bluuebunny/crossref_metadata_2025 huggingface dataset:
Lymphocytic Choriomeningitis Virus Infection Yields Overlapping CD4
+
and CD8
+
T-Cell Responses
Authors: Dow Courtney , Oseroff Carla , Peters Bjoern , Nance-Sotelo Courtney , Sidney John , Buchmeier Michael , Sette Alessandro , Mothé Bianca R.
Published: October 2008

Activation of CD4
+
T cells helps establish and sustain other immune responses. We have previously shown that responses against a broad set of nine CD4
+
T-cell epitopes were present in the setting of lymphocytic choriomeningitis virus (LCMV) Armstrong infection in the context of H-2
d
. This is quite disparate to the H-2
b
setting, where only two epitopes have been identified. We were interested in determining whether a broad set of responses was unique to H-2
d
or whether additional CD4
+
T-cell epitopes could be identified in the setting of the H-2
b
background. To pursue this question, we infected C57BL/6 mice with LCMV Armstrong and determined the repertoire of CD4
+
T-cell responses using overlapping 15-mer peptides corresponding to the LCMV Armstrong sequence. We confirmed positive responses by intracellular cytokine staining and major histocompatibility complex (MHC)-peptide binding assays. A broad repertoire of responses was identified, consisting of six epitopes. These epitopes originate from the nucleoprotein (NP) and glycoprotein (GP). Out of the six newly identified CD4
+
epitopes, four of them also stimulate CD8
+
T cells in a statistically significant manner. Furthermore, we assessed these CD4
+
T-cell responses during the memory phase of LCMV Armstrong infection and after infection with a chronic strain of LCMV and determined that a subset of the responses could be detected under these different conditions. This is the first example of a broad repertoire of shared epitopes between CD4
+
and CD8
+
T cells in the context of viral infection. These findings demonstrate that immunodominance is a complex phenomenon in the context of helper responses.
Structural Determinant of Human La Protein Critical for Internal Initiation of Translation of Hepatitis C Virus RNA
Authors: Mondal Tanmoy , Ray Upasana , Manna Asit Kumar , Gupta Romi , Roy Siddhartha , Das Saumitra
Published: October 2008

Human La protein has been implicated in facilitating internal ribosome entry site (IRES)-mediated translation of hepatitis C virus (HCV). Earlier, we demonstrated that the RNA recognition motif (RRM) encompassing residues 112 to 184 of La protein [La (112-184)] interacts with the HCV IRES near the initiator AUG codon. A synthetic peptide, LaR2C (24-mer), derived from La RRM (112-184), retains RNA binding ability, competes with La protein binding to the HCV IRES, and inhibits translation. The peptide interferes with the assembly of 48S complexes, resulting in the accumulation of preinitiation complexes that are incompetent for the 60S ribosomal subunit joining. Here, nuclear magnetic resonance spectroscopy of the HCV IRES-bound peptide complex revealed putative contact points, mutations that showed reduced RNA binding and translation inhibitory activity. The residues responsible for RNA recognition were found to form a turn in the RRM (112-184) structure. A 7-mer peptide comprising this turn showed significant translation inhibitory activity. The bound structure of the peptide inferred from transferred nuclear Overhauser effect experiments suggests that it is a β turn. This conformation is significantly different from that observed in the free RRM (112-184) NMR structure, suggesting paths toward a better-stabilized mimetic peptide. Interestingly, addition of hexa-arginine tag enabled the peptide to enter Huh7 cells and showed inhibition of HCV IRES function. More importantly, the peptide significantly inhibited replication of the HCV monocistronic replicon. Elucidation of the structural determinant of the peptide provides a basis for developing small peptidomimetic structures as potent anti-HCV therapeutics.
Characterization of Simian Immunodeficiency Virus SIV
SM
/Human Immunodeficiency Virus Type 2 Vpx Function in Human Myeloid Cells
Authors: Goujon Caroline , Arfi Vanessa , Pertel Thomas , Luban Jeremy , Lienard Julia , Rigal Dominique , Darlix Jean-Luc , Cimarelli Andrea
Published: October 2008

Human immunodeficiency virus type 2 (HIV-2)/simian immunodeficiency virus SIV
SM
Vpx is incorporated into virion particles and is thus present during the early steps of infection, when it has been reported to influence the nuclear import of viral DNA. We recently reported that Vpx promoted the accumulation of full-length viral DNA following the infection of human monocyte-derived dendritic cells (DCs). This positive effect was exerted following the infection of DCs with cognate viruses and with retroviruses as divergent as HIV-1, feline immunodeficiency virus, and even murine leukemia virus, leading us to suggest that Vpx counteracted an antiviral restriction present in DCs. Here, we show that Vpx is required, albeit to a different extent, for the infection of all myeloid but not of lymphoid cells, including monocytes, macrophages, and monocytoid THP-1 cells that had been induced to differentiate with phorbol esters. The intracellular localization of Vpx was highly heterogeneous and cell type dependent, since Vpx localized differently in HeLa cells and DCs. Despite these differences, no clear correlation between the functionality of Vpx and its intracellular localization could be drawn. As a first insight into its function, we determined that SIV
SM
/HIV-2 and SIV
RCM
Vpx proteins interact with the DCAF1 adaptor of the Cul4-based E3 ubiquitin ligase complex recently described to associate with HIV-1 Vpr and HIV-2 Vpx. However, the functionality of Vpx proteins in the infection of DCs did not strictly correlate with DCAF1 binding, and knockdown experiments failed to reveal a functional role for this association in differentiated THP-1 cells. Lastly, when transferred in the context of a replication-competent viral clone, Vpx was required for replication in DCs.
Characterization of White Spot Syndrome Virus Envelope Protein VP51A and Its Interaction with Viral Tegument Protein VP26
Authors: Chang Yun-Shiang , Liu Wang-Jing , Chou Tsung-Lu , Lee Yuan-Ting , Lee Tai-Lin , Huang Wei-Tung , Kou Guang-Hsiung , Lo Chu-Fang
Published: October 2008

In this study, we characterize a novel white spot syndrome virus (WSSV) structural protein, VP51A (WSSV-TW open reading frame 294), identified from a previous mass spectrometry study. Temporal-transcription analysis showed thatvp51Ais expressed in the late stage of WSSV infection. Gene structure analysis showed that the transcription initiation site ofvp51Awas 135 bp upstream of the translation start codon. The poly(A) addition signal overlapped with the translation stop codon, TAA, and the poly(A) tail was 23 bp downstream of the TAA. Western blot analysis of viral protein fractions and immunoelectron microscopy both suggested that VP51A is a viral envelope protein. Western blotting of the total proteins extracted from WSSV virions detected a band that was close to the predicted 51-kDa mass, but the strongest signal was around 72 kDa. We concluded that this 72-kDa band was in fact the full-length VP51A protein. Membrane topology assays demonstrated that the VP51A 72-kDa protein is a type II transmembrane protein with a highly hydrophobic transmembrane domain on its N terminus and a C terminus that is exposed on the surface of the virion. Coimmunoprecipitation, colocalization, and yeast two-hybrid assays revealed that VP51A associated directly with VP26 and indirectly with VP28, with VP26 acting as a linker protein in the formation of a VP51A-VP26-VP28 complex.
Absence of Replication of Porcine Endogenous Retrovirus and Porcine Lymphotropic Herpesvirus Type 1 with Prolonged Pig Cell Microchimerism after Pig-to-Baboon Xenotransplantation
Authors: Issa Nicolas C. , Wilkinson Robert A. , Griesemer Adam , Cooper David K. C. , Yamada Kazuhiko , Sachs David H. , Fishman Jay A.
Published: October 2008

Porcine endogenous retrovirus (PERV), porcine cytomegalovirus (PCMV), and porcine lymphotropic herpesvirus (PLHV) are common porcine viruses that may be activated with immunosuppression for xenotransplantation. Studies of viral replication or transmission are possible due to prolonged survival of xenografts in baboon recipients from human decay-accelerating factor transgenic or α-1,3-galactosyltransferase gene knockout miniature swine. Ten baboons underwent xenotransplantation with transgenic pig organs. Graft survival was 32 to 179 days. Recipient serial samples of peripheral blood mononuclear cells (PBMC) and plasma were analyzed for PCMV, PERV, and PLHV-1 nucleic acids and viral replication using quantitative PCR assays. The PBMC contained PERV proviral DNA in 10 animals, PLHV-1 DNA in 6, and PCMV in 2. PERV RNA was not detected in any PBMC or serum samples. Plasma PLHV-1 DNA was detected in one animal. Pig cell microchimerism (pig major histocompatibility complex class I and pig mitochondrial cytochrome
c
oxidase subunit II sequences) was present in all recipients with detectable PERV or PLHV-1 (85.5%). Productive infection of PERV or PLHV-1 could not be demonstrated. The PLHV-1 viral load did not increase in serum over time, despite prolonged graft survival and pig cell microchimerism. There was no association of viral loads with the nature of exogenous immune suppression. In conclusion, PERV provirus and PLHV-1 DNA were detected in baboons following porcine xenotransplantation. Viral detection appeared to be due to persistent pig cell microchimerism. There was no evidence of productive infection in recipient baboons for up to 6 months of xenograft function.
Glycosylation of gp41 of Simian Immunodeficiency Virus Shields Epitopes That Can Be Targets for Neutralizing Antibodies
Authors: Yuste Eloìsa , Bixby Jacqueline , Lifson Jeffrey , Sato Shuji , Johnson Welkin , Desrosiers Ronald
Published: October 2008

Human immunodeficiency virus type 1 and simian immunodeficiency virus possess three closely spaced, highly conserved sites for N-linked carbohydrate attachment in the extracellular domain of the transmembrane protein gp41. We infected rhesus monkeys with a variant of cloned SIVmac239 lacking the second and third sites or with a variant strain lacking all three of SIVmac239's glycosylation sites in gp41. For each mutation, asparagine (N) in the canonical N-X-S/T recognition sequence for carbohydrate attachment was changed to the structurally similar glutamine such that two nucleotide changes would be required for a reversion of the mutated codon. By 16 weeks, experimentally infected monkeys made antibodies that neutralized the mutant viruses to high titers. Such antibodies were not observed in monkeys infected with the parental virus. Thus, new specificities were revealed as a result of the carbohydrate attachment mutations, and antibodies of these specificities had neutralizing activity. Unlike monkeys infected with the parental virus, monkeys infected with the mutant viruses made antibodies that reacted with peptides corresponding to the sequences in this region. Furthermore, there was strong selective pressure for the emergence of variant sequences in this region during the course of infection. By analyzing the neutralization profiles of sequence variants, we were able to define three mutations (Q625R, K631N, and Q634H) in the region of the glycosylation site mutations that conferred resistance to neutralization by plasma from the monkeys infected with mutant virus. Based on the reactivity of antibodies to peptides in this region and the colocalization of neutralization escape mutations, we conclude that N-linked carbohydrates in the ectodomain of the transmembrane protein shield underlying epitopes that would otherwise be the direct targets of neutralizing antibodies.
Epigenetic Silencing of Human Immunodeficiency Virus (HIV) Transcription by Formation of Restrictive Chromatin Structures at the Viral Long Terminal Repeat Drives the Progressive Entry of HIV into Latency
Authors: Pearson Richard , Kim Young Kyeung , Hokello Joseph , Lassen Kara , Friedman Julia , Tyagi Mudit , Karn Jonathan
Published: October 2008

The molecular mechanisms utilized by human immunodeficiency virus (HIV) to enter latency are poorly understood. Following the infection of Jurkat T cells with lentiviral vectors that express Tat in
cis
, gene expression is progressively silenced. Silencing is greatly enhanced when the lentiviral vectors carry an attenuated Tat gene with the H13L mutation. Individual clones of lentivirus-infected cells showed a wide range of shutdown rates, with the majority showing a 50% silencing frequency between 30 to 80 days. The silenced clones characteristically contained a small fraction (0 to 15%) of activated cells that continued to express d2EGFP. When d2EGFP
+
and d2EGFP
−
cell populations were isolated from the shutdown clones, they quickly reverted to the original distribution of inactive and active cells, suggesting that the d2EGFP
+
cells arise from stochastic fluctuations in gene expression. The detailed analysis of transcription initiation and elongation using chromatin immunoprecipitation (ChIP) assays confirms that Tat levels are restricted in the latently infected cells but gradually rise during proviral reactivation. ChIP assays using clones of latently infected cells demonstrate that the latent proviruses carry high levels of deacetylated histones and trimethylated histones. In contrast, the cellular genes IκBα and GAPDH had high levels of acetylated histones and no trimethylated histones. The levels of trimethylated histone H3 and HP1-α associated with HIV proviruses fell rapidly after tumor necrosis factor alpha activation. The progressive shutdown of HIV transcription following infection suggests that epigenetic mechanisms targeting chromatin structures selectively restrict HIV transcription initiation. This decreases Tat production below the levels that are required to sustain HIV gene expression.
Experimental Evolution of Human Influenza Virus H3 Hemagglutinin in the Mouse Lung Identifies Adaptive Regions in HA1 and HA2
Authors: Keleta Liya , Ibricevic Aida , Bovin Nicolai V. , Brody Steven L. , Brown Earl G.
Published: October 2008

The genetic basis for virulence and host switching in influenza A viruses (FLUAV) is largely unknown. Because the hemagglutinin (HA) protein is a determinant of these properties, HA evolution was mapped in an experimental model of mouse lung adaptation. Variants of prototype A/Hong Kong/1/68 (H3N2) (wild-type [wt] HK) human virus were selected in both longitudinal and parallel studies of lung adaptation. Mapping of HA mutations found in 11 independently derived mouse-adapted populations of wt HK identified 27 mutations that clustered within two distinct regions in or near the globular frameworks of the HA1 and HA2 subunits. The adaptive mutations demonstrated multiple instances of convergent evolution involving four amino acid positions (162, 210, and 218 in HA1 and 154 in HA2). By use of reverse genetics, convergent HA mutations were shown to affect cell tropism by enhancing infection and replication in primary mouse tracheal epithelial cells in vitro and mouse lung tissue in vivo. Adaptive HA mutations were multifunctional, affecting both median pH of fusion and receptor specificity. Specific mutations within both adaptive regions were shown to increase virulence in a mouse lung model. The occurrence of mutations in the HA1 and HA2 adaptive regions of natural FLUAV host range and virulent variants of avian and mammalian viruses is discussed. This study has identified adaptive sites and regions within the HA1 and HA2 subunits that may guide future studies of viral adaptation and evolution in nature.
Role of Ebola Virus VP30 in Transcription Reinitiation
Authors: Martínez Miguel J. , Biedenkopf Nadine , Volchkova Valentina , Hartlieb Bettina , Alazard-Dany Nathalie , Reynard Olivier , Becker Stephan , Volchkov Viktor
Published: October 2008

VP30 is a phosphoprotein essential for the initiation of Ebola virus transcription. In this work, we have studied the effect of mutations in VP30 phosphorylation sites on the ebolavirus replication cycle by using a reverse genetics system. We demonstrate that VP30 is involved in reinitiation of gene transcription and that this activity is affected by mutations at the phosphorylation sites.
Overexpression of Thiol/Disulfide Isomerases Enhances Membrane Fusion Directed by the Newcastle Disease Virus Fusion Protein
Authors: Jain Surbhi , McGinnes Lori W. , Morrison Trudy G.
Published: October 2008

Newcastle disease virus (NDV) fusion (F) protein directs membrane fusion, which is required for virus entry and cell-cell fusion. We have previously shown that free thiols are present in cell surface-expressed NDV F protein and that blocking the production of free thiols by thiol-disulfide exchange inhibitors inhibited the membrane fusion mediated by F protein (J Virol. 81:2328-2339, 2007). Extending these observations, we evaluated the role of the overexpression of two disulfide bond isomerases, protein disulfide isomerase (PDI) and ERdj5, in cell-cell fusion mediated by NDV glycoproteins. The overexpression of these isomerases resulted in significantly increased membrane fusion, as measured by syncytium formation and content mixing. The overexpression of these isomerases enhanced the production of free thiols in F protein when expressed without hemagglutination-neuraminidase (HN) protein but decreased free thiols in F protein expressed with HN protein. By evaluating the binding of conformation-sensitive antibodies, we found that the overexpression of these isomerases favored a postfusion conformation of surface-expressed F protein in the presence of HN protein. These results suggest that isomerases belonging to the PDI family catalyze the production of free thiols in F protein, and free thiols in F protein facilitate membrane fusion mediated by F protein.
Heparan Sulfate-Independent Cell Binding and Infection with Furin-Precleaved Papillomavirus Capsids
Authors: Day Patricia M. , Lowy Douglas R. , Schiller John T.
Published: October 2008

Papillomavirus infection normally involves virion binding to cell surface heparan sulfate proteoglycans (HSPGs). However, we found that human papillomavirus type 16 pseudovirions efficiently bound and infected cells lacking HSPGs if their L2 capsid protein was precleaved by furin, a cellular protease required for infection. The inability of pseudovirions to efficiently bind and infect cultured primary keratinocytes was also overcome by furin precleavage, suggesting that the defect involves altered HSPG modification. We conclude that the primary function of HSPG binding is to enable cell surface furin cleavage of L2 and that binding to a distinct cell surface receptor(s) is a subsequent step of papillomavirus infection.
Simian Immunodeficiency Virus (SIV)-Specific CD8+T-Cell Responses in Vervet African Green Monkeys Chronically Infected with SIVagm
Authors: Zahn Roland C. , Rett Melisa D. , Korioth-Schmitz Birgit , Sun Yue , Buzby Adam P. , Goldstein Simoy , Brown Charles R. , Byrum Russell A. , Freeman Gordon J. , Letvin Norman L. , Hirsch Vanessa M. , Schmitz Jörn E.
Published: October 2008

African green monkeys (AGM) do not develop overt signs of disease following simian immunodeficiency virus (SIV) infection. While it is still unknown how natural hosts like AGM can cope with this lentivirus infection, a large number of investigations have shown that CD8+T-cell responses are critical for the containment of AIDS viruses in humans and Asian nonhuman primates. Here we have compared the phenotypes of T-cell subsets and magnitudes of SIV-specific CD8+T-cell responses in vervet AGM chronically infected with SIVagm and rhesus monkeys (RM) infected with SIVmac. In comparison to RM, vervet AGM exhibited weaker signs of immune activation and associated proliferation of CD8+T cells as detected by granzyme B, Ki-67, and programmed death 1 staining. By gamma interferon enzyme-linked immunospot assay and intracellular cytokine staining, SIV Gag- and Env-specific immune responses were detectable at variable but lower levels in vervet AGM than in RM. These observations demonstrate that natural hosts like SIV-infected vervet AGM develop SIV-specific T-cell responses, but the disease-free course of infection does not depend on the generation of robust CD8+T-cell responses.
Effect of Zeolite ZSM-5 Particle Size in the Synthesis of 1,4-Diazabicyclo[2.2.2]octane
Authors: Trejbal Jiří , Pašek Josef , Petrisko Miroslav
Published: October 2008

The effect of the particle size of zeolite ZSM-5 in the synthesis of 1,4-diazabicyclo[2.2.2]octane from ethylenediamine was studied. The activity of the catalyst and its selectivity for 1,4-diazabicyclo[2.2.2]octane increase with decreasing particle size of zeolite ZSM-5.
Application of Calcined Layered Double Hydroxides as Catalysts for Abatement of N2O Emissions
Authors: Obalová Lucie , Kovanda František , Jirátová Květuše , Pacultová Kateřina , Lacný Zdenek
Published: October 2008

The results of catalytic decomposition of N2O over mixed oxide catalysts obtained by calcination of layered double hydroxides (LDHs) are summarized. Mixed oxides were prepared by thermal treatment (500 °C) of coprecipitated LDH precursors with general chemical composition of MII1-xMIIIx(OH)2(CO3)x/2·yH2O, where MII was Ni, Co, Cu and/or Mg, MIII was Mn, Fe and/or Al, and the MII/MIII molar ratio was adjusted to 2. The influence of chemical composition of the MII-MIII mixed oxide catalysts on their activity and stability in N2O decomposition was examined. The highest N2O conversion was reached over Ni-Al (4:2) and Co-Mn-Al (4:1:1) catalysts. Their suitability for practical application was proved in simulated process stream in the presence of O2, NO, NO2 and H2O. It was found that N2O conversion decreased with increasing amount of oxygen in the feed. The presence of NO in the feed caused a slight decrease in N2O conversion. A strong decrease in the reaction rate was observed over the Ni-Al catalyst in the presence of NO2 while no N2O conversion decrease was observed over the Co-Mn-Al catalyst. Water vapor inhibited the N2O decomposition over all tested catalysts. The obtained kinetic data for N2O decomposition in a simulated process stream over the Co-Mn-Al catalyst were used for a preliminary reactor design. The packed bed volume necessary for N2O emission abatement in a HNO3 production plant was calculated as 35 m3 for waste gas flow rate of 30 000 m3 h-1.
Aromatic Transformation in Fluidized Bed Reactors
Authors: Rabiu Sule , Al-Khattaf Sulaiman
Published: October 2008

In this work three important aromatic transformations, namely: toluene disproportionation, toluene methylation and m-xylene isomerization, were investigated in a riser simulator which closely mimics the operation of commercial fluidized bed reactors. The transformations were studied over a ZSM-5 based catalyst with medium acidity of 0.23 mmol/g and a series of Y zeolites of acidities between 0.55 and 0.03 mmol/g. For pure toluene feed, it was observed that conversion over the ZSM-5 based catalyst and the weakly acidic Y zeolite (USY-1) was very low. However, with the highly acidic Y zeolite (H-Y), significant toluene conversion was observed with paring reaction more prominent than disproportionation. On the other hand, when toluene was alkylated with methanol, higher toluene conversions were achieved over both the ZSM-5 based and the weakly acidic USY-1 catalysts as compared to when pure toluene feed was used. In addition, p-xylene/o-xylene (P/O) ratios higher than the equilibrium values were obtained in the reaction product over both catalysts. Finally, for m-xylene isomerization it was found that m-xylene conversion increased initially as the acidity of the catalyst increased up to 0.1 mmol/g beyond which any further increase in acidity resulted in a slight decrease in the m-xylene conversion.
Synthesis and Catalytic Evaluation of Ferrierite-Related Materials Synthesized in the Presence of co-Structure Directing Agents
Authors: García Raquel , Pinar Ana Belén , Márquez-Alvarez Carlos , Sastre Enrique , Pérez-Pariente Joaquín
Published: October 2008

We report on the systematic exploration of zeolite synthesis using a combination of organic molecules of different size. The effect of changing the co-structure directing agent, co-SDA, (tetramethylammonium or quinuclidine) and its replacement by sodium cations, when used together with the bulky organic cation 1-benzyl-1-methylpyrrolidinium (bmp) is analyzed and compared with preparations where bmp is replaced by the related cation (S)-1-benzyl-2-hydroxymethyl-1-methylpyrrolidinium (bmprol). The tendency to direct the synthesis to ferrierite or ferrierite-like materials depending on the particular combination of bulky organic cation and co-SDA is discussed. The catalytic activity of some of the materials synthesized was tested in the isomerization of m-xylene.
Disproportionation of Alkanes via Molecular Redistribution and Molecular Averaging
Authors: Chen Cong-Yan , O'Rear Dennis J.
Published: October 2008

In this paper the disproportionation of alkanes via molecular redistribution (MR) and molecular averaging (MA) is discussed. MR/MA chemistry consists of three steps occurring in one single catalyst bed over a bifunctional catalyst system: dehydrogenation of alkanes to olefinic intermediates, metathesis (disproportionation) of these olefin species and hydrogenation of the metathesis products to alkanes. MR/MA represents a unique and rare example of bifunctional heterogeneous catalysis while there are many examples of acid components being one of the bifunctional elements with a metal, e.g., in reforming, hydrocracking and isomerization reactions. MR/MA chemistry provides simple processes which can be accomplished otherwise only via combinations of other existing chemistries. In this paper, we will use MR of pentanes as an example to demonstrate one industrial application of the MR chemistry.
Synthesis of Fructone and Acylal Using Hexagonally Ordered Mesoporous Aluminosilicate Catalyst
Authors: Vinu Ajayan , Justus Josena , Balasubramanian Veerappan Vaithilingam , Halligudi Shivappa Basappa , Ariga Katsuhiko , Mori Toshiyuki
Published: October 2008

Hexagonally ordered mesoporous AlSBA-15 with different nSi/nAl ratios have been hydrothermally synthesized using the non-ionic copolymer Pluronic P123 surfactant as the structure directing agent and characterized by XRD, N2 adsorption-desorption, and ammonia-temperature programmed desorption (pyridine-TPD). Acetal and acylal formation reactions of organic carbonyl compounds were efficiently catalyzed by AlSBA-15 under liquid-phase reaction conditions and the results were compared with the MFI, BEA and AlMCM-41(23). Of the catalysts studied, AlSBA-15(45) showed the highest activity in both the acetalization and acylal reactions of the carbonyl compounds under the optimized reaction conditions, and could be recycled several times without loss in activity. AlSBA-15(45) catalyst is highly stable, efficient, chemoselective, and environmental friendly, which could open the possibility for environment benign approach for the synthesis of acetals, acylals and its derivatives under mild reaction conditions.
New Templating Route for Synthesis of Mesoporous Alumina
Authors: Žilková Naděžda , Čejka Jiří , Murafa Nataliya , Zukal Arnošt
Published: October 2008

Synthesis of mesoporous alumina made by nanocasting using polymer spheres matrix is reported. In contrast to all other recipes described in the literature so far, mesoporous alumina prepared by the nanocasting method consists of irregularly ordered particles exhibiting pores of ca. 25 nm in size. The void volume among the particles constitutes a porous system with narrow pore size distribution in the mesopore region.
Kinetics of Reduction of Cu Ions in MFI Zeolite Investigated by H2-TPR Method
Authors: Bulánek Roman , Čičmanec Pavel
Published: October 2008

The temperature programmed reduction with hydrogen (H2-TPR) profiles of the Cu-MFI zeolite matrix were measured. The effect of the Cu ions loading and the heating rate on the H2-TPR profiles was investigated. The obtained TPR profiles were evaluated by different methods in order to obtain kinetic parameters and the reduction process mechanism. It was observed that the results given by convenient methods based on the simple power-law kinetics cannot be used for evaluation of at least the reduction of monovalent copper. Based on the reaction rate dependence on the degree of conversion, an autocatalytic reaction mechanism model was suggested for monovalent copper reduction. The autocatalytic effect was ascribed to nanoclusters of metallic copper, which is formed during the reduction. The parameters of this model were obtained by fitting the reaction rate equation to experimental data. The simulated TPR profiles well describe the position and relative height of peaks in experimental TPR profiles. Using our approach to evaluation of kinetic parameters we found the activation energies for reduction of Cu2+, direct reduction of Cu+and autocatalytic reduction of Cu+equal to 91, 67 and 38 kJ mol-1, respectively. All the mentioned processes are controlled by the kinetics of order ca. 1.5.
Dehydrocyclization of Diphenylamine to Carbazole Over Platinum Catalysts
Authors: Vlčko Miroslav , Cvengrošová Zuzana , Hronec Milan
Published: October 2008

The gas-phase dehydrocyclization of diphenylamine (DPA) to carbazole over alumina-supported 0.4 wt.% Pt catalysts in a fix-bed reactor has been studied. The reaction was carried out at a temperature of 550 °C in the presence of hydrogen. All catalysts became well dispersed Pt after in situ reduction. Pt catalysts prepared in the presence of a competitive adsorbate (citric acid) were reasonably active during first hours on stream (DPA conversion higher than 90%). However, later, their activity decreased rapidly, except the catalyst prepared in the presence of a higher concentration of the competitive agent. The same trend was observed for the Pt catalyst prepared by wet impregnation. The activity of the catalysts prepared by a microemulsion technique was very high and stable during testing, the conversion of DPA being higher than 93%. However, the selectivities of catalysts prepared in the presence of citric acid gradually decreased with time on stream (TOS). The initial selectivityof such prepared catalysts for carbazole was about 60%. The same trend was observed for catalysts prepared by microemulsion technique. The highest selectivities, 73%, were obtained over the catalysts prepared by wet impregnation; it dropped after 6 days of testing to about 62%.
Synthesis and Structure of Permethylcyclopentadienyltitanium Diisopropoxide Zwitterionic Complex
Authors: Varga Vojtech , Pinkas Jiří , Císařová Ivana , Gyepes Róbert , Mach Karel , Kubišta Jiří , Horáček Michal
Published: October 2008

Half-sandwich pentamethylcyclopentadienyltitanium chloroisopropoxides [Ti(η5-C5Me5)-Ti(Oi-Pr)nCl3-n] (n = 1 (1) or 2 (2)) and methylisopropoxides [Ti(η5-C5Me5)Ti(Oi-Pr)nMe3-n] (n = 1 (3) or 2 (4)) were prepared and characterized by spectroscopic methods, and compound 1 by single crystal X-ray diffraction analysis. Compounds 3 and 4 were reacted with an equimolar quantity of B(C6F5)3, however, only compound 4 afforded a crystalline product of limited stability at ambient temperature. Its single crystal X-ray diffraction analysis revealed that it is the zwitterionic complex [(η5-C5Me5)Ti(Oi-Pr)2]+[(μ-Me)B(C6F5)3]- (5) and its crystal structure is very similar to the recently reported tert-butoxy complex [(η5-C5Me5)-Ti(Ot-Bu)2]+[(μ-Me)B(C6F5)3]- (6). The 1H, 13C, and 19F NMR spectra in C6D6 solution also showed the features analogous to those of 6. 1D NOESY experiments proved a close through space interaction of irradiated C5Me5 or OCHMe2 protons with the bridging Ti···Me-B group. The NMR data indicate the inner sphere ion pair structure of 5 in C6D6, like for 6. The crystal structure geometry of the C-H bonds of the Ti···Me-B group fulfils conditions for their agostic interaction with the titanium centre. Although structurally similar to 6, compound 5 is less thermally stable apparently due to a lower bulkiness of Oi-Pr group compared to that of Ot-Bu group.
The Feasibility of Ni-Alumina Catalysts in Oxidative Dehydrogenation of Ethane
Authors: Čapek Libor , Vaněk Lukáš , Smoláková Lucie , Bulánek Roman , Adam Jiří
Published: October 2008

The contribution deals with the development on the efficient Ni-alumina catalyst for the oxidative dehydrogenation (ODH) of ethane to ethene. The performance of Ni-alumina catalysts with varying nickel loadings and with thermal pretreatment was studied. We contribute to the understanding of the relationship between the activity of nickel species in ODH of ethane and its distribution. To analyze this effect, Ni-alumina catalysts were analyzed by UV-VIS spectroscopy, and H2-TPR profile. Ni-alumina catalysts were highly active and selective (ca. 80%) in the ODH of ethane. The catalysts contained both tetrahedral and octahedral nickel species, suggesting that nickel aluminate represented a partial spinel, where Ni(II) ions occupy both octahedral and tetrahedral sites of the oxygen lattice. It was suggested that the octahedral nickel species were more active than the tetrahedral ones.
Effect of Temperature, Pressure and Volume of Reacting Phase on Photocatalytic CO2 Reduction on Suspended Nanocrystalline TiO2
Authors: Kočí Kamila , Obalová Lucie , Plachá Daniela , Lacný Zdenek
Published: October 2008

The effect of temperature, pressure and volume of reactant solution on the photocatalytic reduction of CO2at suspended TiO2was studied in an annular batch photoreactor. Reaction products in the liquid phase (methanol, formaldehyde) and in the gas phase (methane, ethane, carbon monoxide, molecular oxygen and hydrogen) were analysed by gas chromatography. The photocatalytic reduction of CO2was not sensitive significantly to small temperature variations within 10 K. The CO2pressure at carbonation of the solution influenced the selectivity of the CO2conversion to methane and methanol, while the dihydrogen yield was higher by two orders of magnitude and independent of the pressure. The dependence of the product yields on the volume of the liquid phase confirmed the fact that the requirement for perfect mixing was difficult to fulfil for the annular configuration of the reactor.
Structural Study of Tailored Titania Thin Layers
Authors: Šolcová Olga , Matějová Lenka , Krejčíková Simona , Matěj Zdeněk , Kužel Radomír , Strýhal Zdeněk , Benada Oldřich
Published: October 2008

Thin nanolayers of titania prepared by repeated dip-coating of silica glass into a transparent homogeneous sol made from nonionic surfactants with various numbers of oxyethylene units were studied. Calcination in air stream was used to convert transparent gel layers into anatase layers. The surface morphology, roughness, structure and texture properties were estimated by nitrogen physical adsorption, X-ray diffraction characterization, atomic force microscopy, transmission and scanning electron microscopy. Additionally, the contact angle determination was tested as a rapid method for evaluation of the titania layer surface quality. The influence of the number of oxyethylene units in surfactants on texture and structure properties of the prepared titania layers was found and discussed.
Common acute oncological emergencies: diagnosis, investigation and management
Authors: Walji N , Chan A K , Peake D R
Published: October 2008

In the UK an aging population is resulting in more people being diagnosed with cancer, and an increasing number of treatment options means that many patients live significantly longer with their disease. It is anticipated therefore that an increasing number of patients will present to primary and secondary care with acute complications of cancer, or the treatment thereof. Many doctors have limited experience in managing patients with cancer and acute oncological emergencies. This article reviews the diagnosis and management of four common oncological emergencies: febrile neutropenia, metastatic spinal cord compression, superior vena cava obstruction, and malignancy associated hypercalcaemia. It is vital to recognise these conditions, as failure to implement immediate and appropriate treatment may result in significant morbidity or death.
Cross-sectional survey of disturbed behaviour in patients in general hospitals in Leeds
Authors: Kannabiran M , Deshpande S , Walling A , Alagarsamy J , Protheroe D , Trigwell P
Published: October 2008

Aim

To describe the prevalence and nature of disturbed behaviour, in the general hospital setting.

Method

A cross-sectional survey was conducted, from July to October 2006, in all adult inpatient wards within the six general hospitals in Leeds of patients presenting with disturbed behaviour in the preceding 7 days. Disturbed behaviour was defined as behaviour interfering with care of the patient or with that of other patients, or behaviour that placed the patient, the staff or others at risk. Anonymised data were collected using a semi-structured questionnaire.

Results

All of the 87 hospital wards were studied, containing a total of 1773 beds. 42 male and 26 female patients (n = 68) were identified by nursing staff as patients with disturbed behaviour in the time period covered, with 33 patients being ⩽65 years of age and 35 being elderly (>65 years of age). An almost equal proportion of the younger and older patient groups placed themselves or others at risk. In the majority of cases, aggressive behaviour by patients was directed towards staff rather than other patients. 60 patients required additional staff time due to the disturbed behaviour, 34 required additional medication, and 22 patients were referred to liaison psychiatry.

Conclusions

Disturbed behaviour presents in the general hospital in less than 4% of patients, both above and below the age of 65 years, but consumes a disproportionate amount of resources. Responses required to manage this include additional medication, additional staff time or other interventions. The quantity and nature of disturbed behaviour in the general hospital have implications for effective service provision and development.
Changing education to improve patient care
Authors: Leach D C
Published: October 2008

Health professionals need competencies in improvement skills if they are to contribute usefully to improving patient care. Medical education programmes in the USA have not systematically taught improvement skills to residents (registrars in the UK). The Accreditation Council for Graduate Medical Education (ACGME) has recently developed and begun to deploy a competency based model for accreditation that may encourage the development of improvement skills by the 100 000 residents in accredited programmes. Six competencies have been identified for all physicians, independent of specialty, and measurement tools for these competencies have been described. This model may be applicable to other healthcare professions. This paper explores patterns that inhibit efforts to change practice and proposes an educational model to provide changes in management skills based on trainees' analysis of their own work.
Uptake of Chrysotile Asbestos Fibers Alters Growth and Reproduction of Asiatic Clams
Authors: Belanger Scott E. , Cherry Donald S. , Cairns Jr. John
Published: October 2008

The effects of chrysotile asbestos on siphoning activity, shell and tissue growth, fiber uptake, and gill ultrastructure in adult Asiatic clams (Corbicula sp.) and on larval release and mortality patterns from reproductively active adults were evaluated in 96-h to 30-d experiments at 0–108 fibers/L. Adult siphoning activity was significantly (α = 0.05) depressed in 96-h asbestos exposures when no food was offered or after 30 d when food was available. Shell growth was significantly inhibited in accordance with reduced siphoning. Corbicula exposed to 108 fibers/L accumulated 69.1 fibers/mg dry weight if food was offered. Fiber uptake was not observed at lower concentrations in 96-h or 30-d tests. Adult clams exposed to 108 fibers/L for 30 d accumulated 147.3 and 903.7 fibers/mg in gill and viscera, respectively. Gill tissue was significantly altered at 108 fibers/L and fibers were observed in gill locules and in ctenidial tissue. Fiber dimension analysis suggested that small, thin fibers were preferentially accumulated by both gill and visceral tissues. Significant increases in mortality of larvae exposed to asbestos and decreases in larvae released per milligram of adult dry weight were observed in reproductive adults exposed to asbestos at 104–108 fibers/L. Corbicula is an efficient accumulator of chrysotile asbestos and may be considered for use as an indicator of asbestos contamination.
High-Density Culture of Meiobenthic Harpacticoid Copepods Within a Muddy Sediment Substrate
Authors: Chandler G. Thomas
Published: October 2008

Difficulties in producing a muddy substrate which does not easily foul have made previous efforts to culture mud-inhabiting, estuarine, and marine harpacticoid copepods unsuccessful. Natural, organic-rich muds are unsuitable as a long-term culture medium because they generate detrimental bacterial blooms in stagnant and periodically flushed culture systems. I present some simple procedures to (1) sort muddy sediments into a <125-μm size class, (2) flush away most dissolved organics, (3) sterilize the sediments providing a moderately foul-free culture medium, (4) generate a life-like, flocculent surface layer, and (5) allow easy observation above or below the sediment surface. Five harpacticoids were cultured within 45–90 d to densities 4–11 times their natural field maxima (per 10 cm2): Scottolana canadensis (372), Paronychocamptus huntsmani (380), Onychocamptus mohammed (448), Cletocamptus deitersi (1259), and Nitocra lacustris (1662). Since most mud-inhabiting harpacticoids are larger than 125 μm, simple sieving on a 125-μm screen eliminates culture sediments leaving behing hundreds of clean, easily collected harpacticoids.
Response of Radioactive Trace Metals to Acid–Base Titrations in Controlled Experimental Ecosystems: Evaluation of Transport Parameters for Application to Whole-Lake Radiotracer Experiments
Authors: Santschi Peter H. , Nyffeler Urs P. , Anderson Robert F. , Schiff Sherry L. , O'hara Patricia , Hesslein Raymond H.
Published: October 2008

Radiotracer experiments were carried out in 20 enclosures located in two lakes at the Experimental Lakes Area (ELA), northwestern Ontario, to study pathways of trace metal removal from the water column of shallow lakes. Two removal mechanisms were characterized: (1) sorption to and subsequent transport with falling particles and (2) direct adsorption to surface sediments. Our approach was to measure independently the kinetics of radiotracer sorption, fluxes and concentrations for particles, particle settling velocities, and the "equivalent stagnant boundary film." Our radiotracer results enabled us to test the sensitivity of the tracer removal rates on these rate-determining processes using a numerical transport model. Acid titrations of whole ecosystems revealed that some trace metals (e.g. Mn, Co, and Zn) can diffuse back to the water column as the pH is lowered from 6.5 to 4.8 after 18 d, while others remain tightly bound (e.g. Sn, Fe, Se, Cr, Ag, and Hg isotopes). Subsequent CaCO3 additions to bring back the pH to its original value restored the initial removal conditions for acid-sensitive radiotracers, indicating that the pH sensitivity is reversible. Transport parameters for particle-related pathways or diffusive pathways across the sediment–water interface obtained from our enclosure experiments were used to predict the removal rates of "particle-reactive" 60Co and the "diffusive" pathway tracer 134Cs observed in earlier experiments where radiotracers were added to whole lakes or to larger enclosures.
Fundy Tidal Power Development and Potential Fish Production in the Gulf of Maine
Authors: Campbell Daniel E. , Wroblewski J. S.
Published: October 2008

The possible effects of tidal amplitudes altered by Fundy tidal power development upon potential fish production in the Gulf of Maine are examined with a marine ecosystem model. Three areas off the Maine coast are delineated on the basis of winds, tides, and the extent of vertical mixing. An optimum kinetic energy from wind and tide exists for maximum primary production in the water column. Primary production in the model is the base for a simple pelagic food chain leading from phytoplankton through zooplankton to fish. If the construction of a tidal power dam in the upper Bay of Fundy results in a 5–10% increase in tidal amplitude, our first-order model predicts that enhanced vertical mixing from May to October will increase potential fish production along the Maine west coast by 7–12%. Fish production along the Maine east coast and in offshore waters is predicted to remain at present levels. Climatic variation is predicted to have as large an impact on fish production as man-induced changes in vertical mixing caused by tidal power development.
Optimal Effort Allocation Among Competing Mixed-Species Fisheries, Subject to Fishing Mortality Constraints
Authors: Murawski S. A. , Finn J. T.
Published: October 2008

A linear programming (LP) approach to effort allocation among two or more fisheries (fleets) exploiting several common species/stocks is described and applied to otter trawl fisheries exploiting demersal fish stocks on Georges Bank (northeastern United States). Total instantaneous fishing mortality on a particular species (i) is computed as the linear summation of fishing mortalities generated by each fishery (j):[Formula: see text]where fj is the amount of standardized fishing effort exerted in fishery j and qij is the catchability coefficient for species i taken in fishery j. Mortality on species i due to both directed fishing and by-catch can thus be accounted for in the qij's. Optimal allocation of effort among the j fisheries may be considered a minimization problem (minimize Σfj), subject to the constraints that fishing mortality rates on particular species are maintained at, above, or below certain predefined levels. Fishing mortality goals for individual species can be based on various biological and/or economic criteria: fishing mortality rates that prevent growth or recruitment overfishing, or that optimize productivity from predator–prey systems. Other constraints in the LP model may be included to modify optimal solutions based on various economic and social considerations (e.g. protection of certain fisheries). Sensitivity analyses indicate the general infeasibility of maintaining relatively high or low fishing mortality rates on ubiquitously distributed species, while moderately fishing species with more discrete distributions, due to by-catch considerations.
Bounds on the Optimal Age-at-First-Capture for Stochastic, Age-Structured Fisheries
Authors: Lovejoy William S.
Published: October 2008

This paper addresses the problem of optimally exploiting an age-structured fishery with stochastic, density-dependent recruitment; stochastic dynamics; and cohort-dependent prices, costs, catchabilities, and survival rates. Sufficient conditions are derived for an age-at-first-capture to be a necessary component of the optimal management regime, and a lower bound on this critical age is calculated. The method consists of replacing the stochastic, density-dependent model with more traditional (stochastic, density-independent and deterministic, density-independent) models which yield lower bounds on the optimal escapement. A numerical example demonstrates the practical applicability of the results.
Body Fat Condition in Northeast Atlantic Fin Whales, Balaenoptera physalus, and Its Relationship with Reproduction and Food Resource
Authors: Lockyer Christina
Published: October 2008

Measurements of body girth, blubber thickness, and the lipid content of blubber, muscle, and visceral fat of Icelandic fin whales (Balaenoptera physalus) showed a consistent pattern of body fat condition for each sexual class in all years between 1977 and 1982, with pregnant and anoestrous females being fattest. There was a trend of increasing body fatness between 1977 and 1982 which is supported by data on oil production from the catch. Parallel to this was an apparent increase in food abundance and whale fecundity.