bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity of Human Immunodeficiency Virus Type 1 to Fusion Inhibitors Targeted to the gp41 First Heptad Repeat Involves Distinct Regions of gp41 and Is Consistently Modulated by gp120 Interactions with the Coreceptor
Authors: Derdeyn Cynthia A. , Decker Julie M. , Sfakianos Jeffrey N. , Zhang Zhijun , O'Brien William A. , Ratner Lee , Shaw George M. , Hunter Eric
Published: July 2002

T-20 is a synthetic peptide that corresponds to 36 amino acids within the C-terminal heptad repeat region (HR2) of human immunodeficiency virus type 1 (HIV-1) gp41. T-20 has been shown to potently inhibit viral replication of HIV-1 both in vitro and in vivo and is currently being evaluated in a Phase III clinical trial. T-649 is an inhibitory peptide that also corresponds to 36 amino acids within HR2. This sequence overlaps the T-20 sequence but is shifted 10 residues toward the N terminus of gp41. Both inhibitors are thought to exert their antiviral activity by interfering with the conformational changes that occur within gp41 to promote membrane fusion following gp120 interactions with CD4 and coreceptor molecules. We have shown previously that coreceptor specificity defined by the V3 loop of gp120 modulates sensitivity to T-20 and that a critical region within the N-terminal heptad repeat (HR1) of gp41 is the major determinant of sensitivity (C. A. Derdeyn et al., J. Virol. 74:8358–8367, 2000). This report shows that (i) regions within gp41 distinct from those associated with T-20 sensitivity govern the baseline sensitivity to T-649 and (ii) T-649 sensitivity of chimeric viruses that contain sequences derived from CXCR4- and CCR5-specific envelopes is also modulated by coreceptor specificity. Moreover, the pattern of sensitivity of CCR5-specific chimeras with only minor differences in their V3 loop was consistent for both inhibitors, suggesting that the individual affinity for coreceptor may influence accessibility of these inhibitors to their target sequence. Finally, an analysis of the sensitivity of 55 primary, inhibitor-naive HIV-1 isolates found that higher concentrations of T-20 (
P
< 0.001) and T-649 (
P
= 0.016) were required to inhibit CCR5-specific viruses compared to viruses that utilize CXCR4. The results presented here implicate gp120-coreceptor interactions in driving the complex conformational changes that occur in gp41 to promote fusion and entry and suggest that sensitivity to different HR1-directed fusion inhibitors is governed by distinct regions of gp41 but is consistently modulated by coreceptor specificity.
U
L
31 and U
L
34 Proteins of Herpes Simplex Virus Type 1 Form a Complex That Accumulates at the Nuclear Rim and Is Required for Envelopment of Nucleocapsids
Authors: Reynolds Ashley E. , Ryckman Brent J. , Baines Joel D. , Zhou Yuping , Liang Li , Roller Richard J.
Published: July 2002

The herpes simplex virus type 1 (HSV-1) U
L
34 protein is likely a type II membrane protein that localizes within the nuclear membrane and is required for efficient envelopment of progeny virions at the nuclear envelope, whereas the U
L
31 gene product of HSV-1 is a nuclear matrix-associated phosphoprotein previously shown to interact with U
L
34 protein in HSV-1-infected cell lysates. For these studies, polyclonal antisera directed against purified fusion proteins containing U
L
31 protein fused to glutathione-
S
-transferase (U
L
31-GST) and U
L
34 protein fused to GST (U
L
34-GST) were demonstrated to specifically recognize the U
L
31 and U
L
34 proteins of approximately 34,000 and 30,000 Da, respectively. The U
L
31 and U
L
34 gene products colocalized in a smooth pattern throughout the nuclear rim of infected cells by 10 h postinfection. U
L
34 protein also accumulated in pleiomorphic cytoplasmic structures at early times and associated with an altered nuclear envelope late in infection. Localization of U
L
31 protein at the nuclear rim required the presence of U
L
34 protein, inasmuch as cells infected with a U
L
34 null mutant virus contained U
L
31 protein primarily in central intranuclear domains separate from the nuclear rim, and to a lesser extent in the cytoplasm. Conversely, localization of U
L
34 protein exclusively at the nuclear rim required the presence of the U
L
31 gene product, inasmuch as U
L
34 protein was detectable at the nuclear rim, in replication compartments, and in the cytoplasm of cells infected with a U
L
31 null virus. When transiently expressed in the absence of other viral factors, U
L
31 protein localized diffusely in the nucleoplasm, whereas U
L
34 protein localized primarily in the cytoplasm and at the nuclear rim. In contrast, coexpression of the U
L
31 and U
L
34 proteins was sufficient to target both proteins exclusively to the nuclear rim. The proteins were also shown to directly interact in vitro in the absence of other viral proteins. In cells infected with a virus lacking the U
S
3-encoded protein kinase, previously shown to phosphorylate the U
L
34 gene product, U
L
31 and U
L
34 proteins colocalized in small punctate areas that accumulated on the nuclear rim. Thus, U
S
3 kinase is required for even distribution of U
L
31 and U
L
34 proteins throughout the nuclear rim. Taken together with the similar phenotypes of the U
L
31 and U
L
34 deletion mutants, these data strongly suggest that the U
L
31 and U
L
34 proteins form a complex that accumulates at the nuclear membrane and plays an important role in nucleocapsid envelopment at the inner nuclear membrane.
Human Cytomegalovirus Protein US2 Interferes with the Expression of Human HFE, a Nonclassical Class I Major Histocompatibility Complex Molecule That Regulates Iron Homeostasis
Authors: Ben-Arieh Sayeh Vahdati , Zimerman Baruch , Smorodinsky Nechama I. , Yaacubovicz Margalit , Schechter Chana , Bacik Igor , Gibbs Jim , Bennink Jack R. , Yewdell Jon W. , Coligan John E. , Firat Hüseyin , Lemonnier François , Ehrlich Rachel
Published: July 2002

HFE is a nonclassical class I major histocompatibility complex (MHC) molecule that is mutated in the autosomal recessive iron overload disease hereditary hemochromatosis. There is evidence linking HFE with reduced iron uptake by the transferrin receptor (TfR). Using a panel of HFE and TfR monoclonal antibodies to examine human HFE (hHFE)-expressing cell lines, we demonstrate the expression of stable and fully glycosylated TfR-free and TfR-associated hHFE/β2m complexes. We show that both the stability and assembly of hHFE complexes can be modified by the human cytomegalovirus (HCMV) viral protein US2, known to interfere with the expression of classical class I MHC molecules. HCMV US2, but not US11, targets HFE molecules for degradation by the proteasome. Whether this interference with the regulation of iron metabolism by a viral protein is a means of potentiating viral replication remains to be determined. The reduced expression of classical class I MHC and HFE complexes provides the virus with an efficient tool for altering cellular metabolism and escaping certain immune responses.
Insertions in the gG Gene of Pseudorabies Virus Reduce Expression of the Upstream Us3 Protein and Inhibit Cell-to-Cell Spread of Virus Infection
Authors: Demmin Gretchen L. , Clase Amanda C. , Randall Jessica A. , Enquist L. W. , Banfield Bruce W.
Published: July 2002

The alphaherpesvirus Us4 gene encodes glycoprotein G (gG), which is conserved in most viruses of the alphaherpesvirus subfamily. In the swine pathogen pseudorabies virus (PRV), mutant viruses with internal deletions and insertions in the gG gene have shown no discernible phenotypes. We report that insertions in the gG locus of the attenuated PRV strain Bartha show reduced virulence in vivo and are defective in their ability to spread from cell to cell in a cell-type-specific manner. Similar insertions in the gG locus of the wild-type PRV strain Becker had no effect on the ability of virus infection to spread between cells. Insertions in the gG locus of the virulent NIA-3 strain gave results similar to those found with the Bartha strain. To examine the role of gG in cell-to-cell spread, a nonsense mutation in the gG signal sequence was constructed and crossed into the Bartha strain. This mutant, PRV157, failed to express gG yet had cell-to-cell spread properties indistinguishable from those of the parental Bartha strain. These data indicated that, while insertions in the gG locus result in decreased cell-to-cell spread, the phenotype was not due to loss of gG expression as first predicted. Analysis of gene expression upstream and downstream of gG revealed that expression of the upstream Us3 protein is reduced by insertion of
lacZ
or
egfp
at the gG locus. By contrast, expression of the gene immediately downstream of gG, Us6, which encodes glycoprotein gD, was not affected by insertions in gG. These data indicate that DNA insertions in gG have polar effects and suggest that the serine/threonine kinase encoded by the Us3 gene, and not gG, functions in the spread of viral infection between cells.
Broadly Neutralizing Antibodies Targeted to the Membrane-Proximal External Region of Human Immunodeficiency Virus Type 1 Glycoprotein gp41
Authors: Zwick Michael B. , Labrijn Aran F. , Wang Meng , Spenlehauer Catherine , Saphire Erica Ollmann , Binley James M. , Moore John P. , Stiegler Gabriela , Katinger Hermann , Burton Dennis R. , Parren Paul W. H. I.
Published: July 2002

The identification and epitope mapping of broadly neutralizing anti-human immunodeficiency virus type 1 (HIV-1) antibodies (Abs) is important for vaccine design, but, despite much effort, very few such Abs have been forthcoming. Only one broadly neutralizing anti-gp41 monoclonal Ab (MAb), 2F5, has been described. Here we report on two MAbs that recognize a region immediately C-terminal of the 2F5 epitope. Both MAbs were generated from HIV-1-seropositive donors, one (Z13) from an antibody phage display library, and one (4E10) as a hybridoma. Both MAbs recognize a predominantly linear and relatively conserved epitope, compete with each other for binding to synthetic peptide derived from gp41, and bind to HIV-1
MN
virions. By flow cytometry, these MAbs appear to bind relatively weakly to infected cells and this binding is not perturbed by pretreatment of the infected cells with soluble CD4. Despite the apparent linear nature of the epitopes of Z13 and 4E10, denaturation of recombinant envelope protein reduces the binding of these MAbs, suggesting some conformational requirements for full epitope expression. Most significantly, Z13 and 4E10 are able to neutralize selected primary isolates from diverse subtypes of HIV-1 (e.g., subtypes B, C, and E). The results suggest that a rather extensive region of gp41 close to the transmembrane domain is accessible to neutralizing Abs and could form a useful target for vaccine design.
Origin-Independent Assembly of Kaposi's Sarcoma-Associated Herpesvirus DNA Replication Compartments in Transient Cotransfection Assays and Association with the ORF-K8 Protein and Cellular PML
Authors: Wu Frederick Y. , Ahn Jin-Hyun , Alcendor Donald J. , Jang Won-Jong , Xiao Jinsong , Hayward S. Diane , Hayward Gary S.
Published: July 2002

Six predicted Kaposi's sarcoma virus herpesvirus (KSHV) proteins have homology with other well-characterized herpesvirus core DNA replication proteins and are expected to be essential for viral DNA synthesis. Intact Flag-tagged protein products from all six were produced from genomic expression vectors, although the ORF40/41 transcript encoding a primase-helicase component proved to be spliced with a 127-bp intron. The intracellular localization of these six KSHV replication proteins and the mechanism of their nuclear translocation were investigated. SSB (single-stranded DNA binding protein, ORF6) and PPF (polymerase processivity factor, ORF59) were found to be intrinsic nuclear proteins, whereas POL (polymerase, ORF9), which localized in the cytoplasm on its own, was translocated to the nucleus when cotransfected with PPF. PAF (primase-associated factor, ORF40/41), a component of the primase-helicase tripartite subcomplex together with PRI (primase, ORF56) and HEL (helicase, ORF44), required the presence of all five other replication proteins for efficient nuclear translocation. Surprisingly, even in the absence of a lytic cycle replication origin (ori-Lyt) and any known initiator or origin binding protein, the protein products of all six KSHV core replication genes cooperated in a transient cotransfection assay to form large globular shaped pseudo-replication compartments (pseudo-RC), which excluded cellular DNA. These pseudo-RC structures were confirmed to include POL, SSB, PRI, and PAF but did not contain any newly synthesized DNA. Similar to the human cytomegalovirus system, the peripheries of these KSHV pre-RC were also found to be surrounded by punctate PML oncogenic domains (PODs). Furthermore, by transient cotransfection, the six KSHV core replication machinery proteins successfully replicated a plasmid containing EBV ori-Lyt in the presence of the Epstein-Barr virus-encoded DNA binding initiator protein, ZTA. The KSHV-encoded K8 (ORF-K8) protein, which is a distant evolutionary homologue to ZTA, was incorporated into pseudo-RC structures formed by transient cotransfection with the six core KSHV replication genes. However, unlike ZTA, K8 displayed a punctate nuclear pattern both in transfected cells and at early stages of lytic infection and colocalized with the cellular PML proteins in PODs. Finally, K8 was also found to accumulate in functional viral RC, detected by incorporation of pulse-labeled bromodeoxyuridine into newly synthesized DNA in both tetradecanoyl phorbol acetate-induced JSC-1 primary effusion lymphoblasts and in KSHV lytically infected endothelial cells.
Adaptation of Influenza A Viruses to Cells Expressing Low Levels of Sialic Acid Leads to Loss of Neuraminidase Activity
Authors: Hughes Mark T. , McGregor Martha , Suzuki Takashi , Suzuki Yasuo , Kawaoka Yoshihiro
Published: July 2002

Influenza A viruses possess two virion surface proteins, hemagglutinin (HA) and neuraminidase (NA). The HA binds to sialyloligosaccharide viral receptors, while the NA removes sialic acids from the host cell and viral sialyloligosaccarides. Alterations of the HA occur during adaptation of influenza viruses to new host species, as in the 1957 and 1968 influenza pandemics. To gain a better understanding of the contributions of the HA and possibly the NA to this process, we generated cell lines expressing reduced levels of the influenza virus receptor determinant, sialic acid, by selecting Madin-Darby canine kidney cells resistant to a lectin specific for sialic acid linked to galactose by α(2-3) or α(2-6) linkages. One of these cell lines had less than 1/10 as much
N
-acetylneuraminic acid as its parent cell line. When serially passaged in this cell line, human H3N2 viruses lost sialidase activity due to a large internal deletion in the NA gene, without alteration of the HA gene. These findings indicate that NA mutations can contribute to the adaptation of influenza A virus to new host environments and hence may play a role in the transmission of virus across species.
Biogenesis of the Semliki Forest Virus RNA Replication Complex
Authors: Kujala Pekka , Ikäheimonen Anne , Ehsani Neda , Vihinen Helena , Auvinen Petri , Kääriäinen Leevi
Published: July 2002

The nonstructural (ns) proteins nsP1 to -4, the components of Semliki Forest virus (SFV) RNA polymerase, were localized in infected cells by confocal microscopy using double labeling with specific antisera against the individual ns proteins. All ns proteins were associated with large cytoplasmic vacuoles (CPV), the inner surfaces of which were covered by small invaginations, or spherules, typical of alphavirus infection. All ns proteins were localized by immuno-electron microscopy (EM) to the limiting membranes of CPV and to the spherules, together with newly labeled viral RNA. Along with earlier observations by EM-autoradiography (P. M. Grimley, I. K. Berezesky, and R. M. Friedman, J. Virol. 2:326–338, 1968), these results suggest that individual spherules represent template-associated RNA polymerase complexes. Immunoprecipitation of radiolabeled ns proteins showed that each antiserum precipitated the other three ns proteins, implying that they functioned as a complex. Double labeling with organelle-specific and anti-ns-protein antisera showed that CPV were derivatives of late endosomes and lysosomes. Indeed, CPV frequently contained endocytosed bovine serum albumin-coated gold particles, introduced into the medium at different times after infection. With time, increasing numbers of spherules were also observed on the cell surfaces; they were occasionally released into the medium, probably by secretory lysosomes. We suggest that the spherules arise by primary assembly of the RNA replication complexes at the plasma membrane, guided there by nsP1, which has affinity to lipids specific for the cytoplasmic leaflet of the plasma membrane. Endosomal recycling and fusion of CPV with the plasma membrane can circulate spherules between the plasma membrane and the endosomal-lysosomal compartment.
The SH Integral Membrane Protein of the Paramyxovirus Simian Virus 5 Is Required To Block Apoptosis in MDBK Cells
Authors: He Biao , Lin Grace Y. , Durbin Joan E. , Durbin Russell K. , Lamb Robert A.
Published: July 2002

In some cell types the paramyxovirus simian virus 5 (SV5) causes little cytopathic effect (CPE) and infection continues productively for long periods of time; e.g., SV5 can be produced from MDBK cells for up to 40 days with little CPE. SV5 differs from most paramyxoviruses in that it encodes a small (44-amino-acid) hydrophobic integral membrane protein (SH). When MDBK cells were infected with a recombinant SV5 containing a deletion of the SH gene (rSV5ΔSH), the MDBK cells exhibited an increase in CPE compared to cells infected with wild-type SV5 (recovered from cDNA; rSV5). The increased CPE correlated with an increase in apoptosis in rSV5ΔSH-infected cells over mock-infected and rSV5-infected cells when assayed for annexin V binding, DNA content (propidium iodide staining), and DNA fragmentation (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling assay). In rSV5ΔSH-infected MDBK cells an increase in caspase-2 and caspase-3 activities was observed. By using peptide inhibitors of individual caspases it was found that caspase-2 and caspase-3 were activated separately in rSV5ΔSH-infected cells. Expression of caspase-2 and -3 in rSV5ΔSH-infected MDBK cells appeared not to require STAT1 protein, as STAT1 protein could not be detected in SV5-infected MDBK cells. When mutant mice homologous for a targeted disruption ofSTAT1were used as a model animal system and infected with the viruses it was found that rSV5ΔSH caused less mortality than wild-type rSV5, consistent with the notion of clearance of apoptotic cells in a host species.
Hepatitis B Virus HBx Protein Activation of Cyclin A–Cyclin-Dependent Kinase 2 Complexes and G
1
Transit via a Src Kinase Pathway
Authors: Bouchard Michael , Giannakopoulos Stavros , Wang Edith H. , Tanese Naoko , Schneider Robert J.
Published: July 2002

Numerous studies have demonstrated that the hepatitis B virus HBx protein stimulates signal transduction pathways and may bind to certain transcription factors, particularly the cyclic AMP response element binding protein, CREB. HBx has also been shown to promote early cell cycle progression, possibly by functionally replacing the TATA-binding protein-associated factor 250 (TAF
II
250), a transcriptional coactivator, and/or by stimulating cytoplasmic signal transduction pathways. To understand the basis for early cell cycle progression mediated by HBx, we characterized the molecular mechanism by which HBx promotes deregulation of the G
0
and G
1
cell cycle checkpoints in growth-arrested cells. We demonstrate that TAF
II
250 is absolutely required for HBx activation of the cyclin A promoter and for promotion of early cell cycle transit from G
0
through G
1
. Thus, HBx does not functionally replace TAF
II
250 for transcriptional activity or for cell cycle progression, in contrast to a previous report. Instead, HBx is shown to activate the cyclin A promoter, induce cyclin A–cyclin-dependent kinase 2 complexes, and promote cycling of growth-arrested cells into G
1
through a pathway involving activation of Src tyrosine kinases. HBx stimulation of Src kinases and cyclin gene expression was found to force growth-arrested cells to transit through G
1
but to stall at the junction with S phase, which may be important for viral replication.
Herpes Simplex Virus IE63 (ICP27) Protein Interacts with Spliceosome-Associated Protein 145 and Inhibits Splicing prior to the First Catalytic Step
Authors: Bryant H. E. , Wadd S. E. , Lamond A. I. , Silverstein S. J. , Clements J. B.
Published: July 2002

The multifunctional herpes simplex virus type 1 (HSV-1) protein IE63 (ICP27) interacts with the essential pre-mRNA splicing factor, spliceosome-associated protein 145 (SAP145), and in infected cells IE63 and SAP145 colocalize. This interaction was reduced or abrogated completely using extracts from cells infected with IE63 viral mutants, with mutations in IE63 KH and Sm homology domains, which do not exhibit host shutoff or inhibit splicing. In the presence of IE63, splicing in vitro was inhibited prior to the first catalytic step and the B/C complex formed during splicing was shifted up in mobility and reduced in intensity. With the use of splicing extracts, IE63 and SAP145 both comigrated with the B/C complex, suggesting that they interact within this complex to inhibit B/C complex formation or conversion. The inhibition of splicing may facilitate the export of viral or cellular transcripts, possibly via other protein partners of IE63. These data provide important new insights into how IE63 influences pre-mRNA processing during HSV-1 infection.
A Small Molecule Inhibits and Misdirects Assembly of Hepatitis B Virus Capsids
Authors: Zlotnick Adam , Ceres Pablo , Singh Sushmita , Johnson Jennifer M.
Published: July 2002

Hepatitis B virus (HBV) capsids play an important role in viral nucleic acid metabolism and other elements of the virus life cycle. Misdirection of capsid assembly (leading to formation of aberrant particles) may be a powerful approach to interfere with virus production. HBV capsids can be assembled in vitro from the dimeric capsid protein. We show that a small molecule, bis-ANS, binds to capsid protein, inhibiting assembly of normal capsids and promoting assembly of noncapsid polymers. Using equilibrium dialysis to investigate binding of bis-ANS to free capsid protein, we found that only one bis-ANS molecule binds per capsid protein dimer, with an association energy of −28.0 ± 2.0 kJ/mol (−6.7 ± 0.5 kcal/mol). Bis-ANS inhibited in vitro capsid assembly induced by ionic strength as observed by light scattering and size exclusion chromatography. The binding energy of bis-ANS for capsid protein calculated from assembly inhibition data was −24.5 ± 0.9 kJ/mol (−5.9 ± 0.2 kcal/mol), essentially the same binding energy observed in studies of unassembled protein. These data indicate that capsid protein bound to bis-ANS did not participate in assembly; this mechanism of assembly inhibition is analogous to competitive or noncompetitive inhibition of enzymes. While assembly of normal capsids is inhibited, our data suggest that bis-ANS leads to formation of noncapsid polymers. Evidence of aberrant polymers was identified by light scattering and electron microscopy. We propose that bis-ANS acts as a molecular “wedge” that interferes with normal capsid protein geometry and capsid formation; such wedges may represent a new class of antiviral agent.
Fatty Acid Modification of the Coxsackievirus and Adenovirus Receptor
Authors: van't Hof Wouter , Crystal Ronald G.
Published: July 2002

Membrane-proximal cysteines 259 and 260 in the cytoplasmic tail of the coxsackievirus and adenovirus receptor (CAR) are known to be essential for the tumor suppression activity of CAR. We demonstrate that these residues provide an S-acylation motif for modification of CAR with the fatty acid palmitate. Substitution of alanine for cysteines 259 and 260 results in the additional localization of CAR in perinuclear compartments with no effect on the efficiency of adenovirus infection. The results indicate that palmitylation is important for stable plasma membrane expression and biological activity of CAR but is not critical for adenovirus receptor performance.
Regions of the Herpes Simplex Virus Type 1 Latency-Associated Transcript That Protect Cells from Apoptosis In Vitro and Protect Neuronal Cells In Vivo
Authors: Ahmed Maryam , Lock Martin , Miller Cathie G. , Fraser Nigel W.
Published: July 2002

Recent studies have suggested that the latency-associated transcript (LAT) region of herpes simplex virus type 1 (HSV-1) is effective at blocking virus-induced apoptosis both in vitro and in the trigeminal ganglia of acutely infected rabbits (Inman et al., J. Virol. 75:3636–3646, 2001; Perng et al., Science 287:1500–1503, 2000). By transfecting cells with a construct expressing the
Pst-Mlu
segment of the LAT, encompassing the LAT exon 1, the stable 2.0-kb intron, and 5′ part of exon 2, we confirmed that this region was able to diminish the onset of programmed cell death initiated by anti-Fas and camptothecin treatment. In addition, caspase 8-induced apoptosis was specifically inhibited in cells expressing the
Pst-Mlu
LAT fragment. To further delineate the minimal region of LAT that is necessary for this antiapoptotic function, LAT mutants were used in our cotransfection assays. In HeLa cells, the plasmids lacking exon sequences were the least effective at blocking apoptosis. However, similar to previous work (Inman et al., op. cit.), our data also indicated that the 5′ end of the stable 2.0-kb LAT intron appeared to contribute to the promotion of cell survival. Furthermore, cells productively infected with the 17N/H LAT mutant virus, a virus deleted in the LAT promoter, exon 1, and about half of the intron, exhibited a greater degree of DNA fragmentation than cells infected with wild-type HSV-1. These data support the finding that the exon 1 and 2.0-kb intron region of the LAT transcription unit display an antiapoptotic function both in transfected cells and in the context of the virus infection in vitro. In trigeminal ganglia of mice acutely infected with the wild-type virus, 17, and 17ΔSty, a virus lacking most of exon 1, apoptosis was not detected in cells that were positive for virus particles. However, dual staining was observed in cells from mice infected with 17N/H virus, indicating that the LAT antiapoptotic function demonstrated in cells transfected by LAT-expressing constructs may also play a role in protecting cells from virus-induced apoptosis during acute viral infection in vivo.
Effect of Latent Human Immunodeficiency Virus Infection on Cell Surface Phenotype
Authors: Brooks David G. , Zack Jerome A.
Published: July 2002

Highly active antiretroviral therapy has succeeded in many cases in suppressing virus production in patients infected with human immunodeficiency virus (HIV); however, once treatment is discontinued, virus replication is rekindled. One reservoir capable of harboring HIV in a latent state and igniting renewed infection once therapy is terminated is a resting T cell. Due to the sparsity of T cells latently infected with HIV in vivo, it has been difficult to study viral and cellular interactions during latency. The SCID-hu (Thy/Liv) mouse model of HIV latency, however, provides high percentages of latently infected cells, allowing a detailed analysis of phenotype. Herein we show that latently infected cells appear phenotypically normal. Following cellular stimulation, the virus completes its life cycle and induces phenotypic changes, such as CD4 and major histocompatibility complex class I down-regulation, in the infected cell. In addition, HIV expression following activation did not correlate with expression of the cellular activation marker CD25. The apparently normal phenotype and lack of HIV expression in latently infected cells could prevent recognition by the immune response and contribute to the long-lived nature of this reservoir.
Instability of Solutions of Quaternary Ammonium Permanganates in Dichloromethane
Authors: Holba Vladislav , Košická Renata
Published: July 2002

The paper deals with instability of solutions of quaternary ammonium permanganates, QMnO4 (Q = tetraethyl-, tetra-1-propyl-, tetra-1-butyl-, tetra-1-pentyl-, tetra-1-octyl-, and cetyltrimethylammonium), in dichloromethane and presents the rate constants and activation parameters of the reduction of permanganate. Attention was paid to the properties of colloidal Mn(IV) intermediate. The stability of the solutions depends markedly on the quaternary ammonium salt used.
Microwave Techniques in the Synthesis and Modification of Zeolite Catalysts. A Review
Authors: Cundy Colin S.
Published: July 2002

Microwave dielectric heating is a convenient and effective way of bringing about chemical reactions in suitable (usually polar) media. Microwave-mediated organic synthesis has been the subject of considerable research and microwave heating is being increasingly applied to the synthesis and modification of zeolites and related microporous and mesoporous catalysts. The observed rate enhancements are caused by a variety of thermal effects, including very high rates of temperature rise, bulk superheating and (in non-homogeneous systems) differential heating. Specific, non-thermal activation is unlikely and can usually be excluded. The microwave synthesis of zeolites, zeotypes and mesoporous materials is reviewed, with emphasis on those aspects which differ from conventional thermal methods. Such standard methods are not displaced by microwave techniques and may in some instances be preferable. However, microwave synthesis does offer a high probability of rapid (and in some cases selective) reaction to give a pure product of good crystal quality. Non-synthetic applications of microwave heating in zeolite catalysis are also briefly described. A review with 118 references.
Solubility in the CuCl2-NaCl-H2O System and Hydration Analysis in the Case of Complexation
Authors: Eysseltová Jitka , Zbranek Vladimír , Jirsák Jan
Published: July 2002

The solubility diagram in the title system was studied at 25 °C. The results were compared with contradictional isotherms of other authors and one isotherm being in error was localized and rejected. The reliable solubility branches were treated with hydration analysis, which brings information on ionic processes in saturated solutions. Formation of coordination anions such as [CuCl3]- and [CuCl4]2- was found to be the main ionic process in saturated solutions in spite of the non-existence of the corresponding solid phase. The information obtained by this method for systems where hydration of components and complex formation take place simultaneously is demonstrated and discussed for the first time. A possibility of calculation of activity coefficients of the solute on both crystallization branches is discussed.
Bacteria-Based Sensor for Monitoring Glycerol
Authors: Liu Zhi H. , Wen Meng L. , Yao Yun , Shi Nan H. , Liu Shi Q. , Qiao Ming
Published: July 2002

A new bacteria-based sensor for determination of glycerol was reported, in which mutant bacteria induced from the strain of Bacillus subtilis AS1.398 was used as a biocatalyst. The calibration graph of the proposed sensor was linear in the range of 1-10% (w/v) glycerol and the correlation coefficient was 0.9946. Lifetime of the sensor was more than two weeks. There was no significant interference from substances commonly coexisting in the fermentation broth except acetic acid. The sensor would be useful for monitoring glycerol during fermentation due to its linearity, selectivity, and lifetime. The bacteria could be used as a catalytic enzyme membrane which can reproduce itself in proper matrix.
The psychological impact of injury: effects of prior sport and exercise involvement: Table 1
Authors: Johnston Lynne H , Carroll Douglas
Published: July 2002

Objectives—To test the assumption that the psychological impact of injury varies with involvement in sport and exercise, and that those who are more involved in sport and exercise before injury would experience greater negative affect and retarded recovery.

Method—Patients attending for physiotherapy completed a battery of questionnaires including measures of mood and perceived recovery, at the beginning, middle, and end of formal rehabilitation. Complete data were available for 93 patients.

Results—Those who were more involved in sport and exercise before injury registered higher levels of confusion and perceived their recovery to be less, possibly reflecting greater information needs and a greater mismatch between current status and that before injury in the athletic sample. Reported negative affect did not vary with sport and exercise involvement.

Conclusions—Incapacitation for those not involved in sport and exercise before injury may have much the same affective impact as it does for those with considerable involvement. However, those with considerable involvement did report higher levels of confusion and perceived their recovery to be less towards the end of rehabilitation. This suggests that it may be important to assess affective reactions and perceived recovery during the re-entry phase.
Qualitative and quantitative differences between bile ducts in chronic hepatitis and in primary biliary cirrhosis
Authors: Rubio C A
Published: July 2002

Aim—Lymphocytic infiltration in the portal triads usually conceals the detection—in haematoxylin and eosin (H&E) stained sections—of bile ducts in two liver diseases: chronic hepatitis and primary biliary cirrhosis. The aim was to assess the number and the characteristics of the bile ducts in those diseases with the aid of an antibody to cytokeratin 7 (CK7)

Methods—Consecutive sections from 99 liver biopsies were stained with H&E and anti-CK7.

Results—In H&E sections the total number of central bile ducts in the triads was 52 in primary biliary cirrhosis (n = 37), 69 in chronic hepatitis (n = 43), and 30 in miscellaneous cases (n = 19). Using anti-CK7, the number of central bile ducts was 276 in primary biliary cirrhosis, 348 in chronic hepatitis, and 96 in miscellaneous cases. Central bile ducts with lumen were found in 93.0% of chronic hepatitis cases and in 89.5% of the miscellaneous cases, but in only 13.5% of the primary biliary cirrhosis cases. Peripheral bile ducts in groups of ≥ 4/triad were found in all cases of chronic hepatitis (100%) and in 75.7% primary biliary cirrhosis cases, but only in 10.5% of the miscellaneous cases. In 21.6% of primary biliary cirrhosis cases, no bile ducts (central and/or peripheral) were present.

Conclusions—Anti-CK7 detects bile ducts in the triads that are concealed by chronic inflammatory cells. Central and peripheral bile ducts in groups of ≥ 4 were significantly more common in primary biliary cirrhosis and chronic hepatitis than in other liver diseases. The lack of lumen in central bile ducts, as well as the absence of central and/or peripheral bile ducts in CK7 stained liver sections, seem to be valuable additional parameters in the differential diagnosis between primary biliary cirrhosis and chronic hepatitis.
Prolonged hypoglycaemia following surgical removal of phaeochromocytoma
Authors: Jude E B , Sridhar C B R
Published: July 2002

We report a 34-year-old woman with secondary hypertension diagnosed with a left-sided phaeochromocytoma. Excision of the tumour resulted in recurrent hypoglycaemia up to 6 days post-operatively. We discuss the pathogenesis of hypoglycaemia following removal of the tumour and put forward hypothesis for the recurrent hypoglycaemia.
Milk alkali syndrome—an unusual syndrome causing an unusual complication
Authors: George S , Clark J D A
Published: July 2002

Milk alkali syndrome is rare and although pancreatitis secondary to hypercalcaemia is well recognised, there has only been one other reported case of pancreatitis secondary to the milk alkali syndrome. Such a case, caused by self medication of over the counter medication, is reported.
Identification of highly transformable wheat genotypes for mass production of fertile transgenic plants
Authors: Pellegrineschi A , Noguera L M , Skovmand B , Brito R M , Velazquez L , Salgado M M , Hernandez R , Warburton M , Hoisington D
Published: July 2002

The efficiency of wheat biolistic transformation systems strongly depends on the bombardment parameters, the condition of the donor plant, and the plant genotype chosen for the transformation process. This paper analyzes the transformation efficiency of the 129 wheat sister lines generically called 'Bobwhite', originally obtained from the cross 'Aurora'//'Kalyan'/'Bluebird 3'/'Woodpecker'. A number of factors influencing the transformation were examined, such as the ability to produce embryogenic callus, regeneration in selection medium, and overall transformation performance. Of the 129 genotypes evaluated, eight demonstrated transformation efficiencies above 60% (60 independent transgenic events per 100 immature embryos bombarded). Among the eight genotypes identified, we studied agronomic characteristics such as earliness to identify the most adaptable line(s) for different lab conditions. 'Bobwhite' SH 98 26 was identified as a super-transformable wheat line.Key words: wheat transformation, 'Bobwhite', genotype effect.
Seismic performance of connections in heavy timber construction
Authors: Popovski Marjan , Prion Helmut G.L , Karacabeyli Erol
Published: July 2002

Results from monotonic and quasi-static cyclic tests on connections used in heavy timber construction are presented for two types of fasteners: steel bolts and glulam rivets. Bolted connections with three different diameter bolts, arranged in several configurations, as well as two different configurations of glulam rivet connections were tested. All configurations included a main glulam member and two steel side plates. For bolted connections, the seismic behaviour was found to be primarily dependent on the bolt slenderness ratio. Bolted connections with higher slenderness ratios (smaller diameter bolts) exhibited more ductile behaviour with considerable steel yielding and wood crushing before failure. Glulam riveted connections, which were designed in rivet failure mode, showed superior seismic performance when compared to bolted connections for similar design load levels. Riveted connections were also able to dissipate the highest amount of input energy before the failure was reached.Key words: timber connections, glulam rivets, bolts, ductility, timber, wood, braced frames, seismic performance, heavy timber construction.
Comparative modeling of the phosphatase and kinase domains of protein tyrosine phosphatase and insulin receptor kinase fromDrosophila melanogaster(DPTP61fm), and a computational study of their mutual interactions
Authors: Hati Sanchita , Bhattacharyya Sudeep , Price James V , Tracey Alan S
Published: July 2002

The components and functions of the insulin receptor kinase signaling pathway have been conserved in a broad range of Metazoa ranging from mammals to insects and nematodes. There is a high degree of sequence homology and functional similarity between the human insulin receptor kinase (IRK) and the drosophila (Drosophila melanogaster) form (DIRK) of this enzyme. Similarly, a high degree of homology exists between human protein tyrosine phosphatase 1B (PTP1B) (which directly regulates IRK) and its drosophila counterpart DPTP61F (DPTP). However, genetic and biochemical studies have yet to demonstrate that DPTP61F acts in the DIRK pathway. Comparative structural modeling techniques using the known structures of human IRK and PTP1B as templates have yielded structures for the drosophila enzymes. The derived structures confirm that there is a high level of structural conservation at the tertiary level. Association of the DIRK and DPTP enzymes with each other was then investigated with a view to ascertaining whether DIRK might be a substrate of the DPTP. Evaluation of the interaction surfaces, including hydrophobic patch, shape, hydrogen bonding, and electrostatic compatibility, strongly suggested that the drosophila insulin receptor is a substrate of the DPTP. The interaction surfaces of the human and drosophila enzymes are structurally similar, although changes in critical residues modify possible electrostatic and hydrogen-bonding interactions. This suggests that in the mixed systems, DPTPIRK or PTP1BDIRK, the kinase domain will be a comparatively poor substrate for phosphatase activity when compared with the native systems.Key words: protein tyrosine phosphatase, insulin receptor kinase, Drosophila melanogaster, comparative protein modeling, surface topology, interaction zone.
Dynamics of histone acetylation in vivo. A function for acetylation turnover?
Authors: Waterborg Jakob H
Published: July 2002

Histone acetylation, discovered more than 40 years ago, is a reversible modification of lysines within the amino-terminal domain of core histones. Amino-terminal histone domains contribute to the compaction of genes into repressed chromatin fibers. It is thought that their acetylation causes localized relaxation of chromatin as a necessary but not sufficient condition for processes that repackage DNA such as transcription, replication, repair, recombination, and sperm formation. While increased histone acetylation enhances gene transcription and loss of acetylation represses and silences genes, the function of the rapid continuous or repetitive acetylation and deacetylation reactions with half-lives of just a few minutes remains unknown. Thirty years of in vivo measurements of acetylation turnover and rates of change in histone modification levels have been reviewed to identify common chromatin characteristics measured by distinct protocols. It has now become possible to look across a wider spectrum of organisms than ever before and identify common features. The rapid turnover rates in transcriptionally active and competent chromatin are one such feature. While ubiquitously observed, we still do not know whether turnover itself is linked to chromatin transcription beyond its contribution to rapid changes towards hyper- or hypoacetylation of nucleosomes. However, recent experiments suggest that turnover may be linked directly to steps in gene transcription, interacting with nucleosome remodeling complexes.Key words: histone, acetylation, turnover, chromatin, transcription.
CHARACTERISTICS OF DETERMINISTIC OPTIMAL ROUTING FOR TWO HETEROGENEOUS PARALLEL SERVERS
Authors: OIDA K. , SHINJO K.
Published: July 2002

This paper presents characteristics of optimal routing that assigns each arriving packet to one of two heterogeneous parallel servers, each with its own queue. The characteristics are derived from numerical solutions to an optimization problem, which is to find optimal routing that minimizes the average packet delay under the condition that all of the packets' arrival times as well as all of the packets' sizes are completely known in advance. There are four characteristics: (1) Under light or moderate traffic, the average packet delay of optimal routing is almost the same as that of join the shortest delay (JSD) policy. (2) Under heavier traffic, optimal routing comes to more often use fix queue based on size (FS) policy. (3) Under heavy traffic, optimal routing assigns small packets to the slower server. (4) As the ratio of the slower server's service rate to the faster server's service rate decreases, optimal routing comes to more often use FS policy under light or moderated traffic. These characteristics are verified by the fact that a mimic optimal routing designed based on the four characteristics attains almost the same performance as optimal routing.
C*-ALGEBRAS GENERATED BY UNBOUNDED ELEMENTS
Authors: WORONOWICZ S.L.
Published: July 2002

The main aim of this paper is to provide a proper mathematical framework for the theory of topological non-compact quantum groups, where we have to deal with non-unital C*-algebras. The basic concepts and results related to the affiliation relation in the C*-algebra theory are recalled. In particular natural topologies on the set of affiliated elements and on the set of morphisms are considered. The notion of a C*-algebra generated by a finite sequence of unbounded elements is introduced and investigated. It is generalized to include continuous quantum families of generators. An essential part of the duality theory for C*-algebras is presented including complete proofs of many theorems announced in [17]. The results are used to develop a presentation method of introducing non-unital C*-algebras. Numerous examples related mainly to the quantum group theory are presented.
QUASI *-ALGEBRAS OF OPERATORS AND THEIR APPLICATIONS
Authors: TRAPANI C.
Published: July 2002

The main facts of the theory of quasi*-algebras of operators acting in a rigged Hilbert space are reviewed. The particular case where the rigged Hilbert space is generated by a self-adjoint operator in Hilbert space is examined in more details. A series of applications to quantum theories are discussed.
AN ALGEBRAIC FORMULATION OF LEVEL ONE WESS-ZUMINO-WITTEN MODELS
Authors: BÖCKENHAUER JENS
Published: July 2002

The highest weight modules of the chiral algebra of orthogonal WZW models at level one possess a realization in fermionic representation spaces; the Kac-Moody and Virasoro generators are represented as unbounded limits of even CAR algebras. It is shown that the representation theory of the underlying even CAR algebras reproduces precisely the sectors of the chiral algebra. This fact allows to develop a theory of local von Neumann algebras on the punctured circle, fitting nicely in the Doplicher-Haag-Roberts framework. The relevant localized endomorphisms which generate the charged sectors are explicitly constructed by means of Bogoliubov transformations. Using CAR theory, the fusion rules in terms of sector equivalence classes are proven.
ANALYTIC CONTINUATION OF OPERATORS APPLICATIONS: FROM NUMBER THEORY AND GROUP THEORY TO QUANTUM FIELD AND STRING THEORIES
Authors: WOON S. C.
Published: July 2002

We are used to thinking of an operator acting once, twice, and so on. However, an operator can be analytically continued to the operator raised to a complex power. Applications include (s,r) diagrams and an extension of Fractional Calculus where commutativity of fractional derivatives is preserved, generating integrals and non-standard derivations of theorems in Number Theory, non-integer power series and breaking of Leibniz and Chain rules, pseudo-groups and symmetry deforming models in particle physics and cosmology, non-local effect in analytically continued matrix representations and its connection with noncommutative geometry, particle-physics-like scatterings of zeros of analytically continued Bernoulli polynomials, and analytic continuation of operators in QM, QFT and Strings.
PARTICLE SIMULATION OF COHESIVE GRANULAR MATERIALS
Authors: MATUTTIS HANS-GEORG , SCHINNER ALEXANDER
Published: July 2002

We present two-dimensional molecular dynamics simulations of cohesive regular polygonal particles. The cohesive part of the force-law for the particle–particle interaction is validated by the agreement with existing experimental data. We investigate microscopic parameters, which are not accessible to experiments such as contact length, raggedness of the surface and correlation time. With increasing cohesion, the particles move in clusters for long times.