bluuebunny/crossref_metadata_2025 huggingface dataset:
Interleukin-1 Receptor Signaling Rather than That of Tumor Necrosis Factor Is Critical in Protecting the Host from the Severe Consequences of a Polymicrobe Anaerobic Infection
Authors: Graves Dana T. , Chen Chih-Ping , Douville Christopher , Jiang Yanling
Published: July 2002

Infection of the dental pulp leads to an osteolytic lesion that results from a polymicrobial infection consisting largely of pathogenic anaerobes. Infection causes significant morbidity and mortality mediated by bacterial factors and in some cases by the up-regulation of inflammatory cytokines. The inflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor (TNF), in particular, play a complex and central role in the responses to microbial pathogens. However, relatively little is known about the significance of these cytokines in protecting the host from focal polymicrobial anaerobic infections. To establish the relative importance of IL-1 and TNF in mediating the response to a mixed anaerobic infection, we inoculated the dental pulp of mice with six anaerobic pathogens containing functional deletions of receptors to IL-1 (IL-1R1−/−), TNF (TNFRp55−/−-p75−/−), or both (TNFRp55−/−-IL-1RI−/−). The results indicate that IL-1 receptor signaling and TNF receptor signaling both play similarly important roles in protecting the host from local tissue damage. However, IL-1 receptor signaling is considerably more important than TNF receptor signaling in preventing the spread of infection into surrounding fascial planes, since IL-1R1−/−but not TNFRp55−/−-p75−/−mice exhibited significantly higher morbidity and mortality. Moreover, all of the fatal infections occurred in male mice, suggesting the importance of gender differences in limiting the impact of these infections.
H
2
O
2
, Which Causes Macrophage-Related Stress, Triggers Induction of Expression of Virulence-Associated Plasmid Determinants in
Rhodococcus equi
Authors: Benoit Stephanie , Benachour Abdellah , Taouji Said , Auffray Yanick , Hartke Axel
Published: July 2002

The response of the intracellular pathogen
Rhodococcus equi
to H
2
O
2
treatment, a situation potentially encountered after the oxidative burst of alveolar macrophages, was analyzed. Compared to other bacteria, including
Deinococcus radiodurans
,
R. equi
showed exceptionally high resistance to this stress. A proteomic approach showed that four polypeptides present in the wild-type strain (85F) are missing in the plasmid-cured strain 85F(P-), and by using a DNA macroarray, we identified two plasmid-encoded
vap
genes,
vapA
and
vapG
, whose expression was highly induced by H
2
O
2
treatment. Whereas the transcript size of
vapA
was compatible with a monocistronic mRNA, the transcript of
vapG
was considerably longer. Rapid amplification of cDNA ends PCRs showed that the transcriptional start sites of the two operons were 69 and 269 nucleotides (nt) upstream of the start codon, respectively. Analysis of these leader sequences revealed the presence of a small open reading frame named
podG
, which encodes a sequence of 55 amino acids preceded by a putative ribosome binding site sequence in the
vapG
transcript. Taking this result into account, the untranslated leader of the
podG
/
vapG
operon is 87 nt. Alignment of this sequence with the leader sequences of
vapA
and
vapD
, genes previously shown to be induced by acid, revealed significant homologies. Since our results showed that
vapA
,
vapD,
and
vapG
are genes highly induced by macrophage-related stresses, their gene products may, within the Vap protein family, play a dominant role inside these phagocytic cells and may be the most promising candidates for vaccination strategies.
Physical Map Location of the Multicopy Genes Coding for Ammonia Monooxygenase and Hydroxylamine Oxidoreductase in the Ammonia-Oxidizing Bacterium
Nitrosomonas
sp. Strain ENI-11
Authors: Hirota Ryuichi , Yamagata Akira , Kato Junichi , Kuroda Akio , Ikeda Tsukasa , Takiguchi Noboru , Ohtake Hisao
Published: July 2002

Pulsed-field gel electrophoresis of
Pme
I digests of the
Nitrosomonas
sp. strain ENI-11 chromosome produced four bands ranging from 1,200 to 480 kb in size. Southern hybridizations suggested that a 487-kb
Pme
I fragment contained two copies of the
amoCAB
genes, coding for ammonia monooxygenase (designated

amoCAB
1

and

amoCAB
2

), and three copies of the
hao
gene, coding for hydroxylamine oxidoreductase (

hao
1

,

hao
2

, and

hao
3

). In this DNA fragment,

amoCAB
1

and

amoCAB
2

were about 390 kb apart, while

hao
1

,

hao
2

, and

hao
3

were separated by at least about 100 kb from each other. Interestingly,

hao
1

and

hao
2

were located relatively close to

amoCAB
1

and

amoCAB
2

, respectively. DNA sequence analysis revealed that

hao
1

and

hao
2

shared 160 identical nucleotides immediately upstream of each translation initiation codon. However,

hao
3

showed only 30% nucleotide identity in the 160-bp corresponding region.
Contributions of PBP 5 and
dd
-Carboxypeptidase Penicillin Binding Proteins to Maintenance of Cell Shape in
Escherichia coli
Authors: Nelson David E. , Young Kevin D.
Published: July 2002

Escherichia coli
has 12 recognized penicillin binding proteins (PBPs), four of which (PBPs 4, 5, and 6 and DacD) have
dd
-carboxypeptidase activity. Although the enzymology of the
dd
-carboxypeptidases has been studied extensively, the in vivo functions of these proteins are poorly understood. To explain why
E. coli
maintains four independent loci encoding enzymes of considerable sequence identity and comparable in vitro activity, it has been proposed that the
dd
-carboxypeptidases may substitute for one another in vivo. We tested the validity of this equivalent substitution hypothesis by investigating the effects of these proteins on the aberrant morphology of Δ
dacA
mutants, which produce no PBP 5. Although cloned PBP 5 complemented the morphological phenotype of a Δ
dacA
mutant lacking a total of seven PBPs, controlled expression of PBP 4, PBP 6, or DacD did not. Also, a truncated PBP 5 protein lacking its amphipathic C-terminal membrane binding sequence did not reverse the morphological defects and was lethal at low levels of expression, implying that membrane anchoring is essential for the proper functioning of PBP 5. By examining a set of mutants from which multiple PBP genes were deleted, we found that significant morphological aberrations required the absence of at least three different PBPs. The greatest defects were observed in cells lacking, at minimum, PBPs 5 and 6 and one of the endopeptidases (either PBP 4 or PBP 7). The results further differentiate the roles of the low-molecular-weight PBPs, suggest a functional significance for the amphipathic membrane anchor of PBP 5 and, when combined with the recently determined crystal structure of PBP 5, suggest possible mechanisms by which these PBPs may contribute to maintenance of a uniform cell shape in
E. coli
.
Unusual Methyl-Branched α,β-Unsaturated Acyl Chain Substitutions in the Nod Factors of an Arctic Rhizobium,
Mesorhizobium
sp. Strain N33 (
Oxytropis arctobia
)
Authors: Poinsot Véréna , Bélanger Elaine , Laberge Serge , Yang Guo-Ping , Antoun Hani , Cloutier Jean , Treilhou Michel , Dénarié Jean , Promé Jean-Claude , Debellé Frédéric
Published: July 2002

Mesorhizobium
sp. strain N33 (
Oxytropis arctobia
), a rhizobial strain isolated in arctic Canada, is able to fix nitrogen at very low temperatures in association with a few arctic legume species belonging to the genera
Astragalus, Onobrychis
, and
Oxytropis
. Using mass spectrometry and nuclear magnetic resonance spectroscopy, we have determined the structure of N33 Nod factors, which are major determinants of nodulation. They are pentameric lipochito-oligosaccharides 6-O sulfated at the reducing end and exhibit other original substitutions: 6-O acetylation of the glucosamine residue next to the nonreducing terminal glucosamine and N acylation of the nonreducing terminal glucosamine by methyl-branched acyl chains of the iso series, some of which are α,β unsaturated. These unusual substitutions may contribute to the peculiar host range of N33. Analysis of N33 whole-cell fatty acids indicated that synthesis of the methyl-branched fatty acids depended on the induction of bacteria by plant flavonoids, suggesting a specific role for these fatty acids in the signaling process between the plant and the bacteria. Synthesis of the methyl-branched α,β-unsaturated fatty acids required a functional
nodE
gene.
A Mutation in the 5′ Untranslated Region Increases Stability of
norA
mRNA, Encoding a Multidrug Resistance Transporter of
Staphylococcus aureus
Authors: Fournier Bénédicte , Truong-Bolduc Que Chi , Zhang Xiamei , Hooper David C.
Published: July 2002

NorA, a multidrug efflux pump in
Staphylococcus aureus
, protects the cell from multiple drugs, including quinolones. The
flqB
mutation (T→G) in the 5′ untranslated region upstream of
norA
causes
norA
overexpression of 4.9-fold in
cis
, as measured in
norA
::
blaZ
fusions. The transcriptional initiation site of
norA
was unchanged in mutant and wild-type strains, but the half-life of
norA
mRNA was increased 4.8-fold in the
flqB
mutant compared to the wild-type strain. Computer-generated folding of the first 68 nucleotides of the
norA
transcript predicts an additional stem-loop and changes in a putative RNase III cleavage site in the
flqB
mutant.
High Genetic Variability of the
agr
Locus in
Staphylococcus
Species
Authors: Dufour Philippe , Jarraud Sophie , Vandenesch Francois , Greenland Timothy , Novick Richard P. , Bes Michele , Etienne Jerome , Lina Gerard
Published: July 2002

The
agr
quorum-sensing and signal transduction system was initially described in
Staphylococcus aureus
, where four distinct allelic variants have been sequenced. Western blotting suggests the presence of homologous loci in many other staphylococci, and this has been confirmed for
S. epidermidis
and
S. lugdunensis
. In this study we isolated
agr
-like loci from a range of staphylococci by using PCR amplification from primers common to the six published
agr
sequences and bracketing the most variable region, associated with quorum-sensing specificity. Positive amplifications were obtained from 14 of 34 staphylococcal species or subspecies tested. Sequences of the amplicons identified 24 distinct variants which exhibited extensive sequence divergence with only 10% of the nucleotides absolutely conserved on multiple alignment. This variability involved all three open reading frames involved in quorum sensing and signal transduction. However, these variants retained several protein signatures, including the conserved cysteine residue of the autoinducing peptide, with the exception of
S. intermedius
of pigeon origin, which contained a serine in place of cysteine at this position. We discuss hypotheses on the mode of action and the molecular evolution of the
agr
locus based on comparisons between the newly determined sequences.
Xis Protein Binding to the Left Arm Stimulates Excision of Conjugative Transposon Tn916
Authors: Connolly Kevin M. , Iwahara Mizuho , Clubb Robert T.
Published: July 2002

Tn916and related conjugative transposons are clinically significant vectors for the transfer of antibiotic resistance among human pathogens, and they excise from their donor organisms using the transposon-encoded integrase (Tn916Int) and excisionase (Tn916Xis) proteins. In this study, we have investigated the role of theTn916Xis protein in stimulating excisive recombination. The functional relevance ofTn916Xis binding sites on the arms of the transposon has been assessed in vivo using a transposon excision assay. Our results indicate that inEscherichia colithe stimulatory effect of theTn916Xis protein is mediated by sequence-specific binding to either of its two binding sites on the left arm of the transposon. These sites lie in between the core and arm sites recognized byTn916Int, suggesting that theTn916Xis protein enhances excision in a manner similar to the excisionase protein of bacteriophage λ, serving an architectural role in the stabilization of protein-nucleic acid structures required for strand synapsis. However, our finding that excision inE. coliis significantly enhanced by the host factor HU, but does not depend on the integration host factor or the factor for inversion stimulation, defines clear mechanistic differences between Tn916and bacteriophage λ recombination.
Efficient Extraction of Virus DNA by NucliSens Extractor Allows Sensitive Detection of Hepatitis B Virus by PCR
Authors: Gobbers Erik , Oosterlaken Tom A. M. , van Bussel Mario J. A. W. M. , Melsert Roel , Kroes Aloys C. M. , Claas Eric C. J.
Published: July 2002

The NucliSens Extractor is an automated nucleic acid isolation system based on guanidinium thiocyanate (GuSCN)-silica extraction technology. The system has been validated for the isolation of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) RNAs from human samples in combination with nucleic acid sequence-based amplification- and reverse transcription-PCR-based methods. We evaluated the extractor for hepatitis B virus (HBV) DNA extraction from human samples using a noncommercial HBV DNA PCR. Several sample pretreatment procedures in combination with the extractor were compared with the Qiagen extraction method, and the impact of the sample volume used in the extraction on the sensitivity was investigated. Heating of the lysed sample prior to extractor isolation and the use of a large sample volume resulted in highly sensitive detection of HBV DNA. Incubation of a 1-ml sample in GuSCN at 80°C (10 min) and at 37°C (30 min) allowed detection of 4 and 40 HBV genome equivalents/ml, respectively, in standard dilution panels. Sample lysis in GuSCN at room temperature and proteinase K treatment prior to use of the extractor were less efficient procedures. All clinical samples that were PCR positive after Qiagen extraction and/or that were HBsAg positive were also PCR positive after extractor isolation. HBV DNA, HCV RNA, and HIV type 1 RNA were efficiently coextracted from a single sample, allowing reliable detection of viral genomes.
Performance of the New Bayer VERSANT HCV RNA 3.0 Assay for Quantitation of Hepatitis C Virus RNA in Plasma and Serum: Conversion to International Units and Comparison with the Roche COBAS Amplicor HCV Monitor, Version 2.0, Assay
Authors: Beld Marcel , Sentjens Roel , Rebers Sjoerd , Weegink Christine , Weel Jan , Sol Cees , Boom René
Published: July 2002

We have evaluated the VERSANT HCV RNA 3.0. Assay (HCV 3.0 bDNA assay) (Bayer Diagnostics, Berkeley, Calif.), which is an improved signal amplification procedure for the HCV 2.0 bDNA assay for the quantitation of hepatitis C virus (HCV) RNA in serum or plasma of HCV-infected individuals. The HCV 3.0 bDNA assay has a linear dynamic range of 2.5 × 10
3
to 4.0 × 10
7
HCV RNA copies per ml (c/ml). The performance of the HCV 3.0 bDNA assay was evaluated using three different test panels. An overall specificity of 96.8% relative to the detection limit of the HCV 3.0 bDNA assay was found. The intra- and interrun reproducibilities for both the dilution panel and the NAP (AcroMetrix, Benicia, Calif.) panel were consistent with coefficients of variation of less than 9%. Quantitation with the HCV 3.0 bDNA assay was linear over the entire range of both panels (ranges of 4.4 × 10
3
to 3.5 × 10
6
c/ml and 5 × 10
3
to 2 × 10
6
IU/ml, respectively), with correlation coefficients of 0.999, slopes close to one, and intercepts close to zero. The regression equation indicated that 1 IU corresponded to about 4.8 copies of HCV RNA. A correlation coefficient of 0.941 was found for HCV RNA values (in international units per milliliter) obtained from the HCV 3.0 bDNA assay and the HCV Monitor version 2.0 assay (HCV Monitor 2.0 assay) (Roche Diagnostic Systems, Branchburg, N.J.). Quantitative results obtained close to the lower limit of the HCV 3.0 bDNA assay might imply that its lower limit should be reconsidered and raised, if necessary. It appeared that quantitation values obtained from the HCV Monitor 2.0 assay of between 5 × 10
2
and 10
5
IU/ml were in general higher than those obtained from the HCV 3.0 bDNA assay, whereas values obtained from the HCV Monitor 2.0 assay were underestimated for samples with HCV RNA levels above 10
5
IU/ml.
Clinical Evaluation of a Frozen Commercially Prepared Microdilution Panel for Antifungal Susceptibility Testing of Seven Antifungal Agents, Including the New Triazoles Posaconazole, Ravuconazole, and Voriconazole
Authors: Pfaller M. A. , Diekema D. J. , Messer S. A. , Boyken L. , Huynh H. , Hollis R. J.
Published: July 2002

A commercially prepared frozen broth microdilution panel (Trek Diagnostic Systems, Westlake, Ohio) was compared with a reference microdilution panel for antifungal susceptibility testing of two quality control (QC) strains and 99 clinical isolates of
Candida
spp. The antifungal agents tested included amphotericin B, flucytosine, fluconazole, itraconazole, posaconazole, ravuconazole, and voriconazole. Microdilution testing was performed according to NCCLS recommendations. MIC endpoints were read visually after 48 h of incubation and were assessed independently for each microdilution panel. The MICs for the QC strains were within published limits for both the reference and Trek microdilution panels. Discrepancies among MIC endpoints of no more than 2 dilutions were used to calculate the percent agreement. Acceptable levels of agreement between the Trek and reference panels were observed for all antifungal agents tested against the 99 clinical isolates. The overall agreement for each antifungal agent ranged from 96% for ravuconazole to 100% for amphotericin B. The Trek microdilution panel appears to be a viable alternative to frozen microdilution panels prepared in-house.
Use of Inhibitors To Evaluate Coreceptor Usage by Simian and Simian/Human Immunodeficiency Viruses and Human Immunodeficiency Virus Type 2 in Primary Cells
Authors: Zhang Yi-jun , Lou Bernard , Lal Renu B. , Gettie Agegnehu , Marx Preston A. , Moore John P.
Published: July 2002

We have used coreceptor-targeted inhibitors to investigate which coreceptors are used by human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency viruses (SIV), and human immunodeficiency virus type 2 (HIV-2) to enter peripheral blood mononuclear cells (PBMC). The inhibitors are TAK-779, which is specific for CCR5 and CCR2, aminooxypentane-RANTES, which blocks entry via CCR5 and CCR3, and AMD3100, which targets CXCR4. We found that for all the HIV-1 isolates and all but one of the HIV-2 isolates tested, the only relevant coreceptors were CCR5 and CXCR4. However, one HIV-2 isolate replicated in human PBMC even in the presence of TAK-779 and AMD3100, suggesting that it might use an undefined, alternative coreceptor that is expressed in the cells of some individuals. SIVmac239 and SIVmac251 (from macaques) were also able to use an alternative coreceptor to enter PBMC from some, but not all, human and macaque donors. The replication in human PBMC of SIVrcm(from a red-capped mangabey), a virus which uses CCR2 but not CCR5 for entry, was blocked by TAK-779, suggesting that CCR2 is indeed the paramount coreceptor for this virus in primary cells.
Potential Role for Luman, the Cellular Homologue of Herpes Simplex Virus VP16 (α Gene
trans
-Inducing Factor), in Herpesvirus Latency
Authors: Lu Rui , Misra Vikram
Published: July 2002

The cascade of herpes simplex virus (HSV) gene expression that results in viral replication begins with the activation of viral immediate-early (IE) genes by the virion-associated protein VP16. VP16 on its own is inefficient at associating with complexes formed on IE gene promoters and depends upon the cellular factor HCF for its activity. In this respect VP16 mimics the host basic leucine zipper (bZIP) protein Luman, which also requires HCF for activating transcription. Our objective is to explore interactions between Luman and HCF and to determine if they play a role in the biology of herpesviruses. In this report we show that in cultured cells ectopically expressed Luman was retained in the cytoplasm, where it colocalized with Calnexin, a protein normally associated with the endoplasmic reticulum (ER). Retention of Luman in the ER depends on a hydrophobic segment of the protein that probably serves as a transmembrane domain. Deletion of this domain changed the intracellular location of Luman so that most of the mutant protein was in the nucleus of cells. While HCF was present in the nucleus of most cells, in cells expressing Luman it was retained in the cytoplasm where the two proteins colocalized. This cytoplasmic association of Luman and HCF could also be demonstrated in neurons in trigeminal ganglia removed from cattle soon after death. Cells in tissue culture that expressed Luman, but not a mutant form of the protein that fails to bind HCF, were resistant to a productive infection with HSV type 1 (HSV-1). We hypothesize that similar Luman-HCF interactions in sensory neurons in trigeminal ganglia result in the suppression of viral replication and the establishment of latency. Interestingly, Luman could activate the promoters of IE110 and LAT, two genes that are critical for reactivation of HSV-1 from latency. This suggests a role for Luman in the reactivation process as well.
Characterization of Human Immunodeficiency Virus Type 1 in Saliva and Blood Plasma by V3-Specific Heteroduplex Tracking Assay and Genotype Analyses
Authors: Freel Stephanie A. , Williams John M. , Nelson Julie A. E. , Patton Lauren L. , Fiscus Susan A. , Swanstrom Ronald , Shugars Diane C.
Published: July 2002

The gp120 V3-encoding region of human immunodeficiency virus type 1 (HIV-1) RNA derived from the saliva and blood plasma of 11 individuals was characterized by heteroduplex tracking assay and sequence analyses. R5-like viral variants were identified in both fluids of all subjects. X4-like variants were detected in the plasma and/or saliva of three subjects, indicating that X4-like variants are not excluded from the saliva compartment. Viral subpopulations were similar in both fluids of most subjects, suggesting that HIV-1 in oral fluids and blood may stem from a common source. These findings raise the possibility of using saliva as a noninvasive fluid for evaluating and monitoring viral evolution in infected persons.
Acutely Transforming Avian Leukosis Virus Subgroup J Strain 966: Defective Genome Encodes a 72-Kilodalton Gag-Myc Fusion Protein
Authors: Chesters P. M. , Howes K. , McKay J. C. , Payne L. N. , Venugopal K.
Published: July 2002

Avian leukosis virus subgroup J (ALV-J), the most recent member of the avian retroviruses, is predominantly associated with myeloid leukosis in meat-type chickens. We have previously demonstrated that the acutely transforming virus strain 966, isolated from an ALV-J-induced tumor, transformed peripheral blood monocyte and bone marrow cells in vitro and induced rapid-onset tumors, suggesting transduction of oncogenes (L. N. Payne, A. M. Gillespie, and K. Howes, Avian Dis. 37:438–450, 1993). In order to understand the molecular basis for the rapid transformation and tumor induction, we have determined the complete genomic structure of the provirus of the 966 strain. The sequence of the 966 provirus clone revealed that its genome is closely related to that of HPRS-103 but is defective, with the entire
pol
and parts of the
gag
and
env
genes replaced by a 1,491-bp sequence representing exons 2 and 3 of the c-
myc
gene. LSTC-IAH30, a stable cell line derived from turkey monocyte cultures transformed by the 966 strain of ALV-J, expressed a 72-kDa Gag-Myc fusion protein. The identification of the
myc
gene in 966 virus as well as in several other ALV-J-induced tumors suggested that the induction of myeloid tumors by this new subgroup of ALV occurs through mechanisms involving the activation of the c-
myc
oncogene.
Strength of Envelope Protein Interaction Modulates Cytopathicity of Measles Virus
Authors: Plemper Richard K. , Hammond Anthea L. , Gerlier Denis , Fielding Adele K. , Cattaneo Roberto
Published: July 2002

To understand the molecular determinants of measles virus (MV) cytopathicity, we have characterized mutant viruses exhibiting a more-extensive cell-to-cell fusion while maintaining efficient replication to high titers. A virus which is modified by the addition of an 8-amino-acid Flag epitope tag at the cytoplasmic tail of its H (for MV hemagglutinin) envelope glycoprotein replicates efficiently, has an increased cytopathicity, possesses a greater infectivity per particle, and has an altered protein composition compared with that of unmodified MV. The mutant phenotype is not specifically linked to the epitope sequence, since an alternatively added HA (for influenza virus-derived hemagglutinin) epitope tag caused similar effects. We demonstrate that both epitope tags weaken the interaction between the H and fusion (F) glycoproteins in virus-infected cells. This reduction in strength of H/F interaction is independent of the presence of the viral matrix (M) protein. Viruses with this less stable complex are more sensitive to neutralization by a soluble octameric form of the CD46 receptor, consistent with their increased fusogenicity. Similar analyses of glycoproteins derived from MV strains with reduced cytopathicities confirm that the strength of H and F glycoprotein interaction is a modulator of viral fusogenicity.
Polarographic and Voltammetric Determination of 7-[4-Methyl-5-phenyl-2-(1,2,3-triazolyl)]-3-phenylcoumarin
Authors: Barek Jiří , Hrnčíř Roman
Published: July 2002

The polarographic behaviour of the optical whitening agent 7-[4-methyl-5-phenyl-2-(1,2,3-triazolyl)]-3-phenylcoumarin was studied in mixed aqueous-methanolic solutions. Conditions were found for quantitating the substance by tast polarography, differential pulse polarography, differential pulse voltammetry at a hanging mercury drop electrode, and adsorption stripping voltammetry over the concentration regions of 2 - 10, 0.1 - 10, 0.02 - 1 and 0.004 - 1 μmol l-1, respectively. The methods developed were applied to a direct determination of the substance in a technological product.
Constitution and Properties of the 8,8'-μ-(H2NO)=(1,2-C2B9H10)2-3-Co Bridged Cobaltaborane
Authors: Plešek Jaromír , Rajabi Farzaneh Hosseinpour , Vangani Veena , Fusek Jiří
Published: July 2002

Constitution of 8,8'-μ-H2N(-O-)(1,2-C2B9H10)2-3-Co sandwich has been elucidated 17 years after its first synthesis, via high resolution NMR methods supplemented by mass spectrometry. The species gives relevant "oximes" with acetone and benzaldehyde and is quantitatively methylated to the N,N'-dimethyl derivative, which shows an interesting redox disproportionation to a triatomically bridged sandwich with a 8,8'-μ-O-CH=N(Me)- bridge between both ligands. Several other "peculiar" reactions of this dimethyl derivative are discussed. On reductive cleavage of the parent hydroxylamine the non-bridged 8-HO-8-H3N(1,2-C3B3H10)2-3-Co zwitterion is obtained. Mono-, di- and trimethylated derivatives of this non-bridged species are characterized.
1H NMR Study of 3,5-Disubstituted 6-Oxo-1,6-dihydro-1,2,4-triazines
Authors: Nálepa Karel , Halama Aleš , Nevěčná Taťjana , Bekárek Vojtěch
Published: July 2002

1H NMR spectra have been measured of seven 3,5-disubstituted 6-oxo-1,6-dihydro-1,2,4-triazines, and tautomerism of these compounds has been evaluated in connection with the nature of substituents, medium, and temperature. The title compounds exist in their benzyl or benzylidene forms or as a mixture of both forms. Thermodynamic characteristics of the transition between the two forms have been determined from the temperature dependence of NMR spectra of three derivatives.
Nucleophilic Substitution in a Series of 4-Nitronicotinic Acid 1-Oxide Derivatives
Authors: Pohl Radek , Prutianov Viktor , Smrčková-Voltrová Svatava
Published: July 2002

Nucleophilic substitution of the nitro group in 4-nitro-3-pyridinecarboxanilide 1-oxide (IIa) afforded 4-hydroxy- (IIb), 4-chloro- (IIc), 4-methoxy- (IId), 4-ethoxy- (IIe), and 4-dimethylamino-3-pyridinecarboxanilide (IIf). The 1H and 13C NMR chemical shifts of the pyridine moiety were correlated with the Hammett constants of the substituent in position 4, with the exception of compound IIb. The reason of this phenomenon is discussed.
Synthesis of Enantiomeric N-(2-Phosphonomethoxypropyl) Derivatives of Purine and Pyrimidine Bases. I. The Stepwise Approach
Authors: Holý Antonín , Masojídková Milena
Published: July 2002

The (R)- and (S)-N-(2-phosphonomethoxypropyl) derivatives of purine and pyrimidine bases (PMP derivatives) exhibit very high activity against retroviruses. This paper describes the synthesis of enantiomeric 9-(2-phosphonomethoxypropyl)adenines (I and XXVII), 9-(2-phosphonomethoxypropyl)-2,6-diaminopurines (II and XXXI), 9-(2-phosphonomethoxypropyl)guanines (III and XXIX) and 1-(R)-(2-phosphonomethoxypropyl)cytosine (XIX) by alkylation of N-protected N-(2-hydroxypropyl) derivatives of the corresponding bases with bis(2-propyl) p-toluenesulfonyloxymethylphosphonate (X), followed by stepwise N- and O-deprotection of the intermediates. The key intermediates, N-(2-hydroxypropyl) derivatives IX and XXV, were obtained by alkylation of the appropriate heterocyclic base with (R)- or (S)-2-(2-tetrahydropyranyloxy)propyl p-toluenesulfonate (VII or XXIII) and acid hydrolysis of the resulting N-[2-(2-tetrahydropyranyloxy)propyl] derivatives VIII and XXII. The chiral synthons were prepared by tosylation of (R)- or (S)-2-(2-tetrahydropyranyloxy)propanol (VI or XXI) available by reduction of enantiomeric alkyl 2-O-tetrahydropyranyllactates V and XXI with sodium bis(2-methoxyethoxy)aluminum hydride. This approach was used for the synthesis of cytosine, adenine and 2,6-diaminopurine derivatives, while compounds derived from guanine were prepared by hydrolysis of 2-amino-6-chloropurine intermediates. Cytosine derivative IXe was also synthesized by alkylation of 4-methoxy-2-pyrimidone followed by ammonolysis of the intermediate IXf.
Study of the Growth Centres of the Anionic Polymerization of (Meth)acrylates. VI. MO LCAO SCF Study of the Model Dimer, Its Solvation and Aggregation States
Authors: Dybal Jiří , Kříž Jaroslav
Published: July 2002

The nature of the intramolecular coordination in dimethyl 2-lithio-2,4,4-trimethylglutarate (I) as the model of living dimer of methyl methacrylate was studied by comparison with the specific solvation of methyl 2-lithioisobutyrate, using ab initio SCF calculations with the 3-21G basis set. In both cases, electron-density donation from the incident oxygen leads to a weak coordination bond (20 to 30% of full covalency) accompanied by polarization and weakening of the original O-Li bond. The directionality of any O-Li or C-Li bond in all the systems under study is poor and the position of Li results from a complex interplay of covalent and electrostatic interactions with its molecular environment. The covalent part of the bond system can be characterized as a system of polycentric electron-defficient bonds. Possible conformational geometries of I were examined by ab initio calculations and the results were compared to those of the semiempirical MNDO method. The inclination of MNDO to create artificial local energy minima in previously unsuspected cases was detected and shown to be avoidable if the valence sphere of Li is saturated by electron donors. The formation of aggregation dimers of I was studied by MNDO and the most stable conformers were found. The study was paralleled for the di-tert-butyl ester analogue of I. The tendency of I to intramolecular coordination and self-aggregation is discussed in view of the known kinetics of the first steps of anionic propagation.
Light Scattering from Associating Polymers in Solution
Authors: Burchard Walther , Dolega Robert , Stockmayer Walter H.
Published: July 2002

The effects of polymolecularity on the second and third light-scattering virial coefficients are calculated for some sample distributions and compared to the values obtained from an approximate treatment by Burchard and coworkers. It is concluded that the Burchard scheme, designed to facilitate the evaluation of light scattering data for associating systems, is generally reliable.
Study of Structure and Reactivity of Spirobi-2(5H)-furanones
Authors: Jakubcová Mária , Végh Daniel , Leško Ján , Mastihuba Vladimír
Published: July 2002

Reactions of 4,9-dibromo-1,6-dioxaspiro[4.4]nona-3,8-dien-2,7-dione (I) and 3,7-dibromo-1,6- dioxaspiro[4.4]nona-3,8-dien-2,7-dione (II) with nucleophiles yielding spirolactones IIIa-IIIg are described. The ring opening reactions of spirobilactones are discussed.
Preparation of (R)-(-)-6,6'-Bis(3,5-dinitrobenzamido)biphenyl-2,2'-dicarboxylic Acid, a Potential Chiral HPLC Selector
Authors: Tichý Miloš , Závada Jiří
Published: July 2002

The title optically active diacid I has been prepared as a potential selector for chiral stationary phase in the HPLC separation of enantiomers.
Cobaltacarboranylacetylene 8,8'-(μ-CHC-CH2S)-(1,2-C2B9H10)2-3-Co(III): Synthesis, Characterization and Polymerization of New Substituted Acetylene
Authors: Vohlídal Jiří , Plešek Jaromír , Sedláček Jan , Císařová Ivana , Matějka Pavel , Heřmánek Stanislav
Published: July 2002

Synthesis, structure and properties of 8,8'-(μ-propargylthio)bis(1,2-dicarbollido)cobaltate, 8,8'-(μ-CHC-CH2S)-(1,2-C2B9H10)2-3-Co(III), are described (NMR, IR, and UV spectra, mass spectrum, X-ray structure, dipole moment) and transformation of this acetylenic monomer into a π-conjugated homopolymer is reported.
Annelation to the Quinazoline Ring. Preparation of Some Substituted 2H-Imidazo- and 2,3-Dihydropyrimido[1,2-c]quinazolines
Authors: Špirková Katarína , Stankovský Štefan
Published: July 2002

Preparation of some substituted 2H-imidazo[1,2-c]quinazolin-3-ones (2a-2f) and 2,3-dihydropyrimido[1,2-c]quinazolin-4-ones (3a-3c) by reaction of corresponding 3H-quinazoline-4-thiones (1a-1d) with amino acid esters is described. IR, 1H NMR and 13C NMR spectra of the compounds synthesized are presented.
Antioxidant Building Blocks I. The Unexpected C-Acetylation of 2,6-Di-tert-butylphenol with Isopropenyl Acetate
Authors: Gizur Tibor , Ferenczy György G. , Ágai-Csongor Éva , Domány György
Published: July 2002

While the reaction of some 2-substituted and 2,6-disubstituted phenols with isopropenyl acetate resulted in the corresponding phenol acetates, in the reaction of 2,6-di-tert-butylphenol, a useful starting material of antioxidant building blocks, under the same conditions 4-acetyl-2,6-di- tert-butylphenol was the only product.
On the Stereoselectivity of the (-)-Dimenthyl Malonate Addition to α,β-Unsaturated Ketones
Authors: Šebo Ľubomír , Alföldi Juraj , Rihs Grety , Toma Štefan
Published: July 2002

The Michael addition of (-)-dimenthyl malonate to eight α,β-unsaturated ketones has been studied. The ratio of diastereomers was calculated on the basis of the 1H NMR spectra of the crude reaction products. The diastereomer excess varied from 10 to 50%, depending on the structure of the starting enone. The pure diastereomer produced by addition of (-)-dimenthyl malonate to 2-benzylidene-1,4-indandione was isolated by repeated crystallization. X-ray analysis has shown that the isomer is (-)-dimenthyl (R)-2-[1-(1,3-dioxoindan-2-yl)-1-phenylmethyl]malonate (5a). The predominating diastereomers of (-)-dimenthyl(3-ferrocenyl-3-oxophenylpropyl)malonate (1a) and (-)-dimenthyl-2-(1-(1,3-dioxo[3]ferrocenophan-2-yl)-1-phenyl malonate (6a) were also isolated in pure state by careful crystallization.
Comparison of (R)-(-)-6,6'-Bis(3,5-dinitrobenzamido)biphenyl-2,2'-dicarboxylic and (S)-(+)-6,6'-Bis-(3,5-dinitrobenzamidomethyl)biphenyl-2,2'-dicarboxylic Acids as Chiral HPLC Selectors
Authors: Tichý Miloš , Ridvan Luděk , Závada Jiří
Published: July 2002

The title optically active diacids (R)-I and (S)-II of known absolute configuration were investigated as selectors in HPLC separation of enantiomers. With a standard set of benzamido alcohols and biaryl compounds, the separation was less efficient and less general than that found for selectors based on studied previously.
Preparation of New Optically Active Furanoids Containing Various Aza-Heterocyclic Moieties
Authors: Werfeli Ali , Čejka Jan , Klecán Ondřej , Kratochvíl Bohumil , Kuthan Josef
Published: July 2002

The aldehyde 2 prepared from [5-(2,3-O-isopropylidene-β-D-erythrofuranosyl)-2-methylfuran-3-yl]methanol (1) was converted to E,Z-oximes 3, 4 and imine derivative 5 by the reaction with hydroxylamine and pyridin-2-yl amine, respectively. The Knoevenagel reaction with malonic acid afforded exclusively the 3-substituted acrylic acid 6 while corresponding Hantzsch 1,4-dihydropyridines 7 and 8 were obtained by the reaction of aldehyde 2 with ethyl acetoacetate or acetylacetone and ammonia. 3,5-Dicyano-1,4-dihydropyridine derivative 9 was isolated only in forms of hydrates after the reaction of aldehyde 2 with 3-aminocrotonitrile. 1,4-Dihydropyridines 7 and 9 were aromatized to corresponding pyridines 10 and 11. Isoxazoles 12, 13 and isoxazolines 14, 15 were prepared by 1,3-cycloaddition of appropriate dienophiles to a nitrile oxide generated from aldoximes 3, 4. Ferricyanide oxidation of 1-{[5-(2,3-O-isopropylidene-β-D-erythrofuranosyl)-2-methylfuran-3-yl]methyl}pyridinium chloride (17a), -3-methylpyridinium chloride (19a) and the corresponding isoquinolinium chloride 21a gave optically active pyridin-2(1H)-ones 22, 23 and 2H-isoquinolone derivative 24 while the procedure with 2-methylpyridinium salt 18a and 4-methylpyridinium salt 20a led to complex mixtures of products. Reaction of 2,4,6-triphenylpyrylium perchlorate with furanoid amine 26 afforded a mixture of major 2,4,6-triphenylpyridine, minor pyridinium perchlorate 25 and primary alcohol 1. The absolute configuration of the studied compounds has been confirmed by X-ray analysis of the Schiff base 5.
A Convenient One-Pot Synthesis of α-Isothiocyanatoethers and Unusual Course of Some of Its Nucleophilic Displacement Reactions
Authors: Bernát Juraj , Kristian Pavol , Guspanová Jana , Imrich Ján , Bušová Tatiana
Published: July 2002

A simple new method has been devised for the preparation of α-isothiocyanatoethers 1a-1f in good yields by reaction of PO(NCS)3 or (PhO)2PONCS with an equimolar mixture of aldehydes and alcohols. The course of nucleophilic additions of methanol, amines and hydrazine to 1a-1f is described.
Sterically Crowded Heterocycles. IX. New α,β-Unsaturated Ketones Containing Imidazo[1,2-a]quinoline, Imidazo[2,1-a]isoquinoline, Benzo[h]imidazo[1,2-a]quinoline and Imidazo[1,2-a]-1,10-phenanthroline Moieties
Authors: Böhm Stanislav , Strnad Tomáš , Ruppertová Iveta , Kuthan Josef
Published: July 2002

(Z)-1,3-Diphenyl-3-(2-phenylimidazo[1,2-a]heteroaryl)prop-2-en-1-ones 2-6 and isomeric [1-heteroaryl-3,5-diphenylpyrrol-2-yl]phenylmethanones 17-20 were prepared by the ferricyanide oxidation of quaternary pyridinium salts 12-16. Axial chirality and helicity of the molecules of 4 and 6 are discussed using various energy data obtained by the quantum chemical PM3 method.
Synthesis and Reactions of 8-Hydrazinofuro[2',3':4,5]pyrrolo-[1,2-d][1,2,4]triazines
Authors: Krutošíková Alžbeta , Mastik Slavomír , Dandárová Miloslava , Lyčka Antonín
Published: July 2002

5-Ethyl-8-hydrazinofuro[2',3':4,5]pyrrolo[1,2-d][1,2,4]triazine (4a) and its 2-methyl derivative 4b were prepared from 4H-furo[3,2-b]pyrrole-5-carbohydrazides 1a and 1b, respectively. Compounds 1a and 1b reacted with triethyl orthopropionate to give 2a and 2b which afforded with phosphorus(V) sulfide corresponding thiones 3a and 3b. The title compounds 4a and 4b were made by treatment of 3a and 3b with hydrazine hydrate. By reactions of triethyl orthoesters with the title compounds and similar derivatives furo[2'3':4,5]pyrrolo[1,2-d][1,2,4]triazolo[3,4-f][1,2,4]triazines 5a-5j were prepared. Reactions of compounds 4 with some aldehydes and isocyanates led to hydrazones 6a-6c and semicarbazones 7a and 7b, respectively.
The Incorporation of SF6 Into Graphite and Other Materials
Authors: Vondrák Jiří , Sedlaříková Marie , Liedermann Karel
Published: July 2002

The formation of intercalation compounds from sulfur fluoride SF6 and layered substrates was observed. The process is accelerated if the substrate had been preexposed to SF6 partly decomposed by electric spark discharges. The amount of intercalated SF6 decreases in the series graphite > molybdenum disulfide > boron nitride. The promotion effect is explained by exfoliation of the substrate due to highly reactive fission products of SF6.
Synthesis and Spectral Properties of Methyl 6-Acetyl- or 6-Cyano-3-amino-2-benzoyl-7-furyl-5-methylindolizine-8-carboxylates
Authors: Chudík Miloslav , Marchalín Štefan , Havrilová Katarína
Published: July 2002

Good yields of methyl 6-acetyl- or 6-cyano-3-amino-2-benzoyl-5-methyl-7-(5-substituted-2-furyl)indolizine-8-carboxylates (5a-5f) were obtained in the reaction of corresponding 5-acetyl- or 5-cyano-2-formyl-4-(5-substituted-2-furyl)-6-methyl-1,4-dihydropyridine-3-carboxylated (4a-4f) with 3-phenyl-3-oxopropanenitrile. Spectral properties of the indolizines 5 are discussed.
Extraction of Selected Organic Bases from Water into Chloroform by Means of the Cobaltacarborane Anion
Authors: Navrátil Oldřich , Skaličan Zdeněk , Kobliha Zbyněk , Halámek Emil
Published: July 2002

The cobaltacarborane anion labelled with 60Co was used to study the solvent extraction and stability of its ion associates with a series of organic nitrogen base cations or quaternary salts, some of which are psychoactive. The aqueous phase was 0.1 M HCl, the organic phase was chloroform. The extraction constants of the ion associates were calculated. A method was devised for competitive extraction of ion associates with additional dye anions which are used in the extraction-photometric determination of selected bases.
Progress in Partial Synthesis of a Marine Secosterol from Gersemia fruticosa: Preparation of the Steroidal Core Unit
Authors: Kuhl Alexander , Kreiser Wolfgang
Published: July 2002

The synthesis of the requisite protected steroidal core unit 13 en route to secosterol 1, a cytotoxic constituent of the soft coral Gersemia fruticosa, is described. The conversion of the intermediate precursor 3 into 13 succeeds through oxidative side chain degradation, deoxygenation of C-12 via reductive desulfurization and cleavage of the C-ring moiety by ozonolysis.
New Potential Inhibitors of Pheromonal Attractionin the Oriental Fruit Moth, Cydia molesta
Authors: Hoskovec Michal , Hovorka Oldřich , Kalinová Blanka , Koutek Bohumír , Svatoš Aleš , Šaman David , Vlček Kamil , Vrkoč Jan
Published: July 2002

New analogues of (Z)-dodec-8-en-1-yl acetate (Z8-12:OAc, 1), the main sex pheromone component of the Oriental fruit moth, Cydia molesta, were designed by formally transferring the terminal propyl group from the C-9 to the C-7 position to form vinyl-branched (2, 3) or, after isomerization, ethylidene-branched (4) structures and by replacing the -CH=CH- grouping by the -S-CH2- moiety (5, 6). Their biological activities were studied both electrophysiologically and behaviourally (laboratory mating and wind tunnel experiments). All the structural modifications resulted in analogues whose electroantennographic activities were lower than that of 1 following the order 1 >> 6 ≈ 5 >> 2 ≈ 4 ≈ 3. The single sensillum recording activities indicated that all the analogues stimulate the same Z8-12:OAc receptor neurone. In behavioural experiments, the analogues were generally found to reduce the ability of males to find a pheromone source, however, to different degrees. The highest inhibitory effect (90%) was observed for the thia analogues 5 and 6. The results support the view that the inhibitory properties of the analogues should not be entirely associated with their pheromone-mimicking capabilities.
Catalyst Selection for Hydrogenation of 1,2-Dihydroacenaphthylene
Authors: Hanika Jiří , Sporka Karel , Macoun Petr , Kysilka Vladimír
Published: July 2002

The activity of ruthenium, palladium, and nickel catalysts for the hydrogenation of 1,2-dihydroacenaphthylene in cyclohexane solution was studied at temperatures up to 180 °C and pressures up to 8 MPa. The GC-MS technique was used to identify most of the perhydroacenaphthylene stereoisomers, whose fractions in the product were found dependent on the nature of the active component of the catalyst. The hydrogenation was fastest on the palladium catalyst (3% Pd/C). The nickel catalyst Ni-NiO/Al2O3, which is sufficiently active also after repeated use, can be recommended for practical application. The activation energy of 1,2-dihydroacenaphthylene hydrogenation using this catalyst is 17 kJ/mol, the reaction order with respect to hydrogen is unity.
Reaction of 18β,19β-Epoxylupan-21-one Derivatives with Acids: A Way to 21,22-Disubstituted Lup-18-ene Triterpenoids
Authors: Klinotová Eva , Čermáková Jitka , Rejzek Martin , Křeček Václav , Sejbal Jan , Olšovský Petr , Klinot Jiří
Published: July 2002

Depending on the conditions and the acid employed, 18β,19β-epoxy-28-hydroxy- 21-oxolupan-3β-yl acetate (2a) and 18β,19β-epoxy-21-oxolupane-3β,28-diyl diacetate (2b) on treatment with acid gave three types of products: (i) 28-nor derivatives: 21-oxo-28-norlupa-16,18-dien-3β-yl acetate (6), 19β-hydroxy-21-oxo-28-norlup-17-en-3β-yl acetate (7) and 17ξ-hydroxy-21-oxo-28-norlup-18-en-3β-yl acetate (8), (ii) lupa-12,18-dien-21-ones 4a and 4b, and (iii) 22β-substituted lup-18-en-21-one derivatives of the type 5. The formation of 22β-substituted derivatives of the type 5 probably proceeds in the enol form of epoxy ketone 2. Opening of the epoxide ring with shift of the double bond to position 19(21) and attack by nucleophilic species at C-22 followed by elimination of water and re-formation of the 22-oxo group leads to derivatives of the type 5.
Intramolecular Mannich Reaction of 2-Oxotryptamines with Acetone Yielding Spiro[indole-3,3'-pyrrolidin]-2-ones
Authors: Incze Mária , Dörnyei Gábor , Kajtár-Peredy Mária , Szántay Csaba
Published: July 2002

2-Oxotryptamines undergo intramolecular Mannich-type cyclization with acetone to give 2',2'-dimethylspiro[indole-3,3'-pyrrolidin]-2-ones. In presence of an alkylating reagent, this reaction gives the corresponding 1'-substituted products.
Synthesis of 1,1,5,6-Tetramethyl- and 7-Isopropyl-1,1-dimethyl-1,2,3,4-tetrahydronaphthalene
Authors: Mane Ramchandra Bhimrao , Kadam Abhijit Jaysingrao , Salunkhe Rajashree Sandeep
Published: July 2002

4-(2,3-Dimethylphenyl)butanoic acid (4) was treated with excess of methyllithium to yield 5-(2,3-dimethylphenyl)-2-methylpentan-2-ol (6) which was cyclodehydrated using Dowex 50W-X8 resin, trifluoroacetic acid or polyphosphoric acid (PPA) to furnish 1,1,5,6-tetramethyl-1,2,3,4-tetrahydronaphthalene (1). The acid 4 was cyclized with PPA to furnish 5,6-dimethyl-3,4-dihydronaphthalen-1(2H)-one (5) which was converted into 1 by reaction with dimethylzinc and titanium tetrachloride. 4-(4-Isopropylphenyl)butanoic acid (7) on esterification followed by Grignard reaction with methylmagnesium iodide furnished 5-(4-isopropylphenyl)-2-methylpentan-2-ol (9), which was cyclodehydrated as above to yield 7-isopropyl-1,1-dimethyl-1,2,3,4-tetrahydronaphthalene (2).
Reactions of Zirconacyclopentadienes with Propargyl Halides Leading to (Buta-2,3-dien-1-yl)benzenes
Authors: Kotora Martin , Noguchi Yoshinori , Takahashi Tamotsu
Published: July 2002

The reaction of 1,1-bis(η5-cyclopentadienyl)-1-zirconacyclopenta-2,4-dienes with propargyl halides in the presence of a catalytic or a stoichiometric amount of CuCl afforded benzene derivatives. This reaction involves SN2' type of attack of organocopper intermediate to propargyl halide followed by intramolecular carbometallation, and coupling with the second molecule of propargyl halide.