bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for Early Local Viral Replication and Local Production of Antiviral Immunity upon Mucosal Simian-Human Immunodeficiency Virus SHIV
89.6
Infection in
Macaca nemestrina
Authors: Ambrose Zandrea , Larsen Kay , Thompson Jannelle , Stevens Yvonne , Finn Eric , Hu Shiu-Lok , Bosch Marnix L.
Published: July 2002

Transmission of human immunodeficiency virus type 1 (HIV-1) is largely a result of heterosexual exposure, leading many investigators to evaluate mucosal vaccines for protection against intravaginal (i.vag.) transmission in macaque models of AIDS. Relatively little is known, however, about the dynamics of viral replication and the ensuing immune response following mucosal infection. We have utilized a simian-human immunodeficiency virus (SHIV) to study the differences in viremia, CD4 T-cell percentages, and mucosal and systemic anti-SHIV humoral and cellular immune responses during primary infection of animals infected either intravenously (i.v.) or i.vag. Positive viral cocultures, peripheral blood mononuclear cell viral load peaks, and CD4 cell declines were delayed by 1 week in the i.vag. inoculated animals compared to the animals infected i.v., demonstrating delayed viral spreading to the periphery. In contrast, mucosal anti-SHIV antibody levels were greater in magnitude and arose more rapidly and mucosal CD8
+
T-cell responses were enhanced in the i.vag. group animals, whereas both the magnitudes and times of onset of systemic immune responses for the animals in the two groups did not differ. These observations demonstrate that compartmentalization of viral replication and induction of local antiviral immunity occur in the genital tract early after i.vag. but not i.v. inoculation. Induction of mucosal immunity to target this local, contained replication should be a goal in HIV vaccine development.
Induction of Potent Immune Responses by Cationic Microparticles with Adsorbed Human Immunodeficiency Virus DNA Vaccines
Authors: O'Hagan Derek , Singh Manmohan , Ugozzoli Mildred , Wild Carl , Barnett Susan , Chen Minchao , Schaefer Mary , Doe Barbara , Otten Gillis R. , Ulmer Jeffrey B.
Published: July 2002

The effectiveness of cationic microparticles with adsorbed DNA at inducing immune responses was investigated in mice, guinea pigs, and rhesus macaques. Plasmid DNA vaccines encoding human immunodeficiency virus (HIV) Gag and Env adsorbed onto the surface of cationic poly(lactide-coglycolide) (PLG) microparticles were shown to be substantially more potent than corresponding naked DNA vaccines. In mice immunized with HIVgagDNA, adsorption onto PLG increased CD8+T-cell and antibody responses by ∼100- and ∼1,000-fold, respectively. In guinea pigs immunized with HIVenvDNA adsorbed onto PLG, antibody responses showed a more rapid onset and achieved markedly higher enzyme-linked immunosorbent assay and neutralizing titers than in animals immunized with naked DNA. Further enhancement of antibody responses was observed in animals vaccinated with PLG/DNA microparticles formulated with aluminum phosphate. The magnitude of anti-Env antibody responses induced by PLG/DNA particles was equivalent to that induced by recombinant gp120 protein formulated with a strong adjuvant, MF-59. In guinea pigs immunized with a combination vaccine containing HIVenvand HIVgagDNA plasmids on PLG microparticles, substantially superior antibody responses were induced against both components, as measured by onset, duration, and titer. Furthermore, PLG formulation overcame an apparent hyporesponsiveness of theenvDNA component in the combination vaccine. Finally, preliminary data in rhesus macaques demonstrated a substantial enhancement of immune responses afforded by PLG/DNA. Therefore, formulation of DNA vaccines by adsorption onto PLG microparticles is a powerful means of increasing vaccine potency.
Herpes Simplex Virus Triggers and Then Disarms a Host Antiviral Response
Authors: Mossman Karen L. , Macgregor Pascale F. , Rozmus Jacob J. , Goryachev Andrew B. , Edwards Aled M. , Smiley James R.
Published: July 2002

Virus infection induces an antiviral response that is predominantly associated with the synthesis and secretion of soluble interferon. Here, we report that herpes simplex virus type 1 virions induce an interferon-independent antiviral state in human embryonic lung cells that prevents plaquing of a variety of viruses. Microarray analysis of 19,000 human expressed sequence tags revealed induction of a limited set of host genes, the majority of which are also induced by interferon. Genes implicated in controlling the intracellular spread of virus and eliminating virally infected cells were among those induced. Induction of the cellular response occurred in the absence of de novo cellular protein synthesis and required viral penetration. In addition, this response was only seen when viral gene expression was inhibited, suggesting that a newly synthesized viral protein(s) may function as an inhibitor of this response.
Direct Activation of Innate and Antigen-Presenting Functions of Microglia following Infection with Theiler's Virus
Authors: Olson Julie K. , Girvin Ann M. , Miller Stephen D.
Published: July 2002

Microglia are resident central nervous system (CNS) macrophages. Theiler's murine encephalomyelitis virus (TMEV) infection of SJL/J mice causes persistent infection of CNS microglia, leading to the development of a chronic-progressive CD4+T-cell-mediated autoimmune demyelinating disease. We asked if TMEV infection of microglia activates their innate immune functions and/or activates their ability to serve as antigen-presenting cells for activation of T-cell responses to virus and endogenous myelin epitopes. The results indicate that microglia lines can be persistently infected with TMEV and that infection significantly upregulates the expression of cytokines involved in innate immunity (tumor necrosis factor alpha, interleukin-6 [IL-6], IL-18, and, most importantly, type I interferons) along with upregulation of major histocompatibility complex class II, IL-12, and various costimulatory molecules (B7-1, B7-2, CD40, and ICAM-1). Most significantly, TMEV-infected microglia were able to efficiently process and present both endogenous virus epitopes and exogenous myelin epitopes to inflammatory CD4+Th1 cells. Thus, TMEV infection of microglia activates these cells to initiate an innate immune response which may lead to the activation of naive and memory virus- and myelin-specific adaptive immune responses within the CNS.
Deletion of β-Strand and α-Helix Secondary Structure in Normal Prion Protein Inhibits Formation of Its Protease-Resistant Isoform
Authors: Vorberg Ina , Chan Kaman , Priola Suzette A.
Published: July 2002

A fundamental event in the pathogenesis of transmissible spongiform encephalopathies (TSE) is the conversion of a normal, proteinase K-sensitive, host-encoded protein, PrP-sen, into its protease-resistant isoform, PrP-res. During the formation of PrP-res, PrP-sen undergoes conformational changes that involve an increase of β-sheet secondary structure. While previous studies in which PrP-sen deletion mutants were expressed in transgenic mice or scrapie-infected cell cultures have identified regions in PrP-sen that are important in the formation of PrP-res, the exact role of PrP-sen secondary structures in the conformational transition of PrP-sen to PrP-res has not yet been defined. We constructed PrP-sen mutants with deletions of the first β-strand, the second β-strand, or the first α-helix and tested whether these mutants could be converted to PrP-res in both scrapie-infected neuroblastoma cells (Sc
+
-MNB cells) and a cell-free conversion assay. Removal of the second β-strand or the first α-helix significantly altered both processing and the cellular localization of PrP-sen, while deletion of the first β-strand had no effect on these events. However, all of the mutants significantly inhibited the formation of PrP-res in Sc
+
-MNB cells and had a greatly reduced ability to form protease-resistant PrP in a cell-free assay system. Thus, our results demonstrate that deletion of the β-strands and the first α-helix of PrP-sen can fundamentally affect PrP-res formation and/or PrP-sen processing.
Effects of Deletion and Overexpression of the
Autographa californica
Nuclear Polyhedrosis Virus
FP25K
Gene on Synthesis of Two Occlusion-Derived Virus Envelope Proteins and Their Transport into Virus-Induced Intranuclear Membranes
Authors: Rosas-Acosta Germán , Braunagel Sharon C. , Summers Max D.
Published: July 2002

Partial deletions within
Autographa californica
open reading frame 61 (
FP25K
) alter the expression and accumulation profile of several viral proteins and the transport of occlusion-derived virus (ODV)-E66 to intranuclear membranes during infection (S. C. Braunagel et al., J. Virol. 73:8559–8570, 1999). Here we show the effects of a full deletion and overexpression of FP25K on the transport and expression of two ODV envelope proteins, ODV-E66 (E66) and ODV-E25 (E25). Deletion and overexpression of FP25K substantially altered the levels of expression of E66 during infection. Compared with cells infected with wild-type (wt) virus, the levels of E66 were reduced fivefold in cells infected with a viral mutant lacking FP25K (ΔFP25K) and were slightly increased in cells infected with a viral mutant overexpressing FP25K (FP25K
polh
). In contrast, no significant changes were observed in the levels of E25 among wt-, ΔFP25K-, and FP25K
polh
-infected cells. The changes observed in the levels of E66 among the different viral mutants were not accompanied by changes in either the time of synthesis, membrane association, protein turnover, or steady-state transcript abundance. Deletion of FP25K also substantially altered the transport and localization of E66 during infection. In cells infected with the ΔFP25K mutant virus, E66 accumulated in localized regions at the nuclear periphery and the outer nuclear membrane and did not traffic to intranuclear membranes. In contrast, in cells infected with the FP25K
polh
mutant virus E66 trafficked to intranuclear membranes. For comparison, E25 was normally transported to intranuclear membranes in both ΔFP25K- and FP25K
polh
-infected cells. Altogether these studies suggest that FP25K affects the synthesis of E66 at a posttranscriptional level, probably by altering the translation of E66; additionally, the block in transport of E66 at the nuclear envelope in ΔFP25K-infected cells suggests that the pathway of E66 trafficking to the inner nuclear membrane and intranuclear microvesicles is specifically regulated and must be influenced by factors that do not control the traffic of E25.
C-Terminal Domain of the Epstein-Barr Virus LMP2A Membrane Protein Contains a Clustering Signal
Authors: Matskova Liudmila , Ernberg Ingemar , Pawson Tony , Winberg Gösta
Published: July 2002

The latency-regulated transmembrane protein LMP2A interferes with signaling from the B-cell antigen receptor by recruiting the tyrosine kinases Lyn and Syk and by targeting them for degradation by binding the cellular E3 ubiquitin ligase AIP4. It has been hypothesized that this constitutive activity of LMP2A requires clustering in the membrane, but molecular evidence for this has been lacking. In the present study we show that LMP2A coclusters with chimeric rat CD2 transmembrane molecules carrying the 27-amino-acid (aa) intracellular C terminus of LMP2A and that this C-terminal domain fused to the glutathione-
S
-transferase protein associates with LMP2A in cell lysates. This molecular association requires neither the cysteine-rich region between aa 471 and 480 nor the terminal three aa 495 to 497. We also show that the juxtamembrane cysteine repeats in the LMP2A C terminus are the major targets for palmitoylation but that this acylation is not required for targeting of LMP2A to detergent-insoluble glycolipid-enriched membrane microdomains.
Human Cytomegalovirus Open Reading Frame TRL11/IRL11 Encodes an Immunoglobulin G Fc-Binding Protein
Authors: Lilley Brendan N. , Ploegh Hidde L. , Tirabassi Rebecca S.
Published: July 2002

Several herpesviruses encode Fc receptors that may play a role in preventing antibody-mediated clearance of the virus in vivo. Human cytomegalovirus (HCMV) induces an Fc-binding activity in cells upon infection, but the gene that encodes this Fc-binding protein has not been identified. Here, we demonstrate that the HCMV AD169 open reading frame TRL11 and its identical copy, IRL11, encode a type I membrane glycoprotein that possesses IgG Fc-binding capabilities.
The A20R Protein Is a Stoichiometric Component of the Processive Form of Vaccinia Virus DNA Polymerase
Authors: Klemperer Nancy , McDonald William , Boyle Kathleen , Unger Beth , Traktman Paula
Published: July 2002

In vitro analysis of the catalytic DNA polymerase encoded by vaccinia virus has demonstrated that it is innately distributive, catalyzing the addition of <10 nucleotides per primer-template binding event in the presence of 8 mM MgCl
2
or 40 mM NaCl (W. F. McDonald and P. Traktman, J. Biol. Chem. 269:31190–31197, 1994). In contrast, cytoplasmic extracts isolated from vaccinia virus-infected cells contain a highly processive form of DNA polymerase, able to catalyze the replication of a 7-kb template per binding event under similar conditions. To study this holoenzyme, we were interested in purifying and characterizing the vaccinia virus processivity factor (VPF). Our previous studies indicated that VPF is expressed early after infection and has a native molecular mass of ∼48 kDa (W. F. McDonald, N. Klemperer, and P. Traktman, Virology 234:168–175, 1997). Using these criteria, we established a six-step chromatographic purification procedure, in which a prominent ∼45-kDa band was found to copurify with processive polymerase activity. This species was identified as the product of the A20 gene. By use of recombinant viruses that direct the overexpression of A20 and/or the DNA polymerase, we verified the physical interaction between the two proteins in coimmunoprecipitation experiments. We also demonstrated that simultaneous overexpression of A20 and the DNA polymerase leads to a specific and robust increase in levels of processive polymerase activity. Taken together, we conclude that the A20 gene encodes a component of the processive DNA polymerase complex. Genetic data that further support this conclusion are presented in the accompanying report, which documents that temperature-sensitive mutants with lesions in the A20 gene have a DNA
−
phenotype that correlates with a deficit in processive polymerase activity (A. Punjabi et al, J. Virol. 75:12308–12318, 2001).
Antiviral Effect of
N
-Butyldeoxynojirimycin against Bovine Viral Diarrhea Virus Correlates with Misfolding of E2 Envelope Proteins and Impairment of Their Association into E1-E2 Heterodimers
Authors: Branza-Nichita Norica , Durantel David , Carrouée-Durantel Sandra , Dwek Raymond A. , Zitzmann Nicole
Published: July 2002

The iminosugar
N
-butyldeoxynojirimycin (
N
B-DNJ), an endoplasmic reticulum α-glucosidase inhibitor, has an antiviral effect against bovine viral diarrhea virus (BVDV). In this report, we investigate the molecular mechanism of this inhibition by studying the folding pathway of BVDV envelope glycoproteins in the presence and absence of
N
B-DNJ. Our results show that, while the disulfide-dependent folding of E2 glycoprotein occurs rapidly (2.5 min), the folding of E1 occurs slowly (30 min). Both BVDV envelope glycoproteins associate rapidly with calnexin and dissociate with different kinetics. The release of E1 from the interaction with calnexin coincides with the beginning of E1 and E2 association into disulfide-linked heterodimers. In the presence of
N
B-DNJ, the interaction of E1 and E2 with calnexin is prevented, leading to misfolding of the envelope glycoproteins and inefficient formation of E1-E2 heterodimers. The degree of misfolding and the lack of association of E1 and E2 into disulfide-linked complexes in the presence of
N
B-DNJ correlate with the dose-dependent antiviral effect observed for this iminosugar.
Langat Virus M Protein Is Structurally Homologous to prM
Authors: Holbrook Michael R. , Wang Heiman , Barrett Alan D. T.
Published: July 2002

Langat (LGT) virus M protein has been generated in a recombinant system. Antiserum raised against the LGT virus M protein neutralizes tick-borne encephalitis serocomplex flaviviruses but not mosquito-borne flaviviruses, indicating that the M protein is exposed on the surface of virions. The antiserum recognizes intracellular LGT virus prM/M and binds to prM and M in Western blots of whole-cell lysates and purified virus, respectively. These data suggest that the prM and M proteins are structurally similar under native conditions and support the hypothesis that the “pr” portion of prM facilitates proper folding of the M protein for expression on the virion surface.
Mutation Spectra of Herpes Simplex Virus Type 1 Thymidine Kinase Mutants
Authors: Lu Qiaosheng , Hwang Ying T. , Hwang Charles B. C.
Published: July 2002

To examine whether the exonuclease activity intrinsic to the polymerase (Pol) of herpes simplex virus type 1 can influence the mutational spectra, we applied the denaturing gradient gel electrophoresis (DGGE) system combined with sequencing to characterize thymidine kinase mutants isolated from both the wild-type virus and a mutant deficient in exonuclease activity, Y7. Wild-type viruses produced predominately frameshift mutations (67%), whereas Y7 replicated a significantly lower proportion of frameshifts (21%;
P
< 0.005). Furthermore, the majority of substitutions were transitional changes in both groups, although they distributed differently. The implications of these findings are discussed.
Murine Coronavirus Replication-Induced p38 Mitogen-Activated Protein Kinase Activation Promotes Interleukin-6 Production and Virus Replication in Cultured Cells
Authors: Banerjee Sangeeta , Narayanan Krishna , Mizutani Tetsuya , Makino Shinji
Published: July 2002

Analyses of mitogen-activated protein kinases (MAPKs) in a mouse hepatitis virus (MHV)-infected macrophage-derived J774.1 cell line showed activation of two MAPKs, p38 MAPK and c-Jun N-terminal kinase (JNK), but not of extracellular signal-regulated kinase (ERK). Activation of MAPKs was evident by 6 h postinfection. However, UV-irradiated MHV failed to activate MAPKs, which demonstrated that MHV replication was necessary for their activation. Several other MHV-permissive cell lines also showed activation of both p38 MAPK and JNK, which indicated that the MHV-induced stress-kinase activation was not restricted to any particular cell type. The upstream kinase responsible for activating MHV-induced p38 MAPK was the MAPK kinase 3. Experiments with a specific inhibitor of p38 MAPK, SB 203580, demonstrated that MHV-induced p38 MAPK activation resulted in the accumulation of interleukin-6 (IL-6) mRNAs and an increase in the production of IL-6, regardless of MHV-induced general host protein synthesis inhibition. Furthermore, MHV production was suppressed in SB 203580-treated cells, demonstrating that activated p38 MAPK played a role in MHV replication. The reduced MHV production in SB 203580-treated cells was, at least in part, due to a decrease in virus-specific protein synthesis and virus-specific mRNA accumulation. Interestingly, there was a transient increase in the amount of phosphorylation of the translation initiation factor 4E (eIF4E) in infected cells, and this eIF4E phosphorylation was p38 MAPK dependent; it is known that phosphorylated eIF4E enhances translation rates of cap-containing mRNAs. Furthermore, the upstream kinase responsible for eIF4E phosphorylation, MAPK-interacting kinase 1, was also phosphorylated and activated in response to MHV infection. Our data suggested that host cells, in response to MHV replication, activated p38 MAPK, which subsequently phosphorylated eIF4E to efficiently translate certain host proteins, including IL-6, during virus-induced severe host protein synthesis inhibition. MHV utilized this p38 MAPK-dependent increase in eIF4E phosphorylation to promote virus-specific protein synthesis and subsequent progeny virus production. Enhancement of virus-specific protein synthesis through virus-induced eIF4E activation has not been reported in any other viruses.
Membrane Association and Dimerization of a Cysteine-Rich, 16-Kilodalton Polypeptide Released from the C-Terminal Region of the Coronavirus Infectious Bronchitis Virus 1a Polyprotein
Authors: Ng Lisa F. P. , Liu D. X.
Published: July 2002

More than 10 mature proteins processed from coronavirus gene 1-encoded polyproteins have been identified in virus-infected cells. Here, we report the identification of the most C-terminal cleavage product of the 1a polyprotein as a 16-kDa protein in infectious bronchitis virus-infected Vero cells. Indirect immunofluorescence demonstrated that the protein exhibits a distinct perinuclear punctate staining pattern, suggesting that it is associated with cellular membranes. Positive staining observed on nonpermeabilized cells indicates that the protein may get transported to the cell surface, but no secretion of the protein out of the cells was observed. Treatment of the membrane fraction prepared from cells expressing the 16-kDa protein with Triton X-100, a high pH, and a high concentration of salts showed that the protein may be tightly associated with intracellular membranes. Dual-labeling experiments demonstrated that the 16-kDa protein colocalized with the 5′-bromouridine 5′-triphosphate-labeled viral RNA, suggesting that it may be associated with the viral replication machinery. Sequence comparison of the 16-kDa protein with the equivalent products of other coronaviruses showed multiple conserved cysteine residues, and site-directed mutagenesis studies revealed that these conserved residues may contribute to dimerization of the 16-kDa protein. Furthermore, increased accumulation of the 16-kDa protein upon stimulation with epidermal growth factor was observed, providing preliminary evidence that the protein might be involved in the growth factor signaling pathway.
Search for Hepatitis C Virus Negative-Strand RNA Sequences and Analysis of Viral Sequences in the Central Nervous System: Evidence of Replication
Authors: Radkowski Marek , Wilkinson Jeffrey , Nowicki Marek , Adair Debra , Vargas Hugo , Ingui Craig , Rakela Jorge , Laskus Tomasz
Published: July 2002

Patients with chronic hepatitis C are more likely to have significant changes in their physical and mental well-being than patients with liver disease of other etiology, and hepatitis C virus (HCV) has been occasionally implicated in diseases of the central nervous system. We analyzed the presence of the HCV negative-strand RNA sequence, which is the viral replicative intermediary, in autopsy brain tissue samples from six HCV-infected patients. Negative-strand HCV RNA was searched for by a strand-specific
Tth
-based reverse transcriptase PCR, and viral sequences amplified from brain tissue and serum were compared by single-strand conformational polymorphism analysis and direct sequencing. HCV RNA negative strands were detected in brain tissue in three patients. In two of these patients, serum- and brain-derived viral sequences were different and classified as belonging to different genotypes. In one of the latter patients, HCV RNA negative strands were detected in lymph node and, while being different from serum-derived sequences, were identical to those present in the brain. The results of the present study suggest that HCV can replicate in the central nervous system, probably in cells of the macrophage/monocyte lineage.
Heterologous Movement Protein Strongly Modifies the Infection Phenotype of Cucumber Mosaic Virus
Authors: Huppert Emese , Szilassy Dénes , Salánki Katalin , Divéki Zoltán , Balázs Ervin
Published: July 2002

A hybrid virus (CMVcymMP) constructed by replacing the movement protein (MP) of cucumber mosaic cucumovirus (CMV) with that of cymbidium ringspot tombusvirus (CymRSV) was viable and could efficiently spread both cell to cell and long distance in host plants. The hybrid virus was able to move cell to cell in the absence of functional CP, whereas CP-deficient CMV was restricted to single inoculated cells. In several
Chenopodium
and
Nicotiana
species, the symptom phenotype of the hybrid virus infection was clearly determined by the foreign MP gene. In
Nicotiana debneyi
and
Nicotiana tabacum
cv. Xanthi, the hybrid virus could move systemically, contrary to CymRSV.
Hepatitis A Virus Suppresses Monocyte-to-Macrophage Maturation In Vitro
Authors: Wünschmann Sabina , Becker Britta , Vallbracht Angelika
Published: July 2002

To analyze the pathogenetic mechanism of hematopoietic dysregulation associated with hepatitis A virus (HAV) infections, we studied the influence of HAV on monocyte (MO)-to-macrophage (MAC) maturation in vitro. Exposure of peripheral blood-derived mononuclear cells (MNC) to HAV led to diminished adherence of MO to plastic. Furthermore, HAV inhibited the ability of peripheral blood MO to differentiate toward MAC. Freshly isolated and 14-day-old MO cultures demonstrated reduced differentiation and decreased phagocytic capacity after challenge with HAV. Viral replication in MO/MAC cultures was confirmed by titration of infectious virus. We also determined the influence of HAV on the MO/MAC population in human long-term bone marrow cultures (LTBMCs). Inoculation of bone marrow MNC with HAV suppressed the establishment of an adherent stromal layer containing a reduced number of MAC. Furthermore, increased MO numbers in the nonadherent fraction of HAV-challenged LTBMCs are indicative of the disturbance of MO adherence. These findings suggest that HAV infection leads to a disorder of the mononuclear phagocytic system which may contribute to functional abnormalities of the bone marrow stroma.
Fluorescence Reagents for Labelling of Biomolecules. Part I. Synthesis and Spectral Characterization of 2- and 4-Substituted 9-Isothiocyanatoacridines
Authors: Mazagová Dana , Sabolová Danica , Kristian Pavol , Imrich Ján , Antalík Marián , Podhradský Dušan
Published: July 2002

9-Isothiocyanatoacridines VIII - XIV were prepared from the corresponding 9-chloroacridines I - VII. The IR, 1H NMR, 13C NMR and fluorescence spectra of the products are given. The 13C NMR chemical shifts of the C-9 ipso carbon atom exhibit a trend that is in accord with the Hammett constants of substituents bonded to the C-2 carbon. Effect of these substituents on the chemical shift of C-NCS was only small. The dependence of hydrolysis of isothiocyanates VIII - XIV on pH of the medium was studied. It was found that 9-isothiocyanatoacridines do not undergo hydrolysis at pH 7 - 10. The relative fluorescence intensities (F/F0) of compounds VIII - XIV at pH 7.4 have been determined in comparison with that of 9-aminoacridine. No direct dependence between the fluorescence intensity and the polar character of substituents has been found.
Photochemical Hydroxylation of Salicylic Acid Derivatives with Hydrogen Peroxide, Catalyzed with Fe(III) and Sensitized with Methylene Blue
Authors: Luňák Stanislav , Muzart Jacques , Brodilová Jiřina
Published: July 2002

Substitution of hydrogen in the carboxy or hydroxy group of a salicylic acid molecule with a methyl group, which hinders the coordination of Fe(III), results in a pronounced reduction of photocatalytic effects. The complex of Fe(III) with salicylic acid is the precursor of the thermal catalyst arising on irradiation.
On Instabilities in Horizontal Two-Phase Flow
Authors: Ebner Lothar , Fialová Marie
Published: July 2002

Two regions of instabilities in horizontal two-phase flow were detected. The first was found in the transition from slug to annular flow, the second between stratified and slug flow. The existence of oscillations between the slug and annular flows can explain the differences in the limitation of the slug flow in flow regime maps proposed by different authors. Coexistence of these two regimes is similar to bistable behaviour of some differential equation solutions.
Operation Regimes of Fluidized Beds
Authors: Hartman Miloslav , Beran Zdeněk , Svoboda Karel , Veselý Václav
Published: July 2002

The state of the art has been reviewed in the analysis and description of flow or contacting pattern in gas-solid contacting units where a gas flows upwards through a bed of solids. The flow regime or contacting mode varies widely, depending on the particle size, particle density, gas density, gas viscosity, gas velocity and column geometry. The influence of such variables is reflected in the particle classification schemes and regime diagrams to cover the operation regions of common gas-solid reactors and contactors. In general, fluidized beds can be operated in six different regimes: particulate (homogeneous) fluidization, bubbling fluidization, slugging fluidization, turbulent fluidization, fast fluidization and pneumatic conveying. The bubbling beds can be further classified into three different modes of contacting: fast bubble regime, slow bubble regime and rapidly growing bubble regime. Characteristic features of all the regimes as well as the transitions between them are discussed. Current research interests, supported by practical needs, are oriented toward the operation conditions and contactor geometry of high velocity units.
Electrochemical Dissolution of Goethite by Abrasive Stripping Voltammetry
Authors: Grygar Tomáš , Šubrt Jan , Boháček Jaroslav
Published: July 2002

Abrasive stripping voltammetry was applied to the investigation of the reductive dissolution of some iron(III) oxides and hydroxy-oxides, particularly goethite (α-FeOOH), in acid media. The electrode reaction directly involves the solid phase, and the reaction pathway depends on the phase composition and particle shape. This can be used for a qualitative and quantitative characterization of goethite. The results of a quantitative analysis of a mixture of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH) are compared with those of IR and Moessbauer spectroscopic examination. The effects of the particle appearance (shape, crystal intergrowth) on the results of the voltammetric and chronoamperometric measurements are discussed.
Synthesis and Antituberculotic Activity of Some Substituted 3-Arylamino-5-cyano-2-pyrazinecarboxamides
Authors: Doležal Martin , Hartl Jiří , Lyčka Antonín , Buchta Vladimír , Odlerová Želmíra
Published: July 2002

Nucleophilic substitution of 3-chloro-5-cyano-2-pyrazinecarboxamide by substituted anilines afforded substituted 3-arylamino-5-cyano-2-pyrazinecarboxamides I-X. The structures of compounds were confirmed by elemental analysis, UV, IR and 1H NMR spectra. The assessment of in vitro antimycotic and antimycobacterial activities of the compounds was carried out. The highest antituberculotic activity against M. tuberculosis in this series was shown by 3-anilino- 5-cyano-2-pyrazinecarboxamide (I), whose efficacy was the same as that of pyrazinecarboxamide.
Reactions of 4-Amino-3-penten-2-one and Its NSubstituted Derivatives with Diazonium Ions
Authors: Macháček Vladimír , Čegan Alexandr , Halama Aleš , Rožňavská Olga , Štěrba Vojeslav
Published: July 2002

Azo coupling reactions of benzenediazonium salts with substituted 4-amino-3-penten-2-ones take place at the C-3 atom. 1H and 13C NMR spectroscopy has been used to study the structure of both the starting enaminones and coupling products. In CDCl3, 3-(4-chlorophenylhydrazono)-2-(4-methylphenylimino)-4-pentanone exists in hydrazo form whereas 4-amino-3-(4-chlorophenylazo)-3-penten-2-one is present as a mixture of two azo compounds differing probably in the arrangement of the intramolecular hydrogen bond. The azo coupling reaction kinetics have been studied in acetate buffers and methanol-water or tert-butyl alcohol-water mixtures. The coupling rate has been found independent of pH and buffer concentration. The reaction orders with respect to the starting compounds have been determined and the reaction mechanism is suggested. Linear dependence has been found between log kobs and substituent constants according to the Hammett or Yukawa-Tsuno equations.
Synthesis of Enantiomeric N-(2-Phosphonomethoxypropyl) Derivatives of Purine and Pyrimidine Bases. II. The Synthon Approach
Authors: Holý Antonín , Dvořáková Hana , Masojídková Milena
Published: July 2002

Another approach to (R)- and (S)-N-(2-phosphonomethoxypropyl) derivatives of purine and pyrimidine bases (PMP derivatives) I and II is described, consisting in alkylation of the heterocyclic base with (R)- and (S)-2-[bis(2-propyl)phosphonylmethoxy]propyl p-toluenesulfonates (X and XVIII) followed by transsilylation of the intermediary N-[2-bis(2-propyl)phosphonylmethoxypropyl] derivatives XI and XIX. The key intermediates X and XVIII were obtained from 1-benzyloxypropanols VI and XIV by two routes: (i) condensation with bis(2-propyl) p-toluenesulfonyloxymethylphosphonate (XIII), hydrogenolysis of the obtained 1-benzyloxy-2-bis(2-propyl)phosphonylmethoxypropanes VIII and XVI over Pd/C to 2-bis(2-propyl)phosphonylmethoxypropanols IX and XVII and tosylation of the latter or (ii) chloromethylation of compounds VI and XIV and subsequent reaction of the chloromethyl ethers VII and XV with tris(2-propyl) phosphite and further processing of the benzyl ethers VIII and XVI analogous to the enantiomeric propanols IX and XVII. This approach was used for the synthesis of derivatives of adenine (Ia, IIa), 2,6-diaminopurine (Ib, IIb) and 3-deazaadenine (Ic, IIc). Their guanine counterparts Ie and IIe were prepared by hydrolysis of 2-amino-6-chloropurine intermediates XId and XIXd. 6-Chloropurine was converted into diester XIi by reaction with tosylate X, which on reaction with thiourea and subsequent ester cleavage afforded the 6-thiopurine derivative Ij. Analogously, 2-amino-6-chloropurine derivative XId reacted with thiourea to give 9-(R)-(2-phosphonomethoxypropyl)-2-thioguanine (If), or with dimethylamine under formation of (2-phosphonomethoxypropyl)-2-amino-6-dimethylaminopurine (Ig). Hydrogenolysis of compound XId gave 9-(R)-(2-phosphonomethoxypropyl)-2-aminopurine (Ik). Hydrolytic deamination of adenine derivatives Ia and IIa led to enantiomeric (2-phosphonomethoxypropyl)hypoxanthines Ih and IIh.
Synthesis of a Scaffold for the Creation of Non-Peptide Libraries
Authors: Kasal Alexander , Kohout Ladislav , Lebl Michal
Published: July 2002

5β-Cholanic acid derivative XVII was prepared as a skeleton for the creation of non-peptide libraries. In positions 3, 7 and 12, different functional groups were designed in order to provide for the attachment of various building blocks linked to them.
Crystal and Molecular Structure of Lithium Benzohydroxamate-Benzohydroxamic Acid (1 : 1) Adduct
Authors: Řeřicha Roman , Císařová Ivana , Podlaha Jaroslav
Published: July 2002

The crystal structure of the title compound was determined by single crystal X-ray diffraction. It consists of molecules of benzohydroxamic acid, its O-deprotonated anions and lithium cations in the 1 : 1 : 1 molar ratio. Although the molecular geometry of the anion is very similar to that of the acid, these units can be unambiguously distinguished since the short hydrogen bond between the OH group of the acid and the N-bonded oxygen atom of the anion is remarkably asymmetric. This bond, together with the lithium cations (being surrounded by five oxygens), links the units into chains running in the crystallographic ab plane. The coordination polyhedron around Li represents a rare example of an almost undistorted LiO5 square pyramidal arrangement.
Carbocyclic Phosphonate-Based Nucleotide Analogs Related to PMEA. I. Racemic trans-Configured Derivatives
Authors: Liboska Radek , Masojídková Milena , Rosenberg Ivan
Published: July 2002

Racemic trans-N-(2-phosphonomethoxycycloalkyl) derivatives of heterocyclic bases, a novel type of nucleotide analogs related to 9-(2-phosphonomethoxyethyl)adenine (PMEA), are reported. The synthesis of fully protected adenine- (5), hypoxanthine- (7), guanine- (11), thymine- (13), uracil- (16) and cytosine-containing (18) carbocyclic nucleotide analogs is based on the reaction of trans-2-hydroxycycloalkyl derivatives of N-protected nucleobases (2, 10, 12, 14, 17) with diisopropyl tosyloxymethanephosphonate. Deprotection of these compounds afforded the title nucleotide analogs. The starting nucleoside derivatives have been prepared via nucleophilic oxirane ring opening of cycloalkene oxides with various protected or free nucleobases.
Fumaria densiflora DC. Alkaloids
Authors: Táborská Eva , Bochořáková Hana , Soušek Jaromír , Sedmera Petr , Vavrečková Ctirada , Šimánek Vilím
Published: July 2002

Twenty isoquinoline alkaloids were identified in the aerial part of Fumaria densiflora DC. In addition to bicuculline, densiflorine, fumaritine, fumariline, scoulerine, coptisine, cryptopine, parfumine, protopine, and sinactine which have been found previously, the following alkaloids were isolated for the first time from this species: adlumine, fumaricine, fumaritridine, fumarophycine, fumarofine, corytuberine, cis-N-methylstylopinium iodide, stylopine, and two new 1-benzylisoquinoline alkaloids, viz. fumaflorine and fumaflorine methyl ester. The cytoprotectivity of extracts of F. densiflora and F. officinalis, and that of protopine, cryptopine, and parfumine was tested on primary cultures of rat hepatocytes intoxicated with carbon tetrachloride. The cytoprotective effect of the extracts is associated with the alkaloids.
Sterically Crowded Heterocycles. VIII. Preparative Photoisomerization of Some Imidazo[1,2-a]pyridines
Authors: Kubík Richard , Böhm Stanislav , Čejka Jan , Havlíček Vladimír , Strnad Tomáš , Kratochvíl Bohumil , Kuthan Josef
Published: July 2002

UV-Illumination of (Z)-3-(2-phenylimidazo[1,2-a]pyridin-3-yl)-1,3-diphenylprop-2-en-1-one (1a) or its 6-methyl and 6-iodo derivatives 1c and 1g resulted in minor (E)-isomers 2a, 2c, and 2g and prevailing (E,Z)-mixtures of N-(pyridin-2-yl)-[(3,5-diphenylfuran-2-yl)phenylmethylidene]amines 3a, 3c, and 3g while only corresponding furanoic derivatives 3b and 3d-3f were obtained from 5-methyl (1b), 7-methyl (1d), 8-methyl (1e), and 5-phenyl (1f) derivatives of the (Z)-ketone 1a. VIS-Illumination of (Z)-1,3-diphenyl-3-(2-phenylimidazo[1,2-a]benzo[I]quinolin-3-yl)prop-2-en-1-one (4) led to N-(benzo[h]quinolin-2-yl)-[(3,5-diphenylfuran-2-yl)phenylmethylidene]amine (5). Photoisomers 2a, 2c, 2g, 3a-3g, and 5 were isolated and the molecular structure of 3c was X-ray determined. Mechanism of the photoisomerization is discussed using semiempirical quantum chemical calculations and compared with mass spectra of compounds 1a, 2a, 3a, 1g, 2g, and 3g.
Conformational Studies on Diribonucleoside Monophosphate Analogs Containing a Nonisosteric, Isopolar, Phosphonate-Based Internucleotide Linkage
Authors: Zajíček Jaroslav , Rosenberg Ivan , Liboska Radek , Točík Zdeněk , Fazakerley G. Victor , Guschlbauer Wilhelm , Holý Antonín
Published: July 2002

Two types of (2'-5') and (3'-5') isomers of phosphonate analogs of diribonucleotides derived from 2'-, 3'- or 5'-O-phosphonomethyl ribonucleosides, that differ in the position of methylene group in the phosphonate internucleotide linkage, have been studied in aqueous solution by NMR techniques in order to compare their basic structural features with those of the natural (3'-5') diribonucleotides. Despite the additional methylene group in the ribose-phosphate backbone, dinucleoside phosphonates are structurally and conformationally very similar to their natural counterparts.
Synthesis of (19E)-3β,7β-Dihydroxy-17-oxoandrost-5-en-19-al 19-(O-Carboxymethyl)oxime, New Hapten for 7β-Hydroxydehydroepiandrosterone (3β,7β-Dihydroxyandrost-5-en-17-one)
Authors: Pouzar Vladimír , Slavíková Tereza , Černý Ivan
Published: July 2002

(19E)-3β,7β-Dihydroxy-17-oxoandrost-5-en-19-al 19-(O-carboxymethyl)oxime (26) was prepared in 15 steps from 17-oxoandrost-5-en-3β-yl benzoate (2, DHEA benzoate). Protection of position 17 by a borohydride reduction and acetylation, subsequent functionalization of position 19 by hypoiodite reaction, oxidation to 19-aldehyde and oximation gave successively (19E)-19-oxoandrost-5-ene-3β,17β-diyl 17-acetate 3-benzoate 19-(O-carboxymethyl)oxime methyl ester (10). Then 7-keto group was introduced by allylic oxidation with chromium(VI) oxide-3,5-dimethylpyrazole complex and stereoselectively reduced by borohydride in the presence of cerium(III) ions into 7β-hydroxy group. After protection as 7-isobutyrate the acetate at position 17 was removed and oxidation recovered 17-ketone. Final deprotection revealed both hydroxyl and carboxyl groups, giving desired 19-CMO 7β-hydroxy DHEA designed as hapten for immunassays.
Syntheses of Steroid O-(3-Carboxypropyl)oximes
Authors: Slavíková Tereza , Pouzar Vladimír , Černý Ivan
Published: July 2002

The syntheses of O-(3-carboxypropyl)oxime derivatives, i.e. bis-homologues of O-(carboxymethyl)oxime derivatives (CMO), derived from dehydroepiandrosterone, testosterone and estradiol are presented. Both the reaction of steroid ketone with O-(3-carboxypropyl)hydroxylamine, and the reaction of sodium salt of steroid oxime with ethyl 4-bromobutyrate were alternatively evaluated, together with some other methods using successive chain lengthening. The compatibility with acetyl and methoxymethyl protecting groups was studied.
Template-Directed Syntheses of Catenanes
Authors: Bělohradský Martin , Raymo Françisco M. , Stoddart J. Fraser
Published: July 2002

The art and science of introducing mechanical-interlocking at the molecular level in order to generate catenanes - molecules composed of two or more macrocyclic components - offers the opportunity of constructing a new range of molecular compounds possessing intriguing properties. However, the topological features displayed by catenanes has rendered the syntheses of such molecular compounds an extremely challenging task for synthetic chemists to address. Their early syntheses were based upon either statistical approaches - the threading of a small amount of a macrocycle on to an acyclic precursor as a chance event - or directed approaches, relying upon the temporary introduction of covalent bonds in the multistep synthesis of a so-called precatenane, followed by its conversion ultimately into a catenane. These approaches afforded catenanes in very low yields overall and only after following tedious and laborious synthetic procedures. Fortunately, however, with the advent of supramolecular chemistry, template-directed methods that allow us to self-assemble [n]catenanes much more efficiently have become available. Numerous successful template-directed syntheses have now emerged - some by chance and others by design. These methods have been based upon (i) metal coordinating, (ii) hydrogen bonding, (iii) solvophobic, and/or (iv) π-π stacking interactions which have been found to govern self-assembly processes to catenated compounds from appropriate precursors. Their relative simplicity, the high degree of control with which they can be employed, and the remarkable efficiency with which they proceed has already provided the opportunity to synthetic chemists to self-assemble a series of [n]catenanes, incorporating from two up to five mechanically-interlocked macrocyclic components.
Study on N-Demethylation of N,N-Dimethyl-4-aminoazobenzene and N-Nitrosamines by Prostaglandin H Synthase
Authors: Stiborová Marie , Frei Eva , Schmeiser Heinz H.
Published: July 2002

The in vitro enzymatic metabolism of carcinogenic N,N-dimethyl-4-aminoazobenzene, N-nitroso-N-methylaniline and N-nitroso-N,N-dimethylamine was investigated using ram seminal vesicle microsomal prostaglandin H synthase. Both N-nitrosamines are not converted by the studied enzyme. Formaldehyde is produced by the prostaglandin H synthase catalyzed reaction from N,N-dimethyl-4-aminoazobenzene. Arachidonic acid and hydrogen peroxide serve as cofactors for the oxidation of N,N-dimethyl-4-aminoazobenzene. The apparent Michaelis constant and the maximal velocity values for N,N-dimethyl-4-aminoazobenzene as a substrate are 64 μmol/l and 51.2 nmol HCHO/min/mg protein, respectively. In addition to formaldehyde, N-methyl-4-aminoazobenzene and 4-aminoazobenzene, two unknown substances are the products of the N,N-dimethyl-4-aminoazobenzene oxidation. The oxidation of N,N-dimethyl-4-aminoazobenzene catalyzed by prostaglandin H synthase is inhibited by glutathione, ascorbate and NADH. The results suggest that prostaglandin H synthase metabolizes N,N-dimethyl-4-aminoazobenzene through a one-electron oxidation mechanism, giving rise to free radicals.
Nitrogen(II) Oxide (Nitric Oxide, NO): Its Origin, Fate and Physiological Significance. A Review
Authors: Vetrovsky Petr , Entlicher Gustav
Published: July 2002

The nitrogen oxide (NO), a free radical molecule, plays a key role in the regulation of mammalian physiology and pathophysiology, e.g., in cardiovascular, nervous or immune systems. This molecule is produced from guanidino moiety of amino acid L-arginine with NG-hydroxy-L-arginine as intermediate and L-citrulline as a co-product of this reaction. This conversion is catalyzed by an ezyme called NO-synthase. The NO-synthase belongs to the cytochrome P450 superfamily and four its isoenzymes are known so far. Two (denoted NOS-I and III) are constitutive, generate lower amounts (pmol) of NO and are regulated by Ca++/calmodulin system. The others (NOS-II and IV) are inducible, produce a larger quantity of NO (nmol) and are regulated at a transcriptional level. The constitutive form is present, for example, in endothelial and neuronal cells whereas the inducible form is de novo synthesized as a consequence of certain stimuli (including cytokines) in macrophages, vascular smooth muscle cells and other cells. There are several target molecules for NO depending on cells. The most frequent target is supposed to be the soluble guanylate cyclase. However, superoxide anion is a very important target for NO, too. The reaction between these two molecules leads to the production of peroxynitrite, the fate of which depends on environmental conditions. Therefore, the importance of this reaction is still debated. This review deals with the nature of NO, the mechanisms of its production, the role of intermediate NG-hydroxy-L-arginine and summarizes the biology of superoxide anion with respect to its reaction with NO. A review with 218 references.
Modelling of the Deactivation of Polymer-Supported Palladium Catalysts in the Hydrogenation of 4-Nitrotoluene
Authors: Králik Milan , Fišera Roman , Zecca Marco , D'Archivio Angelo A. , Galantini Luciano , Jeřábek Karel , Corain Benedetto
Published: July 2002

The kinetics of the hydrogenation of 4-nitrotoluene over Pd catalysts supported on sulfonated polystyrene and simultaneous deactivation of these catalysts were investigated. Reaction rates of both the hydrogenation and the dissolution of Pd crystallites were related to the total Pd surface. The average radius of ideal spherical crystallites, as determined by X-ray powder diffraction analysis, was taken as the starting value of the crystallite size. Stability of the polymer network was checked by Inverse Steric Exclusion Chromatography (ISEC). The ESR and Static Gradient field Spin Echo (SGSE) NMR spectroscopies were used to assess the accessibility and diffusivity before and after deactivation experiments. Langmuir-Hinshelwood type kinetic models were applied to describe the hydrogenation of 4-nitrotoluene. The kinetic law was incorporated into a more comprehensive model involving also diffusion of reactants inside catalytic particles. Simultaneous treatment of a few sets of kinetic data from batch hydrogenation carried out at 0.25-0.75 MPa yielded reliable values of model parameters. The model showed an increasing rate of dissolution of palladium with decreasing concentration of hydrogen and increasing concentration of 4-nitrotoluene. The latter fact supports the hypothesis that the nitro compound is the oxidant responsible for the dissolution of palladium.
One-Step Conversion of Oxetane-Fused to 1,3-Oxazine-Fused Steroids
Authors: Hajnal Andrea , Wölfling János , Schneider Gyula
Published: July 2002

In a ring-expansion reaction, alkyl and aryl nitriles, in the presence of tetrafluoroboric acid-diethyl ether complex, react with 3-methoxy-16β,17β-dihydro-4'H-oxeto[3',2':16,17]estra-1,3,5(10)-triene to give 3-methoxy-16β,17β-dihydro-4'H-[1,3]-oxazino[5',6':16,17]estra-1,3,5(10)-triene derivatives. Under similar conditions 3-methoxy-16α,17α-dihydro-4'H-oxeto[3',2':16,17]estra-1,3,5(10)-triene undergoes a Wagner-Meerwein rearrangement.