bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple
N
-Acyl Homoserine Lactone Signals of
Rhizobium leguminosarum
Are Synthesized in a Distinct Temporal Pattern
Authors: Blosser-Middleton Renée S. , Gray Kendall M.
Published: July 2002

A common form of bacterial quorum sensing involves the production and release of acyl homoserine lactone (AHL) signal metabolites. The nitrogen-fixing symbiont
Rhizobium leguminosarum
reportedly produces at least six different AHLs, but little is known about the regulation of biosynthesis of these molecules. We used a radiolabeling protocol to quantify the relative amounts of AHLs synthesized over time by
R. leguminosarum
cells with and without the symbiosis plasmid pRL1JI. Cells containing pRL1JI were found to produce three predominant signals. In decreasing order of abundance, these were
N
-(3-oxo)octanoyl homoserine lactone [(3-O)C
8
HSL],
N
-octanoyl homoserine lactone, and
N
-hexanoyl homoserine lactone. Cells without pRL1JI produced only two major signals,
N
-(3-hydroxy-7-
cis
)tetradecanoyl homoserine lactone [(3-OH)C
14:1
HSL] and (3-O)C
8
HSL. Each AHL exhibited a distinct temporal pattern of synthesis, suggesting that each AHL is subject to unique regulatory mechanisms. While (3-O)C
8
HSL was produced in both cultures, the patterns of synthesis were different in cells with and without pRL1JI, possibly as a result of redundant gene functions that are present on both the chromosome and the symbiosis plasmid. None of the AHLs appeared to regulate its own biosynthesis, although exogenous (3-OH)C
14:1
HSL did activate synthesis of the three AHLs made by cells containing pRL1JI. These results indicate that the synthesis of multiple AHLs in
R. leguminosarum
is regulated by complex mechanisms that operate independently of quorum sensing itself but that (3-OH)C
14:1
HSL can supersede these controls in pRL1JI-containing cells. This work provides an important global perspective for AHL regulation that both complements and contrasts with the results of previous studies performed with isolated gene systems.
Combination of Reverse Transcriptase PCR Analysis and Immunoglobulin M Detection on Filter Paper Blood Samples Allows Diagnostic and Epidemiological Studies of Measles
Authors: De Swart Rik L. , Nur Yassin , Abdallah Abdallah , Kruining Hans , El Mubarak H. Sittana , Ibrahim Salah A. , Van Den Hoogen Bernadette , Groen Jan , Osterhaus Albert D. M. E.
Published: July 2002

As measles control and elimination campaigns progress, laboratory confirmation of clinically diagnosed measles cases becomes increasingly important. However, in many tropical countries collection and storage of clinical specimens for this purpose are logistically complicated. In this study it is shown that blood samples spotted on filter paper are suitable for the laboratory diagnosis of measles using a combination of reverse transcriptase PCR (RT-PCR) analysis and immunoglobulin M (IgM) detection. First, it was shown that in vitro measles virus (MV)-infected cells diluted in human blood and spotted on filter paper can be detected by RT-PCR. Small amounts of infected cells remained detectable after 25 weeks of storage of the filter paper at room temperature, 4 weeks at 37°C, or 2 weeks at 45°C. Subsequently, this RT-PCR was applied to filter paper blood samples collected from 117 clinically diagnosed measles patients in Sudan in 1997 and 1998. Prior laboratory diagnosis had confirmed 90 cases as acute MV infections, while 27 proved to be nonmeasles rash disease cases. Positive RT-PCR signals were detected in filter paper blood samples of 43 of the 90 confirmed cases (48%) but in none of the 27 nonmeasles cases. In addition, MV-specific IgM levels measured in reconstituted filter paper samples correlated well with those measured in plasma samples. Measles diagnosis based on the combination of filter paper RT-PCR and IgM detection had a sensitivity and specificity of 99 and 96%, respectively. An advantage of this diagnostic approach is that sequencing of RT-PCR products allows phylogenetic analysis of the MV strain involved.
TaqMan 5′-Nuclease Human Immunodeficiency Virus Type 1 PCR Assay with Phage-Packaged Competitive Internal Control for High-Throughput Blood Donor Screening
Authors: Drosten C. , Seifried E. , Roth W. K.
Published: July 2002

Screening of blood donors for human immunodeficiency virus type 1 (HIV-1) infection by PCR permits the earlier diagnosis of HIV-1 infection compared with that by serologic assays. We have established a high-throughput reverse transcription (RT)-PCR assay based on 5′-nuclease PCR. By in-tube detection of HIV-1 RNA with a fluorogenic probe, the 5′-nuclease PCR technology (TaqMan PCR) eliminates the risk of carryover contamination, a major problem in PCR testing. We outline the development and evaluation of the PCR assay from a technical point of view. A one-step RT-PCR that targets the
gag
genes of all known HIV-1 group M isolates was developed. An internal control RNA detectable with a heterologous 5′-nuclease probe was derived from the viral target cDNA and was packaged into MS2 coliphages (Armored RNA). Because the RNA was protected against digestion with RNase, it could be spiked into patient plasma to control the complete sample preparation and amplification process. The assay detected 831 HIV-1 type B genome equivalents per ml of native plasma (95% confidence interval [CI], 759 to 936 HIV-1 B genome equivalents per ml) with a ≥95% probability of a positive result, as determined by probit regression analysis. A detection limit of 1,195 genome equivalents per ml of (individual) donor plasma (95% CI, 1,014 to 1,470 genome equivalents per ml of plasma pooled from individuals) was achieved when 96 samples were pooled and enriched by centrifugation. Up to 4,000 plasma samples per PCR run were tested in a 3-month trial period. Although data from the present pilot feasibility study will have to be complemented by a large clinical validation study, the assay is a promising approach to the high-throughput screening of blood donors and is the first noncommercial test for high-throughput screening for HIV-1.
Pandemic Spread of Cholera: Genetic Diversity and Relationships within the Seventh Pandemic Clone of
Vibrio cholerae
Determined by Amplified Fragment Length Polymorphism
Authors: Lan Ruiting , Reeves Peter R.
Published: July 2002

The seventh cholera pandemic started in 1961 and continues today. A collection of 45 seventh pandemic isolates of
V. cholerae
sampled over a 33-year period were analyzed by amplified fragment length polymorphism (AFLP) fingerprinting. All but four pairs and one set of three isolates were distinguished. AFLP revealed far more variation than ribotyping, which was until now the most useful method of revealing variation within the pandemic clone. Unfortunately, the ribotype variation observed is mainly due to recombination between the multiple copies of the
rrn
genes (R. Lan and P. R. Reeves, Microbiology
144:
1213–1221, 1998), which makes changes susceptible to repeat occurrences and reversion. This AFLP study shows that particularly for the common ribotypes G and H, such events have indeed occurred. AFLP grouped most of the 45 isolates into two clusters. Cluster I consists mainly of strains from the 1960s and 1970s, while cluster II contains mainly strains from the 1980s and 1990s, revealing a temporal pattern of change in the clone. This is best seen in the relationships of the strains from Africa, which correlate with the epidemiology of epidemics on that continent. The data confirm independent introductions to Africa during the 1970s outbreak and reveal several other African introductions. In the 1991 cholera upsurge, isolates from the Southern and Eastern African epidemic focus are markedly different from those from the West African epidemic focus. An isolate from 1987 in Algeria was identical to the West epidemic isolates, suggesting that the strain was present in Africa at least 3 years before causing large outbreaks. These observations have major implications for our understanding of cholera epidemiology.
Induction of Cellular Genes Is Mediated by the Bel1 Transactivator in Foamy Virus-Infected Human Cells
Authors: Wagner Andrea , Doerks Anja , Aboud Mordechai , Alonso Angel , Tokino Takashi , Flügel Rolf M. , Löchelt Martin
Published: July 2002

To gain insight into human foamy virus (HFV; also called spumaretrovirus)-induced alterations of cellular genes, the expression profiles of defined genes in HFV-infected primary human cells were analyzed by cDNA array assays. Several distinct cellular genes activated by HFV infection were identified; the identities of the cellular genes were confirmed by RNA blot analyses. Compared with mock-infected controls, the concentrations of cellular Kip2, Egr-1, COUP-TF1, insulin-like growth factor II (IGF-II), and EphB3 mRNAs were significantly increased in HFV-infected cells and showed a gene-specific and time-dependent induction. Immunoblot analyses with antibodies against some of the cellular gene products revealed increased levels of the corresponding proteins. To investigate mechanisms of HFV-induced alterations in cellular gene expression, the capacity of known HFV genes to increase expression of defined cellular genes was analyzed by transient expression experiments. Plasmids that encode the HFV Bel1 transcriptional transactivator were necessary and sufficient to strongly increase expression of p57Kip2, IGF-II, and EphB3 genes in 293T cells. Potential mechanisms and consequences of activation of cellular genes during HFV infection and Bel1 transactivation of the Kip2 gene are discussed.
CD8+-Cell Antiviral Factor Activity Is Not Restricted to Human Immunodeficiency Virus (HIV)-Specific T Cells and Can Block HIV Replication after Initiation of Reverse Transcription
Authors: Le Borgne Sylvie , Février Michèle , Callebaut Christian , Lee Steven P. , Rivière Yves
Published: July 2002

CD8+lymphocytes from human immunodeficiency virus (HIV)-infected patients can suppress in vitro HIV replication in CD4+T cells by a noncytolytic mechanism involving secreted CD8+-cell antiviral factor(s) (CAF). Using an HIV Nef-specific cytotoxic-T-lymphocyte (CTL) line and autologous CD4+T cells infected with anef-deleted HIV-1 virus, we demonstrated that, after a priming antigenic stimulation, this suppression does not require the presence of the specific antigen during the effector phase. Furthermore, using an Epstein-Barr virus (EBV)-specific CTL line from an HIV-seronegative donor, we demonstrated that the ability to inhibit HIV replication in a noncytolytic manner is not restricted to HIV-specific effector cells; indeed, EBV-specific CTL were as efficient as HIV-specific effectors in suppressing R5 or X4 HIV-1 strain replication in vitro. This HIV-suppressive activity mediated by a soluble factor(s) present in the culture supernatant was detectable for up to 14 days following stimulation of EBV-specific CD8+cells with the cognate epitope peptide. Following acute infection of CEM cells with an X4 strain of HIV-1, EBV-specific CTL line supernatant containing HIV-suppressive activity did not block virus entry but was shown to interfere with virus replication after the first template switching of reverse transcription. Our results suggest that the noncytolytic control of HIV replication by EBV-specific CD8+T lymphocytes corresponded to a CAF-like activity and thus demonstrate that CAF production may not be restricted to CTL induced during HIV disease. Moreover, CAF acts after reverse transcription at least for X4 isolate replication inhibition.
Design and Packaging of Adeno-Associated Virus Gene Targeting Vectors
Authors: Hirata Roli K. , Russell David W.
Published: July 2002

Adeno-associated virus (AAV) vectors can transduce cells by several mechanisms, including (i) gene addition by chromosomal integration or episomal transgene expression or (ii) gene targeting by modification of homologous chromosomal sequences. The latter process can be used to correct a variety of mutations in chromosomal genes with high fidelity and specificity. In this study, we used retroviral vectors to introduce mutant alkaline phosphatase reporter genes into normal human cells and subsequently corrected these mutations with AAV gene targeting vectors. We find that increasing the length of homology between the AAV vector and the target locus improves gene correction rates, as does positioning the mutation to be corrected in the center of the AAV vector genome. AAV-mediated gene targeting increases with time and multiplicity of infection, similar to AAV-mediated gene addition. However, in contrast to gene addition, genotoxic stress did not affect gene targeting rates, suggesting that different cellular factors are involved. In the course of these studies, we found that (i) vector genomes less than half of wild-type size could be packaged as monomers or dimers and (ii) packaged dimers consist of inverted repeats with covalently closed hairpins at either end. These studies should prove helpful in designing AAV gene targeting vectors for basic research or gene therapy.
Murine Cytomegalovirus Stimulates Cellular Thymidylate Synthase Gene Expression in Quiescent Cells and Requires the Enzyme for Replication
Authors: Gribaudo Giorgio , Riera Ludovica , Lembo David , De Andrea Marco , Gariglio Marisa , Rudge Thomas L. , Johnson Lee F. , Landolfo Santo
Published: July 2002

Herpesviruses accomplish DNA replication either by expressing their own deoxyribonucleotide biosynthetic genes or by stimulating the expression of the corresponding cellular genes. Cytomegalovirus (CMV) has adopted the latter strategy to allow efficient replication in quiescent cells. In the present report, we show that murine CMV (MCMV) infection of quiescent fibroblasts induces both mRNA and protein corresponding to the cellular thymidylate synthase (TS) gene, which encodes the enzyme that catalyzes the de novo synthesis of thymidylic acid. The increase in TS gene expression was due to an increase in gene transcription, since the activity of a reporter gene driven by the mouse TS promoter was induced following MCMV infection. Mutagenesis of the potential E2F-responsive element immediately upstream from the TS essential promoter region abolished the virus-mediated stimulation of the TS promoter, suggesting that the transactivating activity of MCMV infection was E2F dependent. Cotransfection experiments revealed that expression of the viral immediate-early 1 protein was sufficient to mediate the increase in TS promoter activity. Finally, MCMV replication and viral DNA synthesis were found to be inhibited by ZD1694, a quinazoline-based folate analog that inhibits TS activity. These results demonstrate that upregulation of cellular TS expression is required for efficient MCMV replication in quiescent cells.
Variable-Loop-Deleted Variants of the Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Can Be Stabilized by an Intermolecular Disulfide Bond between the gp120 and gp41 Subunits
Authors: Sanders Rogier W. , Schiffner Linnea , Master Aditi , Kajumo Francis , Guo Yong , Dragic Tatjana , Moore John P. , Binley James M.
Published: July 2002

We have described an oligomeric gp140 envelope glycoprotein from human immunodeficiency virus type 1 that is stabilized by an intermolecular disulfide bond between gp120 and the gp41 ectodomain, termed SOS gp140 (J. M. Binley, R. W. Sanders, B. Clas, N. Schuelke, A. Master, Y. Guo, F. Kajumo, D. J. Anselma, P. J. Maddon, W. C. Olson, and J. P. Moore, J. Virol. 74:627–643, 2000). In this protein, the protease cleavage site between gp120 and gp41 is fully utilized. Here we report the characterization of gp140 variants that have deletions in the first, second, and/or third variable loop (V1, V2, and V3 loops). The SOS disulfide bond formed efficiently in gp140s containing a single loop deletion or a combination deletion of the V1 and V2 loops. However, deletion of all three variable loops prevented formation of the SOS disulfide bond. Some variable-loop-deleted gp140s were not fully processed to their gp120 and gp41 constituents even when the furin protease was cotransfected. The exposure of the gp120-gp41 cleavage site is probably affected in these proteins, even though the disabling change is in a region of gp120 distal from the cleavage site. Antigenic characterization of the variable-loop-deleted SOS gp140 proteins revealed that deletion of the variable loops uncovers cryptic, conserved neutralization epitopes near the coreceptor-binding site on gp120. These modified, disulfide-stabilized glycoproteins might be useful as immunogens.
Two Distinct Activities Contribute to the Oncogenic Potential of the Adenovirus Type 5 E4orf6 Protein
Authors: Nevels Michael , Rubenwolf Susanne , Spruss Thilo , Wolf Hans , Dobner Thomas
Published: July 2002

Previous studies have shown that the adenovirus type 5 (Ad5) E4orf6 gene product displays features of a viral oncoprotein. It initiates focal transformation of primary rat cells in cooperation with Ad5 E1 genes and confers multiple additional transformed properties on E1-expressing cells, including profound morphological alterations and dramatically accelerated tumor growth in nude mice. It has been reported that E4orf6 binds to p53 and, in the presence of the Ad5 E1B-55kDa protein, antagonizes p53 stability by targeting the tumor suppressor protein for active degradation. In the present study, we performed a comprehensive mutant analysis to assign transforming functions of E4orf6 to distinct regions within the viral polypeptide and to analyze a possible correlation between E4orf6-dependent p53 degradation and oncogenesis. Our results show that p53 destabilization maps to multiple regions within both amino- and carboxy-terminal parts of the viral protein and widely cosegregates with E4orf6-dependent acceleration of tumor growth, indicating that both effects are related. In contrast, promotion of focus formation and morphological transformation require only a carboxy-terminal segment of the E4 protein. Thus, these effects are completely independent of p53 stability, but may involve other interactions with the tumor suppressor. Our results demonstrate that at least two distinct activities contribute to the oncogenic potential of Ad5 E4orf6. Although genetically separable, both activities are largely mediated through a novel highly conserved, cysteine-rich motif and a recently described arginine-faced amphipathic alpha helix, which resides within a carboxy-terminal “oncodomain” of the viral protein.
Involvement of the Mannose Receptor in Infection of Macrophages by Influenza Virus
Authors: Reading Patrick C. , Miller Joanna L. , Anders E. Margot
Published: July 2002

Influenza viruses A/PR/8/34 (PR8; H1N1), A/Aichi/68 X-31 (HKx31; H3N2), and A/Beijing/89 X-109 (BJx109; H3N2) show marked differences in their ability to infect murine macrophages, including resident alveolar and peritoneal macrophages as well as the macrophage-derived cell line J774. The hierarchy in infectivity of the viruses (PR8 < HKx31 < BJx109) resembles that of their reactivity with mannose-binding lectins of the collectin family. Since the macrophage mannose receptor recognizes the same spectrum of monosaccharides as the collectins do, we investigated the possible involvement of this receptor in infection of macrophages by influenza virus. In competitive binding studies, the binding of125I-labeled mannosylated bovine serum albumin to macrophages was inhibited by the purified hemagglutinin and neuraminidase (HANA) glycoproteins of influenza virus but not by HANA that had been treated with periodate to oxidize its oligosaccharide side chains. The inhibitory activity of HANA from the three strains of virus differed markedly and correlated with the infectivity of each virus for macrophages. Infection of macrophages, but not MDCK cells, by influenza virus was inhibited by yeast mannan. A variant line of J774 cells, J774E, which expresses elevated levels of the mannose receptor, was more readily infected than J774, and the sensitivity of J774E cells to infection was greatly reduced by culture in the presence ofd-mannose, which down-modulated mannose receptor expression. Together, the data implicate the mannose receptor as a major endocytic receptor in the infectious entry of influenza virus, and perhaps other enveloped viruses, into murine macrophages.
Low Dynamic State of Viral Competition in a Chronic Avian Hepadnavirus Infection
Authors: Zhang Yong-Yuan , Summers Jesse
Published: July 2002

The dynamic state of infection of 11 ducks with the duck hepatitis B virus was investigated. Chronic infections were established in newly hatched ducklings by inoculation with a mixture of wild-type virus and a mutant virus with a partial replication defect. As expected, the wild-type virus was rapidly enriched in the virus population during the spread of infection. Enrichment thereafter was correlated with normal growth of the liver, with the average mutant-to-wild-type ratio stabilizing for at least 2 months beyond the time at which the liver mass stabilized. Using experimentally determined growth rates for the mutant and wild-type viruses, we estimated that after the spread of infection, competition between the two virus strains was limited by the amount of replication required to infect new hepatocytes in the growing livers. The results suggest that, in a chronically infected liver, the selection of variants with a replication rate advantage is inefficient and that the emergence of such variants would depend on induced liver cell turnover, such as that occurring during chronic hepatitis.
Downregulation of Major Histocompatibility Complex Class I Molecules by Kaposi's Sarcoma-Associated Herpesvirus K3 and K5 Proteins
Authors: Ishido Satoshi , Wang Chunyang , Lee Bok-Soo , Cohen George B. , Jung J. U.
Published: July 2002

The T-cell-mediated immune response plays a central role in the defense against intracellular pathogens. To avoid this immune response, viruses have evolved elaborate mechanisms that target and modulate many different aspects of the host's immune system. A target common to many of these viruses is the major histocompatibility complex (MHC) class I molecules. Kaposi's sarcoma-associated herpesvirus (KSHV) encodes K3 and K5 zinc finger membrane proteins which remove MHC class I molecules from the cell surface. K3 and K5 exhibit 40% amino acid identity to each other and localize primarily near the plasma membrane. While K3 and K5 dramatically downregulated class I molecules, they displayed different specificities in downregulation of HLA allotypes. K5 significantly downregulated HLA-A and -B and downregulated HLA-C only weakly, but not HLA-E, whereas K3 downregulated all four HLA allotypes. This selective downregulation of HLA allotypes by K5 was partly due to differences in amino acid sequences in their transmembrane regions. Biochemical analyses demonstrated that while K3 and K5 did not affect expression and intracellular transport of class I molecules, their expression induced rapid endocytosis of the molecules. These results demonstrate that KSHV has evolved a novel immune evasion mechanism by harboring similar but distinct genes, K3 and K5, which target MHC class I molecules in different ways.
Convergent Evolution of Reverse Transcriptase (RT) Genes of Human Immunodeficiency Virus Type 1 Subtypes E and B following Nucleoside Analogue RT Inhibitor Therapies
Authors: Sato Hironori , Tomita Yasuhiro , Shibamura Kayo , Shiino Teiichiro , Miyakuni Tuyoshi , Takebe Yutaka
Published: July 2002

Changes in the drug susceptibility, gene lineage, and deduced amino acid sequences of the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) subtype E following 3′-azido-3′-deoxythymidine (AZT) monotherapy or AZT–2′,3′-dideoxyinosine combination therapy were examined with sequential virus isolates from a single family. The changes were compared to those reported for HIV-1 subtype B, revealing striking similarities in selected phenotype and amino acids independent of differences in the RT backbone sequences that constantly distinguish the two subtypes. Particularly, identical amino acid substitutions were present simultaneously at four different positions (D67N, K70R, T215F, and K219Q) for high-level AZT resistance. These data suggest that HIV-1 subtypes E and B evolve convergently at the phenotypic and amino acid levels when the nucleoside analogue RT inhibitors act as selective forces.
A Single Amino Acid Change in the Murine Leukemia Virus Capsid Gene Responsible for the

Fv1
nr

Phenotype
Authors: Jung Yong Tae , Kozak Christine A.
Published: July 2002

The
nr
allele at the mouse
Fv1
restriction locus governs resistance to B-tropic and some N-tropic murine leukemia viruses (MLVs). Sequence analysis and site-specific mutagenesis of N-tropic MLVs identified a single amino acid difference responsible for this restriction that is distinct from the site that governs N or B tropism. Viruses with other substitutions at this site were evaluated for altered replication patterns.
Limitations to Replication of Hepatitis Delta Virus in Avian Cells
Authors: Chang Jinhong , Moraleda Gloria , Taylor John
Published: July 2002

Human hepatitis delta virus (HDV) is a natural subviral agent that uses hepatitis B virus as a helper. Experimentally, HDV can be made to replicate in woodchucks, using woodchuck hepatitis B virus as a helper virus. Also, independent of such helper activity, replication of the HDV RNA genome can be achieved in many mammalian cells. In this study we examined whether such replication could also be achieved in avian cells. We used cotransfection strategies and initially found no detectable genome replication in chicken LMH cells relative to the mammalian cell line Huh7, used as a positive control. We also found that, in contrast to transfected Huh7 cells, the avian cell line was readily and efficiently killed by expression of the delta protein. Three strategies were used to reduce such killing: (i) the delta protein was expressed from a separate expression vector, the amount of which was then reduced as much as 33-fold; (ii) the protein was expressed transiently, using a promoter under tetracycline control; and (iii) the transfected cells were treated with Z-VAD-fmk, a broad-spectrum caspase inhibitor, which reduced cell killing. This last result indicated that cell killing occurred via an apoptotic pathway. After application of these three strategies to reduce cell killing, together with a novel procedure to improve the signal-to-noise ratio in Northern analyses, replication of the HDV genome was then detected in LMH cells. However, even after removal of obvious signs of toxicity, the amount was still >50 times lower than in the Huh7 cells. Our findings explain previous unsuccessful attempts to demonstrate replication of the HDV genome in avian cells and establish the precedent that in certain situations HDV replication can be cytotoxic.
Naturally Occurring V1-
env
Region Variants Mediate Simian Immunodeficiency Virus SIVmac Escape from High-Titer Neutralizing Antibodies Induced by a Protective Subunit Vaccine
Authors: Petry Harald , Pekrun Katja , Hunsmann Gerhard , Jurkiewicz Elke , Lüke Wolfgang
Published: July 2002

Macaques which developed high-titer neutralizing antibodies (htNAb) after immunization with a virion-derived oligomeric envelope glycoprotein subunit vaccine were protected against a homologous simian immunodeficiency virus SIVmac challenge. Here we demonstrate that the htNAb could be overcome by V1-
env
region variants isolated ex vivo from an SIVmac-infected macaque. The results further suggest that the development of V1-
env
region neutralization escape mutants is also necessary for survival of the virus in infected macaques. The immunological capacity of a single variable region to induce neutralizing antibodies in vaccinated and infected macaques initiate new ideas for a successful vaccine strategy.
Correct Integration of Model Substrates by Ty1 Integrase
Authors: Moore Sharon P. , Garfinkel David J.
Published: July 2002

The retrovirus-like mobile genetic element of
Saccharomyces cerevisiae
, Ty1, transposes to new genomic locations via the element-encoded integrase (IN). Here we report that purified recombinant IN catalyzed correct integration of a linear DNA into a supercoiled target plasmid. Ty1 virus-like particles (VLPs) integrated donor DNA more efficiently than IN. VLP and IN-mediated insertions occurred at random sites in the target. Mg
2+
was preferred over Mn
2+
for correct integration, and neither cation enhanced nonspecific nuclease activity of IN. Products consistent with correct integration events were also obtained by Southern analysis. Recombinant IN and VLPs utilized many, but not all, linear donor fragments containing non-Ty1 ends, including a U3 mutation which has been shown to be defective for transposition in vivo. Together, our results suggest that IN is sufficient for Ty1 integration in vitro and IN interacts with exogenous donors less stringently than with endogenous elements.
Immunization with a Modified Vaccinia Virus Expressing Simian Immunodeficiency Virus (SIV) Gag-Pol Primes for an Anamnestic Gag-Specific Cytotoxic T-Lymphocyte Response and Is Associated with Reduction of Viremia after SIV Challenge
Authors: Seth Aruna , Ourmanov Ilnour , Schmitz Jorn E. , Kuroda Marcelo J. , Lifton Michelle A. , Nickerson Christine E. , Wyatt Linda , Carroll Miles , Moss Bernard , Venzon David , Letvin Norman L. , Hirsch Vanessa M.
Published: July 2002

The immunogenicity and protective efficacy of a modified vaccinia virus Ankara (MVA) recombinant expressing the simian immunodeficiency virus (SIV) Gag-Pol proteins (MVA-gag-pol) was explored in rhesus monkeys expressing the major histocompatibility complex (MHC) class I allele, MamuA*01. Macaques received four sequential intramuscular immunizations with the MVA-gag-polrecombinant virus or nonrecombinant MVA as a control. Gag-specific cytotoxic T-lymphocyte (CTL) responses were detected in all MVA-gag-pol-immunized macaques by both functional assays and flow cytometric analyses of CD8+T cells that bound a specific MHC complex class I-peptide tetramer, with levels peaking after the second immunization. Following challenge with uncloned SIVsmE660, all macaques became infected; however, viral load set points were lower in MVA-gag-pol-immunized macaques than in the MVA-immunized control macaques. MVA-gag-pol-immunized macaques exhibited a rapid and substantial anamnestic CTL response specific for the p11C, C-M Gag epitope. The level at which CTL stabilized after resolution of primary viremia correlated inversely with plasma viral load set point (P= 0.03). Most importantly, the magnitude of reduction in viremia in the vaccinees was predicted by the magnitude of the vaccine-elicited CTL response prior to SIV challenge.
Herpes Simplex Virus Type 1 Blocks the Apoptotic Host Cell Defense Mechanisms That Target Bcl-2 and Manipulates Activation of p38 Mitogen-Activated Protein Kinase To Improve Viral Replication
Authors: Zachos George , Koffa Margy , Preston Chris M. , Clements J. Barklie , Conner Joe
Published: July 2002

Wild-type (wt) herpes simplex virus type 1 (HSV-1) suppresses cell death. We investigated the apoptotic pathways triggered during infection with mutant viruses
ts
k and 27lacZ (which lack functional ICP4 and ICP27 viral proteins, respectively) and examined the mechanisms used by wt HSV-1 to protect against programmed cell death induced by the DNA-damaging compound cisplatin. In our studies, we used BHK and HeLa cells, with similar results. We suggest that a decrease in the levels of Bcl-2 protein is a key event during apoptosis induced by the mutant viruses and that Bcl-2 levels are targeted by (i) a decrease of bcl-2 RNA, (ii) caspase-related proteolysis, and (iii) p38 mitogen-activated protein kinase (p38MAPK)-dependent destabilization of Bcl-2 protein. We show that wt HSV-1, but not the mutant viruses, maintains bcl-2 RNA and protein levels during infection and protects from the cisplatin-induced decrease in bcl-2 RNA; our data suggest that both ICP27 and ICP4 are required for this function. Additionally, wt HSV-1 evades but does not actively block activation of caspases. Although wt HSV-1 induces p38MAPK activation during infection, it prevents p38MAPK-dependent destabilization of Bcl-2 and exploits p38MAPK stimulation to enhance transcription of specific viral gene promoters to increase viral yields.
Polyadenylation in Rice Tungro Bacilliform Virus:
cis
-Acting Signals and Regulation
Authors: Rothnie Helen M. , Chen Gang , Fütterer Johannes , Hohn Thomas
Published: July 2002

The polyadenylation signal of rice tungro bacilliform virus (RTBV) was characterized by mutational and deletion analysis. The
cis
-acting signals required to direct polyadenylation conformed to what is known for plant poly(A) signals in general and were very similar to those of the related cauliflower mosaic virus. Processing was directed by a canonical AAUAAA poly(A) signal, an upstream UG-rich region considerably enhanced processing efficiency, and sequences downstream of the cleavage site were not required. When present at the end of a transcription unit, the
cis
-acting signals for 3′-end processing were highly efficient in both monocot (rice) and dicot (
Nicotiana plumbaginifolia
) protoplasts. In a promoter-proximal position, as in the viral genome, the signal was also efficiently processed in rice protoplasts, giving rise to an abundant “short-stop” (SS-) RNA. The proportion of SS-RNA was considerably lower in
N. plumbaginifolia
protoplasts. In infected plants, SS-RNA was hardly detectable, suggesting either that SS-RNA is unstable in infected plants or that read-through of the promoter-proximal poly(A) site is very efficient. SS-RNA is readily detectable in transgenic rice plants (A. Klöti, C. Henrich, S. Bieri, X. He, G. Chen, P. K. Burkhardt, J. Wünn, P. Lucca, T. Hohn, I. Potrylus, and J. Fütterer, 1999.
Plant Mol. Biol
. 40:249–266), thus the absence of SS-RNA in infected plants can be attributed to poly(A) site bypass in the viral context to ensure production of the full-length pregenomic viral RNA. RTBV poly(A) site suppression thus depends both on context and the expression system; our results suggest that the circular viral minichromosome directs assembly of a transcription-processing complex with specific properties to effect read-through of the promoter-proximal poly(A) signal.
Reverse-Phase High Performance Liquid Chromatography of Metal Chelates of 4-(2-Pyridylazo)resorcinol and 4-(2-Thiazolylazo)resorcinol. Simultaneous Determination of Low Concentrations of Co, Ni and Fe
Authors: Doležal Josef , Sommer Lumír
Published: July 2002

The behaviour of stable and inert metal chelates of 4-(2-pyridylazo)resorcinol and 4-(2-thiazolylazo)resorcinol in RP HPLC and in its ion-pair modification (IP RP HPLC) on Separon SGX RPS silica gel was studied. Good results were obtained by the ion-pair variant in water methanol solutions at pH 7 in the presence of cetyltrimethylammonium bromide. The technique proved to be convenient for the preconcentration, separation and quantitation of low concentrations of Fe, Co, and Ni in waters.
Determination of Some Nitrophenols by Atomic Absorption Spectrometry (AAS) After Extraction of Ionic Associates Involving the Bipyridylocopper(II) or Phenanthrolinocopper(II) Complex
Authors: Stužka Václav , Souček Jaromír
Published: July 2002

A new method has been developed for the indirect determination of nitroso- and nitrophenols by atomic absorption spectrometry (AAS) after extraction of ionic associates involving bipyridylocopper(II) (CuDP) or phenanthrolinocopper(II) (CuPH) complexes. Nitrobenzene and methyl isobutyl ketone appeared to be suitable for the extraction. It was possible to determine several tenths to hundredths of a milligram of nitrophenol in a litre. Extractable associates with CuDP and CuPH are formed by phenols possessing two substituents or by higher molecular weight phenols such as naphthol or hydroxyquinoline. Monosubstituted phenols fail to form associates of this kind.
Reductive Carbonylation of Nitrobenzene to N,N-Diethyl-N'-phenylurea
Authors: Macho Vendelín , Králik Milan , Ligač Gabriel , Bojsová Eva , Vojček Loránt
Published: July 2002

Reductive carbonylation of nitrobenzene with carbon monoxide and diethylamine at 363-443 K and initial CO pressures 6-17 MPa in the presence of a catalyst consisting of sulfur or a sulfur compound and a vanadium(V) compound in a basic medium yields N,N-diethyl-N'-phenylurea as the main product. Formation of the side products (aniline, N,N'-diphenylurea, and N-phenylformamide) is affected significantly by water admixtures. The efficiency of sulfur components increases in the order: S : CS2 : H2S : COS = 1 : 1.2 : 5.7 : 8. The presence of the vanadium(V) compound, although not prerequisite, has promoting effect. The selectivity and reaction rate of the carbonylation increases with increasing CO pressure. Water affects negatively above all the selectivity of the reaction (at 0.24 wt.% water in diethylamine, maximum selectivity exceeds 80%, at 1.6 wt.% water it is only ca 60%). The effect of reaction conditions and the course of side reactions is discussed.
Convergence Properties of Quasiclassical Trajectory Calculations on Dynamics of Autoionization Event in He(23S)-D2 Penning Ionization
Authors: Vojtík Jan , Kotal Richard
Published: July 2002

An analysis of the degree of convergence of theoretical pictures of the dynamics of the autoionization event He(23S)-D2(v" = 0) -> [He...D2+(v')] + e is presented for a number of batches of Monte Carlo calculations differing in the number of the trajectories run. The treatment of the dynamics consists in 2D classical trajectory calculations based on static characteristics which include a quantum mechanical treatment of the perturbed D2(v" = 0) and D2+(v') vibrational motion. The vibrational populations are dynamical averages over the local widths of the He(23S)-D2(v" = 0) state with respect to autoionization to D2+(...He) in its v'th vibrational level and the Penning electron energies are related to the local differences between the energies of the corresponding perturbed D2(v" = 0)(...He*) and D2+(v')(...He) vibrational states. Special attention is paid to the connection between the requirements on the degree of convergence of the classical trajectory picture of the event and the purpose of the calculations. Information is obtained regarding a scale of the trajectory calculations required for physically sensible applications of the model to an interpretation of different type of experiments on the system: total ionization cross section measurements, Penning ionization electron spectra, subsequent 3D classical trajectory calculations of branching ratios of the products of the postionization collision process, and interpretation of electron ion coincidence measurements of the product branching ratios for individual vibrational levels of the nascent Penning ion.
The Effect of p-Toluidine on the Two-Step Electroreduction of Zn(II) in Water-Methanol and Water-Dimethylformamide
Authors: Marczewska Barbara
Published: July 2002

The acceleration effect of p-toluidine on the electroreduction of Zn(II) on the mercury electrode surface in binary mixtures water-methanol and water-dimethylformamide is discussed. The obtained apparent and true forward rate constants of Zn(II) reduction indicate that the rate constant of the first electron transfer increases in the presence of p-toluidine. The acceleration effect may probably be accounted for by the concept of the formation on the mercury electrode an activated complex, presumably composed of p-toluidine and solvent molecules.
Adsorption of Butyl Acetate on Mercury Electrode and Its Effect on Electroreduction of Zn Cations
Authors: Gugała Dorota , Sieńko Dorota , Saba Jadwiga
Published: July 2002

Adsorption of butyl acetate on the mercury electrode in 1 M, 0.5 M or 0.1 M NaClO4 is described. Differential capacity curves obtained in these solutions for various butyl acetate concentrations point to the strongest decrease in capacity in 0.1 M NaClO4 for the smallest concentration of the ester tested. At the same time the heights of desorption peaks in the solutions tested decrease in the following order: 1 M > 0.5 M > 0.1 M NaClO4. The obtained results show dynamic competitive adsorption in the ClO4--H2O-ester system. In all the systems studied the zero charge potential values determined with a streaming electrode are shifted towards positive potential with increasing ester concentration. These results suggest that the polar molecule of the ester adsorbs on the mercury electrode with its hydrophobic end while hydrophilic ester group is directed towards the solution. The values of the relative surface excess obtained in the range of potentials where the strong adsorption occurs, virtually do not depend on the base electrolyte concentration. The values of the Gibbs energy of adsorption ∆G0 determined from the Frumkin isotherm have also similar values at base concentrations of the electrolyte tested. The values of interaction constant A are radically different: the adsorbed molecules undergo repulsive force in 1 M NaClO4, whereas in 0.5 M and 0.1 M NaClO4 they are under weak attraction. In the range of more negative potentials, the adsorption layer was investigated following the kinetics of the reduction of Zn++ as a pilot ion. It was stated that the concentration of the base electrolyte fundamentally affects the process: the inhibition of butyl acetate decreases in the order 1 M > 0.5 M > 0.1 M NaClO4.
Effect of Alkali Halides Upon Photocurrent Due to Emission of Electrons from Dropping Mercury Electrode Into Water
Authors: Cecchi Teresa , Passamonti Paolo , Pucciarelli Filippo
Published: July 2002

When dropping mercury electrode (DME) dipped in ultrapure water, thoroughly deaerated with pure hydrogen, is irradiated with UV light, we can observe a cathodic photocurrent in the non-faradaic region of the polarographic curve, in the absence of scavengers of hydrated electrons. Newly we have followed the effect on photocurrent of initial very small additions of alkali metal chlorides to pure water. By repeated experiments, we could show that first additions of the alkali metal halides increase the photocurrent and that the already known suppression of photocurrent by addition of halides begins only after the halide concentration exceeds ca 10-4 mol l-1. We could show for the first time that in ultrapure water and dilute electrolyte solutions, the photocurrent follows a modified seven-halves law. The extent of the positive effect of small additions of alkali metal halides on photocurrent depends on the nature of each alkali metal cation. The reason for this specificity is discussed.
Pseudomyxoma peritonei
Authors: Jivan S , Bahal V
Published: July 2002

Pseudomyxoma peritonei is a relatively rare and poorly understood condition in which mucus accumulates within the peritoneal cavity. The presence of cells in the mucin, either inflammatory or neoplastic, distinguishes it from simple acellular mucus ascites caused by mucinous spillage. There is widespread seeding of the peritoneal and omental surfaces with a heavy cancerous glaze. This is principally a complication of borderline or malignant neoplasm of the ovary and/or appendix.

This paper describes two cases of previously healthy women who both presented with an acute abdomen, and were diagnosed postoperatively with pseudomyxoma peritonei. In addition, literature on the clinical presentation, diagnostic procedures, and treatment options has been briefly reviewed.
The enigmatic mating behaviour and reproduction of a simultaneous hermaphrodite, the nudibranchAeolidiella glauca(Gastropoda, Opisthobranchia)
Authors: Karlsson Anna , Haase Martin
Published: July 2002

Hermaphroditic mating behaviour is poorly investigated and understood, especially in internally fertilized species. This study describes the mating behaviour and reproduction of the simultaneous hermaphrodite Aeolidiella glauca. Unlike other nudibranchs, A. glauca was found to transfer sperm via external spermatophores that were attached to the partner's back. Despite an elaborate courtship, the actual spermatophore transfer, which always involved two animals only, was of short duration. In most matings (88%) spermatophores were reciprocally exchanged. Shortly after transfer the ventral spermatophore cover dissolved and some sperm gathered on the epidermis. A few even penetrated epidermal cells, occasionally causing considerable damage. Most sperm, however, migrated along the body surface towards the gonopore. Migrating sperm needed 45 h to reach and enter the gonopore, but sperm consumption by the recipient sometimes delayed this process. Almost 30% of spermatophores fell off soon after transfer, but spermatophores from reciprocal matings and those placed in certain positions stayed on for longer. Slugs mated readily with different partners and egg production was very high. However, sperm from a single mating may not suffice to fertilize all eggs. Aeolidiella glauca's unique mating behaviour may offer ample opportunities for both sperm competition and alternative sperm utilization.
ENTROPY DENSITIES FOR GIBBS STATES OF QUANTUM SPIN SYSTEMS
Authors: HIAI FUMIO , PETZ DÉNES
Published: July 2002

This paper is a contribution to the general theory of quantum spin systems. We deal with a general theory in the sense that no concrete interaction shows up but an arbitrary relatively short-range interaction is chosen.

It is well known that the mean entropy plays an important role in the thermodynamics of quantum spin systems: it is one of the ingredients of the Lanford–Ruelle–Robinson variational principle. We show that in the background of the existence of the mean entropy, there is an operator convergence which resembles the McMillan theorem from information theory. Asymptotic equipartition property and several entropy densities are investigated, in particular, the relation of the Gibbs condition to relative entropies.

Although this paper is not intended to be a review, we try to give an overview of the theory of quantum Gibbs states in the mathematical sense. The paper is organized as follows. Section 1 provides an introduction and further sections contain our new results. Each section is closed with a short discussion on sources and references.
COHERENT STATES AND THEIR GENERALIZATIONS: A MATHEMATICAL OVERVIEW
Authors: TWAREQUE ALI S. , ANTOINE J.-P. , GAZEAU J.-P. , MUELLER U.A.
Published: July 2002

We present a survey of the theory of coherent states (CS) and some of their generalizations, with emphasis on the mathematical structure, rather than on physical applications. Starting from the standard theory of CS over Lie groups, we develop a general formalism, in which CS are associated to group representations which are square integrable over a homogeneous space. A further step allows us to dispense with the group context altogether, and thus obtain the so-called reproducing triples and continuous frames introduced in some earlier work. We discuss in detail a number of concrete examples, namely semisimple Lie groups, the relativity groups and various types of wavelets. Finally we turn to some physical applications, centering on quantum measurement and the quantization/dequantization problem, that is, the transition from the classical to the quantum level and vice versa.
POLARIZATION EFFECTS IN NITRIDE SEMICONDUCTOR HETEROSTRUCTURES
Authors: MORKOÇ HADIS , CINGOLANI ROBERTO , SALA F. DELLA , DICARLO A. , LUGLI P. , GIL BERNARD
Published: July 2002

Wide bandgap nitride semiconductors have recently attracted a high level of attention owing to their direct bandgaps in the visible to ultraviolet regions of the spectrum and favorable transport properties, coupled with large dielectric strengths which pave the way for excellent emitters, detectors, and power amplifiers. Owing to the ionic nature of these semiconductors coupled with the lack of inversion symmetry in the wurtzitic form, which is the more stable form, spontaneous polarization charge at heterointerfaces and piezoelectric polarization charge due to strain are induced. In this paper, following a description of these effects, their impact on sample modulation-doped structures and multiple quantum wells are discussed.