bluuebunny/crossref_metadata_2025 huggingface dataset:
The Interaction of Bacteriophage P2 B Protein with
Escherichia coli
DnaB Helicase
Authors: Odegrip Richard , Schoen Stephan , Haggård-Ljungquist Elisabeth , Park Kyusung , Chattoraj Dhruba K.
Published: July 2002

Bacteriophage P2 requires several host proteins for lytic replication, including helicase DnaB but not the helicase loader, DnaC. Some genetic studies have suggested that the loading is done by a phage-encoded protein, P2 B. However, a P2 minichromosome containing only the P2 initiator gene
A
and a marker gene can be established as a plasmid without requiring the P2
B
gene. Here we demonstrate that P2 B associates with DnaB. This was done by using the yeast two-hybrid system in vivo and was confirmed in vitro, where
35
S-labeled P2 B bound specifically to DnaB adsorbed to Q Sepharose beads and monoclonal antibodies directed against the His-tagged P2 B protein were shown to coprecipitate the DnaB protein. Finally, P2 B was shown to stabilize the opening of a reporter origin, a reaction that is facilitated by the inactivation of DnaB. In this respect, P2 B was comparable to λ P protein, which is known to be capable of binding and inactivating the helicase while acting as a helicase loader. Even though P2 B has little similarity to other known or predicted helicase loaders, we suggest that P2 B is required for efficient loading of DnaB and that this role, although dispensable for P2 plasmid replication, becomes essential for P2 lytic replication.
N-Glycans of F Protein Differentially Affect Fusion Activity of Human Respiratory Syncytial Virus
Authors: Zimmer Gert , Trotz Ina , Herrler Georg
Published: July 2002

The human respiratory syncytial virus (Long strain) fusion protein contains six potential N-glycosylation sites: N27, N70, N116, N120, N126, and N500. Site-directed mutagenesis of these positions revealed that the mature fusion protein contains three N-linked oligosaccharides, attached to N27, N70, and N500. By introducing these mutations into the F gene in different combinations, four more mutants were generated. All mutants, including a triple mutant devoid of any N-linked oligosaccharide, were efficiently transported to the plasma membrane, as determined by flow cytometry and cell surface biotinylation. None of the glycosylation mutations interfered with proteolytic activation of the fusion protein. Despite similar levels of cell surface expression, the glycosylation mutants affected fusion activity in different ways. While the N27Q mutation did not have an effect on syncytium formation, loss of the N70-glycan caused a fusion activity increase of 40%. Elimination of both N-glycans (N27/70Q mutant) reduced the fusion activity by about 50%. A more pronounced reduction of the fusion activity of about 90% was observed with the mutants N500Q, N27/500Q, and N70/500Q. Almost no fusion activity was detected with the triple mutant N27/70/500Q. These data indicate that N-glycosylation of the F
2
subunit at N27 and N70 is of minor importance for the fusion activity of the F protein. The single N-glycan of the F
1
subunit attached to N500, however, is required for efficient syncytium formation.
Adaptation of Chimeric Retroviruses In Vitro and In Vivo: Isolation of Avian Retroviral Vectors with Extended Host Range
Authors: Barsov Eugene V. , Payne William S. , Hughes Stephen H.
Published: July 2002

We have designed and characterized two new replication-competent avian sarcoma/leukosis virus-based retroviral vectors with amphotropic and ecotropic host ranges. The amphotropic vector RCASBP-M2C(797-8), was obtained by passaging the chimeric retroviral vector RCASBP-M2C(4070A) (6) in chicken embryos. The ecotropic vector, RCASBP(Eco), was created by replacing the
env
-coding region in the retroviral vector RCASBP(A) with the
env
region from an ecotropic murine leukemia virus. It replicates efficiently in avian DFJ8 cells that express murine ecotropic receptor. For both vectors, permanent cell lines that produce viral stocks with titers of about 5 × 10
6
CFU/ml on mammalian cells can be easily established by passaging transfected avian cells. Some chimeric viruses, for example, RCASBP(Eco), replicate efficiently without modifications. For those chimeric viruses that do require modification, adaptation by passage in vitro or in vivo is a general strategy. This strategy has been used to prepare vectors with altered host range and could potentially be used to develop vectors that would be useful for targeted gene delivery.
Hairpin Loop Structure in the 3′ Arm of the Influenza A Virus Virion RNA Promoter Is Required for Endonuclease Activity
Authors: Leahy Michael B. , Dobbyn Helen C. , Brownlee George G.
Published: July 2002

Previous studies have shown that the 5′ arm of the influenza A virus virion RNA promoter requires a hairpin loop structure for efficient endonuclease activity of influenza virus RNA polymerase, an activity that is required for the cap-snatching activity of primers from host pre-mRNA. Here we examine whether a hairpin loop is also required in the 3′ arm of the viral RNA promoter. We study point mutations at each nucleotide position (1 to 12) within the 3′ arm of the promoter as well as complementary “rescue” mutations which restored base pairing in the stem of a potential hairpin loop. Our results suggest that endonuclease activity is absolutely dependent on the presence of a 3′ hairpin loop structure. This is the first direct evidence for RNA secondary structure within the 3′ arm being required for a specific stage, i.e., endonuclease cleavage, in the influenza virus replicative cycle.
Conserved CDR3 Regions in T-Cell Receptor (TCR) CD8+T Cells That Recognize the Tax11-19/HLA-A*0201 Complex in a Subject Infected with Human T-Cell Leukemia Virus Type 1: Relationship of T-Cell Fine Specificity and Major Histocompatibility Complex/Peptide/TCR Crystal Structure
Authors: Bourcier Katarzyna D. , Lim Dong-Gyun , Ding Yuan-Hua , Smith Kathrine J. , Wucherpfennig Kai , Hafler David A.
Published: July 2002

We investigated the T-cell receptor (TCR) repertoire of CD8+T cells that recognize the Tax11-19 immunodominant epitope of Tax protein expressed by human T-cell leukemia virus (HTLV-1) that is implicated in the disease HTLV-1-associated myelopathy (HAM/TSP). A panel of Tax11-19-reactive CD8+T-cell clones was generated by single-cell cloning of Tax11-19/HLA-A*0201 tetramer-positive peripheral blood lymphocytes from an HTLV-1-infected individual. The analyses of TCR usage revealed that the combination of diverse TCR alpha and beta chains could be used for the recognition of Tax11-19 but the major population of T-cell clones (15 of 24 clones) expressed the TCR V beta 13S1 and V alpha 17 chain. We found striking similarities in CDR3 regions of TCR alpha and beta chains between our major group of CD8+T-cell clones and those originating from different subjects as previously reported, including TCRs with resolved crystal structures. A 3-amino-acid sequence (PG-G) in the CDR3 region of the V beta chain was conserved among all the Tax11-19-reactive T-cell clones expressing V beta 13S1 and V alpha 17 chains. Conserved amino acids in the CDR3 region do not directly contact the Tax11-19 peptide, as corroborated by the crystal structure of B7-TCR, a TCR that is almost identical to VB13S1 clones isolated in this study. Analysis of fine peptide specificity using altered peptide ligands (APL) of Tax11-19 revealed a similar recognition pattern among this panel of T-cell clones. These data suggest that the PG-G amino acids in the CDR3 beta loop provide a structural framework necessary for the maintenance of the tertiary TCR structure.
The
cis
-Acting Family of Repeats Can Inhibit as well as Stimulate Establishment of an
oriP
Replicon
Authors: Leight Elizabeth R. , Sugden Bill
Published: July 2002

Previously we have shown that the establishment of an
oriP
replicon is dependent on its epigenetic modification, which occurs in only 1 to 10% of proliferating cells (E. R. Leight and B. Sugden, Mol. Cell. Biol. 21:4149–4161, 2001). To gain insights into the
cis
-acting requirements for the establishment of
oriP
replicons, we monitored the replication of
oriP
plasmid derivatives for several weeks following their introduction into cells. In EBNA-1-positive 143B and H1299 cells, plasmids containing only the region of dyad symmetry (DS) of
oriP
replicated but were lost more rapidly from cells than were
oriP
plasmids, demonstrating that the family of repeats (FR) of
oriP
acts in
cis
to stimulate replication in these cells. Unexpectedly, we found that the DS plasmid was established efficiently in 293/EBNA-1 cells, being lost at a rate of only 8% per cell generation over 24 days posttransfection. However, plasmids containing the FR in addition to the DS of
oriP
replicated but were lost at a rate of approximately 30% per cell generation in 293/EBNA-1 cells, indicating that the FR inhibits
oriP
's establishment in this cell line. FR's enhancement of transcription of a promoter in
cis
and FR's ability to inhibit replication fork movement do not account solely for
oriP
's inefficient establishment. In addition, DNA looping between FR and DS neither stimulates nor inhibits replication. Deletion of 11 EBNA-1 binding sites in the FR or replacement of the FR with DS sequences, however, does overcome the inhibitory activity of the FR, thereby allowing efficient establishment of the
oriP
derivative in 293/EBNA-1 cells.
The Retroviruses Human Immunodeficiency Virus Type 1 and Moloney Murine Leukemia Virus Adopt Radically Different Strategies To Regulate Promoter-Proximal Polyadenylation
Authors: Furger Andre , Monks Joan , Proudfoot Nick J.
Published: July 2002

Maximal gene expression in retroviruses requires that polyadenylation in the 5′ long terminal repeat (LTR) is suppressed. In human immunodeficiency virus type 1 (HIV-1) the promoter-proximal poly(A) site is blocked by interaction of U1 snRNP with the closely positioned major splice donor site (MSD) 200 nucleotides downstream. Here we investigated whether the same mechanism applies to down-regulate 5′ LTR polyadenylation in Moloney murine leukemia virus (MoMLV). Although the same molecular architecture is present in both viruses, the MoMLV poly(A) signal in the 5′ LTR is active whether or not the MSD is mutated. This surprising difference between the two retroviruses is not due to their actual poly(A) signals or MSD sequences, since exchange of either element between the two viral sequences does not alter their ability to regulate 5′ LTR poly(A) site use. Instead we demonstrate that sequence between the cap and AAUAAA is required for MSD-dependent poly(A) regulation in HIV-1, indicating a key role for this part of the LTR in poly(A) site suppression. We also show that the MoMLV poly(A) signal is an intrinsically weak RNA-processing signal. This suggests that in the absence of a poly(A) site suppression mechanism, MoMLV is forced to use a weak poly(A) signal.
Rapid CD4+T-Cell Loss Induced by Human Immunodeficiency Virus Type 1NCin Uninfected and Previously Infected Chimpanzees
Authors: Novembre Francis J. , de Rosayro Juliette , Nidtha Soumya , O'Neil Shawn P. , Gibson Terri R. , Evans-Strickfaden Tammy , Hart Clyde E. , McClure Harold M.
Published: July 2002

To investigate the pathogenicity of a virus originating in a chimpanzee with AIDS (C499), two chimpanzees were inoculated with a plasma-derived isolate termed human immunodeficiency virus type 1NC(HIV-1NC). A previously uninfected chimpanzee, C534, experienced rapid peripheral CD4+T-cell loss to fewer than 26 cells/μl by 14 weeks after infection. CD4+T-cell depletion was associated with high plasma HIV-1 loads but a low virus burden in the peripheral lymph node. The second chimpanzee, C459, infected 13 years previously with HIV-1LAV, experienced a more protracted course of peripheral CD4+T-cell loss after HIV-1NCinoculation, resulting in fewer than 200 cells/μl by 96 weeks postinoculation. The quantities of viral RNA in the plasma and peripheral lymph node from C459 were below the lower limits of detection prior to inoculation with HIV-1NCbut were significantly and persistently increased after superinfection, with HIV-1NCrepresenting the predominant viral genotype. These results show that viruses derived from C499 are more pathogenic for chimpanzees than any other HIV-1 isolates described to date.
Muscle-Specific Overexpression of the Adenovirus Primary Receptor CAR Overcomes Low Efficiency of Gene Transfer to Mature Skeletal Muscle
Authors: Nalbantoglu J. , Larochelle N. , Wolf E. , Karpati G. , Lochmuller H. , Holland P. C.
Published: July 2002

Significant levels of adenovirus (Ad)-mediated gene transfer occur only in immature muscle or in regenerating muscle, indicating that a developmentally regulated event plays a major role in limiting transgene expression in mature skeletal muscle. We have previously shown that in developing mouse muscle, expression of the primary Ad receptor CAR is severely downregulated during muscle maturation. To evaluate how global expression of CAR throughout muscle affects Ad vector (AdV)-mediated gene transfer into mature skeletal muscle, we produced transgenic mice that express the CAR cDNA under the control of the muscle-specific creatine kinase promoter. Five-month-old transgenic mice were compared to their nontransgenic littermates for their susceptibility to AdV transduction. In CAR transgenics that had been injected in the tibialis anterior muscle with AdVCMVlacZ, increased gene transfer was demonstrated by the increase in the number of transduced muscle fibers (433 ± 121 in transgenic mice versus 8 ± 4 in nontransgenic littermates) as well as the 25-fold increase in overall β-galactosidase activity. Even when the reporter gene was driven by a more efficient promoter (the cytomegalovirus enhancer–chicken β-actin gene promoter), differential transducibility was still evident (893 ± 149 versus 153 ± 30 fibers;
P
< 0.001). Furthermore, a fivefold decrease in the titer of injected AdV still resulted in significant transduction of muscle (253 ± 130 versus 14 ± 4 fibers). The dramatic enhancement in AdV-mediated gene transfer to mature skeletal muscle that is observed in the CAR transgenics indicates that prior modulation of the level of CAR expression can overcome the poor AdV transducibility of mature skeletal muscle and significant transduction can be obtained at low titers of AdV.
SLAM (CD150)-Independent Measles Virus Entry as Revealed by Recombinant Virus Expressing Green Fluorescent Protein
Authors: Hashimoto Koji , Ono Nobuyuki , Tatsuo Hironobu , Minagawa Hiroko , Takeda Makoto , Takeuchi Kaoru , Yanagi Yusuke
Published: July 2002

Wild-type measles virus (MV) strains use human signaling lymphocyte activation molecule (SLAM) as a cellular receptor, while vaccine strains such as the Edmonston strain can use both SLAM and CD46 as receptors. Although the expression of SLAM is restricted to cells of the immune system (lymphocytes, dendritic cells, and monocytes), histopathological studies with humans and experimentally infected monkeys have shown that MV also infects SLAM-negative cells, including epithelial, endothelial, and neuronal cells. In an attempt to explain these findings, we produced the enhanced green fluorescent protein (EGFP)-expressing recombinant MV (IC323-EGFP) based on the wild-type IC-B strain. IC323-EGFP showed almost the same growth kinetics as the parental recombinant MV and produced large syncytia exhibiting green autofluorescence in SLAM-positive cells. Interestingly, all SLAM-negative cell lines examined also showed green autofluorescence after infection with IC323-EGFP, although the virus hardly spread from the originally infected individual cells and thus did not induce syncytia. When the number of EGFP-expressing cells after infection was taken as an indicator, the infectivities of IC323-EGFP for SLAM-negative cells were 2 to 3 logs lower than those for SLAM-positive cells. Anti-MV hemagglutinin antibody or fusion block peptide, but not anti-CD46 antibody, blocked IC323-EGFP infection of SLAM-negative cells. This infection occurred under conditions in which entry via endocytosis was inhibited. These results indicate that MV can infect a variety of cells, albeit with a low efficiency, by using an as yet unidentified receptor(s) other than SLAM or CD46, in part explaining the observed MV infection of SLAM-negative cells in vivo.
Intracellular Localization of the
Peanut Clump Virus
Replication Complex in Tobacco BY-2 Protoplasts Containing Green Fluorescent Protein-Labeled Endoplasmic Reticulum or Golgi Apparatus
Authors: Dunoyer Patrice , Ritzenthaler Christophe , Hemmer Odile , Michler Pierre , Fritsch Christiane
Published: July 2002

RNA-1 of
Peanut clump virus
(PCV) encodes the proteins P131 and P191, containing the signature motifs of replication proteins, and P15, which regulates viral RNA accumulation. In PCV-infected protoplasts both P131 and P191 were immunodetected in the perinuclear region. Laser scanning confocal microscopy (LSCM) showed that P131 and P191 colocalized with neosynthesized 5-bromouridine 5′-triphosphate-labeled RNA and double-stranded RNA, demonstrating that they belong to the replication complex. On the contrary, the P15 fused to the enhanced green fluorescent protein (EGFP) never colocalized with the two proteins. In endoplasmic reticulum (ER)-GFP transgenic BY-2 protoplasts, the distribution of the green fluorescent-labeled ER was strongly modified by PCV infection. LSCM showed that both P131 and P191 colocalized with ER green fluorescent bodies accumulating around the nucleus during infection. The replication process was not inhibited by cerulenin and brefeldin A, suggesting that PCV replication does not depend on de novo-synthesized membrane and does not require transport through the Golgi apparatus. Electron microscopy of ultrathin sections of infected protoplasts showed aggregates of broken ER but also visualized vesicles, some of which resembled modified peroxisomes. The results suggest that accumulation of PCV during infection is accompanied by specific association of PCV RNA-1-encoded proteins with membranes of the ER and other organelles. The concomitant extensive rearrangement of these membranous structures leads to the formation of intracellular compartments in which synthesis and accumulation of the viral RNA occur in defined areas.
Differential Activation of Influenza A Virus Endonuclease Activity Is Dependent on Multiple Sequence Differences between the Virion RNA and cRNA Promoters
Authors: Leahy Michael B. , Zecchin Giuseppe , Brownlee George G.
Published: July 2002

Influenza virus endonuclease activity was studied in vitro with model virion RNA (vRNA) and cRNA molecules. We show that endonuclease activity can be partially rescued by transplanting vRNA-like promoter features into the model cRNA promoter. This study defines three distinctive features within the vRNA promoter—absent in the cRNA promoter—that are required for endonuclease cleavage.
Analysis of Hantavirus Genetic Diversity in Argentina: S Segment-Derived Phylogeny
Authors: Bohlman Marlene C. , Morzunov Sergey P. , Meissner John , Taylor Mary Beth , Ishibashi Kimiko , Rowe Joan , Levis Silvana , Enria Delia , St. Jeor Stephen C.
Published: July 2002

Nucleotide sequences were determined for the complete S genome segments of the six distinct hantavirus genotypes from Argentina and for two cell culture-isolated Andes virus strains from Chile. Phylogenetic analysis indicates that, although divergent from each other, all Argentinian hantavirus genotypes group together and form a novel phylogenetic clade with the Andes virus. The previously characterized South American hantaviruses Laguna Negra virus and Rio Mamore virus make up another clade that originates from the same ancestral node as the Argentinian/Chilean viruses. Within the clade of Argentinian/Chilean viruses, three subclades can be defined, although the branching order is somewhat obscure. These are made of (i) “Lechiguanas-like” virus genotypes, (ii) Maciel virus and Pergamino virus genotypes, and (iii) strains of the Andes virus. Two hantavirus genotypes from Brazil, Araraquara and Castello dos Sonhos, were found to group with Maciel virus and Andes virus, respectively. The nucleocapsid protein amino acid sequence variability among the members of the Argentinian/Chilean clade does not exceed 5.8%. It is especially low (3.5%) among oryzomyine species-associated virus genotypes, suggesting recent divergence from the common ancestor. Interestingly, the Maciel and Pergamino viruses fit well with the rest of the clade although their hosts are akodontine rodents. Taken together, these data suggest that under conditions in which potential hosts display a high level of genetic diversity and are sympatric, host switching may play a prominent role in establishing hantavirus genetic diversity. However, cospeciation still remains the dominant factor in the evolution of hantaviruses.
Role of Lymphotoxin α in T-Cell Responses during an Acute Viral Infection
Authors: Suresh M. , Lanier Gibson , Large Mary Katherine , Whitmire Jason K. , Altman John D. , Ruddle Nancy H. , Ahmed Rafi
Published: July 2002

The importance of lymphotoxin α (LTα) in lymphoid organogenesis is well established. Although LTα has been implicated in the pathogenesis of T-cell-mediated immunopathologies, the requirement for LTα in T-cell activation and effector function in vivo is not well understood. To determine the role of LTα in T-cell activation in vivo, we compared the generation of antigen-specific T-cell responses between wild type (+/+) and LTα-deficient (LTα−/−) mice during an acute infection with lymphocytic choriomeningitis virus (LCMV). Our studies showed that LCMV-infected LTα−/−mice had a profound impairment in the activation and expansion of virus-specific CD8 T cells in the spleen, as determined by cytotoxicity assays, intracellular staining for gamma interferon, and staining with major histocompatibility complex class I tetramers. Further, the nonlymphoid organs of LTα−/−mice also contained substantially lower number of LCMV-specific CD8 T cells than those of +/+ mice. Greatly reduced virus-specific CD8 T-cell responses in LTα−/−mice led to a defect in LCMV clearance from the tissues. In comparison to that in +/+ mice, the activation of LCMV-specific CD4 T cells was also significantly attenuated in LTα−/−mice. Adoptive transfer experiments were conducted to determine if abnormal lymphoid architecture in LTα−/−mice caused the impairment in the activation of LCMV-specific T-cell responses. Upon adoptive transfer into +/+ mice, the activation and expansion of LCMV-specific LTα−/−T cells were restored to levels comparable to those of +/+ T cells. In a reciprocal cell transfer experiment, activation of +/+ T cells was significantly reduced upon transfer into LTα−/−mice. These results showed that impairment in the activation of LCMV-specific T cells in LTα−/−mice may be due to abnormal lymphoid architecture and not to an intrinsic defect in LTα−/−T cells.
Kinetics and Mechanism of Acid Catalyzed Decomposition of 1-Phenyl-3,3-dialkyltriazenes
Authors: Ludwig Miroslav , Valášková Pavla , Pytela Oldřich
Published: July 2002

Five model 1-phenyl-3,3-dialkyltriazenes (methyl, ethyl, 2-propyl, butyl, cyclohexyl) have been synthesized and their acid-catalyzed decomposition kinetics have been investigated spectrophotometrically in aqueous ethanol (40 vol.%) with pivalic acid as the catalyst. The results show that the rate-determining step is catalyzed by the proton. The decrease in the observed rate constant at higher concentrations of pivalic acid is explained by the formation of an unreactive complex of the nondissociated acid and respective triazene. The steric effect of alkyl groups on the catalytic rate constants is discussed.
Chemometrical Analysis of Substituent Effects. V. ortho Effect
Authors: Pytela Oldřich , Liška Josef
Published: July 2002

The dissociation constants of nineteen ortho substituted benzoic acids have been determined in eight organic solvents (methanol, ethanol, acetone, dimethyl sulfoxide, dimethylformamide, acetonitrile, pyridine, 1,2-dichloroethane). The correlation between the σI, σR, and υ constants were unsuccessful due to neglecting the description of intramolecular hydrogen bond effect. The method of conjugated deviations has been applied to the results obtained and to those given in literature for ortho substituted benzoic acids (the dissociation constants, the reaction with diphenyldiazomethane, 33 sets), and values of three types of substituent constants have been determined for 29 substituents. The first of these substituent constants, σoi, describes the electronic effects and was adjusted with the application of the isoparameter relation (σoi as a function of σmi) suggested in previous communications. This constant (after excluding the substituents NHCOCH3 and OCOCH3) correlates very well (R = 0.993) with the σI and σR constants. The second substituent constant, σHGi, describes the interaction of the reaction centre (the oxygen atom of carboxylate anion) with the substituent, and it has non-zero values for the substituents OH, SH, NH2, NHCH3, NHCOCH3, COOH, CONH2, and SO2NH2. The third substituent constant, σSi, describes the steric effects and is not significantly related to any of the known quantities of this type. The set given was tested together with the triad of σI, σR, and υ on the definition set and on a set extended by other 28 sets of processes with ortho substituted compounds. On the whole, the set of substituent constants suggested explains 94.6% of variability of data, whereas only 66.0% are explained with the use of σI, σR, and u constants. Moreover, the tests have shown that the σoi constant is not suitable for interpretations of processes involving direct conjugation between the reaction centre and substituent.
Toughness of Oriented Polymers
Authors: Raab Miroslav , Sova Miloš
Published: July 2002

This review article supported by some original photographs and model diagrams summarizes the mechanisms of toughness in oriented semicrystalline polymeric materials. In particular, crack propagation mechanisms in rubber-modified and oriented polymeric systems are compared. The Cook-Gordon mechanism of crack blunting in anisotropic materials can explain the low-temperature impact resistance of oriented semicrystalline polymers, fracture behaviour of biological composite structures and also the effects of photo-oxidative degradation on mechanical behaviour of oriented films.
QSAR Study on Antibacterial Effects of Benzimidazole and Imidazopyridine Derivatives
Authors: Özden Seçkin , Ertepinar Hamide , Geban Ömer
Published: July 2002

A set of benzimidazole (I) and imidazopyridine (II) derivatives previously tested for their antibacterial activities against Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), and Bacillus subtilis (B. subtilis) were analyzed by quantitative structure-activity relationship (QSAR) and the activity contributions for structural and substituent effects were determined using multiple regression procedure. The resulting QSAR revealed that for the activity contribution against S. aureus and P. aeruginosa the substituents of p-position on the phenyl moiety play important role, and besides the p-substituents the substituents in other positions improve the activity. For the potency against E. coli, the character of six membered ring of the fused ring system becomes important besides the substituents effects at the p-position of the phenyl group. It was also found that both the benzimidazole ring system and p-substituted benzyl moiety have significant structural effects besides the lipophilicity of the substituents at R3 for the activity against B. subtilis.
Polarographic and Voltammetric Determination of 1-(4-Methoxyphenyl)-3-methyltriazene
Authors: Barek Jiří , Pertileová Eva , Mejstřík Viktor , Moreira Josino C. , Zima Jiří
Published: July 2002

The polarographic behaviour of 1-(4-methoxyphenyl)-3-methyltriazene in a mixed aqueous-methanolic medium was investigated by tast polarography and differential pulse polarography at a dropping mercury electrode, constant-potential coulometry at a large area mercury electrode and cyclic voltammetry at a hanging mercury drop electrode. A mechanism has been proposed for its polarographic reduction and optimal conditions have been found for its determination by tast polarography in the concentration range 2-100 μmol l-1 and by differential pulse polarography at a dropping mercury electrode, differential pulse voltammetry at a hanging mercury drop electrode and linear scan voltammetry at a hanging mercury drop electrode in the concentration range 0.2-100 μmol l-1. The sensitivity of the determination can be further improved through adsorptive accumulation of the test substance on the surface of the hanging mercury drop electrode; fifteen-second accumulation in stirred solution allows determination in the range 0.01-0.1 μmol l-1.
Analysis of the Labial Gland Secretion of the Cuckoo-Bumblebee (Psithyrus vestalis) Males and Synthesis of Abundant Geranylcitronellol
Authors: Valterová Irena , Svatoš Aleš , Hovorka Oldřich
Published: July 2002

Labial glands of the cuckoo-bumblebee males of the species Psithyrus vestalis were extracted and the components of their secretions were identified. Chemical composition of the males' signal of Psithyrus vestalis has not yet been described in the literature. We found geranycitronellyl acetate to be the main component (48%). Geranylcitronellol and (Z)-15-eicosen-1-ol were present in the secretion in lower amounts. Long-chain aldehydes, acetates, and hydrocarbons formed only minor components of the mixture. The identification of minor components was based on GC-MS, while the more abundant compounds were isolated and fully characterized by spectral and chemical methods. For the structure confirmation, geranylcitronellol was prepared from geranyl bromide via a three-step synthesis.
Silicon-29 NMR Spectra of tert-Butyldimethylsilyl and Trimethylsilyl Derivatives of Some Non-Rigid Diols
Authors: Kvíčalová Magdalena , Blechta Vratislav , Kobylczyk Krzysztof , Piekos Ryszard , Schraml Jan
Published: July 2002

29Si NMR spectra of trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBDMS) derivatives of selected diols were measured under standardized conditions (i.e., in diluted CDCl3 solutions). Application of the recently reported correlation between the chemical shifts in TMS and TBDMS derivatives revealed considerable and systematic deviations which exceeded experimental errors and error estimates from the correlation. Two possible explanations of the deviations are considered: interaction between the two bulky substituent groups and invalidity of the reported correlation for simple hydroxy derivatives. An independent study of analogous derivatives of monohydroxy compounds has shown that the linear correlation holds but the slope and intercept are significantly different from those reported previously on the basis of a study of amino acid derivatives. The data obtained for the diol derivatives fit the new correlation very well and no indication of an interaction between the bulky TBDMS groups was noticed. However, deviations do occur in branched diol derivatives in which branching reduces accessibility of the oxygen atoms surface to associate with proton donors. The largest deviation was found when intramolecular hydrogen bond was formed.
Transport of Adefovir (PMEA) in Human T-Lymphoblastoid Cells
Authors: Olšanská Lenka , Cihlar Tomas , Votruba Ivan , Holý Antonín
Published: July 2002

The uptake of [3H]PMEA by human T-lymphoblastoid cells (CCRF-CEM) apparently proceeds by fluid-phase endocytosis. The transport kinetics was shown to be nonconcentrative and nonsaturable. The uptake takes place even at a low temperature (4 °C), is strictly dependent on the intracellular level of ATP, is not substantially affected by cell suspension density and is not competitively inhibited by other PME derivatives.
Metallaborane Reaction Chemistry. Part 4. Polyhedral Thiametallaborane Synthesis via Direct Incorporation of Sulfur Into Metallaboranes
Authors: Kim Young-hee , Greatrex Robert , Kennedy John D.
Published: July 2002

A preliminary investigation of the direct reaction of elemental sulfur with the representative metallaboranes [6-(η5-C5Me5)-nido-6-RhB9H13] and [6-(η6-MeC6Me4i-Pr)-nido-6-RuB9H13] in the presence of base gives products that result from (i) the addition of one sulfur vertex and (ii) the addition of two sulfur vertices into the metallaborane cluster, as well as (iii) boron-vertex elimination accompanied by sulfur-vertex addition. Products characterised include [7-(η5-C5Me5)-nido-7,11,12-RhS2B9H9], [7-(η6-MeC6H4i-Pr)-nido-7,11,12-RuS2B9H9], [8-(η6-MeC6H4i-Pr)-nido-8,7-RuSB9H11], and a species tentatively identified as [9-(η6-MeC6H4i-Pr)-nido-9,7,8-RuS2B8H8].
Functionalization of Lupane-3β,28-diyl Diacetate with Chromium(VI) Oxide. Part 2
Authors: Sejbal Jan , Klinot Jiří , Buděšínský Miloš , Protiva Jiří
Published: July 2002

Oxidation of lupane-3β,28-diyl diacetate (1) with chromium trioxide was reported already earlier to give small amounts of products functionalized in position 19β and 11 (19β-hydroxylupane-3β,28-diyl diacetate (3) and 11-oxolupane-3β,28-diyl diacetate (6)), together with products of subsequent oxidation, 21-oxolup-18-ene-3β,28-diyl diacetate (4) and anhydride (5). Now we identified further products, arising by functionalization in positions 12, 16 and 21 (12-hydroxy-11-oxolup-12-ene-3β,28-diyl diacetate (8), 12-oxolupane-3β,28-diyl diacetate (9), 11-oxolup-12-ene-3β,28-diyl diacetate (17), 21-oxolupane-3β,28-diyl diacetate (20) and 16-oxolupane-3β,28-diyl diacetate (22)), either as such or after conversion into other derivatives. The obtained compounds were further transformed and structure of the prepared derivatives was confirmed by 1H NMR, 13C NMR and mass spectroscopy.
Axially Chiral Bis(α-amino Acid)s and Their Deamino Analogues. Synthesis and Configurational Assignment
Authors: Tichý Miloš , Ridvan Luděk , Buděšínský Miloš , Závada Jiří , Podlaha Jaroslav , Císařová Ivana
Published: July 2002

The axially chiral bis(α-amino acid)s cis-2 and trans-2 as possible building blocks for polymeric structures of novel type of helicity were prepared. Their configuration has been determined by NMR spectroscopy and, in the case of the trans-isomer, confirmed by single-crystal X-ray diffraction. Analogous pair of stereoisomeric diacids cis-3 and trans-3, devoid of the amino groups, was also prepared and their configuration assigned. The observed differences in the NMR spectra of cis- and trans-isomers of 2 and 3 are discussed from the viewpoint of their different symmetry properties.
Preparation of Steroid Olefins from Heptafluorobutyrates
Authors: Dalibová Lucie , Kohout Ladislav
Published: July 2002

Steroids with hydroxyl group in positions 2, 3, 6, 7, 17 and 20 were esterified with heptafluorobutyric anhydride. The obtained esters on treatment with lithium bromide in N,N-dimethylacetamide in the presence of pyridinium tosylate afforded the corresponding olefins in high yields.
Synthesis of Steroid O-(ω-Hydroxyalkyl)oximes by Reduction of Corresponding O-(ω-Carboxyalkyl)oxime Derivatives
Authors: Slavíková Tereza , Pouzar Vladimír , Černý Ivan
Published: July 2002

Steroid O-(ω-hydroxyalkyl)oximes with varying alkyl chain length were prepared from the corresponding carboxylic acids using the reduction of mixed anhydrides with sodium borohydride. An unexpected reaction course was observed with O-(2-carboxyethyl)oximes of 3-oxo-4-ene steroids, where a 4,5-dihydroisoxazol-3(2H)-one derivative was formed as a side product.
Conformational Preference of Two Toad Poison Bufadienolides, Cinobufagin and Bufotalin
Authors: Kamano Yoshiaki , Kotake Ayano , Nogawa Toshihiko , Hashima Hirohumi , Tozawa Machiko , Morita Hiroshi , Takeya Koichi , Itokawa Hideji , Matsuo Ichiro , Ichihara Yoshitatsu , Drašar Pavel , Pettit George R.
Published: July 2002

The solution state conformations of pyran-2-one ring (E ring) of two toad poison bufadienolides, cinobufagin and bufotalin, were analyzed by using NOE experiments at low temperatures and molecular dynamics simulation study. The rotation of E ring of the two bufadienolides, was found to be affected by the 14β,15β-epoxy and 16β-acetoxy groups and to be restricted at low temperatures. In the experimental, cinobufagin and bufotalin were isolated from Ch'an Su by the new chromatographic methods using the hydrophobic gel sephadex LH-20 and HP-cellulofine as carriers.
Competitive Catalytic Hydrogenation in Unsaturated Hydrocarbon Systems With Sterically Hindered Double Bonds
Authors: Kačer Petr , Laate Leiv , Červený Libor
Published: July 2002

A competitive hydrogenation of unsaturated hydrocarbons (a-methylstyrene, cyclohexene, 1-methylcyclohex-1-ene, 1-tert-butylcyclohex-1-ene and 3-tert-butylcyclohex-1-ene) in binary and ternary systems with palladium-, platinum- and rhodium-supported catalysts in a semibatch isothermal reactor at 20 °C under atmospheric pressure was studied. It was found that considerable variance in selectivity values of competitive hydrogenation in a series of substrates with increasing substituent bulkiness is caused by differences in adsorption and in reactivity of adsorbed molecules. In the case of ternary systems, a change in selectivity of competitive hydrogenation of two substrates was observed, due to the presence of a third substance, caused by a competitive adsorption of all three substrates and their interaction on a catalytic surface.
Temperature Dependent Solvent Effects in Photochemistry of 1-Phenylpentan-1-ones
Authors: Klán Petr , Literák Jaromír
Published: July 2002

Temperature dependent solvent effects have been investigated on the Norrish Type II reaction of 1-phenylpentan-1-one and its p-methyl derivative. Efficiencies of the photoreaction were studied in terms of solvent polarity and base addition as a function of temperature. Such a small structure change as the p-methyl substitution in 1-phenylpentan-1-one altered the temperature dependent photoreactivity in presence of weak bases. The experimental results suggest that the hydrogen bonding between the Type II biradical intermediate OH group and the solvent is weaker for 1-(4-methylphenyl)pentan-1-one than that for 1-phenylpentan-1-one at 20 °C but the interactions probably vanish in both cases at 80 °C.
Heme Peroxidases: Structure, Function, Mechanism and Involvement in Activation of Carcinogens. A Review
Authors: Stiborová Marie , Mikšanová Markéta , Martínek Václav , Frei Eva
Published: July 2002

Peroxidases are enzymes playing an important role in large and diverse numbers of physiological processes in organisms including human. We have attempted in this article to summarize and review the important structural and catalytic properties of principal classes of heme peroxidases as well as their biological functions. Major reactions catalyzed by these enzymes (a conventional peroxidase cycle, reactions using O2and halogenations) and their mechanism are reviewed, too. Moreover, the reaction mechanisms by which peroxidases are implicated in bioactivation of xenobiotic chemicals are presented. Numerous chemicals including protoxicants and procarcinogens are metabolized by equally numerous chemical reactions catalyzed by peroxidases. The unifying theme is the radical nature of the oxidations. The direct conventional peroxidase reaction forming reactive species is generally responsible for the activation of procarcinogenic substrates of peroxidases. The subsequent formation of a superoxide anion radical and peroxy radicals is necessary for activation of chemicals that are poor substrates for peroxidases. The significance of studies concerning the reactions catalyzed by peroxidases is underlined in the present review article. A review with 166 references.
Effect of Framework Charge Density on Catalytic Activity of Copper Loaded Molecular Sieves of Chabazite Structure in Nitrogen(II) Oxide Decomposition
Authors: Dědeček Jiří , Vondrová Alena , Čejka Jiří
Published: July 2002

NO decomposition over Cu-loaded molecular sieves of chabazite structure with different framework negative charge density was investigated. Cu-ZnAlPO-34 with framework charge density (Al + P)/Zn = 15 exhibited high and stable catalytic activity in NO decomposition while Cu-chabazite with Si/Al = 2.7 was inactive. This evidences that the number of aluminum atoms balancing Cu ions in cationic sites controls the catalytic activity of Cu ion. Ions balanced by single framework aluminum atoms exhibit high activity in NO decomposition while ions balanced by two framework aluminum atoms are inactive. Topology of cationic sites is not the limiting parameter for NO decomposition over Cu ions located in molecular sieves.
Stereoselective 1,3-Dipolar Cycloaddition of a Nitrile Ylide Photochemically Generated from 2,3-Diphenyl-2H-azirine to Substituted Methylene Lactones
Authors: Častulík Jakub , Jonas Jaroslav , Mazal Ctibor
Published: July 2002

The nitrile ylide photochemically generated from 2,3-diphenyl-2H-azirine adds to both isomers of 3-(tosyloxymethylene)tetrahydrofuran-2-one with excellent regio- and stereoselectivity giving spiroheterocyclic products in moderate yields. X-Ray structure determination showed dibutolactone to have the E-configuration; the corresponding Z-isomer was prepared photochemically.
On the Reaction of Deacetylvindoline with Thionyl Chloride
Authors: Hájíček Josef , Hanuš Vladimír
Published: July 2002

Reaction of deacetylvindoline (2) with excess thionyl chloride gave rise to hexacyclic 6,10-dichloro-6,17-epithio-11-methoxy-1-methyltabersonine (4) as a single product in 43.5% yield. The structure was deduced from 1H and 13C 1D and 2D NMR experiments as well as from mass spectra. A tentative mechanism of this complex transformation was also proposed.
Interaction of ZnO with ZSM-5 Zeolites
Authors: Rojasová Edita , Smiešková Agáta , Hudec Pavol , Židek Zdenek
Published: July 2002

The possibility of introduction of zinc from ZnO into cationic positions of H- and NH4-ZSM-5 zeolites by solid-state ion exchange was investigated. It was concluded that during thermal pretreatment of a mechanical mixture of ZnO with acid forms of ZSM-5 zeolite, introduction of Zn species into cationic positions as a consequence of the proposed solid-state ion exchange proceeds, but its degree is limited. It indicates that the extent of interaction of Zn species is probably controlled by the concentration of cationic sites on the external surface of the zeolite.
FTIR Study of Metal Zeolites. Determination of Co(II) Cation in Co-Beta Zeolite by Deuterated Acetonitrile Adsorption
Authors: Kuriyavar Satish , Bortnovsky Oleg , Tvarůžková Zdena , Sobalík Zdeněk
Published: July 2002

FTIR spectra of deuterated acetonitrile (ACD) adsorbed on Co-Beta zeolite were investigated. By analysing the IR region of zeolite framework perturbation, the conditions for the prevailing presence of the Co-ACD complex with 1 : 1 stochiometry were established. Analysis of the C≡N region with overlapping bands OH···ACD (2 297 cm-1), and Lewis(Al)···ACD (2 325 cm-1), provided a value of molar absorption coefficient for a band of Co-ACD complex in Co-Beta at 2 310 cm-1 equal to 7.12 ± 0.3 cm μmol-1.
New Cyclodimerization Reaction of (3,5-Di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetic Acid
Authors: Nesvadba Peter , Rzadek Piotr , Rist Günther
Published: July 2002

(3,5-Di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetic acid 1a underwent on heating a new cyclodimerization reaction affording a 1 : 1 mixture of the racemic cis- and trans-isomeric lactone-acids 2. The decisive structure elucidation of 2 was carried out after its mild esterification with diazomethane and separation of the racemic isomeric methyl esters 3a and 3b. The attempted esterification of 2 with methanol and sulfuric acid gave only the methyl diarylacetate 4. In contrast to 1a, which contains the carboxylic acid functionality no cyclodimerization was observed with the corresponding methyl ester 1b or nitrile 1c.
Construction of Interconnected Acidity Functions Based on ortho Substituted Anilines and N-Methylanilines as Indicators
Authors: Pytela Oldřich , Kulhánek Jiří , Jirásková Eva , Nevěčná Taťjana
Published: July 2002

The log I values of 15 mainly ortho substituted derivatives of aniline and N-methylaniline have been measured spectrophotometrically in sulfuric, perchloric, and methanesulfonic acids. A new algorithm has been suggested for construction of acidity functions enabling simultaneous and independent construction of acidity functions in various media under the condition of equal values of pKa of the same indicators in the given media. The so-called interconnected acidity functions have been constructed with using this algorithm and the log I values measured in the above media, and the pKa values have been calculated. The resulting acidity functions and pKa values agree well with the corresponding literature data.
Synthesis of N-Acetyl-3-phenylisoserinates of Sesquiterpenoid Alcohols of Lactarius Origin
Authors: Barycki Rafał , Gumułka Maria , Masnyk Marek , Daniewski Włodzimierz M. , Kobus Mirosław , Łuczak Mirosław
Published: July 2002

Important biological properties of Taxol i.e. 13-N-benzoyl-(2R,3S)-3-phenylisoserinate of baccatin III and also N-benzoyl-(2R,3S)-3-phenylisoserinates of several sesquiterpenoid alcohols of Lactarius origin prompted us to synthesize N-acetyl-3-phenylisoserinates of latter alcohols in order to check and compare their biological properties. Suitably protected phenylisoserine 5 when reacted with sesquiterpenoid alcohols in the presence of DCC gave appropriate esters 7. These, after catalytic hydrogenation deprotection produced aminols 8, which were acetylated and gave the required N-acetyl-3-phenylisoserinates 9a-9g.
A Facile Route to the 6-Hetaryl Substituted Pyrrolo[1,2-a]thieno[3,2-e]pyrimidine Derivatives
Authors: Volovenko Yulian M. , Resnyanska Elizaveta V. , Tverdokhlebov Anton V.
Published: July 2002

Hitherto unknown 6-hetaryl-4,5,7,8-tetrahydropyrrolo[1,2-a]thieno[3,2-e]pyrimidine-4,7-diones (7a-7g) were prepared by reaction of ethyl 2-aminothiophene-3-carboxylates 5 with 4-chloro-2-hetaryl-3-oxobutanonitriles 4 in DMF at 100 °C. When the same reagents were treated in the presence of triethylamine, a dependence of the reaction pathway on the nature of the hetaryl substituent in chloronitrile component was observed. This was explained in terms of steric factors.
Investigation of factors which might indicate susceptibility to particulate air pollution
Authors: Prescott G J , Lee R J , Cohen G R , Elton R A , Lee A J , Fowkes F G R , Agius R M
Published: July 2002

OBJECTIVES

To determine whether previous symptoms or recognised risk factors of cardiovascular ill health, are associated with an increased likelihood of adverse health effects related to particulate air pollution.

METHODS

Cardiovascular event rates were studied relative to urban concentrations of particulate air pollution and baseline risk factors. The Edinburgh artery study consisted of a cohort of 1592 subjects aged 55–74 and was followed up to the end of March 1998 for a median of 10 years resulting in about 5 million person-days of observation. Baseline measurements included plasma fibrinogen and blood and plasma viscosity. A nested case-control approach was used to investigate a possible interaction between effects of these selected baseline risk factors and particulate air pollution, on subsequent event rates.

RESULTS

During the follow up period there were 343 fatal and non-fatal myocardial infarctions or strokes. Trends in adverse cardiovascular outcomes related to pollution were identified among subjects belonging to the highest baseline quintile of plasma fibrinogen. Evidence for interactions between concentrations of particulate pollution and fibrinogen was not established at conventional levels of significance.

CONCLUSIONS

People with high concentrations of plasma fibrinogen might be more susceptible to adverse cardiovascular effects of particulate air pollution, but limitations of power mean that evidence relating to such an interaction is not conclusive. A range of cardiopulmonary risk factors warrant investigation in relation to possible susceptibility to air pollution.