bluuebunny/crossref_metadata_2025 huggingface dataset:
Similarities and Differences between the Subgenomic and Minus-Strand Promoters of an RNA Plant Virus
Authors: Olsthoorn René C. L. , Haasnoot P. C. Joost , Bol John F.
Published: March 2004

Promoter regions required for minus-strand and subgenomic RNA synthesis have been mapped for several plus-strand RNA viruses. In general, the two types of promoters do not share structural features even though they are recognized by the same viral polymerase. The minus-strand promoter of
Alfalfa mosaic virus
(AMV), a plant virus of the family
Bromoviridae
, consists of a triloop hairpin (hpE) which is attached to a 3′ tRNA-like structure (TLS). In contrast, the AMV subgenomic promoter consists of a single triloop hairpin that bears no sequence homology with hpE. Here we show that hpE, when detached from its TLS, can function as a subgenomic promoter in vitro and can replace the authentic subgenomic promoter in the live virus. Thus, the AMV subgenomic and minus-strand promoters are basically the same, but the minus-strand promoter is linked to a 3′ TLS to force the polymerase to initiate at the very 3′end.
Repression of the Human Papillomavirus E6 Gene Initiates p53-Dependent, Telomerase-Independent Senescence and Apoptosis in HeLa Cervical Carcinoma Cells
Authors: Horner Stacy M. , DeFilippis Rosa Anna , Manuelidis Laertes , DiMaio Daniel
Published: March 2004

Cervical cancer cells express high-risk human papillomavirus (HPV) E6 and E7 proteins. When both HPV oncogenes are repressed in HeLa cervical carcinoma cells, the dormant p53 and retinoblastoma (Rb) tumor suppressor pathways are activated, and the cells undergo senescence in the absence of apoptosis. When the E6 gene is repressed in cells that continue to express an E7 gene, the p53 pathway, but not the Rb pathway, is activated, and both senescence and apoptosis are triggered. To determine the role of p53 signaling in senescence or apoptosis after repression of HPV oncogenes, we introduced a dominant-negative allele of p53 into HeLa cells. Dominant-negative p53 prevented senescence and apoptosis when E6 alone was repressed but did not inhibit senescence when both E6 and E7 were repressed. To determine whether reduced telomerase activity was involved in senescence or apoptosis after E6 repression, we generated HeLa cells stably expressing an exogenous hTERT gene, which encodes the catalytic subunit of telomerase. Although these cells contained markedly elevated telomerase activity and elongated telomeres, hTERT expression did not prevent senescence and apoptosis when E6 alone was repressed. These results demonstrate that when the Rb tumor suppressor pathway is inactivated by the E7 protein, E6 repression activates p53 signaling, which in turn is required for growth inhibition, senescence, and apoptosis. Thus, sustained inactivation of the p53 pathway by the E6 protein is required for maintenance of the proliferative phenotype of HeLa cervical carcinoma cells.
Wild-Type Kaposi's Sarcoma-Associated Herpesvirus Isolated from the Oropharynx of Immune-Competent Individuals Has Tropism for Cultured Oral Epithelial Cells
Authors: Duus Karen M. , Lentchitsky Vivian , Wagenaar Timothy , Grose Charles , Webster-Cyriaque Jennifer
Published: March 2004

Based on the observation that wild-type Kaposi's sarcoma-associated herpesvirus (KSHV) DNA can be detected in the oral cavity of healthy, immunocompetent individuals, we hypothesized that epithelial cells could be infected in vitro by wild-type (WT) KSHV isolated from immunocompetent individuals. Primary oral epithelial (P-EPI) cells and telomerase-immortalized oral epithelial cells were generated from human gingival tissue and were then infected in vitro with WT KSHV isolated from throat wash samples. Markers of lytic and latent KSHV infection were detected in cultures by 24 h postinfection by immunofluorescence confocal microscopic assays. The infectivity of the WT and BCBL virus was blocked by neutralizing antibodies against KSHV gB. The presence of KSHV DNA in these cells was confirmed by real-time PCR amplification of different regions of the viral genome. The significant in vitro viral replication that had occurred was inhibited by ganciclovir and by neutralizing antibodies against gB. When infected cultures were examined by scanning electron microscopy, thousands of KSHV particles were clearly visible across the surfaces of P-EPI cells. The detection of enveloped particles indicated that the infectious cycle had proceeded through assembly and egress. We thus demonstrated that oral WT KSHV isolated from immunocompetent individuals was able to infect and replicate in vitro in a relevant primary cell type. Furthermore, our results provide compelling evidence for KSHV transmission within infected oral epithelial cells derived from healthy, immunocompetent populations.
Human Immunodeficiency Virus Type 1 Nef Activates p21-Activated Kinase via Recruitment into Lipid Rafts
Authors: Krautkrämer Ellen , Giese Simone I. , Gasteier Judith E. , Muranyi Walter , Fackler Oliver T.
Published: March 2004

The Nef protein of human immunodeficiency virus type 1 is an important factor in AIDS pathogenesis. In addition to downregulating CD4 and major histocompatibility complex class I molecules from the cell surface, as well as increasing virion infectivity, Nef triggers activation of the T-cell receptor (TCR) cascade to facilitate virus spread. Signaling pathways that are induced by Nef have been identified; however, it is unclear how and in which subcellular compartment Nef triggers signaling. Nef recruits a multiprotein complex to activate the cellular Pak kinase that mediates downstream effector functions. Since a subpopulation of Nef is present in detergent-insoluble microdomains (lipid rafts) from where physiological TCR signaling is initiated, we tested whether lipid rafts are instrumental for Nef-mediated Pak activation. In flotation analysis, Nef-associated Pak activity exclusively fractionated with lipid rafts. Activation of Pak in the presence of Nef coincided with lipid raft recruitment of the kinase, which was otherwise excluded from detergent-insoluble microdomains. Experimental solubilization of lipid rafts interfered with the association of Pak activity with Nef. To analyze the importance of the raft localization for Nef function more rigorously, we generated a palmitoylated Nef (PalmNef). PalmNef was highly enriched in lipid rafts and associated with significantly higher levels of Pak activity than Nef. Notably, activation of Pak by its physiological activators, Cdc42 and Rac, also occurred in lipid rafts and required raft integrity. Together, these data suggest that Nef induces signal transduction via the recruitment of a signaling machinery including Pak into lipid rafts, thereby mimicking a physiological cellular mechanism to initiate the TCR cascade.
Essential Role of the NV Protein of
Novirhabdovirus
for Pathogenicity in Rainbow Trout
Authors: Thoulouze Maria-Isabel , Bouguyon Edwige , Carpentier Catherine , Brémont Michel
Published: March 2004

Novirhabdovirus, infectious hematopoietic necrosis virus (IHNV), and viral hemorrhagic septicemia virus (VHSV) are fish rhabdoviruses that, in comparison to the other rhabdoviruses, contain an additional gene coding for a small nonvirion (NV) protein of unassigned function. A recombinant IHNV with the NV gene deleted but expressing the green fluorescent protein (rIHNV-ΔNV) has previously been shown to be efficiently recovered by reverse genetics (S. Biacchesi et al., J. Virol. 74:11247-11253, 2000). However, preliminary experiments suggested that the growth in cell culture of rIHNV-ΔNV was affected by the NV deletion. In the present study, we show that the growth in cell culture of rIHNV-ΔNV is indeed severely impaired but that a normal growth of rIHNV-ΔNV can be restored when NV is provided in
trans
by using fish cell clones constitutively expressing the NV protein. These results indicate that NV is a protein that has a crucial biological role for optimal replication of IHNV in cell culture. Although IHNV and VHSV NV proteins do not share any significant identity, we show here that both NV proteins play a similar role since a recombinant IHNV virus, rIHNV-NV
VHSV
, in which the IHNV NV open reading frame has been replaced by that of VHSV, was shown to replicate as well as the wild-type (wt) IHNV into fish cells. Finally, data provided by experimental fish infections with the various recombinant viruses strongly suggest an essential role of the NV protein for the pathogenicity of IHNV. Furthermore, we show that juvenile trout immunized with NV-knockout IHNV were protected against challenge with wt IHNV. That opens a new perspective for the development of IHNV attenuated live vaccines.
CD4-Independent Infection of Astrocytes by Human Immunodeficiency Virus Type 1: Requirement for the Human Mannose Receptor
Authors: Liu Ying , Liu Hao , Kim Byung Oh , Gattone Vincent H. , Li Jinliang , Nath Avindra , Blum Janice , He Johnny J.
Published: March 2004

Human immunodeficiency virus type 1 (HIV-1) infection occurs in the central nervous system and causes a variety of neurobehavioral and neuropathological disorders. Both microglia, the residential macrophages in the brain, and astrocytes are susceptible to HIV-1 infection. Unlike microglia that express and utilize CD4 and chemokine coreceptors CCR5 and CCR3 for HIV-1 infection, astrocytes fail to express CD4. Astrocytes express several chemokine coreceptors; however, the involvement of these receptors in astrocyte HIV-1 infection appears to be insignificant. In the present study using an expression cloning strategy, the cDNA for the human mannose receptor (hMR) was found to be essential for CD4-independent HIV-1 infectivity. Ectopic expression of functional hMR rendered U87.MG astrocytic cells susceptible to HIV-1 infection, whereas anti-hMR serum and hMR-specific siRNA blocked HIV-1 infection in human primary astrocytes. In agreement with these findings, hMR bound to HIV-1 virions via the abundant and highly mannosylated sugar moieties of HIV-1 envelope glycoprotein gp120 in a Ca2+-dependent fashion. Moreover, hMR-mediated HIV-1 infection was dependent upon endocytic trafficking as assessed by transmission electron microscopy, as well as inhibition of viral entry by endosomo- and lysosomotropic drugs. Taken together, these results demonstrate the direct involvement of hMR in HIV-1 infection of astrocytes and suggest that HIV-1 interaction with hMR plays an important role in HIV-1 neuropathogenesis.
The Differential Sensitivity of Human and Rhesus Macaque CCR5 to Small-Molecule Inhibitors of Human Immunodeficiency Virus Type 1 Entry Is Explained by a Single Amino Acid Difference and Suggests a Mechanism of Action for These Inhibitors
Authors: Billick Erika , Seibert Christoph , Pugach Pavel , Ketas Tom , Trkola Alexandra , Endres Michael J. , Murgolo Nicholas J. , Coates Elizabeth , Reyes Gregory R. , Baroudy Bahige M. , Sakmar Thomas P. , Moore John P. , Kuhmann Shawn E.
Published: March 2004

AD101 and SCH-C are two chemically related small molecules that inhibit the entry of human immunodeficiency virus type 1 (HIV-1) via human CCR5. AD101 also inhibits HIV-1 entry via rhesus macaque CCR5, but SCH-C does not. Among the eight residues that differ between the human and macaque versions of the coreceptor, only one, methionine-198, accounts for the insensitivity of macaque CCR5 to inhibition by SCH-C. Thus, the macaque coreceptor engineered to contain the natural human CCR5 residue (isoleucine) at position 198 is sensitive to HIV-1 entry inhibition by SCH-C, whereas a human CCR5 mutant containing the corresponding macaque residue (methionine) is resistant. Position 198 is in CCR5 transmembrane (TM) helix 5 and is not located within the previously defined binding site for AD101 and SCH-C, which involves residues in TM helices 1, 2, 3, and 7. SCH-C binds to human CCR5 whether residue 198 is isoleucine or methionine, and it also binds to macaque CCR5. However, the binding of a conformation-dependent monoclonal antibody to human CCR5 is inhibited by SCH-C only when residue 198 is isoleucine. These observations, taken together, suggest that the antiviral effects of SCH-C and AD101 involve stabilization, or induction, of a CCR5 conformation that is not compatible with HIV-1 infection. However, SCH-C is unable to exert this effect on CCR5 conformation when residue 198 is methionine. The region of CCR5 near residue 198 has, therefore, an important influence on the conformational state of this receptor.
Specific and Common Alterations in Host Gene Transcript Accumulation following Infection of the Chestnut Blight Fungus by Mild and Severe Hypoviruses
Authors: Allen Todd D. , Nuss Donald L.
Published: March 2004

We report the use of a cDNA microarray to monitor global transcriptional responses of the chestnut blight fungus,
Cryphonectria parasitica
, to infection by mild and severe isolates of virulence-attenuating hypoviruses that share 87 to 93% and 90 to 98% identity at the nucleotide and amino acid levels, respectively. Infection by the mild hypovirus isolate CHV1-Euro7 resulted in differential expression of 166 of the ca. 2,200 genes represented on the microarray (90 upregulated and 76 downregulated). This is roughly half the number of genes scored as differentially expressed after infection by the severe isolate, CHV1-EP713 (295 genes; 132 upregulated and 163 downregulated). Comparison of the lists of genes responsive to infection by the two hypovirus isolates revealed 80 virus-common responsive genes. Infection by CHV1-EP713 also caused changes in gene transcript accumulation that were, in general, of greater magnitude than those observed with CHV1-Euro7 infections. Thus, the host transcriptional response to infection by severe hypovirus CHV1-EP713 appears to be considerably more dynamic than the response to infection by the mild isolate CHV1-Euro7. Real-time reverse transcription-PCR was performed on 39 different clones, with false-positive rates of 3 and 8% observed for the microarray-predicted list of genes responsive to CHV1-EP713 and CHV1-Euro7 infections, respectively. This analysis has allowed an initial assignment for ca. 2,200 unique
C. parasitica
-expressed genes as being unresponsive to hypovirus infection, selectively responsive to a specific hypovirus, or generally responsive to hypovirus infection.
Targeted Correction of Single-Base-Pair Mutations with Adeno-Associated Virus Vectors under Nonselective Conditions
Authors: Liu Xiaoming , Yan Ziying , Luo Meihui , Zak Roman , Li Ziyi , Driskell Ryan R. , Huang Yumao , Tran Nam , Engelhardt John F.
Published: March 2004

Recombinant adeno-associated virus (rAAV) vectors possess the unique ability to introduce genetic alterations at sites of homology in genomic DNA through a mechanism thought to predominantly involve homologous recombination. We have investigated the efficiency of this approach using a mutant enhanced green fluorescent protein (eGFP) fluorescence recovery assay that facilitates detection of gene correction events in living cells under nonselective conditions. Our data demonstrate that rAAV infection can correct a mutant eGFP transgene at an efficiency of 0.1% in 293 cells, as determined by fluorescence-activated cell-sorting analysis. Gene repair was also confirmed using clonal expansion of GFP-positive cells and sequencing of the eGFP transgene. These results support previous findings demonstrating the efficacy of rAAV for gene targeting. In an effort to improve gene-targeting efficiencies, we evaluated several agents known to increase rAAV transduction (i.e., expression of an expressed gene), including genotoxic stress and proteasome inhibitors, but observed no correlation between the level of gene repair and rAAV transduction. Interestingly, however, our results demonstrated that enrichment of G
1
/S-phase cells in the target population through the addition of thymidine moderately (∼2-fold) increased gene correction compared to cells in other cell cycle phases, including G
0
/G1, G
1
, and G
2
/M. These results suggest that the S phase of the cell cycle may more efficiently facilitate gene repair by rAAV. Transgenic mice expressing the mutant GFP were used to evaluate rAAV targeting efficiencies in primary fetal fibroblast and tibialis muscles. However, targeting efficiencies in primary mouse fetal fibroblasts were significantly lower (∼0.006%) than in 293 cells, and no correction was seen in tibialis muscles following rAAV infection. To evaluate the molecular structures of rAAV genomes that might be responsible for gene repair, single-cell injection studies were performed with purified viral DNA in a mutant eGFP target cell line. However, the failure of direct cytoplasm- or nucleus-injected rAAV DNA to facilitate gene repair suggests that some aspect of intracellular viral processing may be required to prime recombinant viral genomes for gene repair events.
The Hemagglutinin-Neuraminidase Protein of Newcastle Disease Virus Determines Tropism and Virulence
Authors: Huang Zhuhui , Panda Aruna , Elankumaran Subbiah , Govindarajan Dhanasekaran , Rockemann Daniel D. , Samal Siba K.
Published: March 2004

The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) plays a crucial role in the process of infection. However, the exact contribution of the HN gene to NDV pathogenesis is not known. In this study, the role of the HN gene in NDV virulence was examined. By use of reverse genetics procedures, the HN genes of a virulent recombinant NDV strain, rBeaudette C (rBC), and an avirulent recombinant NDV strain, rLaSota, were exchanged. The hemadsorption and neuraminidase activities of the chimeric viruses showed significant differences from those of their parental strains, but heterotypic F and HN pairs were equally effective in fusion promotion. The tissue tropism of the viruses was shown to be dependent on the origin of the HN protein. The chimeric virus with the HN protein derived from the virulent virus exhibited a tissue predilection similar to that of the virulent virus, and vice versa. The chimeric viruses with reciprocal HN proteins either gained or lost virulence, as determined by a standard intracerebral pathogenicity index test of chickens and by the mean death time in chicken embryos (a measure devised to classify these viruses), indicating that virulence is a function of the amino acid differences in the HN protein. These results are consistent with the hypothesis that the virulence of NDV is multigenic and that the cleavability of F protein alone does not determine the virulence of a strain.
Kaposi's Sarcoma-Associated Herpesvirus/Human Herpesvirus 8 Envelope Glycoprotein gB Induces the Integrin-Dependent Focal Adhesion Kinase-Src-Phosphatidylinositol 3-Kinase-Rho GTPase Signal Pathways and Cytoskeletal Rearrangements
Authors: Sharma-Walia Neelam , Naranatt Pramod P. , Krishnan Harinivas H. , Zeng Ling , Chandran Bala
Published: March 2004

Human herpesvirus 8 (HHV-8; Kaposi's sarcoma-associated herpesvirus) envelope glycoprotein gB possesses an RGD motif, interacts with α3β1 integrin, and uses it as one of the entry receptors. HHV-8 induces the integrin-dependent focal adhesion kinase (FAK), a critical step in the outside-in signaling pathways necessary for the subsequent phosphorylation of other cellular kinases, cytoskeletal rearrangements, and other functions. As an initial step toward deciphering the role of HHV-8 gB-integrin interaction in infection, signal pathways induced by gB were examined. A truncated form of gB without the transmembrane and carboxyl domains (gBΔTM), a gBΔTM mutant form (gBΔTM-RGA) with an RGD-to-RGA mutation, and inhibitors of cellular kinases were used. HHV-8 gBΔTM, but not gBΔTM-RGA, induced FAK phosphorylation in target cells, which was in part dependent on the presence of α3β1 integrin. FAK was critical for the subsequent phosphorylation of Src by gBΔTM, and Src induction was essential for the phosphorylation of phosphatidylinositol 3-kinase (PI-3K). HHV-8 gBΔTM-induced PI-3K was essential for the induction of RhoA and Cdc42 Rho GTPases that was accompanied by the cytoskeletal rearrangements. These gB-induced morphological changes were inhibited by the PI-3K inhibitors. Ezrin, one of the essential elements required to cross-link the actin cytoskeleton with the plasma membrane and to induce the morphological changes, was induced by the Rho GTPases. Inhibition of cellular tyrosine kinases by the brief treatment of cells with 4′,5,7-trihydroxyisoflavone (genistein) blocked the entry of HHV-8 into target cells. These findings suggest that, independently of other viral glycoproteins and via its RGD motif, HHV-8 gB induces integrin-dependent pre-existing FAK-Src-PI-3K-Rho GTPase kinases. Since these signal pathways play vital roles in host cell endocytosis and movement of particulate materials in the cytoplasm, the early stages of HHV-8 gB interaction with host cells may provide a very conducive environment for the successful infection of target cells.
Role of Minority Populations of Human Immunodeficiency Virus Type 1 in the Evolution of Viral Resistance to Protease Inhibitors
Authors: Charpentier Charlotte , Dwyer Dominic E. , Mammano Fabrizio , Lecossier Denise , Clavel François , Hance Allan J.
Published: March 2004

Human immunodeficiency virus type 1 (HIV-1) drug resistance results from the accumulation of mutations in the viral genes targeted by the drugs. These genetic changes, however, are commonly detected and monitored by techniques that only take into account the dominant population of plasma virus. Because HIV-1-infected patients harbor a complex and diverse mixture of virus populations, the mechanisms underlying the emergence and the evolution of resistance are not fully elucidated. Using techniques that allow the quantification of resistance mutations in minority virus species, we have monitored the evolution of resistance in plasma virus populations from patients failing protease inhibitor treatment. Minority populations with distinct resistance genotypes were detected in all patients throughout the evolution of resistance. The emergence of new dominant genotypes followed two possible mechanisms: (i) emergence of a new mutation in a currently dominant genotype and (ii) emergence of a new genotype derived from a minority virus species. In most cases, these population changes were associated with an increase in resistance at the expense of a reduction in replication capacity. Our findings provide a preliminary indication that minority viral species, which evolve independently of the majority virus population, can eventually become dominant populations, thereby serving as a reservoir of diversity and possibly accelerating the development of drug resistance.
Protein Kinase B/Akt Regulates Coxsackievirus B3 Replication through a Mechanism Which Is Not Caspase Dependent
Authors: Esfandiarei Mitra , Luo Honglin , Yanagawa Bobby , Suarez Agripina , Dabiri Darya , Zhang Jianchang , McManus Bruce M.
Published: March 2004

The role of signaling pathways including the mitogen-activated protein kinases (MAPKs) and phosphatidylinositol 3-kinase (PI3K) during viral infection has gained much recent attention. Our laboratory reported on an important regulatory role for extracellular signal-regulated kinases (ERK1/2), subfamily members of the MAPKs, during coxsackievirus B3 (CVB3) infection. However, the role of the PI3K pathway in CVB3 infection has not been well characterized. CVB3 is the most common known viral infectant of heart muscle that directly injures and kills infected cardiac myocytes during the myocarditic process. In the present study, we investigated the role of protein kinase B (PKB) (also known as Akt), a general downstream mediator of survival signals through the PI3K cascade, in regulating CVB3 replication and virus-induced apoptosis in a well-established HeLa cell model. We have demonstrated that CVB3 infection leads to phosphorylation of PKB/Akt on both Ser-473 and Thr-308 residues through a PI3K-dependent mechanism. Transfection of HeLa cells with a dominant negative mutant of Akt1 or pretreatment of wild-type HeLa cells with the specific PI3K inhibitor LY294002 significantly suppresses viral RNA expression, as reflected in diminished viral capsid protein expression and viral release. Dominant negative Akt1 and LY294002 also increase apoptosis in infected cells, which can be reversed by addition of the general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk). Interestingly, blocking of apoptosis by zVAD.fmk does not reverse the viral RNA translation blockade, indicating that the inhibitory effect of dominant negative Akt1 on viral protein expression is not caspase dependent. In addition, we showed that the attachment of virus to its receptor-coreceptor complex is not sufficient for PKB/Akt activation and that postentry viral replication is required for Akt phosphorylation. Taken together, these data illustrate a new and imperative role for Akt in CVB3 infection in HeLa cells and show that the PI3K/Akt signaling is beneficial to CVB3 replication.
Rubella Virus Capsid Protein Modulates Viral Genome Replication and Virus Infectivity
Authors: Chen Min-Hsin , Icenogle Joseph P.
Published: March 2004

The structural proteins (SP) of the
Togaviridae
can be deleted in defective interfering RNAs. The dispensability of viral SP has allowed construction of noninfectious viral expression vectors and replicons from viruses of the
Alphavirus
and
Rubivirus
genera. Nevertheless, in this study, we found that the SP of rubella virus (RUB) could enhance expression of reporter genes from RUB replicons in
trans
. SP enhancement required capsid protein (CP) expression and was not due to RNA-RNA recombination. Accumulation of minus- and plus-strand RNAs from replicons was observed in the presence of SP, suggesting that SP specifically affects RNA synthesis. By using replicons containing an antibiotic resistance gene, we found 2- to 50-fold increases in the number of cells surviving selection in the presence of SP. The increases depended significantly on the amount of transfected RNA. Small amounts of RNA or templates that replicated inefficiently showed more enhancement. The infectivity of infectious RNA was increased by at least 10-fold in cells expressing CP. Moreover, virus infectivity was greatly enhanced in such cells. In other cells that expressed higher levels of CP, RNA replication of replicons was inhibited. Thus, depending on conditions, CP can markedly enhance or inhibit RUB RNA replication.
Reptilian Reovirus Utilizes a Small Type III Protein with an External Myristylated Amino Terminus To Mediate Cell-Cell Fusion
Authors: Corcoran Jennifer A. , Duncan Roy
Published: March 2004

Reptilian reovirus is one of a limited number of nonenveloped viruses that are capable of inducing cell-cell fusion. A small, hydrophobic, basic, 125-amino-acid fusion protein encoded by the first open reading frame of a bicistronic viral mRNA is responsible for this fusion activity. Sequence comparisons to previously characterized reovirus fusion proteins indicated that p14 represents a new member of the fusion-associated small transmembrane (FAST) protein family. Topological analysis revealed that p14 is a representative of a minor subset of integral membrane proteins, the type III proteins N
exoplasmic
/C
cytoplasmic
(N
exo
/C
cyt
), that lack a cleavable signal sequence and use an internal reverse signal-anchor sequence to direct membrane insertion and protein topology. This topology results in the unexpected, cotranslational translocation of the essential myristylated N-terminal domain of p14 across the cell membrane. The topology and structural motifs present in this novel reovirus membrane fusion protein further accentuate the diversity and unusual properties of the FAST protein family and clearly indicate that the FAST proteins represent a third distinct class of viral membrane fusion proteins.
High Variety of Different Simian T-Cell Leukemia Virus Type 1 Strains in Chimpanzees (Pan troglodytes verus) of the Taï National Park, Côte d'Ivoire
Authors: Leendertz Fabian H. , Junglen Sandra , Boesch Christophe , Formenty Pierre , Couacy-Hymann Emmanuel , Courgnaud Valerie , Pauli Georg , Ellerbrok Heinz
Published: March 2004

We found human T-cell leukemia virus type 1- and simian T-cell leukemia virus type 1 (STLV-1)-related infections in 5 of 10 chimpanzees originating from three groups of wild chimpanzees. The new virus isolates showed a surprising heterogeneity not only in comparison to STLV-1 described previously in other primate species but also between the different chimpanzee groups, within a group, or even between strains isolated from an individual animal. The interdisciplinary combination of virology, molecular epidemiology, and long-term behavioral studies suggests that the primary route of infection might be interspecies transmission from other primates, such as red colobus monkeys, that are hunted and consumed by chimpanzees.
Thyroid transcription factor 1 in pulmonary adenocarcinoma
Authors: Stenhouse G , Fyfe N , King G , Chapman A , Kerr K M
Published: March 2004

Aims:To discover whether variations in thyroid transcription factor 1 (TTF-1) staining in different subtypes and patterns of pulmonary adenocarcinoma are related to the putative origin of the tumour. In addition, to confirm the specificity of TTF-1 for pulmonary (as opposed to other sites) adenocarcinoma, to examine the possible prognostic relevance of TTF-1 positivity in lung cancer, and to review this laboratory’s experience of TTF-1 in diagnostic practice.

Materials/Methods:In total, 128 primary lung adenocarcinomas, 106 primary non-pulmonary adenocarcinomas, and 37 pulmonary non-adenocarcinoma tumours were studied. In addition, 100 cases where TTF-1 was used in routine surgical pathology practice were investigated. Immunoperoxidase staining was performed on formalin fixed, paraffin wax embedded sections using anti-TTF-1 antibody. Staining was evaluated semiquantitatively using the frequency and intensity of nuclear positivity.

Results:None of the 106 non-pulmonary adenocarcinomas expressed TTF-1 and only three of the 37 non-adenocarcinoma lung cancers, all neuroendocrine carcinomas, were positive. Of the pulmonary adenocarcinomas, 75% were strongly positive for TTF-1. Mucinous (two of six) and poorly differentiated adenocarcinomas (four of 10) were less likely to stain. Of the peripheral adenocarcinomas, 33 of 37 were positive, whereas only seven of 14 of those of bronchial origin stained strongly. Atypical adenomatous hyperplasia strongly expressed TTF-1. No “false positives” were encountered in the 100 routine diagnostic cases.

Conclusion:Positive TTF-1 staining is useful in the differential diagnosis of pulmonary adenocarcinomas. TTF-1 may be a lineage marker for tumours arising from the peripheral airway or alveolar epithelium and has no prognostic relevance.
Steatosis and fibrosis in patients with chronic hepatitis C
Authors: Wyatt J , Baker H , Prasad P , Gong Y Y , Millson C
Published: March 2004

Background:Steatosis is present on liver biopsy in approximately 50% of patients with hepatitis C; its association with stage of fibrosis has been reported, but its relation to other fibrosis associated factors is unknown.

Aim:To study the relation between steatosis and other histological features in patients with hepatitis C, and changes in steatosis with time.

Methods:Cross sectional study: 233 routine liver biopsies from 219 patients with hepatitis C; hepatectomy specimens from 65 patients transplanted for hepatitis C cirrhosis. Longitudinal study: 41 patients with two biopsies and 10 patients with three biopsies performed over 2–8 years. Biopsies were scored by the Ishak scheme, and degree of steatosis assessed subjectively. Multivariate analysis was used to study the interaction of fibrosis associated factors. Changes in steatosis over time in individual patients were explored in the longitudinal study.

Results:Steatosis was present in 50% of biopsies. It correlated strongly with fibrosis in non-cirrhotic samples, but declined in cirrhosis, and was unusual in transplant hepatectomy specimens. On multivariate analysis of non-cirrhotic biopsies, steatosis was associated with increasing patient age and remained significantly associated with fibrosis independent of portal inflammation and interface hepatitis. In the longitudinal study, steatosis persisted and increased over time, except in patients developing cirrhosis.

Conclusions:Steatosis is associated with fibrosis independently of necroinflammation, but declines in cirrhosis. It may represent a pathogenic pathway distinct from necroinflammatory activity in the generation of liver fibrosis, and should be included in the assessment of biopsies for clinical and research purposes.
Suspicious urinary cytology with negative evaluation for malignancy in the diagnostic investigation of haematuria: how to follow up?
Authors: Nabi G , Greene D , Donnel M O
Published: March 2004

Aims:To define the natural history of patients with suspicious urinary cytology and negative initial evaluation for malignancy in the investigation of haematuria.

Patients and methods:Data from the hospital information support system on urinary cytology examinations carried out at one centre were audited over a period of 24 months. There were 102 patients who had suspicious urinary cytology for malignant cells with negative initial evaluation. Follow up investigations, treatment, and final outcome were noted.

Results:There were 102 patients with suspicious urinary cytology and negative initial evaluation for malignancy in 24 months, with a mean follow up of 15.7 months. Seventy patients had no obvious pathology on initial investigations. Forty one patients were found to have urological malignancies (29 bladder, eight ureteric, and four prostate) on follow up. All patients diagnosed as having urothelial malignancies on follow up had either persistent suspicious cytology (29) or recurrent haematuria (eight). The mean duration for appearance of lesions was 5.6 months (range, 3–12 months). Three patients had suspicious digital rectal examination and biopsies confirmed adenocarcinoma of the prostate. One patient had urinary retention and transurethral resection of prostate showed prostatic adenocarcinoma. The presence of suspicious cells on repeat urine analysis was the only significant factor in predicting the presence of urothelial tumours (p  =  0.002).

Conclusion:Patients with persistent suspicious/positive cytology or recurrent haematuria need further evaluation and follow up. Asymptomatic patients or patients with obvious benign pathology do not require repeat evaluation. Careful urological evaluation, including prostate, should be carried out in these patients.
The practical application of reflectance spectrophotometry for the demonstration of haemoglobin and its degradation in bruises
Authors: Hughes V K , Ellis P S , Burt T , Langlois N E I
Published: March 2004

Aims:To develop a non-invasive method to demonstrate the presence of haemoglobin and its degradation products in bruises in live human subjects for the purposes of objectively assisting in the determination of the age of a bruise.

Methods:The cuvette holder unit of a Cary 100 Bio UV-Visible Spectrophotometer was replaced with the manufacture’s fibre optic cable and optical reflectance probe. The probe was placed on the skin surface. The absorption spectrum from 780 to 380 nm was collected and transformed into the first derivative. Calculation of the first derivative permits absorption attributed to haemoglobin degradation (primarily to bilirubin, but also haemosiderin) to be separated from absorption by haemoglobin. First derivative and colorimetry values, expressed as CIEL*a*b data, were derived from scans of 50 bruises.

Results:The fibre optic cable and probe allowed the spectrophotometer to collect reproducible absorption spectra of bruises in the skin of living subjects. A bruise at three days has greater negative first derivative values at 480 and 490 nm than does a fresh bruise, indicating the local degradation of haemoglobin. Correlation between the first derivative and the CIEL*a*b “b” values in a series of bruises indicates that the yellow colour in a bruise is proportional to the amount of local haemoglobin breakdown.

Conclusion:The ability to demonstrate the presence of haemoglobin and measure its degradation in bruises in living human subjects by a non-invasive method has not been described previously, and may be of use in the objective ageing of bruises for forensic purposes.
A tale of two sisters
Authors: Gaya D R , McLay A L C , Oien K A , Spooner R J , Reilly T G
Published: March 2004

Hereditary haemochromatosis is the most common inherited disorder in white populations, whereas non-alcoholic steatohepatitis (NASH) is becoming the most common reason for referral for investigation of abnormal liver function tests (LFTs). This report describes two sisters, from similar environments, who were referred to the clinic after being found to be C282Y homozygotes and to have abnormal LFTs. One sister had developed features of haemochromatosis and the other had developed NASH. These cases illustrate the potential non-penetrance of HFE gene mutations and the need to investigate abnormal LFTs fully, even when there is a positive genetic test at the outset.
Unfavourable prognosis of patients with trisomy 18q21 detected by fluorescence in situ hybridisation in t(11;18) negative, surgically resected, gastrointestinal B cell lymphomas
Authors: Krugmann J , Tzankov A , Dirnhofer S , Fend F , Greil R , Siebert R , Erdel M
Published: March 2004

Background:The most frequent cytogenetic alteration in gastrointestinal (GI) B cell lymphoma (BCL) is t(11;18)(q21;q21). GI B cell non-Hodgkin lymphomas lacking this translocation vary in their biology and clinical outcome. The t(11;18) negative subgroup shows increased numerical changes of chromosome 18, although its clinical relevance remains unknown.

Methods:Thirty surgically resected primary GI BCLs were examined—11 low grade marginal zone mucosa associated lymphoid tissue (MALT) lymphomas, four marginal zone lymphomas with diffuse large BCL (DLBCL), and 15 de novo DLBCLs. Chromosome 18 aberrations were examined using interphase fluorescence in situ hybridisation. Trisomy 18 was studied applying a centromere 18 probe and a dual colour probe for the MALT1 gene at 18q21.

Results:Using the MALT1 probe, only one marginal zone MALT lymphoma had a break apart pattern, indicating t(11;18) or variants. In the GI BCLs lacking MALT1 breaks, trisomy 18q21 was seen in seven patients (four with complete trisomy 18 and three with partial trisomy of 18q21). Trisomy 18q21 was found in two of 10 low grade MALT lymphomas and five of 19 GI BCLs with large cell component. Six of 17 patients with trisomy 18q21 presented with ≥stage II and one of 12 with stage I disease. Trisomy 18q21 was associated with significantly shorter disease specific survival in the whole group and GI BCLs with large cell component, but not in the low grade group.

Conclusions:Trisomy 18q21, including MALT1, may be associated with advanced tumour stage and may be a predictor of poor outcome in surgically resected primary GI BCLs.
Serological and genetic characterisation of a unique strain of adenovirus involved in an outbreak of epidemic keratoconjunctivitis
Authors: Adhikary A K , Inada T , Banik U , Mukouyama A , Ikeda Y , Noda M , Ogino T , Suzuki E , Kaburaki T , Numaga J , Okabe N
Published: March 2004

Aims:To characterise a novel strain of adenovirus (Ad) type Ad8 (genome type Ad8I) involved in an epidemic keratoconjunctivitis (EKC) outbreak in Hiroshima city using serological testing and sequence analysis of the fibre and hexon gene.

Methods:A neutralisation test (NT) was performed in microtitre plates containing a confluent monolayer of A549 cells using 100 tissue culture infectious doses of virus and type specific antisera. The haemagglutination inhibition test was also carried out in microtitre plates with rat erythrocytes using four haemagglutination units of virus and twofold dilutions of serum. The fibre gene was sequenced by generating overlapping polymerase chain reaction products or by direct sequencing of genomic DNA. Primer selection was based on alignment of the fibre genes of human adenovirus serotypes Ad8, Ad19, Ad37, Ad9, and Ad15 available from Gene Bank.

Results:The virus strain was specifically neutralised by anti-Ad8 antibodies, although there was a major crossreaction with anti-Ad9 antibodies. Haemagglutination was equally inhibited by anti-Ad8 and anti-Ad9 antibodies. The predicted amino acid sequences of the hypervariable regions (HVRs) of the Ad8I hexon gene showed higher homology with Ad9 (83.3%) than with Ad8 (62.0%). However, the Ad8I fibre knob was more homologous to Ad8 (94.4%) than to Ad9 (91.6%).

Conclusions:Ad8I is a unique strain of adenovirus because of its lower genomic homology with Ad8, major crossreactivity with Ad9 in NT, and mixed genetic organisation of HVRs of the hexon gene. These factors may have enabled the virus to circumvent acquired immunity, resulting in the outbreak.
Cutaneous manifestations of thyroid cancer: a report of four cases and review of the literature
Authors: Alwaheeb S , Ghazarian D , Boerner S L , Asa S L
Published: March 2004

Cutaneous metastases from thyroid carcinoma are rare. This report describes four cases of thyroid carcinoma metastatic to the skin. Two cases were medullary carcinoma and two were papillary thyroid carcinoma. In two cases, skin metastases were the presenting feature of the underlying thyroid carcinoma. Examination of the skin lesions by conventional light microscopy suggested the possibility of metastatic carcinoma and immunohistochemical tests confirmed the diagnosis. Subsequent investigations identified primary thyroid lesions. In two cases, the skin metastasis was the first evidence of the recurrence of known thyroid carcinoma. These cases identify a novel presentation of thyroid carcinoma.
Loss of heterozygosity of the BRCA1 and FHIT genes in patients with sporadic breast cancer from Southern Brazil
Authors: Santos S C L , Cavalli L R , Cavalli I J , Lima R S , Haddad B R , Ribeiro E M S F
Published: March 2004

Aim:The evaluation of allelic losses at the FHIT and the BRCA1 genes and at three other loci at the 17q region in a series of 34 sporadic breast cancer cases from Southern Brazil.

Methods:The samples were evaluated for loss of heterozygosity (LOH) at the FHIT and the BRCA1 genes and at three other microsatellite markers at 17q, and the findings were correlated with clinicopathological parameters.

Results:The BRCA1 intragenic marker, D17S855, had the highest frequency of LOH, detected in 10 of 24 informative cases, followed by the D17S579 (six of 23 informative cases), D17S806 (five of 21 informative cases), and D17S785 markers (five of 21 informative cases). LOH at the FHIT intragenic marker, D3S1300, was found in six of 25 informative cases. In four of the six cases with LOH of the FHIT gene, there was concomitant loss of the BRCA1 intragenic marker.

Conclusions:The frequency of allelic losses in the FHIT and BRCA1 loci in the Southern Brazilian population is similar to that described in the general population. No correlations were found when the total LOH frequency was compared with tumour size, grade, or presence of axillary lymph node metastasis. Further studies using larger sporadic breast cancer samples and additional markers would be useful to confirm these findings, in addition to establishing more specific associations with clinicopathological parameters in this specific population.
Acquired C1 esterase inhibitor deficiency or serendipity? The chance finding of a paraprotein after an apparently low C1 esterase inhibitor concentration
Authors: Sinclair D , Smith A , Cranfield T , Lock R J
Published: March 2004

Acquired C1 esterase inhibitor deficiency is a rare condition, usually presenting after the 2nd decade of life, and is often related to underlying conditions such as autoimmune and lymphoproliferative disorders. This case report describes a man whose initial clinical presentation with acute angioedema and whose initial estimation of a low C1 esterase inhibitor concentration indicated that he had an acquired angioedema, possibly secondary to a B cell neoplasm. A paraprotein was detected, and although its detection was serendipitous because it hinged on a spurious C1 esterase inhibitor result, this case confirms the role of C4 concentrations in the investigation of C1 esterase inhibitor deficiency. It also confirms the need to obtain repeat confirmatory samples before arriving at a diagnosis, however convincing the clinical signs may be.
An audit of splenectomies in a teaching hospital in North India. Are postsplenectomy guidelines being complied with?
Authors: Deodhar M , Kakkar N
Published: March 2004

Aims:Patients with an absent or dysfunctional spleen are at risk of infection by encapsulated and other bacteria. Overwhelming postsplenectomy infection (OPSI) causes most concern because it can result in significant mortality. A retrospective review of splenectomised patients in a tertiary care setting over an eight year period was carried out to determine whether current postsplenectomy guidelines were being followed.

Methods:The cases were identified from the medical records and pathology files and data such as the reason for splenectomy, the preventive measures taken regarding vaccination, and antibiotic prophylaxis, together with their documentation in the discharge notes were assessed.

Results:Fifty six patients were studied. Trauma, both blunt and penetrating, was the most common reason for splenectomy. Thirty six patients received pneumococcal vaccination, with 20 patients having no mention of vaccination in their case notes. The discharge notes of 50 patients mentioned their splenectomised status; however, documentation of vaccination details in the discharge summary was poor, with only three patients having the relevant information recorded. Documentation of the need for future vaccination and precautions required in the asplenic condition was also lacking. Nine patients had postsplenectomy complications, although there were no cases of OPSI.

Conclusions:Adherence to standard guidelines for the management of splenectomised patients was unsatisfactory. There is a need for an improvement of the vaccination rate and careful documentation of this important health risk in the discharge summaries. Maintenance of a splenectomy registry could aid in optimising the management of these patients.
TRANSVERSAL MAGNETIC FIELD EFFECT ON THE POPULATIONS OF EXCITED STATES OF HELIUM ATOMS IN NANOSECOND DISCHARGE
Authors: EL-KORAMY R. A.
Published: March 2004

Mechanism's effect of transversal magnetic field on the populations of excited states of He atoms has been investigated. Furthermore, the dependencies of complete absorption of He(I) spectral line transition 33P0,1,2–23S1 on optical plasma density are calculated by numerical methods taking into consideration the fine-structure and Zeeman splitting schemes of the spectral lines. Using the calculated values and experimental results, the dynamics of the populations of He(I) metastable states 23S1 of the He nanosecond discharge are discussed.
DISSIPATIVE BLACKBODY RADIATION: RADIATION IN A LOSSY CAVITY
Authors: CHOI J. R.
Published: March 2004

We defined normalized density operator that satisfies Liouville–von Neumann equation in terms of the invariant operator. The energy density inside the cavity decreased exponentially with time due to the conductivity of the media. We also evaluated the total number of photons in the cavity.
LOW TEMPERATURE DEPENDENCE OF THE PENETRATION DEPTH IN SUPERCONDUCTOR MgB2 IN THE PRESENCE AND ABSENCE OF IMPURITIES
Authors: SHAHZAMANIAN M. A. , YAVARY H.
Published: March 2004

The large variety of the measured magnetic penetration depth is interpreted by using two microscopic gap models. We calculate the penetration depth of superconductor MgB 2 in low temperatures by using two gap and an anisotropic s-wave gap models. In the two gap model we consider that the total penetration depth is a weighted sum of the contribution from σ- and π-bands and the interaction between these two bands is ignored. The effect of impurities on the σ-band is less than that π-band and there are tremendous modifications of the temperature dependence of the penetration depth for π-band.