bluuebunny/crossref_metadata_2025 huggingface dataset:
Feline Immunodeficiency Virus-Infected Cat Sera Associated with the Development of Broad Neutralization Resistance In Vivo Drive Similar Reversions In Vitro
Authors: Giannecchini Simone , Matteucci Donatella , Ferrari Aldo , Pistello Mauro , Bendinelli Mauro
Published: July 2002

We previously reported that, upon reinoculation into cats, a neutralization-sensitive, tissue culture-adapted strain of feline immunodeficiency virus constantly reverted to the broad neutralization resistance typical of primary virus isolates and identified residue 481 in the V4 region of the surface glycoprotein as a key determinant of the reversion. Here, we found that well-characterized immune sera, obtained from cats in which such reversion had occurred, selected in tissue culture in favor of virus variants that also had a neutralization-resistant phenotype and had amino acid 481 changed, thus indicating that the host's humoral immune response is capable of driving the reversion in the absence of other intervening factors. In contrast, a second group of immune sera, elicited by a virus variant that had already reverted to neutralization resistance in independent cats, induced the emergence of escape mutants lacking broad neutralization resistance and neutralized fewer virus variants. It is proposed that the viral variants used to produce the two sets of sera may have generated different antibody repertoires.
Chimeric Bovine Respiratory Syncytial Virus with Attachment and Fusion Glycoproteins Replaced by Bovine Parainfluenza Virus Type 3 Hemagglutinin-Neuraminidase and Fusion Proteins
Authors: Stope Matthias B. , Karger Axel , Schmidt Ulrike , Buchholz Ursula J.
Published: July 2002

Chimeric bovine respiratory syncytial viruses (BRSV) expressing glycoproteins of bovine parainfluenza virus type 3 (BPIV-3) instead of BRSV glycoproteins were generated from cDNA. In the BRSV antigenome cDNA, the open reading frames of the major BRSV glycoproteins, attachment protein G and fusion protein F, were replaced individually or together by those of the BPIV-3 hemagglutinin-neuraminidase (HN) and/or fusion (F) glycoproteins. Recombinant virus could not be recovered from cDNA when the BRSV F open reading frame was replaced by the BPIV-3 F open reading frame. However, cDNA recovery of the chimeric virus rBRSV-HNF, with both glycoproteins replaced simultaneously, and of the chimeric virus rBRSV-HN, with the BRSV G protein replaced by BPIV-3 HN, was successful. The replication rates of both chimeras were similar to that of standard rBRSV. Moreover, rBRSV-HNF was neutralized by antibodies specific for BPIV-3, but not by antibodies specific to BRSV, demonstrating that the BRSV glycoproteins can be functionally replaced by BPIV-3 glycoproteins. In contrast, rBRSV-HN was neutralized by BRSV-specific antisera, but not by BPIV-3 specific sera, showing that infection of rBRSV-HN is mediated by BRSV F. Hemadsorption of cells infected with rBRSV-HNF and rBRSV-HN proved that BPIV-3 HN protein expressed by rBRSV is functional. Colocalization of the BPIV-3 glycoproteins with BRSV M protein was demonstrated by confocal laser scan microscopy. Moreover, protein analysis revealed that the BPIV-3 glycoproteins were present in chimeric virions. Taken together, these data indicate that the heterologous glycoproteins were not only expressed but were incorporated into the envelope of recombinant BRSV. Thus, the envelope glycoproteins derived from a member of the
Respirovirus
genus can together functionally replace their homologs in a
Pneumovirus
background.
Induction of TAK (Cyclin T1/P-TEFb) in Purified Resting CD4
+
T Lymphocytes by Combination of Cytokines
Authors: Ghose Romi , Liou Li-Ying , Herrmann Christine H. , Rice Andrew P.
Published: July 2002

Combinations of cytokines are known to reactivate transcription and replication of latent human immunodeficiency virus type 1 (HIV-1) proviruses in resting CD4
+
T lymphocytes isolated from infected individuals. Transcription of the HIV-1 provirus by RNA polymerase II is strongly stimulated by the viral Tat protein. Tat function is mediated by a cellular protein kinase known as TAK (cyclin T1/P-TEFb) that is composed of Cdk9 and cyclin T1. We have found that treatment of peripheral blood lymphocytes and purified resting CD4
+
T lymphocytes with the combination of interleukin-2 (IL-2), IL-6, and tumor necrosis factor alpha resulted in an increase in Cdk9 and cyclin T1 protein levels and an increase in TAK enzymatic activity. The cytokine induction of TAK in resting CD4
+
T lymphocytes did not appear to require proliferation of lymphocytes. These results suggest that induction of TAK by cytokines secreted in the microenvironment of lymphoid tissue may be involved in the reactivation of HIV-1 in CD4
+
T lymphocytes harboring a latent provirus.
Orientation of a Novel DNA Binding Site Affects Human Papillomavirus-Mediated Transcription and Replication
Authors: Newhouse Christopher D. , Silverstein Saul J.
Published: July 2002

A consensus binding site for the human papillomavirus (HPV) E2 protein was determined from an unbiased set of degenerate oligonucleotides using cyclic amplification and selection of targets (CASTing). Detectable DNA-protein complexes were formed after six to nine cycles of CASTing. A population of selected binding sites was cloned, and a consensus was determined by statistical analysis of the DNA sequences of individual isolates. Starting from a pool with 20 random bases, a consensus binding site of ACAC-N
5
-GGT was derived. CASTing and electrophoretic mobility shift analyses demonstrate that human but not bovine papillomavirus E2 proteins recognize this sequence. The presence of this sequence in papillomavirus genomes suggests a role for its function. We demonstrate that this site functionally substitutes for the canonical E2 binding site (ACCG-N
4
-CGGT) in both transient-transcription and DNA replication assays. This sequence, in most instances, is interchangeable with the resident E2 binding sites in the context of the HPV type 16 long control region. Where the novel sequence does not support E2-mediated effects on gene expression or DNA replication, we demonstrate that changing the orientation of the novel sequence restores this effect.
Transcriptional Analysis of Marek's Disease Virus Glycoprotein D, I, and E Genes: gD Expression Is Undetectable in Cell Culture
Authors: Tan Xinyu , Brunovskis Peter , Velicer Leland F.
Published: July 2002

The various alphaherpesviruses, including Marek's disease virus (MDV), have both common and unique features of gene content and expression. The entire MDV U
s
region has been sequenced in our laboratory (P. Brunovskis and L. F. Velicar, Virology 206:324–338, 1995). Genes encoding the MDV glycoprotein D (gD), glycoprotein I (gI), and glycoprotein E (gE) homologs have been found in this region, although no gG homolog was found. In this work, transcription of the tandem MDV gD, gI, and gE genes was studied and found to have both unique characteristics and also features in common with other alphaherpesviruses. MDV gD could not be immunoprecipitated from MDV GA-infected duck embryo fibroblast cells by antisera reactive to its TrpE fusion proteins, while gI and gE could be. When the gD gene was subjected to in vitro-coupled transcription-translation, the precursor polypeptide was produced and could be immunoprecipitated by anti-gD. Northern blot, reverse transcriptase PCR, and RNase protection analyses have shown that (i) no mRNA initiating directly from the gD gene could be detected; (ii) a large but low-abundance 7.5-kb transcript spanning five genes, including the one encoding gD, was seen on longer exposure; and (iii) transcription of the gI and gE genes formed an abundant bicistronic 3.5-kb mRNA, as well as an abundant 2.0-kb gE-specific mRNA. Therefore, the MDV gD gene expression is down-regulated at the transcription level in MDV-infected cell culture, which may be related to the cell-associated nature of MDV in fibroblast cells. Compared to the highly gD-dependent herpes simplex virus and the other extreme of the varicella-zoster virus which lacks the gD gene, MDV is an intermediate type of alphaherpesvirus.
RNA Replication from the Simian Virus 5 Antigenomic Promoter Requires Three Sequence-Dependent Elements Separated by Sequence-Independent Spacer Regions
Authors: Keller Michael A. , Murphy Susan K. , Parks Griffith D.
Published: July 2002

We have previously shown for the paramyxovirus simian virus 5 (SV5) that a functional promoter for RNA replication requires proper spacing between two discontinuous elements: a 19-base segment at the 3′ terminus (conserved region I [CRI]) and an 18-base internal region (CRII) that is contained within the coding region of the L protein gene. In the work described here, we have used a reverse-genetics system to determine if the 53-base segment between CRI and CRII contains additional sequence-specific signals required for optimal replication or if this segment functions solely as a sequence-independent spacer region. A series of copyback defective interfering minigenome analogs were constructed to contain substitutions of nonviral sequences in place of bases 21 to 72 of the antigenomic promoter, and the relative level of RNA replication was measured by Northern blot analysis. The results from our mutational analysis indicate that in addition to CRI and CRII, optimal replication from the SV5 antigenomic promoter requires a third sequence-dependent element located 51 to 66 bases from the 3′ end of the RNA. Minigenome RNA replication was not affected by changes in the either the position of this element in relation to CRI and CRII or the predicted hexamer phase of NP encapsidation. Thus, optimal RNA replication from the SV5 antigenomic promoter requires three sequence-dependent elements, CRI, CRII and bases 51 to 66.
Construction and In Vitro Properties of a Series of Attenuated Simian Immunodeficiency Viruses with All Accessory Genes Deleted
Authors: Guan Yongjun , Whitney James B. , Detorio Mervi , Wainberg Mark A.
Published: July 2002

We have generated simplified simian immunodeficiency virus (SIV) constructs lacking the
nef
,
vpr
,
vpx
,
vif
,
tat
, and
rev
genes (Δ6 viruses). To accomplish this, we began with an infectious molecular clone of SIV, i.e. SIVmac239, and replaced the deleted segments with three alternate elements: (i) a constitutive transport element (CTE) derived from simian retrovirus type 1 to replace the Rev/Rev-responsive element (RRE) posttranscriptional regulation system, (ii) a chimeric SIV long terminal repeat (LTR) containing a cytomegalovirus (CMV) promoter to augment transcription and virus production, and (iii) an internal ribosome entry site (IRES) upstream of the
env
gene to ensure expression of envelope proteins. This simplified construct (Δ6CCI) efficiently produced all viral structural proteins, and mature virions possessed morphology typical of wild-type virus. It was also observed that deletion of the six accessory genes dramatically affected both the specificity and efficiency of packaging of SIV genomic RNA into virions. However, the presence of both the CTE and the chimeric CMV promoter increased the specificity of viral genomic RNA packaging, while the presence of the IRES augmented packaging efficiency. The Δ6CCI virus was extremely attenuated in replication capacity yet retained infectiousness for CEMx174 and MT4 cells. We also generated constructs that retained either the
rev
gene or both the
rev
and
vif
genes and showed that these viruses, when complemented by the CMV promoter, i.e., Δ5-CMV and Δ4-CMV, were able to replicate in MT4 cells with moderate and high-level efficiency, respectively. Long-term culture of each of these constructs over 6 months revealed no potential for reversion. We hope to shortly evaluate these simplified constructs in rhesus macaques to determine their long-term safety as well as ability to induce protective immune responsiveness as proviral DNA vaccines.
Mutational Analysis of the v-Rel Dimerization Interface Reveals a Critical Role for v-Rel Homodimers in Transformation
Authors: Liss Andrew S. , Bose, Henry R.
Published: July 2002

The v-
rel
oncogene encoded by reticuloendotheliosis virus strain T is the acutely transforming member of the Rel/NF-κB family of transcription factors. In v-Rel-transformed cells, v-Rel exists as homodimers or heterodimers with the endogenous Rel/NF-κB proteins c-Rel, NF-κB1, NF-κB2, and RelA. To examine the contribution of these complexes to v-Rel-mediated transformation, mutations were introduced into the dimerization interface of v-Rel to generate v-Rel mutants with selective dimerization properties. Nine mutants are described in this study that are defective in homodimer and/or heterodimer formation with specific Rel/NF-κB family members. Viruses expressing mutants that failed to homodimerize but were able to form heterodimeric complexes were unable to transform splenic lymphocytes in vitro, indicating that the dimerization of v-Rel with endogenously expressed Rel/NF-κB proteins is not in itself sufficient for transformation. In addition, two partially transforming mutants were identified that exhibited an impaired ability to form homodimers. Sequence analysis of the proviral DNA from cells transformed by these mutants revealed the presence of multiple secondary mutations in sequences responsible for dimerization and DNA binding. Two of these mutations either enhanced or restored the ability of these proteins to bind DNA as a homodimer. Viruses expressing these proteins transformed cells at levels comparable to or slightly less than v-Rel, suggesting that a threshold level of DNA binding by v-Rel homodimers is required for transformation.
Rhesus Macaque Resistance to Mucosal Simian Immunodeficiency Virus Infection Is Associated with a Postentry Block in Viral Replication
Authors: Peng Bo , Voltan Rebecca , Lim Lulu , Edghill-Smith Yvette , Phogat Sanjay , Dimitrov Dimiter S. , Arora Kamalpreet , Leno Michel , Than Soe , Woodward Ruth , Markham Phillip D. , Cranage Martin , Robert-Guroff Marjorie
Published: July 2002

Elucidation of the host factors which influence susceptibility to human immunodeficiency virus or simian immunodeficiency virus (SIV) infection and disease progression has important theoretical and practical implications. Rhesus macaque 359, a vaccine control animal, resisted two successive intravaginal challenges with SIV
mac251
and failed to seroconvert. Here, after an additional intrarectal SIVmac32H challenge, macaque 359 remained highly resistant to infection. Viral RNA (10
6
copies/ml) was observed in plasma only at week 2 postchallenge. Virus isolation and proviral DNA were positive only once at week eight postchallenge. The animal remained seronegative and cleared SIV in vivo. Its blood and lymph node cells obtained at 49 weeks after intrarectal challenge did not transmit SIV to a naive macaque. We found that the resistance of macaque 359 to SIV infection was not due to a high level of CD8
+
suppressor activity but to an inherent resistance of its CD4
+
T cells. To elucidate the basis for the unusually strong resistance of macaque 359 to SIV infection in vivo and in vitro, we investigated early events of viral infection and replication in CD4
+
cells of macaque 359, including expression and mutation screening of SIV coreceptors and analysis of viral entry and reverse transcription. Mutation screening revealed no genetic alteration in SIV coreceptors. PCR analysis revealed a significant delay in production of early in vitro reverse transcription intermediates in macaque 359 cells compared to susceptible controls, but cell fusion assays showed that SIV entered the CD4
+
CCR5
+
cells of macaque 359 as readily as cells of macaques susceptible to SIV infection. Our results suggest that the resistance of macaque 359 to SIV infection is due to a postentry block in viral replication and implicate a cellular inhibitory mechanism in its CD4
+
T cells. Identification of this host mechanism will help further elucidate the biochemistry of reverse transcription and may suggest therapeutic strategies. Determining the prevalence of this host resistance mechanism among macaques may lead to better design of SIV pathogenesis and vaccine studies.
Cell Type-Specific Replication of Simian Virus 40 Conferred by Hormone Response Elements in the Late Promoter
Authors: Farrell Michael L. , Mertz Janet E.
Published: July 2002

The late genes of SV40 are not expressed at significant levels until after the onset of viral DNA replication. We previously identified two hormone response elements (HREs) in the late promoter that contribute to this delay. Mutants defective in these HREs overexpress late RNA at early, but not late, times after transfection of CV-1PD cells. Overexpression of nuclear receptors (NRs) that recognize these HREs leads to repression of the late promoter in a sequence-specific and titratable manner, resulting in a delay in late gene expression. These observations led to a model in which the late promoter is repressed at early times after infection by NRs, with this repression being relieved by titration of these repressors through simian virus 40 (SV40) genome replication to high copy number. Here, we tested this model in the context of the viral life cycle. SV40 genomes containing mutations in either or both HREs that significantly reduce NR binding without altering the coding of any proteins were constructed. Competition for replication between mutant and wild-type viruses in low-multiplicity coinfections indicated that the +1 HRE offered a significant selective advantage to the virus within a few cycles of infection in African green monkey kidney cell lines CV-1, CV-1P, TC-7, MA-134, and Vero but not in CV-1PD′ cells. Interestingly, the +55 HRE offered a selective disadvantage in MA-134 cells but had no effect in CV-1, CV-1P, TC-7, Vero, and CV-1PD′ cells. Thus, we conclude that these HREs are biologically important to the virus, but in a cell type-specific manner.
Nef Enhances Human Immunodeficiency Virus Type 1 Infectivity in the Absence of Matrix
Authors: Dorfman Tatyana , Popova Elena , Pizzato Massimo , Göttlinger Heinrich G.
Published: July 2002

Nef enhances the serine phosphorylation of the human immunodeficiency virus type 1 matrix (MA) protein, which suggests that MA may be a functional target of Nef. Using mutants that remain infectious despite the absence of most or all of MA, we show in the present study that the ability of Nef to enhance virus infectivity is not compromised even if MA is entirely replaced by a heterologous lipid anchor.
Rapid Construction of Adenoviral Vectors by Lambda Phage Genetics
Authors: McVey Duncan , Zuber Mohammed , Ettyreddy Damodar , Brough Douglas E. , Kovesdi Imre
Published: July 2002

Continued improvements of adenoviral vectors require the investigation of novel genome configurations. Since adenovirus can be generated directly by transfecting packaging cell lines with viral genomes isolated from plasmid DNA, it is possible to separate genome construction from virus production. In this way failure to generate a virus is not associated with an inability to generate the desired genome. We have developed a novel lambda-based system that allows rapid modification of the viral genome by double homologous recombination in
Escherichia coli
. The recombination reaction and newly generated genome may reside in a recombination-deficient bacterial host for enhanced plasmid stability. Furthermore, the process is independent of any restriction endonucleases. The strategy relies on four main steps: (i) homologous recombination between an adenovirus cosmid and a donor plasmid (the donor plasmid carries the desired modification[s] and flanking regions of homology to direct its recombination into the viral genome); (ii) in vivo packaging of the recombinant adenoviral cosmids during a productive lambda infection; (iii) transducing a recombination-deficient
E. coli
lambda lysogen with the generated lysate (the lysogen inhibits the helper phage used to package the recombinant andenoviral cosmid from productively infecting and destroying the host bacteria); (iv) effectively selecting for the desired double-recombinant cosmid. Approximately 10,000 double-recombinant cosmids are recovered per reaction with essentially all of them being the correct double-recombinant molecule. This system was used to generate quickly and efficiently adenoviral genomes deficient in the E1/E3 and E1/E3/E4 regions. The basis of this technology allows any region of the viral genome to be readily modified for investigation of novel configurations.
Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA
Authors: Svoboda Ladislav , Vořechovský Petr
Published: July 2002

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.
Certain Problems with the Application of Stochastic Diffusion Processes for the Description of Chemical Engineering Phenomena. Stochastic Model of Isothermal Continuous Flow Chemical Reactor
Authors: Kudrna Vladimír , Vejmola Libor , Hasal Pavel
Published: July 2002

A model of an isothermal one-dimensional continuous flow chemical reactor operating at the steady state was derived using a stochastic description of motion of the reacting molecules. The model enables evaluation of the conversion of the reacting components. At the limiting parameter values the model yields results identical to those of the simplified models conventionally used in chemical reactor engineering. The model also enables the applicability of Danckwerts' boundary conditions to be assessed from a more general point of view.
Modelling of Phase Diagram Boundaries at Equilibrium of Two Binary Regular Phases
Authors: Vřešťál Jan , Stloukal Ivo
Published: July 2002

The conditions of occurrence of extremes on the solidus and liquidus curves in a binary isobaric phase diagram are specified. The solid and liquid phases are regarded as regular solutions in equilibrium. Two simplifying assumptions are made: (i) the Gibbs function of melting of the pure components is a linear function of temperature; (ii) the two phases in equilibrium are regular solutions with a temperature-dependent regular solution parameter. The conditions of occurrence of inflexion points on the solidus and/or liquidus curves are obtained by modelling.
DNA-Polymerases α, δ and ε from T-Cell Spontaneous Lymphoblastic Leukemia of Sprague-Dawley Inbred Rat: Isolation and Characterization
Authors: Kramata Pavel , Černý Jaroslav , Birkuš Gabriel , Votruba Ivan , Otová Berta , Holý Antonín
Published: July 2002

Using a single isolation procedure and selective assays for the determination of enzyme activity, highly purified DNA-polymerases α, δ and ε were isolated from the lymphoma of Sprague-Dawley inbred rats. For pol α the subunit composition was 170, 70, 57 and 53 kDa with sedimentation coefficient 8.7 S for the native molecule; pol delta consists of two polypeptides (133 and 46 kDa; sedimentation coefficient 8.2 S), while pol ε is a single polypeptide (140 kDa) and its sedimentation coefficient is 7.0 S. Comparison of the interaction of individual enzymes with known inhibitors and proliferating cell nuclear antigen (PCNA) using the template-primer poly dA-oligo dT12-18, gave the following data: (i) pol α is selectively inhibited by N2-(p-butylphenyl)-2'-deoxyguanosine 5'-triphosphate (BuPdGTP) and stimulated by dimethyl sulfoxide; (ii) all the enzymes are inhibited by N-ethylmaleimide and aphidicolin; (iii) PCNA stimulates pol δ approximately 50 times while pol ε is moderately inhibited; (iv) pol α exhibits considerably higher DNA-primase activity with poly dC as template than with poly dT, and negligible 3'-5'-exonuclease activity whereas pol δ and pol ε, which do not exert any DNA-primase activity have approximately the same 3'-5'-exonuclease activity. The ability of individual polymerases to utilize poly dT-oligo dA12-18 as a template-primer at different pH values, ionic strengths and Mg2+-concentrations was also investigated. In comparison to poly dA-oligo dT12-18 template-primer, pol α has 140% of enzyme activity on poly dT-oligo dA12-18 under optimal conditions, whereas the activity of pol ε and pol δ is 4 times and 10 times lower, respectively.
Interpretation of Preferential Adsorption Using Random Phase Approximation Theory
Authors: Benoît Henri C. , Strazielle Claude
Published: July 2002

It has been shown that in light scattering experiments with polymers replacement of a solvent by a solvent mixture causes problems due to preferential adsorption of one of the solvents. The present paper extends this theory to be applicable to any angle of observation and any concentration by using the random phase approximation theory proposed by de Gennes. The corresponding formulas provide expressions for molecular weight, gyration radius, and the second virial coefficient, which enables measurements of these quantities provided enough information on molecular and thermodynamic quantities is available.
The Effect of Small Aliphatic Alcohols on the Dissociation of Tyrosine
Authors: Karpenko Vladimír , Horálková Jana , Kodíček Milan
Published: July 2002

Dissociation of tyrosine was studied in aqueous solutions of methanol, ethanol, 1-propanol, and 2-propanol of various concentrations, when the permittivity of all solutions had the same value. The effect of electrostatic interactions was, consequently, equal and thus the other interactions became more pronounced. On the basis of pK values of tyrosine -OH groups these alcohols can be divided into two groups, the first one including methanol and ethanol, the second one both propanols. The observed differences can be explained only qualitatively as a result of interaction of alcohols with tyrosine and with the surrounding water.
Ring Opening Metathesis Polymerization of Norbornene by WCl6: Formation of WCl5 and WCl4 and Their Catalytic Activity
Authors: Balcar Hynek , Bastl Zdeněk
Published: July 2002

Reaction between WCl6 and norbornene in benzene and cyclohexane, respectively, was investigated using UV/VIS, ESR and XPS spectroscopy in order to establish the main reaction products on the tungsten side and their relation to the initiation of ring opening metathesis polymerization (ROMP) of norbornene. The tungsten compounds: WCl5, insoluble WCl4 and soluble tungsten species having four chlorine atoms bound to tungsten, [WCl4Ln] were found to be the main products. The catalytic activity of the respective compounds in ROMP of norbornene was found to decrease in the order: WCl5 > WCl6 >> WCl4 ~ [WCl4Ln]. The polynorbornenes prepared with both WCl4 and [WCl4Ln] possess higher content of cis double bonds in comparison with polymers prepared with WCl6 and WCl5 catalysts.
Immunosorbents for the Preparation of Mycobacterium bovis BCG Antigen
Authors: Krejčíková Sabina , Beneš Milan J. , Wisingerová Eva , Turková Jaroslava
Published: July 2002

The preparation of immunosorbents for the isolation of Mycobacterium bovis BCG antigen is described. Polyclonal rabbit antibodies are attached both by oriented immobilization following oxidation with periodate to a cellulose and agarose support with hydrazide groups, and directly to agarose activated with cyanogen bromide. The properties of sorbents in relation to the method of preparation and to the support used are compared. The best properties were exhibited by immunosorbent attached to cellulose beads.
Skeletal Isomerization of n-Butane Over Mordeniteand Beta Zeolites
Authors: Babůrek Evžen , Nováková Jana
Published: July 2002

It was found that the addition of platinum (3 wt.%) substantially increases the total n-butane conversion and selectivity to isobutane over H-Beta zeolite. The same holds for H-Mordenite; however, the conversion significantly decreases in time at 350 °C due to the coking of the catalyst. The selectivity to isobutane is the highest at 300 °C over both zeolite types with platinum (over Pt/H-Beta 1.8 times higher than over Pt/H-Mordenite at almost the same conversion levels of 30 and 36%, respectively). The H-forms of both zeolite types are most selective at 250 °C, but the total conversion is low. The results obtained are related to the structural features of both zeolite types.
Aminophospholipid Glycation Causes Lipid Bilayer Structure Alterations and Inhibition of Membrane-Bound Na+,K+-ATPase
Authors: Obšil Tomáš , Amler Evžen , Pavlíček Zdeněk
Published: July 2002

In the present study, we have investigated the possibility that aminophospholipid glycation-mediated perturbations of the POPE/POPC lipid bilayer structure affect the activity and structure of the membrane-bound Na+,K+-ATPase. It was found that both glucose and glyceraldehyde (GCA) reacted with aminophospholipid POPE, forming lipid-linked glycofluorophores with the absorbance and fluorescence properties of protein-linked AGEs. The lipid glycation was accompanied by progressive oxidative modification of unsaturated fatty acid residues. Measurements of the steady-state fluorescence anisotropy of TMA-DPH have been a first attempt at detecting distinctive bilayer structural perturbations induced by aminophospholipid glycation. The steady-state fluorescence anisotropy of TMA-DPH increased with the time of glycation, presumably because of the increased lipid order of the bilayer. To improve the definition of structural alterations of the glycated lipid bilayer, we attempted to measure the dynamics of TMA-DPH and DPH fluorescence. The effect of glycation was both to change the membrane dielectric constant (as probed by TMA-DPH and DPH fluorescence lifetimes) and increase the lipid order (as probed by time-resolved fluorescence anisotropy measurements). The aminophospholipid glycation reduced the activity of Na+,K+-ATPase, which was incorporated into glycated POPE/POPC vesicles. The enzyme inhibition correlated with the increase in the steady-state fluorescence anisotropy of TMA-DPH but not with the concentration of MDA (e.g., lipid oxidation). Therefore the inhibition of Na+,K+-ATPase activity induced by aminophospholipid glycation seems to be related to the modification of the protein molecule conformation through the lipid bilayer structure alterations. The inhibition of Na+,K+-ATPase activity was the sum of at least two factors: the increased lipid order and changed membrane dielectric constant. These factors can alter the lipid-lipid and lipid-protein interactions (e.g., electric multipole-multipole interactions) in membrane and thus provoke the inhibition of membrane bound enzymes.
Cesium and Cesium-Lithium Selenates
Authors: Havlíček David , Mička Zdeněk , Barbořák Václav , Šmejkal Petr
Published: July 2002

The Cs2SeO4-H2SeO4-H2O and Cs2SeO4-Li2SeO4-H2O systems were studied at 30 °C as a basis for determining the conditions for formation of the compound Cs4LiH3(SeO4)4, which has been observed to undergo a ferroelectric phase transition. The results of a solubility study were used to construct a pseudo-ternary cross-section for CsLiSeO4-CsHSeO4-H2O in the quaternary system Cs2SeO4-Li2SeO4-H2SeO4-H2O, which demonstrated that, in the region of crystallization of the compound of interest, a substance with the composition Cs4LiH3(SeO4)4 is actually formed. Attention was further paid to the following newly prepared compounds: cesium-lithium selenate hemihydrate, CsLiSeO4·1/2 H2O, tricesium-lithium bis(selenate) hemihydrate, Cs3Li(SeO4)2·1/2 H2O and hydrogen tricesium bis(selenate) hemihydrate, Cs3H(SeO4)2·1/2 H2O, which were characterized by X-ray, spectral and thermoanalytical data.
Evaluation of the Carbonyl/Chlorine Interaction Parameters in Pentan-3-one-Chloroalkane Mixtures Using the Disquac Group Contribution Model
Authors: Teodorescu Mariana , Wichterle Ivan
Published: July 2002

Thermodynamic behaviour of the eight systems containing pentan-3-one and a chloroalkane, namely 1-chlorobutane, 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, trichloromethane, 1,1,1-trichloroethane, tetrachloromethane and 1,1,2,2-tetrachloro- ethane was interpreted in terms of the DISQUAC group contribution model. It was found that quasichemical term for the contact C=O/Cl in the pentan-3-one-α,ω-dichloroalkane and pentan-3-one-1,1,1-trichloroethane systems is not negligible. The DISQUAC dispersive interchange parameters for C=O/Cl contact in these systems were evaluated from literature data on linear ketone + 1-chloroalkane systems. It was found that the best description of experimental data for systems containing 1-chlorobutane, trichloromethane, tetrachloromethane, and 1,1,2,2-tetrachloroethane is provided using only dispersive contribution of the C=O/Cl contact. The vapour-liquid equilibrium, GE, and HE data were calculated using the DISQUAC model and compared with experimental data. The model provides a fairly consistent description. The relation between the DISQUAC interchange parameters for C=O/Cl contact and the chloroalkane chain length was established.
Pulse Modulation - A Novel Approach to Gradient-Based Flow Injection Techniques
Authors: Herbelin Armando , Ruzicka Jaromir
Published: July 2002

Development of a novel system for generation of gradients in flow injection analysis by pulse modulation is described. These user-selectable gradients are created by computer-controlled mixing of two solutions with a total volume as low as 75 μl and can be delivered under incremental or continuous flow conditions. Applications such as automated, single-standard instrument calibration are expected to benefit from high-precision linear gradients (r2 = 0.99989, n = 55). Gradient methods in biochemisty and immunology such as kinetic measurement of biomolecular interactions will benefit from the small volume of these gradients, especially for analytes with limited availability.
Presumed consent in emergency neonatal research
Authors: Manning D J
Published: July 2002

Current methods of obtaining consent for emergency neonatal research are flawed. They risk aggravating the distress of parents of preterm and other sick neonates. This distress, and the inevitable time constraints, compromise understanding and voluntariness, essential components of adequately informed consent. Current practice may be unjust in over-representing babies of more vulnerable and deprived parents. The research findings may thus not be generalisable. Informing parents antenatally about the possible need for emergency neonatal research, with presumed consent and scope for opting out, would address these problems. It would spare parents of sick neonates, already terrified by their baby's illness, further distress. Experience with opting out suggests that recruitment might increase, thus generating earlier results, without compromising parental understanding of the nature and purpose of the research.
Medicine, lies and deceptions
Authors: Benn Piers
Published: July 2002

This article offers a qualified defence of the view that there is a moral difference between telling lies to one's patients, and deceiving them without lying. However, I take issue with certain arguments offered by Jennifer Jackson in support of the same conclusion. In particular, I challenge her claim that to deny that there is such a moral difference makes sense only within a utilitarian framework, and I cast doubt on the aptness of some of her examples of non-lying deception. But I argue that lies have a greater tendency to damage trust than does non-lying deception, and suggest that since many doctors do believe there is a moral boundary between the two types of deception, encouraging them to violate that boundary may have adverse general effects on their moral sensibilities.
Sickness absence and early retirement on health grounds in the construction industry in Ireland
Authors: Brenner Harold , Ahern William
Published: July 2002

OBJECTIVE

To establish a detailed pattern of the nature and extent of illnesses and injuries among construction workers in Ireland which cause temporary absence from work, and to identify diseases and disabilities which lead to premature retirement from the industry on health grounds.

METHODS

The population base for the study consisted of construction workers who were members of the Construction Federation operatives pension and sick pay scheme. Records of sickness absence since 1981, stored on computer disks, and records of early retirement on health grounds since 1972, stored on microfiche film, were examined. Pertinent data were extracted and transferred to a database; after cleaning and the exclusion of unvalidated data, records of 28 792 absences and 3098 records of early retirement were available for analysis. Data were analysed with Access 97 and Epi Info.

RESULTS

Over the period of the study the mean annual absences were 7.8/100 workers. Three quarters of absences were among younger workers; however, the rate of absence increased with age, as did the mean duration of absence. Injury was the most frequent reason for absence, followed by infectious disease, then musculoskeletal disorders. The mean annual rate of early retirement on health grounds was 5.3/1000 workers. The median age at retirement was 58 years. Cardiovascular disease and musculoskeletal disorders each accounted for nearly one third of the conditions leading to permanent disability on the grounds of which early retirement was granted. During the period of the study, over 677 000 working days were lost due to sickness absence, and over 24 000 potential years of working lives were lost due to early retirement on health grounds.

CONCLUSIONS

The study has shown patterns of sickness absence and early retirement on health grounds in the Irish construction industry which will contribute to the further development of health promotion strategies for construction workers.
Chemotherapy for upper gastrointestinal tumours
Authors: Thomas A L , O'Byrne K , Steward W P
Published: July 2002

The aim of this review is to identify current chemotherapy treatment for tumours of the oesophagus, stomach, pancreas, and liver. The role of both neoadjuvant, adjuvant, and palliative chemotherapy regimens will be discussed. This review will be of interest to oncologists in clarifying current issues regarding chemotherapy, and to physicians in other medical specialties, to increase their general understanding of benefits and drawbacks of chemotherapy in this patient group.
Load-induced stiffness matrix of plates
Authors: Zhou Shi-Jun
Published: July 2002

In this paper, a rectangular plate element for the finite-element method, which takes into consideration the stiffening effect of dead loads, is proposed. The element stiffness matrices that include the effect of dead loads are derived. The effect of dead loads on dynamic behaviors of plates is analyzed using the finite-element method. It is shown that the stiffness of plates increases when the effect of dead loads is included in the calculation and that the effect is more significant for plates with a smaller stiffness. The validity of the proposed procedure is confirmed by numerical examples. Although the finite-element results obtained are in agreement with the approximate closed-form solutions, the proposed method based on a finite-element formulation is more easily applied to practical structures under various support conditions and various types of dead loads.Key words: load-induced stiffness matrix of plate, stiffening effect of dead loads.
Future directions of environmental engineering in Canada
Authors: Smith Daniel W , Mavinic D S , Zytner R G
Published: July 2002

Environmental engineering is one of the most complex and fastest-growing disciplines in engineering. The scope of the field includes issues from public health protection to aesthetics, and from the impact on business development to the development of legislation, standards, regulations, and guidelines, to their enforcement and environmental protection. The issues include contaminants in gases, liquids, and solids and the phase transfers of the contaminants. The sub-specialties of environmental engineering address all these areas including the treatment of water, liquid waste, solid waste, and gaseous materials, protection of the environment through proactive measures, and the development of effective regulations. Environmental engineers have the necessary skills to address these issues and improve the quality of life of humans and other living things in an effective, sustainable, and economical manner. This paper outlines the evolvement of environmental engineering and identifies many of the exciting new directions of environmental engineering profession. Key words: environmental engineering, quality of life, future directions, water, wastewater, air quality, solid wastes, site remediation.
A NEW WEIGHT BALANCED BINARY SEARCH TREE
Authors: CHO SEONGHUN , SAHNI SARTAJ
Published: July 2002

We develop a new class of weight balanced binary search trees called β-balanced binary search trees (β-BBSTs). β-BBSTs are designed to have reduced internal path length. As a result, they are expected to exhibit good search time characteristics. Individual search, insert, and delete operations in an n node β-BBST take O( log n) time for [Formula: see text]. Experimental results comparing the performance of β-BBSTs, WB(α) trees, AVL-trees, red/black trees, treaps, deterministic skip lists and skip lists are presented. Two simplified versions of, β-BBSTs are also developed.
CLOSED SUB-MONODROMY PROBLEMS, LOCAL MIRROR SYMMETRY AND BRANES ON ORBIFOLDS
Authors: MOHRI KENJI , ONJO YOKO , YANG SUNG-KIL
Published: July 2002

We study D-branes wrapping an exceptional four-cycle P(1,a,b) in a blown-up C3/Zm non-compact Calabi–Yau threefold with (m;a,b)=(3;1,1), (4;1,2) and (6; 2, 3). In applying the method of local mirror symmetry we find that the Picard–Fuchs equations for the local mirror periods in the Z3,4,6 orbifolds take the same form as the ones in the local E6,7,8 del Pezzo models, respectively. It is observed, however, that the orbifold models and the del Pezzo models possess different physical properties because the background NS B-field is turned on in the case of Z3,4,6 orbifolds. This is shown by analyzing the periods and their monodromies in full detail with the help of Meijer G-functions. We use the results to discuss D-brane configurations on P(1,a,b) as well as on del Pezzo surfaces. We also discuss the number theoretic aspect of local mirror symmetry and observe that the exponent which governs the exponential growth of the Gromov–Witten invariants is determined by the special value of the Dirichlet L-function.
QUANTUM MECHANICS ON HYPERBOLOIDS
Authors: LUNDBERG LARS-ERIK
Published: July 2002

We consider a quantum theory on hyperboloids, a theory whose symmetry group is the homogeneous Lorentz group and with Schrödinger theory as its nonrelativistic analogue. The Poincaré group is a good approximate symmetry of the scattering matrix.
On the Right Hamiltonian for Singular Perturbations: General Theory
Authors: Neidhardt Hagen , Zagrebnov Valentin
Published: July 2002

Let the pair of self-adjoint operators {A≥0,W≤0} be such that:

(a) there is a dense domain [Formula: see text] such that [Formula: see text] is semibounded from below (stability domain),

(b) the symmetric operator [Formula: see text] is not essentially self-adjoint (singularity of the perturbation),

(c) the Friedrichs extension [Formula: see text] of [Formula: see text] is maximal with respect to W, i.e., [Formula: see text]. [Formula: see text].

Let [Formula: see text] be a regularizing sequence of bounded operators which tends in the strong resolvent sense to W. The abstract problem of the right Hamiltonian is:

(i) to give conditions such that the limit H of self-adjoint regularized Hamiltonians [Formula: see text] exists and is unique for any self-adjoint extension [Formula: see text] of [Formula: see text], (ii) to describe the limit H.

We show that under the conditions (a)–(c) there is a regularizing sequence [Formula: see text] such that [Formula: see text] tends in the strong resolvent sense to unique (right Hamiltonian) [Formula: see text], otherwise the limit is not unique.
Superselection Structure of Massive Quantum Field Theories in 1+1 Dimensions
Authors: Müger Michael
Published: July 2002

We show that a large class of massive quantum field theories in 1+1 dimensions, characterized by Haag duality and the split property for wedges, does not admit locally generated superselection sectors in the sense of Doplicher, Haag and Roberts. Thereby the extension of DHR theory to 1+1 dimensions due to Fredenhagen, Rehren and Schroer is vacuous for such theories. Even charged representations which are localizable only in wedge regions are ruled out. Furthermore, Haag duality holds in all locally normal representations. These results are applied to the theory of soliton sectors. Furthermore, the extension of localized representations of a non-Haag dual net to the dual net is reconsidered. It must be emphasized that these statements do not apply to massless theories since they do not satisfy the above split property. In particular, it is known that positive energy representations of conformally invariant theories are DHR representations.
DEFORMED HARMONIC OSCILLATOR ALGEBRAS DEFINED BY THEIR BARGMANN REPRESENTATIONS
Authors: IRAC-ASTAUD MICHÈLE , RIDEAU GUY
Published: July 2002

Deformed Harmonic Oscillator Algebras are generated by four operators, two mutually adjoint a and a†, and two self-adjoint N and the unity 1 such as: [Formula: see text] The Bargmann Hilbert space is defined as a space of functions, holomorphic in a ring of the complex plane, equipped with a scalar product involving a true integral. In a Bargmann representation, the operators of a Deformed Harmonic Oscillator Algebra act on a Bargmann Hilbert space and the creation (or the annihilation operator) is the multiplication by z. We discuss the conditions of existence of Deformed Harmonic Oscillator Algebras assumed to admit a given Bargmann representation.
ON THE SPECTRAL PROPERTIES OF DISCRETE SCHRÖDINGER OPERATORS
Authors: DE MONVEL ANNE BOUTET , SAHBANI JAOUAD
Published: July 2002

We use the method of the conjugate operator to prove the limiting absorption principle and the absence of the singular continuous spectrum for the discrete Schrödinger operator. We also obtain local decay estimates. Our results apply to a large class of perturbating potentials V tending arbitrarily slowly to zero at infinity.
AN INVESTIGATION OF COMPETITIVE LEARNING FOR AUTONOMOUS CLUSTER IDENTIFICATION IN EMBEDDED SYSTEMS
Authors: McNEILL DEAN K. , CARD HOWARD C. , MURRAY ALAN F.
Published: July 2002

Robust signal processing for embedded systems requires the effective identification and representation of features within raw sensory data. This task is inherently difficult due to unavoidable long-term changes in the sensory systems and/or the sensed environment. In this paper we explore four variations of competitive learning and examine thier suitability as an unsupervised technique for the automated identification of data clusters within a given input space. The relative performance of the four techniques is evaluated through their ability to effectively represent the structure underlying artificial and real-world data distributions. As a result of this study it was found that frequency sensitive competitive learning provides both reliable and efficient solutions to complex data distributions. As well, frequency sensitive and soft competitive learning are shown to exhibit properties which may permit the evolution of an appropriate network strucute through the use of growing or pruning procedures.