERCONDUCTOR
Authors: FILLIPPI M. , SAINI N. L. , OYANAGI H. , BIANCONI A. 
Published: July 2002

We report local structure of Nb3Ge intermetallic superconductor by Ge K-edge extended X-ray absorption fine structure (EXAFS) measurements performed in the temperature range of 6–300 K, with an emphasis to determine the local and instantaneous atomic displacements across the superconducting transition temperature T c . We find that the temperature dependent correlated Debye–Waller factor of the Ge-Nb bonds shows a drop at the T c while cooling the sample, similar to the one observed in the high-T c cuprate superconductors. The results provide a clear indication of an intimacy between the local atomic displacements and the short coherence superconductivity, and suggests that local electron-lattice interaction should be considered to explain the high-T c superconductivity in these materials.
The Place of Dielectric Spectroscopy in Probing Electrorheology
Authors: Kyvelidis S. , Maistros G. M. , Rattray P. , Block H. , Akhavan J. , Tsangaris G. 
Published: July 2002

The measurement of the dielectric spectra of PAnQR based ER fluids under shear and electric fields is discussed and results presented. Data in which either but not both shear or electric fields are present are submitted to analysis in terms of known theories. For flow alone, that analysis provides information on the attenuation of polarization by the uniform shear fields whilst the polarization of quiescent fluids by electric fields may lead to estimates of particles packing within the columns. Permittivity data when both fields are acting is presented, but in the absence of suitable theory, not modelled quantitatively. Empirical correlations are discussed and the conclusion drawn that fibrillation is readily suppressed by even moderate shear rates, although long range dipolar forces still persist to high shear rates. The dc conductance of these fluids have also been measured. This together with permittivity data under ER fluid working conditions has importance in establishing the electrical parameters for any ER fluid.
STABILIZATION OF UNSTABLE PERIODIC ORBITS OF CHAOTIC DISCRETE-TIME SYSTEMS USING PREDICTION-BASED FEEDBACK CONTROL
Authors: HINO TORU , YAMAMOTO SHIGERU , USHIO TOSHIMITSU 
Published: July 2002

In this paper, we consider feedback control that stabilizes unstable periodic orbits (UPOs) of chaotic discrete-time systems. First, we show that there exists a strong necessary condition for stabilization of the UPOs when we use delayed feedback control (DFC) that is known as one of the useful methods for controlling chaotic systems. The condition is similar to that in the fixed point stabilization problem, in which it is impossible to stabilize the target unstable fixed point if the Jacobian matrix of the linearized system around it has an odd number of real eigenvalues greater than unity. In order to stabilize UPOs which cannot be stabilized by the standard DFC, we adopt prediction-based control. We show a necessary and sufficient condition for the stabilization of the UPOs with arbitrary period.
ON THE INTERSECTION OF FINITELY GENERATED SUBGROUPS IN FREE PRODUCTS OF GROUPS
Authors: IVANOV S. V. 
Published: July 2002

A subgroup H of a free product [Formula: see text] of groups Gα, α∈ I, is called factor free if for every [Formula: see text] and β ∈ I one has S H S-1∩ Gβ = {1} (by Kurosh theorem on subgroups of free products, factor free subgroups are free). If K is a finitely generated free group, denote [Formula: see text], where r(K) is the rank of K. It is proven that if H, K are finitely generated factor free subgroups of a free product [Formula: see text] then [Formula: see text]. It is also shown that the inequality [Formula: see text] of Hanna Neumann conjecture on subgroups of free groups does not hold for factor free subgroups of free products.