bluuebunny/crossref_metadata_2025 huggingface dataset:
Replacement of the V3 Region of gp120 with SDF-1 Preserves the Infectivity of T-Cell Line-Tropic Human Immunodeficiency Virus Type 1
Authors: Yonezawa Akihito , Hori Toshiyuki , Takaori-Kondo Akifumi , Morita Rinpei , Uchiyama Takashi
Published: July 2002

Interaction between the human immunodeficiency virus type 1 (HIV-1) envelope and the relevant chemokine receptors is crucial for subsequent membrane fusion and viral entry. Although the V3 region of gp120 is known to determine the cell tropism as well as the coreceptor usage, the significance of the binding of the V3 region to the chemokine receptor has not been fully understood. To address this issue, we adopted the pseudotyped virus infection assay in which the V3 region of the T-cell line-tropic (T-tropic) NL4-3 envelope was replaced with a portion of stromal cell-derived factor 1 (SDF-1), the ligand of CXCR4. The V3 region of the NL4-3 envelope expression vector was replaced with three different stretches of SDF-1 cDNA. Expression of each chimeric envelope protein was confirmed by immunoprecipitation and Western blotting. Luciferase reporter viruses were prepared by cotransfection of the pNL4-3.Luc.E−R−vector and each chimeric envelope expression vector, and the infection assay was then carried out. We showed that pseudotyped viruses with one of the chimeric envelopes, NL4-3/SDF1-51, could infect U87.CD4.CXCR4 but not U87.CD4 or U87.CXCR4 cells and that this infection was inhibited by the ligand of CXCR4, SDF-1β, by anti-human SDF-1 antibody, or by an anti-CD4 antibody, Leu3a, in a dose-dependent manner. Furthermore, chimeric NL4-3/SDF1-51 gp120 significantly inhibited binding of labeled SDF-1 to CXCR4. It was suggested that replacement of the V3 region of the NL4-3 envelope with SDF-1 preserved the CD4-dependent infectivity of T-tropic HIV-1. These results indicate that binding between the V3 region and the relevant coreceptor is important for viral entry, whether its amino acid sequence is indigenous to the virus or not.
Temporary Blockade of the Tumor Necrosis Factor Receptor Signaling Pathway Impedes the Spread of Scrapie to the Brain
Authors: Mabbott Neil A. , McGovern Gillian , Jeffrey Martin , Bruce Moira E.
Published: July 2002

Although the transmissible spongiform encephalopathies (TSEs) are neurodegenerative diseases, their agents usually replicate and accumulate in lymphoid tissues long before infection spreads to the central nervous system (CNS). Studies of a mouse scrapie model have shown that mature follicular dendritic cells (FDCs), which express the host prion protein (PrPc), are critical for replication of infection in lymphoid tissues. In the absence of mature FDCs, the spread of infection to the CNS is significantly impaired. Tumor necrosis factor alpha (TNF-α) secretion by lymphocytes is important for maintaining FDC networks, and signaling is mediated through TNF receptor 1 (TNFR-1) expressed on FDCs and/or their precursors. A treatment that blocks TNFR signaling leads to the temporary dedifferentiation of mature FDCs, raising the hypothesis that a similar treatment would significantly delay the peripheral pathogenesis of scrapie. Here, specific neutralization of the TNFR signaling pathway was achieved through treatment with a fusion protein consisting of two soluble human TNFR (huTNFR) (p80) domains linked to the Fc portion of human immunoglobulin G1 (huTNFR:Fc). A single treatment of mice with huTNFR:Fc before or shortly after intraperitoneal injection with the ME7 scrapie strain significantly delayed the onset of disease in the CNS and reduced the early accumulation of disease-specific PrP in the spleen. These effects coincided with a temporary dedifferentiation of mature FDCs within 5 days of huTNFR:Fc treatment. We conclude that treatments that specifically inhibit the TNFR signaling pathway may present an opportunity for early intervention in peripherally transmitted TSEs.
Transcriptional Downregulation of ORF50/Rta by Methotrexate Inhibits the Switch of Kaposi's Sarcoma-Associated Herpesvirus/Human Herpesvirus 8 from Latency to Lytic Replication
Authors: Curreli Francesca , Cerimele Francesca , Muralidhar Sumitra , Rosenthal Leonard J. , Cesarman Ethel , Friedman-Kien Alvin E. , Flore Ornella
Published: July 2002

Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a cellular dihydrofolate reductase (DHFR) homologue. Methotrexate (MTX), a potent anti-inflammatory agent, inhibits cellular DHFR activity. We investigated the effect of noncytotoxic doses of MTX on latency and lytic KSHV replication in two KSHV-infected primary effusion lymphoma cell lines (BC-3 and BC-1) and in MTX-resistant BC-3 cells (MTX-R-BC-3 cells). Treatment with MTX completely prevented tetradecanoyl phorbol acetate-induced viral DNA replication and strongly decreased viral lytic transcript levels, even in MTX-resistant cells. However, the same treatment had no effect on transcription of cellular genes and KSHV latent genes. One of the lytic transcripts inhibited by MTX, ORF50/Rta (open reading frame), is an immediate-early gene encoding a replication-transcription activator required for expression of other viral lytic genes. Therefore, transcription of genes downstream of ORF50/Rta was inhibited, including those encoding the viral G-protein-coupled receptor (GPCR), viral interleukin-6, and K12/kaposin, which have been shown to be transforming in vitro and oncogenic in mice. Resistance to MTX has been documented in cultured cells and also in patients treated with this drug. However, MTX showed an inhibitory activity even in MTX-R-BC-3 cells. Two currently available antiherpesvirus drugs, cidofovir and foscarnet, had no effect on the transcription of these viral oncogenes and ORF50/Rta. MTX is the first example of a compound shown to downregulate the expression of ORF50/Rta and therefore prevent viral transforming gene transcription. Given that the expression of these genes may be important for tumor development, MTX could play a role in the future management of KSHV-associated malignancies.
Efficient Infection by a Recombinant Kaposi's Sarcoma-Associated Herpesvirus Cloned in a Bacterial Artificial Chromosome: Application for Genetic Analysis
Authors: Zhou Fu-Chun , Zhang Yan-Jin , Deng Jian-Hong , Wang Xin-Ping , Pan Hong-Yi , Hettler Evelyn , Gao Shou-Jiang
Published: July 2002

Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with Kaposi's sarcoma and several other malignancies. The lack of an efficient infection system has impeded the understanding of KSHV-related pathogenesis. A genetic approach was used to isolate infectious KSHV. Recombinant bacteria artificial chromosome (BAC) KSHV containing hygromycin resistance and green fluorescent protein (GFP) markers was generated by homologous recombination in KSHV-infected BCBL-1 cells. Recombinant KSHV genomes from cell clones that were resistant to hygromycin, expressed GFP, and produced infectious virions after induction with tetradecanoyl phorbol acetate (TPA) were rescued in
Escherichia coli
and reconstituted in 293 cells. Several 293 cell lines resulting from infection with recombinant virions induced from a full-length recombinant KSHV genome, named BAC36, were obtained. BAC36 virions established stable latent infection in 293 cells, harboring 1 to 2 copies of viral genome per cell and expressing viral latent proteins, with ≈0.5% of cells undergoing spontaneous lytic replication, which is reminiscent of KSHV infection in Kaposi's sarcoma tumors. TPA treatment induced BAC36-infected 293 cell lines into productive lytic replication, expressing lytic proteins and producing virions that efficiently infected normal 293 cells with a ≈50% primary infection rate. BAC36 virions were also infectious to HeLa and E6E7-immortalized human endothelial cells. Since BAC36 can be efficiently shuttled between bacteria and mammalian cells, it is useful for KSHV genetic analysis. The feasibility of the system was illustrated through the generation of a KSHV mutant with the vIRF gene deleted. This cellular model is useful for the investigation of KSHV infection and pathogenesis.
Novel Form of Fibronectin from Zebrafish Mediates Infectious Hematopoietic Necrosis Virus Infection
Authors: Liu Xiangyu , Collodi Paul
Published: July 2002

The presence of a novel form of zebrafish fibronectin (FN2) on the cell surface increased the cell’s susceptibility to infection by infectious hematopoietic necrosis virus (IHNV). Unlike other fibronectins, FN2 possesses a truncated structure and accumulates on the cell surface instead of in the extracellular matrix. Fish embryo cells expressing recombinant FN2 were more susceptible to IHNV infection, with a greater percentage of cells exhibiting cytopathic effect (CPE) compared to nontransfected control cells. Incubation of nontransfected cells with soluble recombinant FN2 increased IHNV infection, as measured by plaque assay. The number of plaques increased in correlation with the amount of protein added and the length of time that cells were incubated with the protein. Incubation of IHNV with soluble FN2 before addition to cells also increased infection. FN2 immobilized on the culture surface inhibited IHNV infection. The results indicate that FN2 present on the cell surface is able to mediate IHNV attachment and cell entry.
Characterization of Marek's Disease Virus Serotype 1 (MDV-1) Deletion Mutants That Lack UL46 to UL49 Genes: MDV-1 UL49, Encoding VP22, Is Indispensable for Virus Growth
Authors: Dorange Fabien , Tischer B. Karsten , Vautherot Jean-François , Osterrieder Nikolaus
Published: July 2002

Experiments were conducted to investigate the roles of Marek's disease virus serotype 1 (MDV-1) major tegument proteins VP11/12, VP13/14, VP16, and VP22 in viral growth in cultured cells. Based on a bacterial artificial chromosome clone of MDV-1 (BAC20), mutant viruses were constructed in which the MDV-1 homologs of UL46, UL47, UL48, or UL49 were deleted alone and in various combinations. It could be demonstrated that the UL46, UL47, and UL48 genes are dispensable for MDV-1 growth in chicken embryonic skin and quail muscle QM7 cells, although the generated virus mutants exhibited reduced plaque sizes in all cell types investigated. In contrast, a UL49-negative MDV-1 (20Δ49) and a UL48-UL49 (20Δ48-49) doubly negative mutant were not able to produce MDV-1-specific plaques on either cell type. It was confirmed that this growth restriction is dependent on the absence of VP22 expression, because growth of these mutant viruses could be partially restored on cells that were cotransfected with a UL49 expression plasmid. In addition, we were able to demonstrate that cell-to-cell spread of MDV-1 conferred by VP22 is dependent on the expression of amino acids 37 to 187 of MDV-1 VP22, because expression plasmids containing MDV-1 UL49 mutant genes with deletions of amino acids 1 to 37 or 188 to 250 were still able to restore partial growth of the 20Δ49 and 20Δ48-49 viruses. These results demonstrate for the first time that an alphaherpesvirus UL49-homologous gene is essential for virus growth in cell culture.
Interaction of Translation Initiation Factor eIF4B with the Poliovirus Internal Ribosome Entry Site
Authors: Ochs Kerstin , Saleh Lanja , Bassili Gergis , Sonntag Volker H. , Zeller Amandus , Niepmann Michael
Published: July 2002

Poliovirus translation is initiated at the internal ribosome entry site (IRES). Most likely involving the action of standard initiation factors, this highly structured
cis
element in the 5" noncoding region of the viral RNA guides the ribosome to an internal silent AUG. The actual start codon for viral protein synthesis further downstream is then reached by ribosomal scanning. In this study we show that two of the secondary structure elements of the poliovirus IRES, domain V and, to a minor extent, domain VI, are the determinants for binding of the eukaryotic initiation factor eIF4B. Several mutations in domain V which are known to greatly affect poliovirus growth also seriously impair the binding of eIF4B. The interaction of eIF4B with the IRES is not dependent on the presence of the polypyrimidine tract-binding protein, which also binds to the poliovirus IRES. In contrast to its weak interaction with cellular mRNAs, eIF4B remains tightly associated with the poliovirus IRES during the formation of complete 80S ribosomes. Binding of eIF4B to the IRES is energy dependent, and binding of the small ribosomal subunit to the IRES requires the previous energy-dependent association of initiation factors with the IRES. These results indicate that the interaction of eIF4B with the 3" region of the poliovirus IRES may be directly involved in translation initiation.
Degradation of STAT1 and STAT2 by the V Proteins of Simian Virus 5 and Human Parainfluenza Virus Type 2, Respectively: Consequences for Virus Replication in the Presence of Alpha/Beta and Gamma Interferons
Authors: Andrejeva J. , Young D. F. , Goodbourn S. , Randall R. E.
Published: July 2002

Human cell lines were isolated that express the V protein of either simian virus 5 (SV5) or human parainfluenza virus type 2 (hPIV2); the cell lines were termed 2f/SV5-V and 2f/PIV2-V, respectively. STAT1 was not detectable in 2f/SV5-V cells, and the cells failed to signal in response to either alpha/beta interferons (IFN-α and IFN-β, or IFN-α/β) or gamma interferon (IFN-γ). In contrast, STAT2 was absent from 2f/PIV2-V cells, and IFN-α/β but not IFN-γ signaling was blocked in these cells. Treatment of both 2f/SV5-V and 2f/PIV2-V cells with a proteasome inhibitor allowed the respective STAT levels to accumulate at rates similar to those seen in 2fTGH cells, indicating that the V proteins target the STATs for proteasomal degradation. Infection with SV5 can lead to a complete loss of both phosphorylated and nonphosphorylated forms of STAT1 by 6 h postinfection. Since the turnover of STAT1 in uninfected cells is longer than 24 h, we conclude that degradation of STAT1 is the main mechanism by which SV5 blocks interferon (IFN) signaling. Pretreatment of 2fTGH cells with IFN-α severely inhibited both SV5 and hPIV2 protein synthesis. However, and in marked contrast, pretreatment of 2fTGH cells with IFN-γ had little obvious effect on SV5 protein synthesis but did significantly reduce the replication of hPIV2. Pretreament with IFN-α or IFN-γ did not induce an antiviral state in 2f/SV5-V cells, indicating either that the induction of an antiviral state is completely dependent on STAT signaling or that the V protein interferes with other, STAT-independent cell signaling pathways that may be induced by IFNs. Even though SV5 blocked IFN signaling, the addition of exogenous IFN-α to the culture medium of 2fTGH cells 12 h after a low-multiplicity infection with SV5 significantly reduced the subsequent cell-to-cell spread of virus. The significance of the results in terms of the strategy that these viruses have evolved to circumvent the IFN response is discussed.
Separation of the DNA Replication, Segregation, and Transcriptional Activation Functions of Epstein-Barr Nuclear Antigen 1
Authors: Wu Hong , Kapoor Priya , Frappier Lori
Published: July 2002

In latent Epstein-Barr virus infection, the viral EBNA1 protein binds to specific sites in the viral origin of DNA replication,
oriP
, to activate the initiation of DNA replication, enhance the expression of other viral latency proteins, and partition the viral episomes during cell division. The DNA binding domain of EBNA1 is required for all three function, and a Gly-Arg-rich sequence between amino acids 325 and 376 is required for both the transcriptional activation and partitioning functions. We have used mutational analysis to identify additional EBNA1 sequences that contribute to EBNA1 functions. We show that EBNA1 amino acids 8 to 67 contribute to, but are not absolutely required for, EBNA1 replication, partitioning, and transcriptional activation functions. A Gly-Arg-rich sequence (amino acids 33 to 53) that is similar to that of amino acids 325 to 376 and lies within the 8-to-67 region was not responsible for the functional contributions of residues 8 to 67, since deletion of amino acids 34 to 52 alone did not affect EBNA1 functions. We also found that deletion of amino acids 61 to 83 eliminated the transcriptional activity of EBNA1 without affecting partitioning. This mutant also exhibited an increased replication efficiency that resulted in the maintenance of
oriP
plasmids at a copy number approximately fourfold higher than for wild-type EBNA1. The results indicate that the three EBNA1 functions have overlapping but different sequence requirements. Transcriptional activation requires residues 61 to 83 and 325 to 376 and is stimulated by residues 8 to 67; partitioning requires residues 325 to 376 and is stimulated by residues 8 to 67; and replication involves redundant contributions of both the 325-to-376 and 8-to-67 regions.
Repression of African Swine Fever Virus Polyprotein pp220-Encoding Gene Leads to the Assembly of Icosahedral Core-Less Particles
Authors: Andrés Germán , García-Escudero Ramón , Salas María L. , Rodríguez Javier M.
Published: July 2002

African swine fever virus (ASFV) polyprotein pp220, encoded by the CP2475L gene, is an N-myristoylated precursor polypeptide that, after proteolytic processing, gives rise to the major structural proteins p150, p37, p34, and p14. These proteins localize at the core shell, a matrix-like virus domain placed between the DNA-containing nucleoid and the inner envelope. In this study, we have examined the role of polyprotein pp220 in virus morphogenesis by means of an ASFV recombinant, v220i, containing an inducible copy of the CP2475L gene regulated by the
Escherichia coli
repressor-operator system. Under conditions that repress pp220 expression, the virus yield of v220i was about 2.6 log units lower than that of the parental virus or of the recombinant grown under permissive conditions. Electron microscopy revealed that pp220 repression leads to the assembly of icosahedral particles virtually devoid of the core structure. Analysis of recombinant v220i by immunoelectron microscopy, immunoblotting, and DNA hybridization showed that mutant particles essentially lack, besides the pp220-derived products, a number of major core proteins as well as the viral DNA. On the other hand, transient expression of the CP2475L gene in COS cells showed that polyprotein pp220 assembles into electron-dense membrane-bound coats, whereas a mutant nonmyristoylated version of pp220 does not associate with cellular membranes but forms large cytoplasmic aggregates. Together, these findings indicate that polyprotein pp220 is essential for the core assembly and suggest that its myristoyl moiety may function as a membrane-anchoring signal to bind the developing core shell to the inner viral envelope.
E1 Protein of Bovine Papillomavirus Type 1 Interferes with E2 Protein-Mediated Tethering of the Viral DNA to Mitotic Chromosomes
Authors: Voitenleitner Christian , Botchan Michael
Published: July 2002

Eukaryotic viruses can maintain latency in dividing cells as extrachromosomal plasmids. It is therefore of vital importance for viruses to ensure nuclear retention and proper segregation of their viral DNA. The bovine papillomavirus (BPV) E2 enhancer protein plays a key role in these processes by tethering the viral DNA to the host cell chromosomes. Viral genomes that harbor phosphorylation mutations in the E2 gene are transformation defective, and for these mutant genomes, neither the viral DNA nor the E2 protein is detected on mitotic chromosomes, while other key functions of E2 in transcription and replication were wild type. Moreover, secondary mutations in both the E2 and E1 proteins lead to suppression of the phosphorylation mutant phenotype and resulted in reattachment of the viral DNA and the E2 protein onto mitotic chromosomes, suggesting that E1 also plays a role in viral genome partitioning. The E1 protein was cytologically always excluded from mitotic chromatin, either as a suppressor allele or as the wild type. In the absence of other viral proteins, an E2 protein containing alanine substitutions for phosphorylation substrates in the hinge region (E2-A4) was detected as wild-type on mitotic chromosomes. However, when wild-type E1 protein levels were increased in cells expressing either the A4 mutant E2 proteins or wild-type E2, the E2-A4 protein was much more sensitive to chromosomal dislocation than was the wild-type protein. In contrast, suppressor alleles of E1 were not capable of such abrogation of E2 binding (A4 or wild-type) to chromosomes. These results suggest that wild-type E1 can be a negative regulator of the chromosomal attachment of E2.
Outcome of Simian-Human Immunodeficiency Virus Strain 89.6p Challenge following Vaccination of Rhesus Macaques with Human Immunodeficiency Virus Tat Protein
Authors: Silvera Peter , Richardson Max W. , Greenhouse Jack , Yalley-Ogunro Jake , Shaw Nigel , Mirchandani Jyotika , Khalili Kamel , Zagury Jean-Francois , Lewis Mark G. , Rappaport Jay
Published: July 2002

The regulatory proteins Nef, Rev, and Tat of human immunodeficiency virus type 1 (HIV-1) are attractive targets for vaccine development, since induction of effective immune responses targeting these early proteins may best control virus replication. Here we investigated whether vaccination with biologically active Tat or inactive Tat toxoid derived from HIV-1IIIBand simian-human immunodeficiency virus (SHIV) strain 89.6p would induce protective immunity in rhesus macaques. Vaccination induced high titers of anti-Tat immunoglobulin G in all immunized animals by week 7, but titers were somewhat lower in the 89.6p Tat group. Dominant B-cell epitopes mapped to the amino terminus, the basic domain, and the carboxy-terminal region. Tat-specific T-helper responses were detected in 50% of immunized animals. T-cell epitopes appeared to map within amino acids (aa) 1 to 24 and aa 37 to 66. In addition, Tat-specific gamma interferon responses were detected in CD4+and/or CD8+T lymphocytes in 11 of 16 immunized animals on the day of challenge. However, all animals became infected upon intravenous challenge with 30 50% minimal infective doses of SHIV 89.6p, and there were no significant differences in viral loads or CD4+T-cell counts between immunized and control animals. Thus, vaccination with HIV-1IIIBor SHIV 89.6p Tat or with Tat toxoid preparations failed to confer protection against SHIV 89.6p infection despite robust Tat-specific humoral and cellular immune responses in some animals. Given its apparent immunogenicity, Tat may be more effective as a component of a cocktail vaccine in combination with other regulatory and/or structural proteins of HIV-1.
Application of Methylphosphonic Acid Monoalkyl Esters to the Extraction of Some Metals
Authors: Navrátil Oldřich , Sládek Petr
Published: July 2002

The distribution between aqueous nitric acid and benzene was examined for methylphosphonic acid monoalkyl esters where the alkyl was a methyl, propyl, butyl, isobutyl, pentyl, 2-methylbutyl, cyclohexyl or 1,2,2-trimethylpropyl group. The extraction of complexes of these reagents with Ag, Co, Zn, Sc, Yb, Eu and Hf was also investigated. The esters do not dimerize in benzene. The pKa and KD values of the reagents and the corresponding extraction constants were determined. Derivatives containing five and more carbon atoms in the alkyl groups were found practically applicable to the extraction.
Bioengineering Analysis of Incomplete Data from Large-Scale Anaerobic Bioreactor for Waste Water Treatment by Fuzzy Expert System
Authors: Huong Vu Lan , Votruba Jaroslav , Stuchl Ivan
Published: July 2002

The knowledge-based model of an anaerobic waste water treatment plant was designed when the incompleteness of industrial records excluded the application of mass balances. New two step information technology that permits to excerpt the knowledge from industrial data as a set of heuristic rules is described. In the first step, the real numbers are converted to the set of fuzzy ones and arranged as a knowledge data base of an expert system. Secondly, the fuzzy expert system SENECA was used for fuzzy modelling of the process. Three examples of bioengineering analysis are presented. First, the average efficiency of biological degradation was determined. Second, the effect of pH in the input stream was evaluated. Third, the process dynamics and time required to reach the maximum activity of microbial population were estimated. It was possible to detect and evaluate the decrease of the biodegradation efficiency caused by unexpected leakage of xenobiotics.
Acceptor Numbers for Binary Mixtures of Dipolar Aprotic Solvents with Methanol
Authors: Podsiadla Malgorzata , Rzeszotarska Jadwiga , Kalinowski Marek K.
Published: July 2002

Using bis(cyano)bis(9,10-phenanthroline)iron(II) as solvatochromic indicator, the acceptor numbers, AN, were determined for binary mixtures of benzene, benzonitrile, acetonitrile, acetone, N,N-dimethylformamide, dimethyl sulfoxide and hexamethylphosphoric triamide with methanol. Deviations from linearity of the plots of AN values against the molar fraction of the components were interpreted both in terms of changes in solvent liquid structure and in cathegories of preferential solvation.
The Role of Hydrogen Peroxide in Dioxygen Induced Hydroxylation of Salicylic Acid
Authors: Lang Kamil , Wagnerová Dana M. , Brodilová Jiřina
Published: July 2002

The photochemically initiated oxidation of salicylic acid by molecular oxygen in the presence of [Fe(C2O4)3]3- leads to a mixture of 2,3- and 2,5-dihydroxybenzoic acids. Iron(II) generated by the photoreduction is reoxidized by dioxygen. Hydrogen peroxide formed in this reaction takes part in the Fenton reaction in the presence of Fe(II). Experiments with OH. radical scavengers document the role of the radicals in the photochemical and thermal hydroxylation of salicylic acid.
Kinetics of the Reaction Between Solid Active Sodium Carbonate of the Second Generation and the Gaseous Sulfur Dioxide
Authors: Stejskalová Květoslava , Bastl Zdeněk , Mocek Karel
Published: July 2002

The results are presented of a detailed experimental kinetic study of the heterogeneous reaction between gaseous sulfur dioxide and the solid active sodium carbonate of the second generation which has been prepared by a controlled thermal dehydration of higher hydrates of the sodium carbonate. The measurements have been carried out in an all-glass kinetic apparatus with an integral fixed-bed reactor. The reaction course was studied in dependence on genesis and nature of the active sodium carbonate, on temperature and on composition of the gas phase. The reaction rate is significantly affected by presence of the water vapour which acts as a gaseous catalyst. Experimental data have been treated by using the model proposed by Erdos (Collect. Czech. Chem. Commun. 32, 1653 (1967), and the values of the effective reaction rate constants have been computed. The kinetic study of active sodium carbonate of the second generation has been completed by the determination of microstructure (SEM) of solid samples before and after reaction, and by determining the solid surface composition before and after reaction by means of electronic spectra (ESCA).
Infrared Spectroelectrochemical Investigation of Carbon Dioxide Reduction Mediated by the Anion [Ru(SnPh3)(Co)2(iPr-DAB)]- (iPr-DAB = N,N'-Diisopropyl-1,4-diaza-1,3-butadiene)
Authors: Hartl František , Aarnts Maxim P. , Peelen Karin
Published: July 2002

Carbon dioxide was found to react slowly with the coordinatively unsaturated anion [Ru(SnPh3)(CO)2(iPr-DAB)]- electrogenerated in an IR OTTLE cell via bielectronic reduction of [Ru(Cl)(SnPh3)(CO)2(iPr-DAB)]. This reaction produced free CO, CO32-, O2CH- and other two unidentified carboxylato species. The overall process is not catalytic in nature since the anion cannot be recovered after the attack of CO2 due to its conversion into a stable complex tentatively assigned as {Ru0(CO)2(iPr-DAB)}2. Although limited, the inherent reactivity of [Ru(SnPh3)(CO)2(iPr-DAB)]- towards CO2 demonstrated that the strong π-bonding within the (Sn)Ru(iPr-DAB) metallacycle, stabilizing the five-coordinate structure, is slightly less delocalized in comparison with the closely related, but totally inert anions [Mn(CO)3(α-diimine)]- (α-diimine = bpy, iPr-DAB).
Titanium-Catalyzed [4+2] and [6+2] Cycloadditions of 1,4-Bis(trimethylsilyl)buta-1,3-diyne
Authors: Kaagman Jan-Willem F. , Rep Marco , Horáček Michal , Sedmera Petr , Čejka Jiří , Varga Vojtech , Mach Karel
Published: July 2002

The (C2H5)2AlCl/TiCl4 catalyst induces the [4+2] cycloaddition of butadiene or the [6+2] cycloaddition of 1,3,5-cycloheptatriene (CHT) to individual acetylenic moieties of 1,4-bis(trimethylsilyl)buta-1,3-diyne (BSD). Heating of the 2:1 butadiene adduct, bis(2-trimethylsilylcyclohexa-1,4-dien-1-yl), to 250 °C yields 2,2'-bis(trimethylsilyl)biphenyl. The 1:1 adduct of BSD with CHT, 7-trimethylsilyl-8-trimethylsilylethynylbicyclo[4.2.1]nona-2,4-diene, is obtained as virtually the only product if the initial molar ratio CHT : BD equal to 1.86 is used.
Ceramic Cross-Flow Microfiltration in the Presence of Inserts
Authors: Mikulášek Petr , Cakl Jiří , Petráš Zbyněk
Published: July 2002

The influence of inserts with various configurations on permeate flux through a tubular ceramic microfiltration membrane was studied. The commercial metal-working oil emulsion was used in the experiments. A more extensive study of the effect of shear rate on permeate flux was made by comparing the steady-state flux of the empty tube system and the system with inserts. The cross-flow microfiltration with inserts was found to be simple and effective. Analysing experimental results, it was concluded that the introduction of inserts, irrespective of their configurations, resulted in a significant increase in permeate flux compared with results obtained in the empty tube system. The interruption of formation of a boundary layer by the inserts is attributed to mixing and migration of rejected particles from the membrane surface.
The Preparation of Some 13α-Androstanes
Authors: Hanson James R. , Hunter A. Christy , Roquier Sandrine
Published: July 2002

The preparation of 17a-oxa-5α,13α-androstane-3,17-dione, 5α,13α-androstane-3,7,17-trione, 4-chloro- and 4-hydroxy-13α-androst-4-ene-3,17-dione and 13α-androst-4-ene-3,6,17-trione is described.
Conformation of Systemin, a Polypeptide Activator of Proteinase Inhibitor Synthesis in Plants
Authors: Mucha Piotr , Szyk Agnieszka , Rekowski Piotr , Kupryszewski Gotfryd , Slósarek Genowefa , Barciszewski Jan
Published: July 2002

An 18-amino acid polypeptide systemin was synthesized by the solid-phase method and its conformation was studied by circular dichroism spectroscopy. The peptide in solution is a mixture of random coil structure with β-sheet and β-turn motifs as has been previously suggested with NMR spectra. Free zone capillary electrophoresis analysis proved purity and chemical stability of systemin at different pH.
On the Reliability of the Structures of Lead(II) Hydroxo Complexes Obtained by MNDO Method
Authors: Breza Martin , Manová Alena
Published: July 2002

Optimum geometry of tetrahedro-Pb4[(μ3-OH)4]4+ cluster obtained by the semiempirical MNDO method corresponds to Td symmetry. The calculated Pb-Pb (3.70 · 10-10 m) and Pb-O (2.33 · 10-10 m) distances are in reasonable agreement with experimental X-ray data. Additional H2O inclusion makes the agreement worse.
Kinetics of Collision Processes in Dilute Noble Gases
Authors: Kalus René
Published: July 2002

Kinetics of collision processes is analyzed for dilute noble gases within a linear approximation. Dilute gas is treated as a chemically reacting mixture of dimers and monomers. Two elementary reaction models are analyzed employing theoretical rate constants calculated recently from quasiclassical trajectories. Stability of stationary states and relaxation of small concentration perturbations are treated in terms of linearized kinetic equations. The results obtained are generalized for heavier noble gases (neon to xenon). Helium is, because of quantum nature, analyzed separately.
Flow Injection Determination of Acetylsalicylic Acid in Pharmaceutical Preparations with an Amperometric Detector
Authors: Garrido Jorge M. P. J. , Lima José L. F. C. , Matos Cristina D.
Published: July 2002

This paper reports on an automated method based on a flow injection analysis single stream system with amperometric detection for the determination of acetylsalicylic acid in pharmaceutical preparations. The amperometric detection is based on the measurement at 0.8 V vs Ag/AgCl of the current generated when the acetylsalicylic acid hydrolysis product, salicylic acid, is oxidised at a glassy carbon electrode. The current produced is directly related to the concentration of the electroactive specie and the salicylic acid content is proportional to the level of acetylsalicylic acid present in the sample, thus it is possible to determine the concentration of acetylsalicylic acid electrochemically. This system allows a sampling rate of 150 samples per hour without requiring any pre-treatment, apart from dissolving them in a NaOH/KCl buffer, pH 13.0. The results obtained were compared with those obtained using reference methods and demonstrated excellent agreement with relative deviation always lower than 2%.
Enhanced Long-Range Si···N Interactions in Organosilicon Cations. A Theoretical Study
Authors: Havlas Zdeněk , Bock Hans
Published: July 2002

For the model organosilicon cation H3N···SiH3+, potential curves have been calculated by density functional theory at the B3LYP level, by both MP2 and MP4 perturbation procedures and by a Coupled Cluster approach. Relative to the analogous potential curve for the uncharged adduct, H3N···SiH4, a considerable increase of the long-range Si···N interaction accompanied by bond shortening is predicted. For chemical comparison, the structure of the "double R2N-twister" dication salt, [C6H4(CH2NR2)2-Si-(R2NCH2)2C6H4]++Cl2-, reported in the literature as a non-crystalline solid, was optimized by DFT calculations and a minimum for the hexacoordinated organosilicon center with each two Si···N bonds of different lengths was located. To test the reliability of the quantum chemical procedure, in addition the analogous and structurally characterized dication salt, [(3-picoline)4SiH2]++[Cl-···(HCCl3)2]2, which contains a hexacoordinated Si center with 4 equivalent Si···N interactions, has been selected to reproduce its structure by DFT optimization. Both hexacoordinated, tetra-N-surrounded Si dications, substantiate the increase of long-range Si···N interactions as predicted by the potential curves for the model adduct H3N···SiH3+ based on highly correlated calculations.
Lung function measurements in young children with spinal muscle atrophy; a cross sectional survey on the effect of position and bracing
Authors: Tangsrud S E , Carlsen K C Lødrup , Lund-Petersen I , Carlsen K-H
Published: July 2002

BACKGROUND

Spinal muscular atrophy (SMA) affects respiratory muscles, which in addition to progressive scoliosis leads to respiratory impairment. Children with developing scoliosis are usually treated with spinal bracing to delay the progress.

AIMS

To assess the impact of body position and application of spinal bracing on lung function during tidal breathing in children with SMA.

METHODS

Lung function was determined by tidal flow volume loops and passive respiratory mechanics (single breath occlusion technique) in all eight children in southern Norway with SMA type I and II, in both the sitting and supine position. Additional measurements were performed with and without bracing in five children. Muscle strength was assessed by the Brooks scale.

RESULTS

Tidal expiratory volume (VE) and compliance of the respiratory system (CRS) tended to be higher in the sitting compared to the supine position, but this was not statistically significant. However, applying bracing in the sitting position significantly reduced VE. The highest values of CRS and VEwere found in the sitting position without bracing.

CONCLUSION

Impairment of tidal respiration must be considered when applying spinal bracing in very young children developing scoliosis with SMA.
Diagnostic assessment of haemorrhagic rash and fever
Authors: Nielsen H E , Andersen E A , Andersen J , Böttiger B , Christiansen K M , Daugbjerg P , Larsen S O , Lind I , Nir M , Olofsson K
Published: July 2002

AIMS

To establish criteria for early distinction between meningococcal disease and other conditions with similar clinical features, and to identify other causes for haemorrhagic rashes accompanied by fever.

METHODS

In a prospective study, 264 infants and children hospitalised with fever and skin haemorrhages were studied.

RESULTS

We identified an aetiological agent in 28%: 15% had meningococcal disease, 2% another invasive bacterial infection, 7% enterovirus infection, and 4% adenovirus infection. Five clinical variables distinguished between meningococcal disease and other conditions on admission: (1) skin haemorrhages of characteristic appearance; (2) universal distribution of skin haemorrhages; (3) maximum diameter of one or more skin haemorrhages greater than 2 mm; (4) poor general condition (using a standardised observation scheme); and (5) nuchal rigidity. If any two or more of these clinical variables were present, the probability of identifying a patient with meningococcal disease was 97% and the false positive rate was only 12%. This diagnostic algorithm did not identify children in whom septicaemia was caused by other bacterial species.
Sport related proximal femoral fractures: a retrospective review of 31 cases treated in an eight year period
Authors: Habernek Hans , Schmid Lothar , Frauenschuh Eva
Published: July 2002

In an eight year period, 31 patients with proximal femoral fractures resulting from sports accidents were treated by implantation of either a Gamma nail or a dynamic hip screw. Return to work or sports and the time to bone healing did not differ very much between the treatments. Gamma nailing was clearly the best with regard to stability and time to full mobilisation (4.5 days), but required 39 minutes to perform compared with insertion of a dynamic hip screw (27 minutes). The incidence of complications and malalignments did not differ very much between the two, although, when Gamma nailing was first used in the authors' clinic, more intraoperative complications occurred than with the dynamic hip screw. Stable pertrochanteric fractures may be treated with a dynamic hip screw. Unstable pertrochanteric or subtrochanteric fractures are treated with a Gamma nail at the authors' institution.
Overexpression of the CD155 gene in human colorectal carcinoma
Authors: Masson D , Jarry A , Baury B , Blanchardie P , Laboisse C , Lustenberger P , Denis M G
Published: July 2002

BACKGROUND AND AIMS

The Tage4 gene (tumour associated glycoprotein E4) is overexpressed in rat colon tumours and Min mouse intestinal adenomas. The rat Tage4 protein has approximately 40% identity with human CD155, a member of the immunoglobulin superfamily coding for a transmembrane protein capable of serving as an entry receptor for poliovirus, porcine pseudorabies virus, and bovine herpesvirus 1. Analysis of the ratTage4 gene has revealed structural and functional similarities with the human CD155gene. We therefore investigated expression of theCD155 gene in human colorectal carcinomas.

METHODS

Overall CD155 expression was assessed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical analysis using tissue specimens from patients with colorectal adenomas and adenocarcinomas. We also used a qualitative RT-PCR assay to determine relative expression of different splicing variants in each sample.

RESULTS

mRNA levels of CD155 were increased in six of six colorectal cancer tissues compared with the tumour free colon mucosa. Immunohistochemical analysis revealed an increased level of CD155 protein in 12 of 12 samples. The qualitative RT-PCR assay revealed that relative expression of the different CD155 variant transcripts was similar in the different normal and cancer samples tested, indicating that this overexpression is not associated with a particular mRNA variant generated by alternative splicing of the CD155 gene.

CONCLUSION

We have shown for the first time that the CD155 gene is overexpressed in colorectal carcinoma and that this overexpression begins at an early stage in tumorigenesis and continues to late stages.
British community pharmacists' views of physician-assisted suicide (PAS)
Authors: Hanlon Timothy R G , Weiss Marjorie C , Rees Judith
Published: July 2002

Objectives— To explore British community pharmacists' views on PAS , including professional responsibility, personal beliefs, changes in law and ethical guidance.

Design— Postal questionnaire

Setting— Great Britain

Subjects— A random sample of 320 registered full-time community pharmacists

Results— The survey yielded a response rate of 56%. The results showed that 70% of pharmacists agreed that it was a patient's right to choose to die, with 57% and 45% agreeing that it was the patient's right to involve his/her doctor in the process and to use prescription medicines, respectively. Forty-nine per cent said that they would knowingly dispense a prescription for use in PAS were it to be legalised and 54% believed it correct to refuse to dispense such a prescription. Although 53% believed it to be their right to know when they were being involved in PAS, 28% did not. Most pharmacists (90%) said that they would wish to see the inclusion of a practice protocol for PAS in the code of ethics of the Royal Pharmaceutical Society of Great Britain (CE-RPSGB) in the event of a change in the law on PAS. In addition, 89% would wish to see PAS included in the Conscience Clause of the CE-RPSGB. Males were found to be significantly less likely to favour PAS than females (p<0.05), as were those declaring an ethnic/religious background of consideration when dealing with ethical issues in practice compared with their counterparts (p<0.00005).

Conclusion— Pharmacists view their professional responsibility in PAS to be more obligatory than a physician's, in having to provide the means for PAS. It is worrying that a proportion of the respondents prefer to remain in ignorance of the true purpose of a prescription for PAS; a finding at odds with current developments within the pharmaceutical profession. A practice protocol for PAS and an extension of the conscience clause should be considered in the event of PAS becoming legal. Such measures would allow the efficient provision of the pharmaceutical service whilst at the same respecting the personal beliefs of those who object to cooperating in the ending of a life.
Reflections on a new medical cosmology
Authors: Greaves D
Published: July 2002

Since the nineteenth century the theory and practice of mainstream Western medicine has been grounded in the biomedical model. In the later years of the twentieth century, however, it has faced a range of serious problems, which when viewed collectively, remain unresolved despite a variety of responses. The question we now face is whether these problems can be dealt with by modifying and extending the principles underlying the biomedical model, or whether a more radical solution is required. Recent critiques of Western medicine have focused mainly on the biopsychosocial model in relation to the former approach, but it will be contended that this cannot deal adequately with the challenges that medicine currently faces, because although it addresses both the scientific and humanistic aspects of medicine it fails to harmonise them. I shall therefore argue for the necessity of a more radical approach, and suggest that what is required to accomplish this is the development of a new medical cosmology, rooted in an older and more global framework. Such a fundamental change would inevitably involve a long term process which it is not yet possible to fully comprehend let alone specify in detail. Some of the necessary features of such a new medical cosmology can, however, already be distinguished and the outline of these is described.
`He found me very well; for me, I was still feeling sick': The strange worlds of physicians and patients in the 18th and 21st centuries
Authors: Louis-Courvoisier M , Mauron A
Published: July 2002

It is commonplace today to deplore the dissatisfaction of patients with the physician-patient relationship. Furthermore, historical investigation shows that this problem is not really new. We investigated an important source of patients' views in the 18th century, namely the letters of patients received by the famous Swiss physician, Samuel Tissot, and noted remarkably similar feelings of frustration. Yet the medical paradigms of today and of Tissot's times are considerably different. We propose that the persisting problems in the physician-patient relationship are due to a basic dissonance between the patient's ordinary modes of perception and the systematic way of perceiving reality characteristic of the physician. In addition, they reflect the unavoidable chasm between the ultimately private and singular nature of the illness experience, and the general and anonymous stance of medical theory. This chasm is therefore a permanent feature of the patient-physician relationship, predating the advent of scientific medicine, even if the latter reinforced it. In line with the current medical humanities movement, we believe that the engagement of physicians and medical students with literature and the arts helps them explore, and to some extent overcome, the existential divide between the patient's experiential self knowledge and the systematic, impersonal knowledge that plays a central role in medicine. We suggest a few examples of contemporary fiction that may be relevant and useful in this respect.
Vibration perception thresholds in workers with long term exposure to lead
Authors: Chuang Hung-Yi , Schwartz Joel , Tsai Song-Yen , Lee Mei-Ling Ting , Wang Jung-Der , Hu Howard
Published: July 2002

OBJECTIVES

To evaluate the impact of long term occupational exposure to lead on function of the peripheral nervous system as reflected by vibration perception threshold (VPT), measured with a portable vibrameter.

METHODS

217 Workers in a lead battery factory were required to have an annual blood lead measurement during each of the 5 years preceding this study. All were invited to take the VPT test. A total of 206 workers were studied. The associations were analysed between VPTs and current blood lead concentration, mean concentration of blood lead over the past 5 years, maximum blood lead concentration during the past 5 years, index of cumulative blood lead (ICL), time weighted index of cumulative blood lead (TWICL), and percentage of lifespan spent at work in the plant, as well as the other potential confounders. Ordinary multiple regressions, generalised additive models, and hockey stick regression analyses were used to explore the potential existence of a threshold effect of blood lead variables on VPT.

RESULTS

VPT at a frequency of 220 Hz ranged from 6 to 100 (10-2g, or 0.098 m/s2) with a mean (SD) of 19.8 (14.2) for the feet and from 4 to 43 with a mean (SD) of 10.2 (6.1) for the hands. The five variables of exposure to lead were all significantly correlated with VPT of the feet but not the hands. In multiple linear regression analyses, the mean of the blood lead concentrations and the TWICL were significantly associated with VPT of the feet. The relation between VPT of the feet and mean blood lead was shown to be a J shaped curve with a generalised additive model and local smoothing technique. In the hockey stick regression, evidence was found of a threshold effect at a mean blood lead concentration of 31 μg/dl. Above this threshold it was estimated that each increase of 1 μg/dl mean blood lead over 5 years would increase VPT of the feet by 0.29 (10-2g) or 0.028 m/s2(at a frequency of 220 Hz) with other potential confounders held constant.

CONCLUSION

This study suggests that measurement of vibration sensory threshold is a relatively effective tool for detecting lead neuropathy in field studies, and that lead might cause sensory neuropathy with an effect threshold corresponding to a 5 year mean blood lead concentration of 31 μg/dl.