bluuebunny/crossref_metadata_2025 huggingface dataset:
In Utero Infection by Porcine Reproductive and Respiratory Syndrome Virus Is Sufficient To Increase Susceptibility of Piglets to Challenge by
Streptococcus suis
Type II
Authors: Feng Wen-hai , Laster S. M. , Tompkins M. , Brown T. , Xu J.-S. , Altier C. , Gomez W. , Benfield D. , McCaw M. B.
Published: July 2002

Porcine reproductive and respiratory syndrome (PRRS) consistently elevates the frequency of disease and mortality in young pigs. Many different secondary bacterial diseases occur in PRRS virus (PRRSV)-infected pigs. However, to date, establishing a reproducible experimental model of PRRSV infection in weaned pigs, with subsequent clinical disease following secondary bacterial challenge, has been difficult. PRRSV is frequently isolated during outbreaks from weak-born piglets affected by secondary bacterial diseases. This study was performed to investigate the potential role of intrauterine PRRSV infection on piglet susceptibility to secondary bacterial infection. PRRSV-free pregnant sows were intranasally infected at 98 days of gestation with PRRSV strain SD 23983. All piglets born to the PRRSV-infected sows were viremic. Piglets were removed from the sows at birth and deprived of colostrum. Piglets from PRRSV-infected and noninfected sows were randomly assigned to
Streptococcus suis
challenge or control subgroups. At 5 days of age, piglets were challenged intranasally with strain MN 87555 of
S. suis
type II. Total and differential leukocyte counts were performed on blood samples collected at 3 days of age. The numbers of leukocytes, lymphocytes, and monocytes were significantly reduced in the PRRSV-infected piglets. Lesions were observed in bone marrow, brain, lung, heart, spleen, lymph node, tonsil, and thymus of PRRSV-infected piglets. Thymus/body weight ratios of in utero PRRSV-infected piglets were significantly reduced compared to those of non-PRRSV-infected piglets, and thymic lesions were characterized by severe cortical depletion of thymocytes. Lesions were not observed in piglets born to PRRSV-free sows. Overall, 20 out of 22 piglets in the PRRSV-
S. suis
dual-infection group died within 1 week after challenge with
S. suis
(10 of 11 in each of two trials). This contrasts with 1 of 18 piglets in the PRRSV-infection-only group and 5 of 23 piglets in the
S. suis
-challenge-only group (1 of 12 in trial 1 and 4 of 11 in trial 2). No piglets died in the uninfected control groups. Most of the piglets in the PRRSV-
S. suis
dual-infection group developed suppurative meningitis.
S. suis
type II was recovered from their brains and joints. These results indicate that in utero infection by PRRSV makes piglets more susceptible to infection and disease following challenge by
S. suis
type II. In utero infection by PRRSV may provide a useful model to study the interaction between PRRSV and bacterial coinfections in piglets.
Adaptation of Tick-Borne Encephalitis Virus to BHK-21 Cells Results in the Formation of Multiple Heparan Sulfate Binding Sites in the Envelope Protein and Attenuation In Vivo
Authors: Mandl Christian W. , Kroschewski Helga , Allison Steven L. , Kofler Regina , Holzmann Heidemarie , Meixner Tamara , Heinz Franz X.
Published: July 2002

Propagation of the flavivirus tick-borne encephalitis virus in BHK-21 cells selected for mutations within the large surface glycoprotein E that increased the net positive charge of the protein. In the course of 16 independent experiments, 12 different protein E mutation patterns were identified. These were located in all three of the structural domains and distributed over almost the entire upper and lateral surface of protein E. The mutations resulted in the formation of local patches of predominantly positive surface charge. Recombinant viruses carrying some of these mutations in a defined genetic backbone showed heparan sulfate (HS)-dependent phenotypes, resulting in an increased specific infectivity and binding affinity for BHK-21 cells, small plaque formation in porcine kidney cells, and significant attenuation of neuroinvasiveness in adult mice. Our results corroborate the notion that the selection of attenuated HS binding mutants is a common and frequent phenomenon during the propagation of viruses in cell culture and suggest a major role for HS dependence in flavivirus attenuation. Recognition of this principle may be of practical value for designing attenuated flavivirus strains in the future.
RNAs Extracted from Herpes Simplex Virus 1 Virions: Apparent Selectivity of Viral but Not Cellular RNAs Packaged in Virions
Authors: Sciortino Maria-Teresa , Suzuki Mikiko , Taddeo Brunella , Roizman Bernard
Published: July 2002

Following the lead of recent studies on the presence of RNA in virions of human cytomegalovirus, we investigated the presence and identity of RNAs from purified virions of herpes simple virus 1. To facilitate these studies, we designed primers for all known open reading frames (ORFs) and also constructed cDNA arrays containing probes designed to detect all known transcripts. In the first series of experiments, labeled DNA made by reverse transcription of poly(A)
+
RNA extracted from infected HEp-2 or rabbit skin cells hybridized to all but two of the probes in the cDNA array. A similar analysis of the RNA extracted from purified extracellular virions derived from infected HEp-2 cells hybridized to probes representing 24 of the ORFs. In the second series of analyses, we reverse transcribed and amplified by PCR RNAs from purified intracellular or extracellular virions derived from infected HEp-2 or Vero cell lines. The positive RNAs were retested by PCR with and without prior reverse transcription to ensure that the samples tested were free of contaminating DNA. The results were as follows. (i) Only a fraction of viral ORF transcripts were represented in virion RNA, and only nine RNAs (U
L
10, U
L
34/U
L
35, U
L
36, U
L
42, U
L
48, U
L
51, U
S
1/U
S
1.5, U
S
8.5, and U
S
10/U
S
11) were positive in all RT PCR assays. Of these, seven were positive by hybridization to cDNA arrays. (ii) RNA extracted from cells infected with a mutant virus lacking the U
S
8 to U
S
12 genes yielded results similar to those described above, indicating that U
S
11, a known RNA binding protein, does not play a role in packaging RNA in virions. (iii) Cellular RNAs detected in virions were representative of the abundant cellular RNAs. Last, RNA extracted from virions was translated in vitro and the translation products were reacted with antibody to αTIF (VIP16). The immune precipitate contained a labeled protein with the apparent molcular weight of αTIF, indicating that at least one mRNA packaged in virions was intact and capable of being translated. The basis for the apparent selectivity in the packaging of the viral RNAs packaged in virions is unknown.
Rescue of Rabies Virus from Cloned cDNA and Identification of the Pathogenicity-Related Gene: Glycoprotein Gene Is Associated with Virulence for Adult Mice
Authors: Ito Naoto , Takayama Mutsuyo , Yamada Kentaro , Sugiyama Makoto , Minamoto Nobuyuki
Published: July 2002

In order to identify the viral gene related to the pathogenicity of rabies virus, we tried to establish a reverse genetics system of the attenuated RC-HL strain, which causes nonlethal infection in adult mice after intracerebral inoculation. A full-length genome plasmid encoding the complete antigenomic cDNA of the RC-HL strain and helper plasmids containing cDNAs of the complete open reading frame of the N, P, and L genes, respectively, were constructed. After transfection of these plasmids into BHK-21 cells infected with the T7 RNA polymerase-expressing vaccinia virus, infectious rabies virus with almost the same biological properties as those of the wild-type RC-HL strain was rescued. Using this reverse genetics system of the RC-HL strain, we generated a chimeric virus with the open reading frame of the glycoprotein gene from the parent Nishigahara strain, which kills adult mice after intracerebral inoculation, in the background of the RC-HL genome. Since the chimeric virus killed adult mice following intracerebral inoculation, it became evident that the open reading frame of the glycoprotein gene is related to the pathogenicity of the Nishigahara strain for adult mice.
Functional Interaction Map of Lyssavirus Phosphoprotein: Identification of the Minimal Transcription Domains
Authors: Jacob Yves , Real Eléonore , Tordo Noël
Published: July 2002

Lyssaviruses, the causative agents of rabies encephalitis, are distributed in seven genotypes. The phylogenetically distant rabies virus (PV strain, genotype 1) and Mokola virus (genotype 3) were used to develop a strategy to identify functional homologous interactive domains from two proteins (P and N) which participate in the viral ribonucleoprotein (RNP) transcription-replication complex. This strategy combined two-hybrid and green fluorescent protein–reverse two-hybrid assays in
Saccharomyces cerevisiae
to analyze protein-protein interactions and a reverse genetic assay in mammalian cells to study the transcriptional activity of the reconstituted RNP complex. Lyssavirus P proteins contain two N-binding domains (N-BDs), a strong one encompassing amino acid (aa) 176 to the C terminus and a weak one in the 189 N-terminal aa. The N-terminal portion of P (aa 52 to 189) also contains a homomultimerization site. Here we demonstrate that N-P interactions, although weaker, are maintained between proteins of the different genotypes. A minimal transcriptional module of the P protein was obtained by fusing the first 60 N-terminal aa containing the L protein binding site to the C-terminal strong N-BD. Random mutation of the strong N-BD on P protein identified three highly conserved K residues crucial for N-P interaction. Their mutagenesis in full-length P induced a transcriptionally defective RNP. The analysis of homologous interactive domains presented here and previously reported dissections of the P protein allowed us to propose a model of the functional interaction network of the lyssavirus P protein. This model underscores the central role of P at the interface between L protein and N-RNA template.
Segregation of EAV-HP Ancient Endogenous Retroviruses within the Chicken Population
Authors: Sacco M. A. , Venugopal K.
Published: July 2002

Avian leukosis virus subgroup J (ALV-J), an exogenous avian retrovirus, is thought to have evolved by recombination with the highly identical
env
gene of the endogenous avian retrovirus EAV-HP. Embryonic expression of EAV-HP
env
has been suggested to be associated with the induction of immunological tolerance, a feature observed in a significant proportion of meat-type chickens infected with ALV-J. In support of this hypothesis, we demonstrate that EAV-HP loci, some of which could be associated with tolerance, are still segregating within the chicken population.
Structural and Functional Relationship between the Receptor Recognition and Neuraminidase Activities of the Newcastle Disease Virus Hemagglutinin-Neuraminidase Protein: Receptor Recognition Is Dependent on Neuraminidase Activity
Authors: Iorio Ronald M. , Field Gisela M. , Sauvron Jennifer M. , Mirza Anne M. , Deng Ruitang , Mahon Paul J. , Langedijk Johannes P.
Published: July 2002

The terminal globular domain of the paramyxovirus hemagglutinin-neuraminidase (HN) glycoprotein spike has a number of conserved residues that are predicted to form its neuraminidase (NA) active site, by analogy to the influenza virus neuraminidase protein. We have performed a site-directed mutational analysis of the role of these residues in the functional activity of the Newcastle disease virus (NDV) HN protein. Substitutions for several of these residues result in a protein lacking both detectable NA and receptor recognition activity. Contribution of NA activity, either exogenously or by coexpression with another HN protein, partially rescues the receptor recognition activity of these proteins, indicating that the receptor recognition deficiencies of the mutated HN proteins result from their lack of detectable NA activity. In addition to providing support for the homology-based predictions for the structure of HN, these findings argue that (i) the HN residues that mediate its NA activity are not critical to its attachment function and (ii) NA activity is required for the protein to mediate binding to receptors.
Mutation of Host Δ9 Fatty Acid Desaturase Inhibits Brome Mosaic Virus RNA Replication between Template Recognition and RNA Synthesis
Authors: Lee Wai-Ming , Ishikawa Masayuki , Ahlquist Paul
Published: July 2002

All positive-strand RNA viruses assemble their RNA replication complexes on intracellular membranes. Brome mosaic virus (BMV) replicates its RNA in endoplasmic reticulum (ER)-associated complexes in plant cells and the yeast
Saccharomyces cerevisiae
. BMV encodes RNA replication factors 1a, with domains implicated in RNA capping and helicase functions, and 2a, with a central polymerase-like domain. Factor 1a interacts independently with the ER membrane, viral RNA templates, and factor 2a to form RNA replication complexes on the perinuclear ER. We show that BMV RNA replication is severely inhibited by a mutation in
OLE1
, an essential yeast chromosomal gene encoding Δ9 fatty acid desaturase, an integral ER membrane protein and the first enzyme in unsaturated fatty acid synthesis.
OLE1
deletion and medium supplementation show that BMV RNA replication requires unsaturated fatty acids, not the Ole1 protein, and that viral RNA replication is much more sensitive than yeast growth to reduced unsaturated fatty acid levels. In
ole1
mutant yeast, 1a still becomes membrane associated, recruits 2a to the membrane, and recognizes and stabilizes viral RNA templates normally. However, RNA replication is blocked prior to initiation of negative-strand RNA synthesis. The results show that viral RNA synthesis is highly sensitive to lipid composition and suggest that proper membrane fluidity or plasticity is essential for an early step in RNA replication. The strong unsaturated fatty acid dependence also demonstrates that modulating fatty acid balance can be an effective antiviral strategy.
ICP0 Is Required for Efficient Reactivation of Herpes Simplex Virus Type 1 from Neuronal Latency
Authors: Halford William P. , Schaffer Priscilla A.
Published: July 2002

Relative to wild-type herpes simplex virus type 1 (HSV-1), ICP0-null mutant viruses reactivate inefficiently from explanted, latently infected mouse trigeminal ganglia (TG), indicating that ICP0 is not essential for reactivation but plays a central role in enhancing the efficiency of reactivation. The validity of these findings has been questioned, however, because the replication of ICP0-null mutants is impaired in animal models during the establishment of latency, such that fewer mutant genomes than wild-type genomes are present in latently infected mouse TG. Therefore, the reduced number of mutant viral genomes available to reactivate, rather than mutations in the ICP0 gene per se, may be responsible for the reduced reactivation efficiency of ICP0-null mutants. We have recently demonstrated that optimization of the size of the ICP0 mutant virus inoculum and transient immunosuppression of mutant-infected mice with cyclophosphamide can be used to establish wild-type levels of ICP0-null mutant genomes in latently infected TG (W. P. Halford and P. A. Schaffer, J. Virol. 74:5957–5967, 2000). Using this procedure to equalize mutant and wild-type genome numbers, the goal of the present study was to determine if, relative to wild-type virus, the absence of ICP0 function in two ICP0-null mutants,
n
212 and 7134, affects reactivation efficiency from (i) explants of latently infected TG and (ii) primary cultures of latently infected TG cells. Although equivalent numbers of viral genomes were present in TG of mice latently infected with either wild-type or mutant viruses, reactivation of
n
212 and 7134 from heat-stressed TG explants was inefficient (31 and 37% reactivation, respectively) relative to reactivation of wild-type virus (KOS) (95%). Similarly,
n
212 and 7134 reactivated inefficiently from primary cultures of dissociated TG cells plated directly after removal from the mouse (7 and 4% reactivation, respectively), relative to KOS (60% reactivation). The efficiency and kinetics of reactivation of KOS,
n
212, and 7134 from cultured TG cells (treated with acyclovir to facilitate the establishment of latency) in response to heat stress or superinfection with a nonreplicating HSV-1 ICP4
−
mutant,
n
12, were compared. Whereas heat stress induced reactivation of KOS from 69% of latently infected TG cell cultures, reactivation of
n
212 and 7134 was detected in only 1 and 7% of cultures, respectively. In contrast, superinfection with the ICP4
−
virus, which expresses high levels of ICP0, resulted in the production of infectious virus in nearly 100% of cultures latently infected with KOS,
n
212, or 7134 within 72 h. Thus, although latent mutant viral genome loads were equivalent to that of wild-type virus, in the absence of ICP0,
n
212 and 7134 reactivated inefficiently from latently infected TG cells during culture establishment and following heat stress. Collectively, these findings demonstrate that ICP0 is required to induce efficient reactivation of HSV-1 from neuronal latency.
Regulation of Viral Intermediate Gene Expression by the Vaccinia Virus B1 Protein Kinase
Authors: Kovacs Gerald R. , Vasilakis Nikos , Moss Bernard
Published: July 2002

The B1 gene of vaccinia virus encodes a serine/threonine protein kinase that is expressed early after infection. Under nonpermissive conditions, temperature-sensitive mutants (
ts
2 and
ts
25) that map to B1 fail to efficiently replicate viral DNA. Our goal was to extend studies on the function of B1 by determining if the kinase is required for intermediate or late gene expression, two events that ordinarily depend on viral DNA replication. First, we established that early viral gene expression occurred at the nonpermissive temperature. By using a transfection procedure that circumvents the viral DNA replication requirement, we found that reporter genes regulated by an intermediate promoter were transcribed only under conditions permissive for expression of active B1. To assay late gene expression, the T7 RNA polymerase gene was inserted into the genome of
ts
25 to form
ts
25/T7. A DNA replication-independent late gene transcription system was established by cotransfecting plasmids containing T7 promoter-driven late gene transcription factors and a late promoter reporter gene into
ts
25/T7-infected cells. Late genes, unlike intermediate genes, were expressed at the nonpermissive temperature. Last, we showed that overexpression of B1 stimulated intermediate but inhibited late gene expression in cells infected with wild-type virus.
Human Immunodeficiency Virus Type 1 Enters Brain Microvascular Endothelia by Macropinocytosis Dependent on Lipid Rafts and the Mitogen-Activated Protein Kinase Signaling Pathway
Authors: Liu Nancy Q. , Lossinsky Albert S. , Popik Waldemar , Li Xia , Gujuluva Chandrasekhar , Kriederman Benjamin , Roberts Jaclyn , Pushkarsky Tatania , Bukrinsky Michael , Witte Marlys , Weinand Martin , Fiala Milan
Published: July 2002

Brain microvascular endothelial cells (BMVECs) present an incomplete barrier to human immunodeficiency virus type 1 (HIV-1) neuroinvasion. In order to clarify the mechanisms of HIV-1 invasion, we have examined HIV-1 uptake and transcellular penetration in an in vitro BMVEC model. No evidence of productive infection was observed by luciferase, PCR, and reverse transcriptase assays. Approximately 1% of viral RNA and 1% of infectious virus penetrated the BMVEC barrier without disruption of tight junctions. The virus upregulated ICAM-1 on plasma membranes and in cytoplasmic vesiculotubular structures. HIV-1 virions were entangled by microvilli and were taken into cytoplasmic vesicles through surface invaginations without fusion of the virus envelope with the plasma membrane. Subsequently, the cytoplasmic vesicles fused with lysosomes, the virions were lysed, and the vesicles diminished in size. Upon cell entry, HIV-1 colocalized with cholera toxin B, which targets lipid raft-associated GM1 ganglioside. Cholesterol-extracting agents, cyclodextrin and nystatin, and polyanion heparin significantly inhibited virus entry. Anti-CD4 had no effect and the chemokine AOP-RANTES had only a slight inhibitory effect on virus entry. HIV-1 activated the mitogen-activated protein kinase (MAPK) pathway, and inhibition of MAPK/Erk kinase inhibited virus entry. Entry was also blocked by dimethylamiloride, indicating that HIV-1 enters endothelial cells by macropinocytosis. Therefore, HIV-1 penetrates BMVECs in ICAM-1-lined macropinosomes by a mechanism involving lipid rafts, MAPK signaling, and glycosylaminoglycans, while CD4 and chemokine receptors play limited roles in this process.
DNA-Directed Expression of an Animal Virus RNA for Replication-Dependent Colony Formation in
Saccharomyces cerevisiae
Authors: Price B. D. , Ahlquist P. , Ball L. A.
Published: July 2002

To date, the insect nodavirus flock house virus (FHV) is the only virus of a higher eukaryote that has been shown to undergo a full replicative cycle and produce infectious progeny in the yeast
Saccharomyces cerevisiae
. The genome of FHV is composed of two positive-sense RNA segments: RNA1, encoding the RNA replicase, and RNA2, encoding the capsid protein precursor. When yeast cells expressing FHV RNA replicase were transfected with a chimeric RNA composed of a selectable gene flanked by the termini of RNA2, the chimeric RNA was replicated and transmitted to daughter cells indefinitely. In the work reported here, we developed a system in which a selectable chimeric RNA replicon was transcribed from an inducible RNA polymerase II (
polII
) promoter in vivo in yeast. To render marker gene expression absolutely dependent on RNA replication, the primary
polII
transcript was made negative in sense and contained an intron that blocked the translation of cryptic transcripts from the opposite DNA strand. The RNA products of DNA-templated transcription, processing, and RNA replication were characterized by Northern blot hybridization and primer extension analysis. Marker gene expression and colony growth under selective conditions depended strictly on FHV RNA replication, with background colonies arising at a frequency of fewer than 1 in 10
8
plated cells. The utility of the system was demonstrated by introducing a second chimeric replicon and showing that at least two different selectable markers could be simultaneously expressed by means of RNA replication. This is the first example of FHV RNA1-dependent selectable marker expression initiated in vivo and will greatly facilitate the identification and characterization of the requirements and inhibitors of RNA replication.
Characterization of Chromosomally Assigned Replication-Competent Gamma Porcine Endogenous Retroviruses Derived from a Large White Pig and Expression in Human Cells
Authors: Niebert Marcus , Rogel-Gaillard Claire , Chardon Patrick , Tönjes Ralf R.
Published: July 2002

Vertically transmitted endogenous retroviruses pose an infectious risk in the course of pig-to-human transplantation of cells, tissues, and organs. Two classes of polytropic type C porcine endogenous retroviruses (PERV) productively infect human cells in vitro. The cloning and characterization of replication-competent PERV-B sequences from infected human cells (F. Czauderna, N. Fischer, K. Boller, R. Kurth, and R. R. Tönjes, J. Virol. 74:4028-4038, 2000) as well as the cloning of functional PERV-A and -B sequences from porcine cell line PK15 (U. Krach, N. Fischer, F. Czauderna, and R. R. Tönjes, J. Virol. 75:5465-5472, 2001) have been previously described. Here we report the isolation of four full-length proviral sequences from a porcine bacterial artificial chromosome (BAC) library that comprises chromosomally assigned PERV. Clones Bac-PERV-A(130A12) and Bac-PERV-A(151B10) map to pig chromosome 1 and demonstrate close homology to PK15-PERV-A(58) in
env
and to PERV-MSL in long terminal repeat (LTR),
gag
, and
pro/pol
sequences. Clone Bac-PERV-A(463H12) is located on pig chromosome 3 and demonstrates close homology to PK15-PERV-A(58) in
env
and to 293-PERV-B(43) in LTR,
gag
, and
pro/pol
(Czauderna et al.; R. R. Tönjes, F. Czauderna, N. Fischer, U. Krach, K. Boller, P. Chardon, C. Rogel-Gailard, M. Niebert, G. Scheef, A. Werner, and R. Kurth, Transplant Proc. 32:1158-1161, 2000). Clone Bac-PERV-B(192B9) is located on pig chromosome 7 in the swine leukocyte antigen region and is highly homologous with but distinct from the previously described functional clone 293-PERV-B(43) and bears the number of repeats initially observed in the LTRs of clone 293-PERV-A(42) (Czauderna et al.; Krach et al.). Clones Bac-PERV-A(130A12), Bac-PERV-A(151B10), and Bac-PERV-A(463H12) were replication competent upon transfection into susceptible 293 and HeLa cells. Bac-PERV-B(192B9), however, bears two stop codons in
pro/pol
preventing this clone from being replication competent in some individual pigs, but initial screenings indicate that this provirus might be intact in others. The data suggest that the porcine genome harbors a limited number of infectious PERV sequences, allowing for specific screening in different pig breeds.
A Study of the Use of Solubility Isotherms to Obtain Information about Ion Hydration and Ion Pairing in Concentrated Solutions of Electrolytes
Authors: Eysseltová Jitka
Published: July 2002

Computational analysis of solubility isotherms in ternary systems consisting of water and two solutes having a common ion was suggested and the respective software was developed. This hydration analysis was applied to model systems NH4CNS - NaCNS - H2O at 5, 25 and 50 °C and NaX - KX - H2O (X = Cl, Br, I) at 25 °C. The results obtained are discussed and the way in which the hydration analysis gives information on ionic processes in saturated electrolyte solutions is demonstrated.
Multicomponent Spectrophotometric Analysis of Metal Ions Based on Simultaneous or Consecutive Application of Several Reagents
Authors: Perůtka Jiří , Havel Josef , Jančář Luděk
Published: July 2002

This paper deals with nonconventional approaches to multicomponent spectrophotometric analysis consisting of (i) simultaneous or consecutive addition of several nonselective reagents in the multicomponent determination of metal ions, and (ii) the use of absorbance data which have been measured at different pH values or in different experimental conditions and subsequently combined into a single data set, evaluated by the partial least squares method. The following multicomponent mixtures of metal ions with reagents were examined: Co2+ and Fe3+ with nitroso-R-salt and 1,10-phenanthroline; Co2+, Cu2+ and Fe3+ with nitroso-R-salt and zincon; Co2+, Cu2+ and Zn2+ with nitroso- R-salt and zincon; and Cu2+, Zn2+ and Ni2+ with zincon and PAR. The average relative error of determination was 2% (two metal ions) and 5% (three metal ions). Cu2+, Zn2+ and Ni2+ were also quantitated in ALPAKA alloy with relative errors of 4 - 9%.
Molecular Dynamics of Vesicles of Unsaturated Phosphatidylcholines Studied by 13C NMR Spin-Lattice Relaxation
Authors: Zajíček Jaroslav , Ellena Jeffrey F. , Williams Gerald D. , Khadim Mohammad A. , Brown Michael F.
Published: July 2002

13C spin-lattice relaxation times, T1Z, were measured at four different magnetic field strengths for a vesicles of a series of unsaturated 1,2-diacyl-sn-glycero-3-phosphocholines over the temperature range from 5 to 50 °C. The acyl chains of the phosphatidylcholines varied in length from 14 to 18 carbons and in the degree of unsaturation: myristoleoyl (14 : 1), palmitoleoyl (16 : 1), oleoyl (18 : 1), linoleoyl (18 : 2), linolenoyl (18 : 3). For each of the phosphatidylcholines studied the R1Z = (NT1Z)-1 values of the acyl chain methylene carbons, where N is the number of directly bonded hydrogens, decreased from the C2 position which is situated close to the glycerol backbone towards the acyl terminal methyl group. The effect of the double bond was manifested by an increase in R1Z and was less pronounced if it was located closer to the terminal methyl group than in the middle of the chain. A minimum in the T1Z relaxation times was not observed, even for highest frequency of 125.8 MHz and the lowest temperature of 5 °C. In the case of the phosphocholine headgroup and glycerol backbone carbons the T1Z times showed similar temperature and frequency dependencies as the acyl chain carbons. The results of the measurements indicate substantial differences in the dynamics of these systems in the liquid-crystalline state. Analysis of the data using various dynamical models is consistent with a distribution of motions which is not described by a single Lorentzian spectral density. This dispersion appears to be an inherent feature of the dynamics of phosphatidylcholines in the liquid-crystalline state.
Electrochemical Incorporation of Lithium and Sodium into Carbon Black
Authors: Vondrák Jiří
Published: July 2002

Electrochemical insertion of sodium or lithium into carbon black electrodes from perchlorate-propylene carbonate solution occurs under formation of substances close to C12Na and C6Li in potential range from 1.0 to 0 V vs alkali metal electrodes.
Theoretical Study of Thermal Dehydrochlorination of Poly(vinyl chloride) Initiated by Tertiary Chlorine Groupings
Authors: Burda Jaroslav , Lukáš Rudolf
Published: July 2002

Thermal dehydrochlorination of syndiotactic poly(vinyl chloride) sequences initiated by structural defects possessing chlorine atoms bound on tertiary carbon atoms (branched structures) was theoretically studied on the low-molecular-weight models using the semiempirical quantum chemical methods MNDO and AM1. The results are compared with those obtained previously by studying the dehydrochlorination in syndiotactic sequences without defects. It was found that elimination of the first HCl molecule is much easier in the branched structure. However, this effect fast decreases with dehydrochlorination continuing along the chain due to its distinct localization in the closest vicinity of tertiary carbon atom. A detailed evaluation of possible radical and ionic intermediates revealed that for ionic mechanism of dehydrochlorination the effect of branching is perceptible slightly longer.
Radioimmunological and Chromatographic Properties of Tyrosine Methyl Ester Conjugates with Stereoisomeric Steroid Carboxy Derivatives
Authors: Lapčík Oldřich , Hampl Richard , Hill Martin , Stárka Luboslav , Kasal Alexander , Pouzar Vladimír , Putz Zdeněk
Published: July 2002

Pure 3Z (syn) and 3E (anti) stereoisomers of testosterone 3-[O-(2-carboxyethyl)]oxime were synthesized, separated by HPLC or TLC, and used for preparation of tyrosine methyl ester (TME) conjugates by using mixed anhydride or carbodiimide-N-hydroxysuccinimide methods. While the latter method provided more than 96% of product with retained configuration, the mixed anhydride method yielded a mixture containing 26-40% of the opposite stereoisomer. The stereoisomers were used as model compounds, to which the other steroid TMEs and the corresponding radioiodinated products could be aligned according to their chromatographic properties. The TME conjugates of 3-(O-carboxymethyl)oximes of seven 4-en-3-oxo steroids were further prepared by carbodiimide-N-hydroxysuccinimide method. With exception of cortisol, the stereoisomeric (Z and E) radioiodinated TME conjugates could be separated by TLC. In addition, the conjugates with TME and consequently radioiodinated tracers were synthesized from hemisuccinates of cortisol and its 11α-isomer, via 11β- and 11α-hydroxy group. The radioiodinated conjugates were tested as radioligands with rabbit polyclonal antisera raised by using position-homologous conjugates of the respective steroid carboxy derivatives with bovine serum albumin as immunogens. With the exception of 11-deoxycorticosterone, the stereoisomeric Z and E radioiodinated TMEs did not differ in their binding properties. In the case of isomeric cortisol tracers conjugated through position 11 the antisera recognized only the sterically homologous radioligands, but the specificity of the system was poor.
Crystal Structure of Dibromo(η4-1,5-cyclooctadiene)palladium(II)
Authors: Štěpnička Petr , Císařová Ivana
Published: July 2002

The crystal structure of [(η4-C8H12)PdBr2] has been determined by a single crystal X-ray diffraction with R = 3.82% for 2 147 independent diffractions. The compound crystallizes with the symmetry of orthorhombic space group P212121 (No. 19) within the following parameters: a = 7.0785(5) Å, b = 11.1896(9) Å, c = 12.514(1) Å, V = 991.2(1) Å3, Z = 4. The square planar arrangement of ligands around Pd(II) is distorted due to the steric requirements of 1,5-cyclooctadiene in a twisted boat conformation. Formula units are joined by the weak C2-H2...Br1(1 + x, y, z) hydrogen bonds.
Sulfur Analogs of Imidodiphosphoric Acid as Extractants
Authors: Navrátil Oldřich , Tokárová Alena , Sládek Petr , Herrmann Eckhard , Nouaman Moein
Published: July 2002

The distribution of Ag, Zn, Cd, Sc, Eu, Hg, and Hf between mineral acids (HNO3, HCl) and benzene solutions of selected sulfur derivatives of organophosphoric reagents containing the P(X)NHP(X) or (RO3)PS group (X = O, S) was examined. The effect of the organic solvent was also investigated for Hg and some of the reagents. The composition of the complexes extracted was identified, and the corresponding extraction constants were calculated.
3-Bromo-2,5-dihydrofuran-2-one and 4-Bromo-2,5-dihydrofuran-2-one
Authors: Brecker Lothar , Kreiser Wolfgang , Ernst Ludger , Hopf Henning
Published: July 2002

Although 3-bromo-2,5-dihydrofuran-2-one and 4-bromo-2,5-dihydrofuran-2-one were first reported in 1894, considerable ambiguity still exists about the correct structure assignment of the two compounds. The present article gives a brief overview on the varying assignments of constitution and describes a novel method for the formation of 3-bromo-2,5-dihydrofuran-2-one. A comparison is made of the experimental 13C NMR chemical shifts with values predicted by increment calculations and experimental 1JC-C coupling constants are given for both compounds. Secure structural assignments are now available for both isomers.
2-(3-Acylselenoureido)benzonitriles and 2-(3-Acylselenoureido)thiophene-3-carbonitriles. Preparation, Structure Elucidation, Cyclization and Retrocyclization Reactions
Authors: Šibor Jiří , Žůrek Dalimil , Marek Radek , Kutý Michal , Humpa Otakar , Marek Jaromír , Pazdera Pavel
Published: July 2002

Synthesis of 2-(3-acylselenoureido)benzonitriles and 2-(3-acylselenoureido)thiophene- 3-carbonitriles 5a-5f by addition of 2-aminonitriles 4a-4c to benzoyl- or 2,2-dimethyl- propanoylisoselenocyanate and their cycloaddition reactions are described. Structures of compounds 5a-5f were supported by CIMS, FTIR, 1H, 13C, 77Se and 15N NMR spectra. The parameters of 15N and 77Se nuclei were obtained from inverse 1H-X 2D HMBC and GSQMBC correlation experiments at natural abundance. Structure of compound 5b was confirmed by X-ray analysis. The geometry of 5b was optimized by ab initio RHF/DZVP quantum chemistry calculation. A very good correlation between the calculation and experimental data was found. The geometry of 5e was optimized by ab initio DFT/VWN/DZVP quantum chemistry calculation. It was found that title compounds 5a-5f do not undergo isomerization to acylisoselenoureas, in contrast to analogous ester derivatives. Fused 6-imino-6H-1,3- selenazinium salts (chlorides 6a-6f, hydrogensulfates 7a-7f and tetrafluoroborates 8a-8f) were prepared by an acid cyclization of 5a-5f. It was found that neutralization of 6a-6f, 7a-7f and 8a-8f led to their retrocyclization to 5a-5f. Selenoureas 5a-5f with equimolar amounts of methanolic potassium hydroxide afforded potassium salts 9a-9f. Only the salts 9b, 9c, 9e and 9f of the thiophene series were isolated. Their heating in methanol solution led to deacylation of isoselenoureas 10b and 10c. The in situ prepared compounds 9a and 9d cyclized and deacylated to 4-aminoquinazoline-2-selenole 11a under the same conditions. The compounds 5a-5f and 10a-10c cyclized to fused 4-aminopyrimidine-2-selenols 11a, 11b and 4-aminopyrimidine-2-selenone 12c by boiling in methanolic potassium hydroxide solution.
Structures and Synthesis of 4a-Homo-7,19-dinorsteroids, X-Ray Crystallography and NMR Spectroscopy
Authors: Kasal Alexander , Buděšínský Miloš , Pelnař Jan , Bruck Michael A. , Brown Michael F.
Published: July 2002

X-Ray diffraction revealed the absolute configuration of 4aβ-methyl-4a-homo-7,19-dinor- 5α,10α-androstane-3,17-dione. Detailed NMR analysis suggested that the 5α configuration existed in the starting material, 3β-acetoxy-4a-methylidene-4a-homo-7,19-dinor- 5α-androst-9-en-17-one, and related compounds. Thus 5-methyl-5β-estr-9-ene derivatives with a leaving group in position 6β were found to react with nucleophiles to form rearranged 4a-homo-7,19-dinorandrostane derivatives with a 5α configuration.
Synthesis and Resolution of a New C2-Symmetric Chiral Bis-Aniline, trans-1,2-Bis(2-aminophenyl)cyclopentane
Authors: Yang Jin-Song , Kondo Kazuhiro , Murakami Yasuoki
Published: July 2002

New C2-symmetric trans-1,2-bis(2-aminophenyl)cyclopentanes 2a and 2b were synthesized in optically pure forms (99% ee) from the known racemic trans-1,2-bis(2-hydroxyphenyl)cyclopentane (3) by the conversion to its bis-triflate 4 followed by the Buchwald amination and resolution.
Comparison of Approaches to ent-Morphine via Radical, Cationic, and Heck-Type Cyclizations
Authors: Frey Dean A. , Duan Caiming , Ghiviriga Ion , Hudlický Tomáš
Published: July 2002

3-(2-{6S-(2-Bromo-6-methoxyphenoxy)-5S-[tert-butyl(dimethyl)silyloxy)cyclohex-1-en-1-yl}ethyl)oxazol-2(3H)-one 14 was subjected to Heck cyclization conditions to afford diben- zofuran derivative 16. The comparison of stepwise vs cascade approaches to 8 via radical, cationic, and Heck-type cyclizations is discussed.
A New Approach to Imidazo[1,5-a]indole Derivatives
Authors: Kutschy Peter , Suchý Mojmír , Dzurilla Milan , Takasugi Mitsuo , Kováčik Vladimír
Published: July 2002

Reaction of indole-2-carbonyl isothiocyanate (1) with sodium methanethiolate afforded 1-thioxo-1H-imidazo[1,5-a]indol-3(2H)-one (3). Its methylation with methyl iodide in the presence of lithium hydride in dimethylformamide, or potassium carbonate in acetone resulted in the formation of corresponding S- and N-methyl derivatives 4 and 5. N-(Indole-2-carbonyl)thiocarbamates and N-(indole-2-carbonyl)thioureas prepared by treatment of isothiocyanate 1 with corresponding nucleophilic reagents were S-methylated with methyl iodide in acetone in the presence of potassium carbonate. The obtained N-(indole- 2-carbonyl) substituted thiocarbonimidates 15, 16 and isothioureas 17-20 afforded by treatment with lithium hydride in dimethylformamide the derivatives of imidazo[1,5-a]- indol-3-one 23-28 in 49-87% yields. Antifungal activity of the prepared compounds has been examined, using the fungus Bipolaris leersiae. 1-Methylsulfanyl-3H-imidazo-[1,5-a]- indol-3-one (4) exhibited the highest antifungal activity.
Correlation, Relativistic and Adiabatic Corrections to the Ground State Potential Curve of the Hydrogen Molecule
Authors: Micanko Ján , Biskupič Stanislav , Bittererová Martina
Published: July 2002

Correlation, relativistic and adiabatic corrections are computed for the electronic ground state of the hydrogen molecule for r ≤ 12 a.u. In contrast to previous calculations (based on the numerical solution of the Schrödinger equation, mainly done by Wolniewicz et al.), our results are based on the ordinary ab initio treatment using a four-component wave function with fully relativistically reoptimized basis sets and adiabatic corrections by the treatment developed in our laboratory. The calculated energies are fitted to the polynomial/exponential analytical function and the evaluated spectroscopic parameters are compared with those obtained in the same manner from the Wolniewicz data. The results presented show a good agreement with exact numerical calculations published previously.
Effects of pH, Temperature and Various Anions on Thiourea Disappearance in Aqueous Media with Titanium Dioxide Under UV-Irradiation. Photomineralization Kinetics
Authors: Boussaoud Abdelghani , Duc Gerard , Meille Jean Pierre , Petit-Ramel Michelle
Published: July 2002

Disappearance of thiourea in aqueous suspensions of TiO2 or ZnO occurs under near-UV irradiation. The effects of some parameters such as initial concentration of thiourea, temperature, pH and common inorganic anions were examined. The results indicate that the process follows the Langmuir-Hinshelwood type kinetics. In the presence of anions such as nitrates, chlorides and sulfates, the initial disappearance rate of thiourea at pH 6 drops. It is found that the initial rate of thiourea disappearance increases when temperatue of reaction mixture increases. Finally, kinetics of thiourea photomineralization to nitrite, nitrate, sulfite and sulfate are established.
Are doctors altruistic?
Authors: Glannon W , Ross L F
Published: July 2002

There is a growing belief in the US that medicine is an altruistic profession, and that physicians display altruism in their daily work. We argue that one of the most fundamental features of medical professionalism is a fiduciary responsibility to patients, which implies a duty or obligation to act in patients' best medical interests. The term that best captures this sense of obligation is “beneficence”, which contrasts with “altruism” because the latter act is supererogatory and is beyond obligation. On the other hand, we offer several examples in which patients act altruistically. If it is patients and not the doctors who are altruistic, then the patients are the gift-bearers and to that extent doctors owe them gratitude and respect for their many contributions to medicine. Recognising this might help us better understand the moral significance of the doctor-patient relationship in modern medicine.
Exposure to benzene, occupational stress, and reduced birth weight
Authors: Chen Dafang , Cho Sung-Il , Chen Changzhong , Wang Xiaobin , Damokosh Andrew I , Ryan Louise , Smith Thomas J , Christiani David C , Xu Xiping
Published: July 2002

OBJECTIVES

The association between birth weight and exposure to benzene, work stress, and other occupational and environmental hazards was investigated.

METHODS

In a large petrochemical industry, 792 pregnant workers were enrolled and followed up through delivery between May 1996 and December 1998. Exposure to benzene and other solvents was assessed by an industrial hygienist based on each woman's job title and workplace information. Other occupational and environmental exposures and personal information, including perceived work stress, exposure to noise, physical exertion at work, and passive smoking, were obtained by an interview questionnaire. Univariate and multivariate regression models were used to examine the individual and combined associations of occupational and environmental exposures with birth weight, with adjustment for major confounders including gestational age.

RESULTS

In the univariate model, birth weight was negatively associated with exposure to benzene (−58 g (95% confidence interval (95% CI), −115 to −2)) and with work stress (−84 g (95% CI, −158 to −10)). In the multivariate model, there was a significant interaction between exposure to benzene and work stress relative to reduced birth weight, after adjustment for other environmental and occupational exposures and personal variables. Adjusted mean birth weight was 3445 g (95% CI 3401 to 3489) among those with neither exposure, 3430 g for those with exposure to benzene only, 3426 g for those with work stress only, and 3262 g (95% CI 3156 to 3369) for those with both exposures. In other words, there was 183 g (95% CI 65 to 301) reduction in birth weight among those with both exposure to benzene and work stress compared with those with neither exposure. Other work or environmental factors could not explain these findings.

CONCLUSIONS

Low level exposure to benzene and work stress interact to reduce birth weight in this population.
Behçet’s disease
Authors: Kontogiannis V , Powell R J
Published: July 2002

Behçet’s disease is a systemic vasculitis of unknown aetiology characteristically affecting venules. Onset is typically in young adults with recurrent oral and genital ulceration, uveitis, skin manifestations, arthritis, neurological involvement, and a tendency to thrombosis. It has a worldwide distribution but is prevalent in Japan, the Middle East, and some Mediterranean countries. International diagnostic criteria have been proposed, however diagnosis can be problematical, particularly if the typical ulcers are not obvious at presentation. Treatment is challenging, must be tailored to the pattern of organ involvement for each patient and often requires combination therapies.
Effets du N minéral et du génotype de la plante sur la croissance et la nodulation de Faidherbia albida
Authors: Dianda Mahamadi , Chalifour François-P.
Published: July 2002

Sahelian soils are recognized for their low N content, but their mineral N concentrations can often be high enough to inhibit N2 fixation in cultivated legumes. However, the quest for symbiotic plant genotypes tolerant of mineral N is poorly documented for nitrogen-fixing trees. The behaviour of N2 fixing symbioses with regard to nitrogen fertilization was observed in different Faidherbia albida (Del) A. Chev. genotypes. Twelve distinct lineages of the species, obtained from four regions of western Africa, were cultivated for 75 days in the presence of 06 mol·m3 N provided as NH4NO3. Plants were separately inoculated with two Bradyrhizobium strains, and cultivated on sandy soil in a nursery. Aerial and root parts lengths and masses, collar diameters, and ratios of height to length (H/P) of taproot, and aerial to root (MA/MR) parts masses increased with increased N level. Plants showed significant growth differences linked with seed origin, and with lineage for a same origin. Genotypical variations were observed for concentrations as well as C and N total uptakes, C/N ratio measured in aerial parts, and N2 fixation. Nodule number and mass were greatly reduced in the presence of 2 mol·m3 N. The extent of this reduction was dependent, to a lesser degree, on seed origin and Bradyrhizobium strain. Data show that F. albida  Bradyrhizobium symbiosis is highly sensitive to mineral N. It is suggested that selection of symbiotic partners for tolerance to mineral N might greatly improve the agronomic behaviour of F. albida.Key words: Faidherbia albida, lineages, Bradyrhizobium, symbiosis, nodulation, growth, ammonium nitrate.
Skipped reproductive cycles and extensive sporophyte abortion in the desert moss Tortula inermis correspond to unusual rainfall patterns
Authors: Stark Lloyd R
Published: July 2002

A phenological assessment of Tortula inermis (Brid.) Mont. populations in the Mojave Desert, Nevada, U.S.A., over a period of 4 years revealed that the sporophyte cohort initiated in early 1995 remained dormant until early 1998, by which time approximately 66% of the sporophytes had aborted. The viable sporophytes of this cohort were significantly shorter in length and had significantly less biomass than the previous cohort of sporophytes. In the intervening years 1996 and 1997, the sexual reproductive cycle was skipped altogether. The absence of sporophyte initiation in these two years was attributed to reduced winterspring rainfall. The majority of abortive sporophytes aborted in the late embryonic and seta elongation phenophases. The 1997 and 1998 summers were characterized by unusually heavy rains. Following the heavy summer rain events of 1997, sporophyte abortion in the 1995 cohort increased from 9 to 43%, and abortive sporophytes in this cohort further increased to 66% following the summer rains of 1998. Abortive sporophyte biomass averaged 49 µg or 33% of the mean biomass of the viable sporophytes in the cohort at maturity. These data suggest that the summer rain events precipitated two waves of sporophyte abortion, possibly through heavy membrane damage associated with rapid drying and high temperatures while hydrated.Key words: sporophyte abortion, bryophyte, desert, Tortula, desiccation.