bluuebunny/crossref_metadata_2025_split huggingface dataset:
Target Cell Cyclophilin A Modulates Human Immunodeficiency Virus Type 1 Infectivity
Authors: Sokolskaja Elena , Sayah David M. , Luban Jeremy 
Published: November 2004

ABSTRACTThe peptidyl-prolyl isomerase cyclophilin A (CypA) increases the kinetics by which human immunodeficiency virus type 1 (HIV-1) spreads in tissue culture. This was conclusively demonstrated by gene targeting in human CD4+T cells, but the role of CypA in HIV-1 replication remains unknown. Though CypA binds to mature HIV-1 capsid protein (CA), it is also incorporated into nascent HIV-1 virions via interaction with the CA domain of the Gag polyprotein. These findings raised the possibility that CypA might act at multiple steps of the retroviral life cycle. Disruption of the CA-CypA interaction, either by the competitive inhibitor cyclosporine (CsA) or by mutation of CA residue G89 or P90, suggested that producer cell CypA was required for full virion infectivity. However, recent studies indicate that CypA within the target cell regulates HIV-1 infectivity by modulating Ref1- or Lv1-mediated restriction. To examine the relative contribution to HIV-1 replication of producer cell CypA and target cell CypA, we exploited multiple tools that disrupt the HIV-1 CA-CypA interaction. These tools included the drugs CsA, MeIle4-CsA, and Sanglifehrin; CA mutants exhibiting decreased affinity for CypA or altered CypA dependence; HeLa cells with CypA knockdown by RNA interference; and Jurkat T cells homozygous for a deletion of the gene encoding CypA. Our results clearly demonstrate that target cell CypA, and not producer cell CypA, is important for HIV-1 CA-mediated function. Inhibition of HIV-1 infectivity resulting from virion production in the presence of CsA occurs independently of the CA-CypA interaction or even of CypA.
Multiple Genotypes of Influenza B Virus Circulated between 1979 and 2003
Authors: McCullers Jonathan A. , Saito Takehiko , Iverson Amy R. 
Published: November 2004

ABSTRACT
The segmented genome of influenza B virus allows exchange of gene segments between cocirculating strains. Through this process of reassortment, diversity is generated by the mixing of genes between viruses that differ in one or more gene segments. Phylogenetic and evolutionary analyses of all 11 genes of 31 influenza B viruses isolated from 1979 to 2003 were used to study the evolution of whole genomes. All 11 genes diverged into two new lineages prior to 1987. All genes except the NS1 gene were undergoing linear evolution, although the rate of evolution and the degree to which nucleotide changes translated into amino acid changes varied between lineages and by gene. Frequent reassortment generated 14 different genotypes distinct from the gene constellation of viruses circulating prior to 1979. Multiple genotypes cocirculated in some locations, and a sequence of reassortment events over time could not be established. The surprising diversity of the viruses, unrestricted mixing of lineages, and lack of evidence for coevolution of gene segments do not support the hypothesis that the reassortment process is driven by selection for functional differences.
Two Modes of Pseudorabies Virus Neuroinvasion and Lethality in Mice
Authors: Brittle Elizabeth E. , Reynolds Ashley E. , Enquist L. W. 
Published: November 2004

ABSTRACT
We describe two distinct modes of neuroinvasion and lethality after murine flank inoculation with virulent and attenuated strains of pseudorabies virus (PRV). Mice infected with virulent (e.g., PRV-Becker, PRV-Kaplan, or PRV-NIA3) strains self-mutilate their flank skin in response to virally induced pruritus, die rapidly with no identifiable symptoms of central nervous system (CNS) infection such as behavioral abnormalities, and have little infectious virus or viral antigen in the brain. In distinct contrast, animals infected with an attenuated PRV vaccine strain (PRV-Bartha) survive approximately three times longer than wild-type PRV-infected animals, exhibit severe CNS abnormalities, and have an abundance of infectious virus in the brain at the time of death. Interestingly, these animals have no skin lesions and do not appear pruritic at any time during infection. The severe pruritus and relatively earlier time until death induced by wild-type PRV infection may reflect the peripheral nervous system (PNS) and immune responses to infection rather than a fatal, virally induced CNS pathology. Based on previously characterized afferent (sensory) and efferent (motor) neuronal pathways that innervate the skin, we deduced that wild-type virulent strains transit through the PNS via both afferent and efferent routes, whereas PRV-Bartha travels by only efferent routes in the PNS en route to the brain.
CD4+CD25+T Cells Regulate Vaccine-Generated Primary and Memory CD8+T-Cell Responses against Herpes Simplex Virus Type 1
Authors: Toka Felix N. , Suvas Susmit , Rouse Barry T. 
Published: November 2004

ABSTRACTIt has become evident that naturally occurring CD25+regulatory T cells (Tregcells) not only influence self-antigen specific immune response but also dampen foreign antigen specific immunity. This report extends our previous findings by demonstrating that immunity to certain herpes simplex virus (HSV) vaccines is significantly elevated and more effective if Tregcell response is curtailed during either primary or recall immunization. The data presented here show that removal of CD25+Tregcells prior to SSIEFARL-CpG or gB-DNA immunization significantly enhanced the resultant CD8+T-cell response to the immunodominant SSIEFARL peptide. The enhanced CD8+T-cell reactivity in Tregcell-depleted animals was between two- and threefold and evident in both acute and memory stages. Interestingly, removal of CD25+Tregcells during the memory recall response to plasmid immunization resulted in a twofold increase in CD8+T-cell memory pool. Moreover, in the challenge experiments, memory CD8+T cells generated with plasmid DNA in the absence of Tregcells cleared the virus more effectively compared with control groups. We conclude that CD25+Tregcells quantitatively as well as qualitatively affect the memory CD8+T-cell response generated by gB-DNA vaccination against HSV. However, it remains to be seen if all types of vaccines against HSV are similarly affected by CD25+Tregcells and if it is possible to devise means of limiting Tregcell activity to enhance vaccine efficacy.
Human Cytomegalovirus 5-Kilobase Immediate-Early RNA Is a Stable Intron
Authors: Kulesza Caroline A. , Shenk Thomas 
Published: November 2004

ABSTRACT
Immediate-early viral gene products of human cytomegalovirus (HCMV) are derived from several genomic loci and largely serve to establish a cellular environment conducive to viral replication. We have further examined an unusual immediate-early transcript known as the 5-kb RNA, concluding that it is a stable intron encoded by HCMV. The 5-kb RNA is highly AT rich in sequence and lacks open reading frames likely to be translated into protein. We confirmed the absence of polyadenylation of the transcript and showed that it is primarily nuclear localized during viral infection. We mapped the 5′ end of the 5-kb RNA to a consensus splice donor site and localized the 3′ end in the vicinity of a splice acceptor site. In transfection studies, we showed that the 5-kb RNA can be spliced from a heterologous primary transcript. Using bacterial artificial chromosome technology, we constructed a viral recombinant containing a mutation in the 5′ splice donor site that defines the 5′ end of the RNA and found that this mutation eliminates expression of the 5-kb RNA during viral infection. This mutant grows in human fibroblasts without complementation. Taken together, these data support the conclusion that the 5-kb RNA is a stable intron expressed by HCMV.
Structural Requirements of Astrovirus Virus-Like Particles Assembled in Insect Cells
Authors: Caballero Santiago , Guix Susana , Ribes Enric , Bosch Albert , Pintó Rosa M. 
Published: November 2004

ABSTRACT

Expression of the complete ORF2 of human astrovirus serotype 1 (HAstV-1) in the baculovirus system led to the formation of virus-like particles (VLPs) of around 38 nm. The same kind of VLPs were also obtained either with the expression of a truncated form of ORF2 lacking the first 70 amino acids (aa), or with the same truncated form in which those 70 aa were replaced by the green fluorescent protein. All three kinds of VLPs were equally recognized by an anti-HAstV-1 polyclonal antibody and by two monoclonal antibodies (MAbs; 8E7 and 5B7), indicating a nonessential role of those amino acids neither in the capsid assembly nor in the antigen structure. A second type of structure consisting of 16-nm ring-like units was observed in all of the cases, mostly after disassembling the 38-nm VLPs through the addition of EDTA. The removal of the EDTA and the addition of Mg
2+
ions promoted the reassembly of the 38-nm VLPs. The nature of these 16-nm ring-like structures, capsomers or T = 1 VLPs, still remains unclear. Biochemical analysis revealed no differences between the 38-nm VLPs and the 16-nm structures, whereas antigenically, they shared the 8E7 MAb epitope but differed in the 5B7 MAb epitope, with the latter structures being more readily recognized.
Differential Requirement for Cell Fusion and Virion Formation in the Pathogenesis of Varicella-Zoster Virus Infection in Skin and T Cells
Authors: Besser Jaya , Ikoma Minako , Fabel Konstanze , Sommer Marvin H. , Zerboni Leigh , Grose Charles , Arvin Ann M. 
Published: November 2004

ABSTRACT
The protein product of varicella-zoster virus (VZV) ORF47 is a serine/threonine protein kinase and tegument component. Evaluation of two recombinants of the Oka strain, rOka47ΔC, with a C-terminal truncation of ORF47, and rOka47D-N, with a point mutation in the conserved kinase motif, showed that ORF47 kinase function was necessary for optimal VZV replication in human skin xenografts in SCID mice but not in cultured cells. We now demonstrate that rOka47ΔC and rOka47D-N mutants do not infect human T-cell xenografts. Differences in the growth of kinase-defective ORF47 mutants allowed an examination of requirements for VZV pathogenesis in skin and T cells in vivo. Although virion assembly was reduced and no virion transport to cell surfaces was observed, epidermal cell fusion persisted, and VZV polykaryocytes were generated by rOka47ΔC and rOka47D-N in skin. Virion assembly was also impaired in vitro, but VZV-induced cell fusion continued to cause syncytia in cultured cells infected with rOka47ΔC or rOka47D-N. Intracellular trafficking of envelope glycoprotein E and the ORF47 and IE62 proteins, components of the tegument, was aberrant without ORF47 kinase activity. In summary, normal VZV virion assembly appears to require ORF47 kinase function. Cell fusion was induced by ORF47 mutants in skin, and cell-cell spread occurred even though virion formation was deficient. VZV-infected T cells do not undergo cell fusion, and impaired virion assembly by ORF47 mutants was associated with a complete elimination of T-cell infectivity. These observations suggest a differential requirement for cell fusion and virion formation in the pathogenesis of VZV infection in skin and T cells.
Treatment of Acromegaly
Authors: Holdaway Ian M. 
Published: November 2004

Mortality is increased in individuals with acromegaly unless serum growth hormone (GH) levels are below 2 µg/l and serum insulin-like growth factor (IGF)-I levels are normal following treatment. These combined criteria have been used to define remission of the disorder in this review. Transsphenoidal surgery achieves remission targets in an average of 55% of patients. For those not in remission following surgery, options include repeat surgery or use of adjuvant therapy. Fractionated external beam pituitary radiotherapy achieves 10-year remission rates of 47% but leaves patients exposed to excess GH until remission occurs. Stereotactic radiotherapy and gamma knife radiosurgery achieve remission rates of 40% over 3 years, and dopamine agonists produce remission in about 20% of patients. Somatostatin analogues induce remission in 59% of patients within the first year of treatment. The GH receptor antagonist pegvisomant leads to remission in 90% of patients, using IGF-I levels for assessment. Optimal treatment for a patient with acromegaly thus depends on the likely efficacy of treatment, cost, surgical skill, severity of side effects, tolerability, control of tumour growth, and improvement in complications related to tumour mass. A primary surgical approach, followed by medical therapy for those not in remission, remains the preferred option in most centres.
The Effect of Wind Shear and Curvature on the Gravity Wave Drag Produced by a Ridge
Authors: Teixeira Miguel A. C. , Miranda Pedro M. A. 
Published: November 2004

Abstract
The analytical model proposed by Teixeira, Miranda, and Valente is modified to calculate the gravity wave drag exerted by a stratified flow over a 2D mountain ridge. The drag is found to be more strongly affected by the vertical variation of the background velocity than for an axisymmetric mountain. In the hydrostatic approximation, the corrections to the drag due to this effect do not depend on the detailed shape of the ridge as long as this is exactly 2D. Besides the drag, all the perturbed quantities of the flow at the surface, including the pressure, may be calculated analytically.
Promoter trapping reveals significant differences in integration site selection between MLV and HIV vectors in primary hematopoietic cells
Authors: De Palma Michele , Montini Eugenio , de Sio Francesca R. Santoni , Benedicenti Fabrizio , Gentile Alessandra , Medico Enzo , Naldini Luigi 
Published: November 2004

AbstractRecent reports have indicated that human immunodeficiency virus (HIV) and murine leukemia virus (MLV) vectors preferentially integrate into active genes. Here, we used a novel approach based on genetic trapping to rapidly score several thousand integration sites and found that MLV vectors trapped cellular promoters more efficiently than HIV vectors. Remarkably, 1 in 5 MLV integrations trapped an active promoter in different cell lines and primary hematopoietic cells. Such frequency was even higher in growth-stimulated lymphocytes. We show that the different behavior of MLV and HIV vectors was dependent on a different integration pattern within transcribed genes. Whereas MLV-based traps showed a strong bias for promoter-proximal integration leading to efficient reporter expression, HIV-based traps integrated throughout transcriptional units and were limited for expression by the distance from the promoter and the reading frame of the targeted gene. Our results indicate a strong propensity of MLV to establish transcriptional interactions with cellular promoters, a behavior that may have evolved to enhance proviral expression and may increase the insertional mutagenesis risk. Promoter trapping efficiency provides a convenient readout to assess transcriptional interactions between the vector and its flanking genes at the integration site and to compare integration site selection among different cell types and in different growth conditions.
Increased peripheral platelet destruction and caspase-3–independent programmed cell death of bone marrow megakaryocytes in myelodysplastic patients
Authors: Houwerzijl Ewout J. , Blom Nel R. , van der Want Johannes J. L. , Louwes Henk , Esselink Mariet T. , Smit Jan W. , Vellenga Edo , de Wolf Joost Th. M. 
Published: November 2004

AbstractTo investigate underlying mechanisms of thrombocytopenia in myelodysplastic syndrome (MDS), radiolabeled platelet studies were performed in 30 MDS patients with platelet counts less than 100 × 109/L. Furthermore, plasma thrombopoietin and glycocalicin index (a parameter of platelet or megakaryocyte destruction) were determined. Mean platelet life (MPL), corrected for the degree of thrombocytopenia, was reduced in 15 of 30 patients (4.3 ± 0.9 days [mean ± SD] vs 6.0 ± 1.3, P = .0003). Platelet production rate (PPR) was reduced in 25 of 30 patients (68 ± 34 × 109/d vs 220 ± 65, P &lt; .0001). Thrombopoietin levels were not significantly correlated with the PPR. However, the glycocalicin index was significantly higher compared with controls (15 ± 16 vs 0.7 ± 0.2, P = .001) and significantly correlated with the PPR (P = .02, r = -0.5), but not with the MPL (P = 1.8). Ultrastructural studies demonstrated necrosis-like programmed cell death (PCD) in mature and immature megakaryocytes (n = 9). Immunohistochemistry of the bone marrow biopsies demonstrated no positive staining of MDS megakaryocytes for activated caspase-3 (n = 24) or cathepsin D (n = 21), while activated caspase-8 was demonstrated in a subgroup of patients (5/21) in less than 10% of megakaryocytes. These results indicate that the main cause of thrombocytopenia in MDS is caspase-3–independent necrosis-like PCD resulting in a decreased PPR in conjunction with an increased glycocalicin index.
Rapid and large amount of autocrine IL-3 production is responsible for mast cell survival by IgE in the absence of antigen
Authors: Kohno Masayuki , Yamasaki Sho , Tybulewicz Victor L. J. , Saito Takashi 
Published: November 2004

AbstractCross-linking FcϵRI on mast cells by immunoglobulin E (IgE) and antigen (Ag) initiates cascades leading to antiparasitic or allergic responses. It was recently reported that IgE without antigen, IgE(-Ag), actively promotes mast cell survival. Although we have demonstrated that the immunoreceptor tyrosine-based activation motif within FcRγ is essential for IgE(-Ag)–induced mast cell survival, the underlying mechanism remains still unclear. Here, we investigated the mechanism of IgE(-Ag)–induced survival using mast cells lacking several downstream molecules. Lyn and Syk were essential, whereas Fyn, Gab2, and the phosphoinositide 3-kinase–Akt pathway were not critical for survival. Failure of survival in FcRγ-/- bone marrow mast cells (BMMCs) was rescued by coculture with IgE-treated wild-type BMMCs, suggesting that survival is induced not directly through FcϵRI signals. We found that the survival is predominantly mediated by high production of interleukin 3 (IL-3), evidenced by severe impairment of survival by anti–IL-3 and in IL-3-/- BMMCs. The up-regulation of Bcl-xL/Bcl-2 by IgE was abrogated in IL-3-/- BMMCs, whereas the expression of histidine decarboxylase was normally induced. These results indicate that IL-3 plays a crucial role for IgE(-Ag)–induced mast cell survival, functioning in an autocrine manner by inducing the Bcl-xL/Bcl-2 via signal transducer and activator of transduction 5. We further suggest that IgE(-Ag)–mediated gene expression in mast cells is regulated at least 2 mechanisms: autocrine IL-3 dependent and independent.
Prognostic Factors in Resected Stage I Non–Small-Cell Lung Cancer: A Multivariate Analysis of Six Molecular Markers
Authors: Lu Charles , Soria Jean-Charles , Tang Ximing , Xu Xiao-Chun , Wang Luo , Mao Li , Lotan Reuben , Kemp Bonnie , Bekele B. Nebiyou , Feng Lei , Hong Waun K. , Khuri Fadlo R. 
Published: November 2004

PurposeTo analyze the prognostic significance of six molecular biomarkers (death-associated protein kinase [DAPK] promoter methylation, interleukin-10 [IL-10] protein expression, cyclooxygenase-2 [COX-2] mRNA expression, human telomerase reverse transcriptase catalytic subunit [hTERT] mRNA expression, retinoic acid receptor-beta [RAR-β] mRNA expression, and K-ras mutational status) in stage I non–small-cell lung cancer (NSCLC) patients.Patients and MethodsBiomarker analyses were performed on tumors from 94 patients with stage I NSCLC who underwent surgical resection at our institution. A minimum follow-up period of 5 years was required. DAPK methylation was assessed by methylation-specific polymerase chain reaction (PCR). RAR-β, COX-2, and hTERT mRNA levels were determined by in situ hybridization with digoxigenin-labeled antisense riboprobes. K-ras mutation status was determined by the PCR–primer introduced restriction with enrichment for mutant alleles method. IL-10 protein expression was analyzed by immunohistochemistry using a polyclonal antihuman IL-10 antibody. Cancer-specific survival was analyzed with a Cox proportional hazards model. To identify independent prognostic factors, a stepwise selection method was used.ResultsDAPK methylation, IL-10 lack of expression, COX-2 expression, hTERT expression, RAR-β expression, and K-ras mutations were observed in 46.8%, 29.8%, 59.6%, 34.0%, 23.4%, and 34.0% of patients, respectively. In the final model, DAPK methylation and IL-10 lack of expression were significant negative prognostic factors for cancer-specific survival, whereas COX-2 expression was of borderline significance.ConclusionIn this cohort of resected stage I NSCLC patients, molecular markers that independently predict cancer-specific survival have been identified. The prognostic roles of DAPK methylation, IL-10, and other biomarkers in NSCLC merit further investigation.
Colorectal Cancer With Mutation in BRAF, KRAS, and Wild-Type With Respect to Both Oncogenes Showing Different Patterns of DNA Methylation
Authors: Nagasaka Takeshi , Sasamoto Hiromi , Notohara Kenji , Cullings Harry M. , Takeda Masanori , Kimura Keigo , Kambara Takeshi , MacPhee Donald G. , Young Joanne , Leggett Barbara A. , Jass Jeremy R. , Tanaka Noriaki , Matsubara Nagahide 
Published: November 2004

Purpose BRAF mutations are common in sporadic colorectal cancers (CRCs) with a DNA mismatch repair (MMR) deficiency that results from promoter methylation of hMLH1, whereas KRAS mutations are common in MMR proficient CRCs associated with promoter methylation of MGMT. The aim of this study was to further investigate the link between genetic alterations in the RAS/RAF/ERK pathway and an underlying epigenetic disorder. Patients and Methods Activating mutations of BRAF and KRAS were identified and correlated with promoter methylation of 11 loci, including MINT1, MINT2, MINT31, CACNA1G, p16INK4a, p14ARF, COX2, DAPK, MGMT, and the two regions in hMLH1 in 468 CRCs and matched normal mucosa. Results BRAF V599E mutations were identified in 21 (9%) of 234 CRCs, and KRAS mutations were identified in 72 (31%) of 234 CRCs. Mutations in BRAF and KRAS were never found in the same tumor. CRCs with BRAF mutations showed high-level promoter methylation in multiple loci, with a mean number of methylated loci of 7.2 (95% CI, 6.6 to 7.9) among 11 loci examined (P < .0001). Tumors with KRAS mutations showed low-level promoter methylation, and CRCs with neither mutation showed a weak association with promoter methylation, with an average number of methylated loci of 1.8 (95% CI, 1.5 to 2.1) and 1.0 (95% CI, 0.79 to 1.3), respectively. Conclusion In CRC, the methylation status of multiple promoters can be predicted through knowledge of BRAF and, to a lesser extent, KRAS activating mutations, indicating that these mutations are closely associated with different patterns of DNA hypermethylation. These changes may be important events in colorectal tumorigenesis.