bluuebunny/crossref_metadata_2025 huggingface dataset:
40Ar/39Ar thermochronology along a western Québec transect of the Grenville Province, Canada
Authors: MARTIGNOLE J. , REYNOLDS P.
Published: October 2004

Ar/Ar thermochronology on 24 hornblendes, 3 biotites, 2 muscovites and 2 K‐feldspars, collected along a 400 km‐long NW‐SE geotraverse through the Grenville Province in western Québec, is employed to provide time constraints on the intermediate and low temperature stages of cooling of part of the Grenville orogen. In the Grenville Front zone, the c. 1000 Ma time of exhumation previously established from thermobarometric and isotopic studies, is supported by the hornblende age data presented here. From 60 km to 160 km SE of the Front, reworked Archaean migmatites of the parautochthonous Réservoir Dozois terrane (RDT; 1004 Ma‐old metamorphic monazites) contain hornblendes with 972– 950 Ma cooling ages. Assuming metamorphic geotherms between 25 and 30 °C km−1, calculated cooling and unroofing rates are about 6 °C Ma−1 and 0.33 km Ma−1 in the P–T  range 725 °C–800 MPa and 450 °C–400 MPa. Hornblendes from monocyclic rocks of the Mont‐Laurier and Morin terranes (MLT and MT; monazite ages c. 1165 Ma) give ages of about 1040 and 1010 Ma, respectively. Calculation of cooling‐unroofing rates from peak metamorphic conditions in this area is hampered by thermal perturbations associated with the still poorly dated Grenville collision which took place approximately between 1060 and 1020 Ma. Cooling ages of c. 900 Ma for muscovite and biotite and 860–810 Ma for K‐feldspar, show that cooling rates decreased to around 1.5 °C Ma−1 under retrograde greenschist facies conditions in the MLT. On a time vs. distance diagram, the hornblende data define several distinct age ranges, suggesting that each terrane had a characteristic thermal history. Thus, cooling was diachronous and probably non‐homogeneous throughout this segment of the Grenville orogen. The time‐lag between the cooling history of the parautochthon (972–950 Ma) and the allochthons (1040–1010 Ma) is compatible with an earlier (pre‐1040 Ma) peak of metamorphism in the allochthons. The Réservoir Cabonga allochthon was transported toward the NNW from its probable root zone in the MLT during the 1060–1020 Ma Grenvillian collision as a partially cooled slab. The remobilization of the Archaean parautochthon is attributed to this collision. In the Grenville Front zone, slightly older cooling ages and cooling rates initially faster than in the remaining part of the parautochthon are probably as a result of rapid (tectonic?) exhumation shortly after collision. The minor delay (20–30 Ma) in unroofing of the MT compared to the adjacent MLT is most likely related to post‐1040 Ma extensional displacement along the Labelle shear zone. In terranes like those described above where metamorphism is diachronous, determination of cooling rates and the history of exhumation may be meaningless without a firm control on the regional structure. However, identification of contrasting cooling histories contributes to unravelling the independent movement of terranes.
Rapid cooling and exhumation of eclogitic rocks from the Great Caucasus, Russia
Authors: PERCHUK A. , PHILIPPOT P.
Published: October 2004

Diffusion modelling of growth‐zoned garnet is used in combination with standard geothermometric and geobarometric techniques to estimate cooling and denudation rates from the mafic eclogites of the Red Cliff area, Great Caucasus, Russia. Euhedral garnet porphyroblasts exhibit different degrees of prograde growth zoning depending on the size of the grain (100 μm to several mm in diameter). Zoning patterns are mainly expressed in terms of Fe–Mg exchange, with 100*Mg/(Mg+Fe) increasing from 18–20 to 33–37 from core to rim. Geothermobarometry yields conditions of 680±40 °C and a minimum of 1.6±0.2 GPa and of 660±40 °C and 0.8±0.2 GPa for the high‐pressure and retrograde stages of equilibration, respectively. A temperature of 600±40 °C has been recorded for the late‐stage metamorphic overprint in the mica schists surrounding the eclogites. Relaxation of garnet zoning profiles was modelled for three different hypotheticalP–T –ttrajectories, all with an initial temperature of 680 °C and a pressure change of 0.8 GPa. The first two trajectories involve decompression associated with regular cooling down to 660 °C (near isothermal) and 600 °C. The third path is a two‐step trajectory comprising near‐isobaric cooling down to 600 °C followed by isothermal decompression to 0.8 GPa. TheseP–T trajectories cover as wide a range of pressure and temperature changes endured by the rocks as possible, thus representing extreme cases for calculating cooling and exhumation rates. Calculations indicate that the zoning pattern of the smallest garnet (i.e. garnet for which the zoning is most easily eliminated during post‐growth processes) along the different paths can be preserved for the following average exhumation and cooling rates: path 1, 143  mm  a−1and 102 °C Ma−1; path 2, 60 mm a−1and 171 °C Ma−1; path 3, 11–30 mm a−1and 200–400 °C Ma−1. These results are discussed in light of theoreticalP–T–tpaths extracted from thermal models of regions of thickened crust, and from analogue models of accretionary wedge and continental lithosphere subduction.
Grain‐boundary migration of quartz during annealing experiments at high temperatures and pressures, with implications for metamorphic geology
Authors: MASUDA T. , MORIKAWA* T. , NAKAYAMA† Y. , SUZUKI* S.
Published: October 2004

Annealing experiments on agate, quartz schist and metachert at 800–1000 °C, confining pressures of 400 and 800 MPa, and annealing times of 6.0×10–3.6×105s revealed normal grain growth of quartz in the agate, grain‐size increasing with time, but the rate of grain growth decreasing with increasing grain size.

The boundaries of agate with quartz schist and metachert migrated into the agate at the expense of fine‐grained quartz in the agate. The driving force for the migration appears to be the reduction of surface energy associated with removal of fine‐grained quartz in the agate. Assuming the activation energy as Qm=11 kcal mol−1, a general expression for the relationship between velocity of boundary migration (V ) and driving force (P ) is where γ is the specific surface energy of quartz, R is the gas constant and T  is the absolute temperature. The velocity is relatively fast at high temperatures on a geological time‐scale. The expression assists a quantitative understanding of the microstructural development of quartz at metamorphic conditions.
Metamorphic evolution of diamond‐bearing and associated rocks from the Kokchetav Massif, northern Kazakhstan
Authors: ZHANG R. Y. , LIOU J. G. , ERNST W. G. , COLEMAN R. G. , SOBOLEV N. V. , SHATSKY V. S.
Published: October 2004

Representative diamond‐bearing gneisses and dolomitic marble, eclogite and Ti‐clinohumite‐bearing garnet peridotite from Unit I at Kumdy Kol and whiteschist from Unit II at Kulet, eastern Kokchetav Massif, northern Kazakhstan, were studied. Diamond‐bearing gneisses contain variable assemblages, including Grt+Bt+Qtz±Pl±Kfs±Zo±Chl±Tur±Cal and minor Ap, Rt and Zrn; abundant inclusions of diamond, graphite+chlorite (or calcite), phengite, clinopyroxene, K‐feldspar, biotite, rutile, titanite, calcite and zircon occur in garnet. Diamond‐bearing dolomitic marbles consist of Dol+Di±Grt+Phl; inclusions of diamond, dolomite±graphite, biotite, and clinopyroxene were identified in garnet. Whiteschists carry the assemblage Ky+Tlc+Grt+Rt; garnet shows compositional zoning, and contains abundant inclusions of talc, kyanite and rutile with minor phlogopite, chlorite, margarite and zoisite. Inclusions and zoning patterns of garnet delineate the prograde P–T  path. Inclusions of quartz pseudomorphs after coesite were identified in garnet from both eclogite and gneiss. Other ultrahigh‐pressure (UHP) indicators include Na‐bearing garnet (up to 0.14 wt% Na2O) with omphacitic Cpx in eclogite, occurrence of high‐K diopside (up to 1.56 wt% K2O) and phlogopite in diamond‐bearing dolomitic marble, and Cr‐bearing kyanite in whiteschist. These UHP rocks exhibit at least three stages of metamorphic recrystallization. The Fe‐Mg partitioning between clinopyroxene and garnet yields a peak temperature of 800–1000 °C at P >40 kbar for diamond‐bearing rocks, and about 740–780 °C at >28–35 kbar for eclogite, whiteschist and Ti‐bearing garnet peridotite. The formation of symplectitic plagioclase+amphibole after clinopyroxene, and replacement of garnet by biotite, amphibole, or plagioclase mark retrograde amphibolite facies recrystallization at 650–680 °C and pressure less than about 10 kbar. The exsolution of calcite from dolomite, and development of matrix chlorite and actinolite imply an even lower grade greenschist facies overprint at c. 420 °C and 2–3 kbar. A clockwise P–T  path suggests that supracrustal sediments together with basaltic and ultramafic lenses apparently were subjected to UHP subduction‐zone metamorphism within the diamond stability field. Tectonic mixing may have occurred prior to UHP metamorphism at mantle depths. During subsequent exhumation and juxtaposition of many other tectonic units, intense deformation chaotically mixed and mylonitized these lithotectonic assemblages.
Metamorphic field gradients in the Central Alps
Authors: TODD* C. S. , ENGI M.
Published: October 2004

Metamorphic field gradients were determined across the entire amphibolite grade Central Alps (c. 50×100 km). P–T  were calculated from 116 samples acquired from our own field work, from samples provided to us by others, and from rocks with mineral compositions described in the literature. Only fluid‐conserved equilibria were used to determine P–T . The use of an internally consistent thermodynamic database and mineral solid solution models makes the results robust and reduces relative errors. The results are presented in contour maps. Temperature increases from 500 to 550 °C along the limit of amphibolite grade metamorphism in the north and west, to c. 675 °C toward the south at the Insubric line near the town of Bellinzona. Maximum recorded pressures of c. 7 kbar are in a central region c. 20 km north of the Insubric line, and decrease both to the north (5.5 kbar) and south (4.5 kbar). The P–T  results indicate that there is a relatively large area that reached conditions in the sillimanite stability field but developed neither sillimanite nor fibrolite; this is interpreted as a result of kinetic constraints on nucleation and growth because of the small amounts of thermal overstep (<40 °C) of the kyanite‐sillimanite phase boundary. Comparison of P–T  conditions with carbonate isograds in the region indicate that fluids present during metamorphism were not dominated by a homogeneous external source. Examination of the two‐dimensional distribution of pressure and temperature in the context of thermal and tectonic models indicates that two thermal pulses affected the Central Alps during the Tertiary. In the second, heat affected only the southern parts of the area and overprinted the previously established P–T  gradients.
A ternary solid solution model for omphacite and its application to geothermobarometry of eclogites from the Middle Adula nappe (Central Alps, Switzerland)
Authors: MEYRE C. , DE CAPITANI C. , PARTZSCH* J. H.
Published: October 2004

A ternary solid solution model for omphacite with the end‐members jadeite (NaAlSi2O6), diopside (CaMgSi2O6) and hedenbergite (CaFeSi2O6) was derived from experimental data from the literature. The subregular solution model, fitted by linear programming, is best suited to omphacites with very little aegirine component in common eclogites. Applying this solution model to the calculation of equilibrium phase diagrams of eclogites from the Adula nappe (Central Alps, Switzerland) results in large stability fields for common eclogite assemblages (garnet+omphacite+quartz+H2O±kyanite). Within this field the compositions of garnet and omphacite show very little variation. A precise determination of the peak‐pressure and temperature is not possible. The occurrence of amphibole, overgrowing the peak‐pressure assemblage in fresh eclogite, suggests retrograde re‐equilibration, still under eclogite facies conditions. The computation of isopleths for garnet and pyroxene end‐members allows the estimation of the pressure and temperature conditions of this re‐equilibration event (19–21 kbar, c. 700 °C).
The gabbro–eclogite transformation: an oxygen isotope and petrographic study of west Alpine ophiolites
Authors: BARNICOAT A. C. , CARTWRIGHT I.
Published: October 2004

Both magmatic and eclogitic parageneses are preserved in the gabbros of western Alpine ophiolites. Samples with relic magmatic mineralogies display partial transformation to eclogitic assemblages along cracks and grain boundaries. Gabbros with eclogitic mineralogies contain zoned pseudomorphs after olivine, comprising talc‐rich cores with kyanite, Mg‐chloritoid and omphacite in outer cores and garnet rims. The compositional zonation of these olivine pseudomorphs closely parallels that shown by olivines in hydrothermally altered ocean‐floor gabbros.

The eclogitic gabbros are hydrous, containing paragonite, zoisite and other water‐bearing minerals, and it has been suggested that water was introduced during high‐pressure metamorphism. However, the similarity of olivine alteration patterns to those of ocean‐floor gabbros suggests that hydration and local metasomatism leading to the stability of aluminous minerals in olivine sites occurred during hydrothermal alteration prior to subduction. Oxygen‐isotope systematics are consistent with this proposal: Alpine gabbros with magmatic relics have a mean δ18O value of 5.7±0.7, similar to that of unaltered oceanic crust, whereas eclogitic gabbros have a mean δ18O value of 4.8±0.9.This statistically significant difference is consistent with the eclogitic samples having undergone high‐temperature ocean‐floor alteration. The preservation of magmatic and hydrothermal δ18O values in ocean‐floor gabbros that have been metamorphosed at 2–2.5 GPa (60–75 km) implies that the deeper levels of ocean crust have not experienced pervasive fluid flow during subduction or subsequent exhumation. Magmatic assemblages were preserved despite an overstep of eclogitization reactions by at least 0.6–1.1 GPa implying that equilibrium was not attained in undeformed parts of the system because of slow diffusion in water‐deficient rock volumes.
Garnet–orthopyroxene geothermometry and geobarometry: error propagation and equilibration effects
Authors: CARSON* C.J. , POWELL R.
Published: October 2004

Garnet–orthopyroxene geothermometry and geobarometry are widely used in high‐grade metamorphic terranes. These techniques may provide an insight into pressure–temperature (P–T ) paths followed by such terranes, provided various sources of uncertainty are taken into consideration. Analytical uncertainties, particularly with regard to their effect on ferric iron estimation in orthopyroxene, can contribute to the overall uncertainty on the calculated P–T . Additionally, retrograde cation diffusion can affect the Fe–Mg distribution between coexisting garnet and orthopyroxene, consequently affecting P–T  estimates. Recognizing the importance of these effects, and care with both the choice of the grains analysed and analytical techniques, may lead to more reliable P–T  estimation.
The assemblage diaspore+quartz in metamorphic rocks: a petrological, experimental and thermodynamic study
Authors: THEYE T. , CHOPIN C. , GREVEL K.‐D. , OCKENGA E.
Published: October 2004

The upper pressure limit of pyrophyllite is given by the equilibria (i) pyrophyllite=diaspore+quartz and (ii) pyrophyllite=diaspore+coesite. High‐P experimental investigations carried out to locate equilibrium (i) yield brackets between 497 °C/24.8 kbar and 535 °C/25.1 kbar, and between 500 °C/23 kbar and 540 °C/23 kbar. Equilibrium (ii) was bracketed at 550 °C between 26.0 and 28.3 kbar. In the experimental P–T  range, equilibria (i) and (ii) are metastable with respect to kyanite. A stable P–T  grid is calculated using thermodynamic data derived under consideration of the present experimental results. According to these data, the lower pressure limit of the assemblage diaspore+quartz according to equilibrium (i) range from about 12 kbar/300 °C to 20 kbar/430 °C (in the presence of pure water). The upper stability of diaspore+quartz is limited by the reaction diaspore+quartz=kyanite+H2O at about 450 °C (nearly independent of pressure) and, to higher pressure, by the quartz=coesite transition. Equilibrium (ii) is metastable over the whole P–T  range.

Natural occurrences600.S of the diaspore–quartz assemblage in metamorphic rocks in Sulawesi, New Caledonia, Amorgos and the Vanoise are characterized by minerals indicative of high‐P such as ferro‐magnesiocarpholite, glaucophane, sodic pyroxene and lawsonite. The metamorphic P–T  conditions of these rocks are estimated to be in the range 300–400 °C, >8 kbar. These data are compatible with the derived P–T  stability field of the diaspore+quartz assemblage. We conclude that, in metamorphic rocks, diaspore+quartz is, as ferrocarpholite, an indicator for unusual low‐T /very high‐P settings.
Lichen sclerosus et atrophicus of the oral mucosa
Authors: Mendonça E. F. , Ribeiro‐Rotta R. F. , Silva M. A. G. S. , Batista A. C.
Published: October 2004

Lichen sclerosus et atrophicus (LSA) is a chronic, benign, depigmenting disease of the skin and mucous membranes most frequently affecting the female genitalia. Involvement of the oral mucosa without concurrent genital or skin lesions has been reported only occasionally in the literature. In view of the rarity of reported cases, one lesion affecting only the labial mucocutaneous area is presented along with a description of the disease's clinical and histopathological findings.
The expression of the c‐erbB‐2 receptor protein in glandular salivary secretions
Authors: Streckfus Charles F. , Bigler Lenora , Dellinger Tracy , Kuhn Melinda , Chouinard Normand , Dai Xaoli
Published: October 2004

Background:  As the maintenance medium of the oral cavity, saliva is secreted from exocrine glands that include the parotid, submandibular, sublingual, and minor salivary glands. Considering that saliva is a fluid suffused with protein, it is possible that the solubilized by‐products of oncogenic expression may be present in saliva. Recent studies suggest the presence of solubilized extracellular domain portion of the c‐erbB‐2 protein in serum, nipple aspirates, and saliva. As a consequence, the purpose of this study was to determine the presence and concentration of c‐erbB‐2 in major salivary gland secretions.

Methods:  Fifteen healthy women had serum, stimulated whole (SWS), parotid (SP), and submandibular/sublingual (SS) salivary secretions collected. The specimens were analyzed for c‐erbB‐2 using enzyme linked immunosorbent assays (ELISAs). Western blots using c‐erbB‐2 were also performed on these specimens.

Results:  The ELISAs revealed the presence of c‐erbB‐2 in SWS (24.50 Units/ml), SP (19.66 Units/ml), SS (15.59 Units/ml) and serum (1472.15 Units/ml). Western blots confirmed the presence of these 185 kDa proteins.

Conclusions:  These results suggest that the protein, c‐erbB‐2, is present in relatively equal amounts in both SP and SS glandular secretions. Elevated glandular salivary c‐erbB‐2 concentrations could be useful as a preliminary, non‐invasive test in clinical decision making when diagnosing salivary gland carcinomas. Additionally, this marker may have utility in distinguishing between oral lesions that are benign, pre‐malignant and malignant in the oral cavity. Further research is required to determine if these findings have clinical utility.
Enhancement of lesion classification using divergence, curl and curvature of skin pattern
Authors: She Zhishun , Duller A. W. G. , Fish P. J.
Published: October 2004

Background/purpose: The observation that skin pattern tends to be disrupted by malignant but not by benign skin lesions suggests that measurements of skin pattern disruption on simply captured white light optical clinical (WLC) skin images could be a useful contribution to a diagnostic feature set. Previous work which generated a flow field of skin pattern using a measurement of local line direction and variation determined by the minimum eigenvalue and its corresponding eigenvector of the local tensor matrix to measure skin pattern disruption was computationally low cost and encouraging. This paper explores the possibility of extracting new features from the first and second differentiations of this flow field to enhance classification performance.

Methods: The skin pattern was extracted from WLC skin images by high‐pass filtering. The skin line direction was estimated using a local image gradient matrix to produce a flow field of skin pattern. Divergence, curl, mean and Gaussian curvatures of this flow field were computed from the first and second differentiations of this flow field. The difference of these measures combined with skin line direction across the lesion image boundary was used as a lesion classifier.

Results: A set of images of malignant melanoma and benign naevi were analysed as above and the scatter plot in a two‐dimensional dominant feature space using principal component analysis showed excellent separation of benign and malignant lesions. A receiver operating characteristic plot enclosed an area of 0.96.

Conclusions: The experimental results show that the divergence, curl, mean and Gaussian curvatures of the flow field can increase lesion classifier accuracy. Combined with skin line direction they are promising features for distinguishing malignant melanoma from benign lesions and the methods used are computationally efficient which is important if their use is to be considered in clinical practice.
Teledentistry in the United States: a new horizon of dental care
Authors: Sanchez Dils E , Lefebvre C , Abeyta K
Published: October 2004

Teledentistry has been developing since 1994 as a means to allow dental professionals to communicate with one another over long distances. It allows collaboration by multiple practitioners regarding a patient and the necessary treatment for this patient. Teledentistry can be greatly utilized with rural communities or those of underserved populations. It would increase the accessibility of specialists, besides decreasing time and cost associated with specialty consultations. Real‐time videoconferencing and store and forward techniques are the mostly commonly used methodologies for teledentistry. Teledentistry will become more widely seen and utilized by the increase in digital media found in dental practices.
Oral bacteria and clinical variables in dependent individuals at a special facility*
Authors: Wårdh I , Wikström M , Sörensen S
Published: October 2004

The oral health of dependent residents at special facilities has often been reported as being poor, but it is difficult to relate oral health to general health and define the need for oral health care. Microbiological analyses of the oral flora have been suggested as a suitable method for evaluating oral health in this group of patients. A study was performed at a nursing facility where 33 individuals participated. The aim was to describe their oral flora in relation to other health variables and to classify the residents on different risk levels. An oral examination of the residents was made at the facility, together with a 3‐day food record and an oral microbiological analysis. The analysis classified the residents in different categories according to both acid‐producing bacteria and the flora correlated with a reduction in general health. The categories were based on previous studies conducted at the Department of Microbiology (Faculty of Odontology in Göteborg). The present study revealed that the level for acid‐producing bacteria was high in 12 individuals and the micriobial level according to decreased general health was high in seven individuals. A high level of acid‐producing bacteria was related to functional impairment, which was in turn related to nutritional problems and help with oral hygiene. The microbial level according to the reduction in general health did not significantly correlate with other variables.
Nuclear Heat Shock Response and Novel Nuclear Domain 10 Reorganization in Respiratory Syncytial Virus-Infected A549 Cells Identified by High-Resolution Two-Dimensional Gel Electrophoresis
Authors: Brasier Allan R. , Spratt Heidi , Wu Zheng , Boldogh Istvan , Zhang Yuhong , Garofalo Roberto P. , Casola Antonella , Pashmi Jawad , Haag Anthony , Luxon Bruce , Kurosky Alexander
Published: October 2004

The pneumovirus respiratory syncytial virus (RSV) is a leading cause of epidemic respiratory tract infection. Upon entry, RSV replicates in the epithelial cytoplasm, initiating compensatory changes in cellular gene expression. In this study, we have investigated RSV-induced changes in the nuclear proteome of A549 alveolar type II-like epithelial cells by high-resolution two-dimensional gel electrophoresis (2DE). Replicate 2D gels from uninfected and RSV-infected nuclei were compared for changes in protein expression. We identified 24 different proteins by peptide mass fingerprinting after matrix-assisted laser desorption ionization-time of flight mass spectrometry (MS), whose average normalized spot intensity was statistically significant and differed by ±2-fold. Notable among the proteins identified were the cytoskeletal cytokeratins, RNA helicases, oxidant-antioxidant enzymes, the TAR DNA binding protein (a protein that associates with nuclear domain 10 [ND10] structures), and heat shock protein 70- and 60-kDa isoforms (Hsp70 and Hsp60, respectively). The identification of Hsp70 was also validated by liquid chromatography quadropole-TOF tandem MS (LC-MS/MS). Separate experiments using immunofluorescence microscopy revealed that RSV induced cytoplasmic Hsp70 aggregation and nuclear accumulation. Data mining of a genomic database showed that RSV replication induced coordinate changes in Hsp family proteins, including the 70, 70-2, 90, 40, and 40-3 isoforms. Because the TAR DNA binding protein associates with ND10s, we examined the effect of RSV infection on ND10 organization. RSV induced a striking dissolution of ND10 structures with redistribution of the component promyelocytic leukemia (PML) and speckled 100-kDa (Sp100) proteins into the cytoplasm, as well as inducing their synthesis. Our findings suggest that cytoplasmic RSV replication induces a nuclear heat shock response, causes ND10 disruption, and redistributes PML and Sp100 to the cytoplasm. Thus, a high-resolution proteomics approach, combined with immunofluorescence localization and coupled with genomic response data, yielded unexpected novel insights into compensatory nuclear responses to RSV infection.
Redistribution of Cellular and Herpes Simplex Virus Proteins from the Trans-Golgi Network to Cell Junctions without Enveloped Capsids
Authors: Wisner Todd W. , Johnson David C.
Published: October 2004

Herpes simplex virus (HSV) and other alphaherpesviruses assemble enveloped virions in the trans-Golgi network (TGN) or endosomes. Enveloped particles are formed when capsids bud into TGN/endosomes and virus particles are subsequently ferried to the plasma membrane in TGN-derived vesicles. Little is known about the last stages of virus egress from the TGN/endosomes to cell surfaces except that the HSV directs transport of nascent virions to specific cell surface domains, i.e., epithelial cell junctions. Previously, we showed that HSV glycoprotein gE/gI accumulates extensively in the TGN at early times after infection and also when expressed without other viral proteins. At late times of infection, gE/gI and a cellular membrane protein, TGN46, were redistributed from the TGN to epithelial cell junctions. We show here that gE/gI and a second glycoprotein, gB, TGN46, and another cellular protein, carboxypeptidase D, all moved to cell junctions after infection with an HSV mutant unable to produce cytoplasmic capsids. This redistribution did not involve L particles. In contrast to TGN membrane proteins, several cellular proteins that normally adhere to the cytoplasmic face of TGN, Golgi, and endosomal membranes remained primarily dispersed throughout the cytoplasm. Therefore, cellular and viral membrane TGN proteins move to cell junctions at late times of HSV infection when the production of enveloped particles is blocked. This is consistent with the hypothesis that there are late HSV proteins that reorganize or redistribute TGN/endosomal compartments to promote virus egress and cell-to-cell spread.
Evaluation of the Functional Involvement of Human Immunodeficiency Virus Type 1 Integrase in Nuclear Import of Viral cDNA during Acute Infection
Authors: Ikeda Tamako , Nishitsuji Hironori , Zhou Xin , Nara Nobuo , Ohashi Takashi , Kannagi Mari , Masuda Takao
Published: October 2004

Nuclear import of viral cDNA is a critical step for establishing the proviral state of human immunodeficiency virus type 1 (HIV-1). The contribution of HIV-1 integrase (IN) to the nuclear import of viral cDNA is controversial, partly due to a lack of identification of its bona fide nuclear localization signal. In this study, to address this putative function of HIV-1 IN, the effects of mutations at key residues for viral cDNA recognition (PYNP at positions 142 to 145, K156, K159, and K160) were evaluated in the context of viral replication. During acute infection, some mutations (N144Q, PYNP>KL, and KKK>AAA) severely reduced viral gene expression to less than 1% the wild-type (WT) level. None of the mutations affected the synthesis of viral cDNA. Meanwhile, the levels of integrated viral cDNA produced by N144Q, PYNP>KL, and KKK>AAA mutants were severely reduced to less than 1% the WT level. Quantitative PCR analysis of viral cDNA in nuclei and fluorescence in situ hybridization analysis showed that these mutations significantly reduced the level of viral cDNA accumulation in nuclei. Further analysis revealed that IN proteins carrying the N144Q, PYNP>KL, and KKK>AAA mutations showed severely reduced binding to viral cDNA but kept their karyophilic properties. Taken together, these results indicate that mutations that reduced the binding of IN to viral cDNA resulted in severe impairment of virus infectivity, most likely by affecting the nuclear import of viral cDNA that proceeds integration. These results suggest that HIV-1 IN may be one of the critical constituents for the efficient nuclear import of viral cDNA.
Cells Lacking NF-κB or in Which NF-κB Is Not Activated Vary with Respect to Ability To Sustain Herpes Simplex Virus 1 Replication and Are Not Susceptible to Apoptosis Induced by a Replication-Incompetent Mutant Virus
Authors: Taddeo Brunella , Zhang Weiran , Lakeman Fred , Roizman Bernard
Published: October 2004

Earlier we reported that NF-κB is activated by protein kinase R (PKR) in herpes simplex virus 1-infected cells. Here we report that in PKR
−/−
cells the yields of wild-type virus are 10-fold higher than in PKR
+/+
cells. In cells lacking NF-κB p50 (
nfkb1
), p65 (
relA
), or both p50 and p65, the yields of virus were reduced 10-fold. Neither wild-type nor mutant cells undergo apoptosis following infection with wild-type virus. Whereas PKR
+/+
and NF-κB
+/+
control cell lines undergo apoptosis induced by the d120 (Δα4) mutant of HSV-1, the mutant PKR
−/−
and NF-κB
−/−
cell lines were resistant. The evidence suggests that the stress-induced apoptosis resulting from d120 infection requires activation of NF-κB and that this proapoptotic pathway is blocked in cells in which NF-κB is not activated or absent. Activation of NF-κB in the course of viral infection may have dual roles of attempting to curtain viral replication by rendering the cell susceptible to apoptosis induced by the virus and by inducing the synthesis of proteins that enhance viral replication.
Accumulation of Cytoplasmic β-Catenin and Nuclear Glycogen Synthase Kinase 3β in Epstein-Barr Virus-Infected Cells
Authors: Everly David N. , Kusano Shuichi , Raab-Traub Nancy
Published: October 2004

Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with cancers in immunocompromised populations. EBV establishes a latent infection and immortalizes and transforms B lymphocytes. Several latent proteins have profound effects on cellular growth, including activation of NF-κB, phosphatidylinositol 3′-OH kinase (PI3K) signaling, and notch signaling. Activation of PI3K can affect the activity of β-catenin, the target of the wnt signaling pathway. Deregulation of β-catenin is associated with a number of malignancies. To determine if β-catenin is regulated by EBV infection, EBV-infected cells were examined for β-catenin levels and localization. β-Catenin was increased in EBV-positive tumor cell lines compared to EBV-negative lines, in EBV-infected Burkitt's lymphoma cell lines, and in EBV-transformed lymphoblastoid cell lines (LCL). In contrast to wnt signaling, EBV consistently induced the accumulation of β-catenin in the cytoplasm but not the nucleus. The β-catenin regulating kinase, glycogen synthase kinase 3β (GSK3β), was shown to be phosphorylated and inactivated in EBV-infected lymphocytes. Inactivated GSK3β was localized to the nucleus of EBV-infected LCL. Neither the cytoplasmic accumulation of β-catenin nor the nuclear inactivation of GSK3β was affected by the inhibition of PI3K signaling. These data indicate that latent infection with EBV has unique effects on β-catenin signaling that are distinct from activation of wnt and independent of its effects on PI3K.
Ubiquitination of Human T-Cell Leukemia Virus Type 1 Tax Modulates Its Activity
Authors: Peloponese Jean-Marie , Iha Hidekatsu , Yedavalli Venkat R. K. , Miyazato Akiko , Li Yan , Haller Kerstin , Benkirane Monsef , Jeang Kuan-Teh
Published: October 2004

Human T-cell leukemia virus type 1 (HTLV-1) encodes a 40-kDa Tax phosphoprotein. Tax is a transcriptional activator which modulates expression of the viral long terminal repeat and transcription of many cellular genes. Because Tax is a critical HTLV-1 factor which mediates viral transformation of T cells during the genesis of adult T-cell leukemia, it is important to understand the processes which can activate or inactivate Tax function. Here, we report that ubiquitination of Tax is a posttranscriptional mechanism which regulates Tax function. We show that ubiquitination does not target Tax for degradation by the proteasome. Rather, ubiquitin addition modifies Tax in a proteasome-independent manner from an active to a less-active transcriptional form.
A Negative Regulatory Element (Base Pairs −204 to −177) of the EICP0 Promoter of Equine Herpesvirus 1 Abolishes the EICP0 Protein's
trans
-Activation of Its Own Promoter
Authors: Kim Seong K. , Albrecht Randy A. , O'Callaghan Dennis J.
Published: October 2004

The early EICP0 protein is a powerful
trans
-activator that activates all classes of equine herpesvirus 1 (EHV-1) promoters but, unexpectedly,
trans
-activates its own promoter very weakly. Transient transfection assays that employed constructs harboring deletions within the EICP0 promoter indicated that EICP0
cis
-acting sequences within bp −224 to −158 relative to the first ATG abolished the EICP0 protein's
trans
-activation of its own promoter. When inserted into the promoters of other EHV-1 genes, this sequence also downregulated activation of the immediate-early IE(−169/+73), early thymidine kinase TK(−215/+97), and late glycoprotein K gK(−83/+14) promoters, indicating that the
cis
-acting sequence (−224 to −158) downregulated expression of representative promoters of all classes of EHV-1 genes and contains a negative regulatory element (NRE). To define the
cis
-acting element(s), three synthetic oligonucleotides (Na [bp −224 to −195], Nb [bp −204 to −177], and Nc [bp −185 to −156]) were synthesized and cloned upstream of the EICP0(−157/−21) promoter. Of the three synthetic sequences, only the Nb oligonucleotide caused the downregulation of the EICP0 promoter. The NRE was identified as a 28-bp element to lie at −204 to −177 that encompassed the sequence of ([−204]AGATACAGATGTTCGATAAATTGGAACC[−177]). Gel shift assays performed with mouse L-M, rabbit RK-13, and human HeLa cell nuclear extracts and γ-
32
P-labeled wild-type and mutant NREs demonstrated that a ubiquitous nuclear protein(s) (NRE-binding protein, NREBP) binds specifically to a sequence (bp −193 to −183) in the NRE. The NREBP is also present in the nucleus of EHV-1-infected cells; however, the amount of NREBP in EHV-1-infected L-M cells that bound to the Nb oligonucleotide was reduced compared to that in uninfected L-M cells. Transient transfection assays showed that deletions or mutations within the NREBP-binding site abolished the NRE activity of the EICP0 promoter. These results suggested that the NREBP may mediate the NRE activity of the EICP0 promoter and may function in the coordinate expression of EHV-1 genes.
Membrane Binding Properties and Terminal Residues of the Mature Hepatitis C Virus Capsid Protein in Insect Cells
Authors: Ogino Tomoaki , Fukuda Hiroyuki , Imajoh-Ohmi Shinobu , Kohara Michinori , Nomoto Akio
Published: October 2004

The immature core protein (p23, residues 1 to 191) of hepatitis C virus undergoes posttranslational modifications including intramembranous proteolysis within its C-terminal signal sequence by signal peptide peptidase to generate the mature form (p21). In this study, we analyzed the cleavage site and other amino acid modifications that occur on the core protein. To produce the posttranslationally modified core protein, we used a baculovirus-insect cell expression model system. As previously reported, p23 is processed to form p21 in insect as well as in mammalian cells. p21 was found to be associated with the cytoplasmic membrane, and its significant portion behaved as an integral membrane protein. The protein was purified from the membrane by a simple and unique procedure on the basis of its membrane-binding properties and solubility in detergents. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of purified p21 showed that the average molecular mass (
m/z
19,307) of its single-charged ion differs by
m/z
1,457 from that calculated for p23. To determine the posttranslational modifications, tryptic p21 peptides were analyzed by MALDI-TOF MS. We found three peptides that did not match the theoretically derived peptides of p23. Analysis of these peptides by MALDI-TOF tandem MS revealed that they correspond to N-terminal peptides (residues 2 to 9 and 2 to 10) starting with α-
N
-acetylserine and C-terminal peptide (residues 150 to 177) ending with phenylalanine. These results suggest that the mature core protein (molecular mass of 19,306 Da) includes residues 2 to 177 and that its N terminus is blocked with an acetyl group.
The C-Mer Gene Is Induced by Epstein-Barr Virus Immediate-Early Protein BRLF1
Authors: Li Yuling , Mahajan Nupam P. , Webster-Cyriaque Jennifer , Bhende Prasanna , Hong Gregory K. , Earp H. Shelton , Kenney Shannon
Published: October 2004

BRLF1 (R) is one of two Epstein-Barr virus (EBV) immediate-early proteins that mediate the switch from the latent to the lytic form of viral replication. In this report, we show that R induces expression of the cellular C-mer gene in a variety of cell lines. C-mer expression was detected in lymphoblastoid cells immortalized with wild-type EBV but not in lymphoblastoid cells immortalized with an EBV that had BRLF1 deleted. Oral hairy leukoplakia tongue tissue, which contains the lytic form of EBV replication, also has enhanced C-mer expression. C-mer is a receptor tyrosine kinase activated by the ligand Gas6. C-mer is required for phagocytosis of apoptotic debris by monocytes/macrophages and retinal pigment epithelial cells and is capable of producing an antiapoptotic signal. Modulation of the C-mer signal transduction cascade by a variety of different approaches did not alter the ability of R to induce lytic EBV gene transcription. Therefore, C-mer activation may be important for some other aspect of lytic EBV infection.
Effects on Rotavirus Cell Binding and Infection of Monomeric and Polymeric Peptides Containing α2β1 and αxβ2 Integrin Ligand Sequences
Authors: Graham Kate L. , Zeng Weiguang , Takada Yoshikazu , Jackson David C. , Coulson Barbara S.
Published: October 2004

Integrin-using rotaviruses bind MA104 cell surface α2β1 integrin via the Asp-Gly-Glu (DGE) sequence in virus spike protein VP4 and interact with αxβ2 integrin during cell entry through outer capsid protein VP7. Infection is inhibited by the α2β1 ligand Asp-Gly-Glu-Ala (DGEA) and the αxβ2 ligand Gly-Pro-Arg-Pro (GPRP), and virus-α2β1 binding is increased by α2β1 activation. In this study, we analyzed the effects of monomers and polymers containing DGEA-, GPRP-, and DGEA-related peptides on rotavirus binding and infection in intestinal (Caco-2) and kidney (MA104) cells and virus binding to recombinant α2β1. Blockade of rotavirus-cell binding and infection by peptides and anti-α2 antibody showed that Caco-2 cell entry is dependent on virus binding to α2β1 and interaction with αxβ2. At up to 0.5 mM, monomeric DGEA and DGAA inhibited binding to α2β1 and infection. At higher concentrations, DGEA and DGAA showed a reduced ability to inhibit virus-cell binding and infection that depended on virus binding to α2β1 but occurred without alteration in cell surface expression of α2, β2, or αvβ3 integrin. This loss of DGEA activity was abolished by genistein treatment and so was dependent on tyrosine kinase signaling. It is proposed that this signaling activated existing cell surface α2β1 to increase virus-cell attachment and entry. Polymeric peptides containing DGEA and GPRP or GPRP only were inhibitory to SA11 infection at approximately 10-fold lower concentrations than peptide monomers. As polymerization can improve peptide inhibition of virus-receptor interactions, this approach could be useful in the development of inhibitors of receptor recognition by other viruses.
Inhibition of Epstein-Barr Virus (EBV) Reactivation by Short Interfering RNAs Targeting p38 Mitogen-Activated Protein Kinase or c-mycin EBV-Positive Epithelial Cells
Authors: Gao Xiangrong , Wang Haoran , Sairenji Takeshi
Published: October 2004

Latent Epstein-Barr virus (EBV) is reactivated by 12-O-tetradecanoylphorbol-13-acetate (TPA) in EBV-infected cells. In this study, we found that TPA up-regulated phosphorylation of p38, a mitogen-activated protein kinase, and activated c-mycmRNA in EBV-positive epithelial GT38 cells. The EBV immediate-early gene BZLF1 mRNA and its product ZEBRA protein were induced following TPA treatment. Protein kinase C inhibitors, 1-(5-isoquinolinesulphonyl)-2, 5-dimethylpiperazine (H7) and staurosporine, inhibited the induction of p38 phosphorylation and the activation of c-Myc by TPA. The p38 inhibitor SB203580 blocked both p38 phosphorylation and ZEBRA expression by TPA. Pretreatment of GT38 cells with the nitric oxide (NO) donorS-nitroso-N-acetylpenicillamine inhibited p38 phosphorylation and c-Myc activation by TPA, suggesting that NO may inhibit EBV reactivation via both p38 and c-Myc. By using short interfering RNA (siRNA) targeting either p38 or c-myc, we found that p38 or c-mycsiRNA specifically inhibited expression of the respective gene and also suppressed the induction of ZEBRA and EBV early antigen. The interferon (IFN)-responsive gene expression tests ruled out the possibility that the antiviral effect of siRNA is dependent on IFN. Our present study demonstrates for the first time that either p38 or c-mycsiRNA can efficiently inhibit TPA-induced EBV reactivation in GT38 cells, indicating that p38- and/or c-myc-associated signaling pathways may play critical roles in the disruption of EBV latency by TPA.
The Varicella-Zoster Virus Open Reading Frame 63 Latency-Associated Protein Is Critical for Establishment of Latency
Authors: Cohen Jeffrey I. , Cox Edward , Pesnicak Lesley , Srinivas Shamala , Krogmann Tammy
Published: October 2004

Varicella-zoster virus (VZV) expresses at least six viral transcripts during latency. One of these transcripts, derived from open reading frame 63 (ORF63), is one of the most abundant viral RNAs expressed during latency. The VZV ORF63 protein has been detected in human and experimentally infected rodent ganglia by several laboratories. We have deleted >90% of both copies of the ORF63 gene from the VZV genome. Animals inoculated with the ORF63 mutant virus had lower mean copy numbers of latent VZV genomes in the dorsal root ganglia 5 to 6 weeks after infection than animals inoculated with parental or rescued virus, and the frequency of latently infected animals was significantly lower in animals infected with the ORF63 mutant virus than in animals inoculated with parental or rescued virus. In contrast, the frequency of animals latently infected with viral mutants in other genes that are equally or more impaired for replication in vitro, compared with the ORF63 mutant, is similar to that of animals latently infected with parental VZV. Examination of dorsal root ganglia 3 days after infection showed high levels of VZV DNA in animals infected with either ORF63 mutant or parental virus; however, by days 6 and 10 after infection, the level of viral DNA in animals infected with the ORF63 mutant was significantly lower than that in animals infected with parental virus. Thus, ORF63 is not required for VZV to enter ganglia but is the first VZV gene shown to be critical for establishment of latency. Since the present vaccine can reactivate and cause shingles, a VZV vaccine based on the ORF63 mutant virus might be safer.
Amino-Terminal Region of the Human Immunodeficiency Virus Type 1 Nucleocapsid Is Required for Human APOBEC3G Packaging
Authors: Luo Kun , Liu Bindong , Xiao Zuoxiang , Yu Yunkai , Yu Xianghui , Gorelick Robert , Yu Xiao-Fang
Published: October 2004

APOBEC3G exerts its antiviral activity by targeting to retroviral particles and inducing viral DNA hypermutations in the absence of Vif. However, the mechanism by which APOBEC3G is packaged into virions remains unclear. We now report that viral genomic RNA enhances but is not essential for human APOBEC3G packaging into human immunodeficiency virus type 1 (HIV-1) virions. Packaging of APOBEC3G was also detected in HIV-1 Gag virus-like particles (VLP) that lacked all the viral genomic RNA packaging signals. Human APOBEC3G could be packaged efficiently into a divergent subtype HIV-1, as well as simian immunodeficiency virus, strain mac, and murine leukemia virus Gag VLP. Cosedimentation of human APOBEC3G and intracellular Gag complexes was detected by equilibrium density and velocity sucrose gradient analysis. Interaction between human APOBEC3G and HIV-1 Gag was also detected by coimmunoprecipitation experiments. This interaction did not require p6, p1, or the C-terminal region of NCp7. However, the N-terminal region, especially the first 11 amino acids, of HIV-1 NCp7 was critical for HIV-1 Gag and APOBEC3G interaction and virion packaging. The linker region flanked by the two active sites of human APOBEC3G was also important for efficient packaging into HIV-1 Gag VLP. Association of human APOBEC3G with RNA-containing intracellular complexes was observed. These results suggest that the N-terminal region of HIV-1 NC, which is critical for binding to RNA and mediating Gag-Gag oligomerization, plays an important role in APOBEC3G binding and virion packaging.