bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Hybrid System Capable of Efficient Lentiviral Vector Production and Stable Gene Transfer Mediated by a Single Helper-Dependent Adenoviral Vector
Authors: Kubo Shuji , Mitani Kohnosuke 
Published: February 2003

ABSTRACT

To achieve efficient and sustained gene expression, we developed a new lentivirus/adenovirus hybrid vector (LA vector) that encodes sequences required for production of a human immunodeficiency virus-based lentiviral vector (i.e., a lentiviral vector, a
gag/pol/rev
expression cassette, a tetracycline-inducible envelope cassette, and the tetracycline-inducible transcriptional activator cassette) in a single helper-dependent adenovirus vector backbone. Via either transfection or infection, human cell lines transduced with the LA vector produced a lentiviral vector in a doxycycline-dependent manner at titers up to 10
5
to 10
6
green fluorescent protein transducing units per ml, which are comparable to the titers obtained by conventional multiple plasmid transfection methods. Efficient spread and persistent expression of the transgene were observed in cells maintained in long-term culture that had been infected with the LA vector. Furthermore, when cocultured with adherent cells infected with the LA vector, the human T-cell leukemia cell line was successfully transduced with a marker gene. This LA vector possesses the advantages of efficient gene transfer from an adenoviral vector and stable integration from a lentiviral vector; therefore, it might have potential for a variety of gene therapy applications.
The Avian Retrovirus Avian Sarcoma/Leukosis Virus Subtype A Reaches the Lipid Mixing Stage of Fusion at Neutral pH
Authors: Earp Laurie J. , Delos Sue E. , Netter Robert C. , Bates Paul , White Judith M. 
Published: February 2003

ABSTRACT

We previously showed that the envelope glycoprotein (EnvA) of avian sarcoma/leukosis virus subtype A (ASLV-A) binds to liposomes at neutral pH following incubation with its receptor, Tva, at ≥22°C. We also provided evidence that ASLV-C fuses with cells at neutral pH. These findings suggested that receptor binding at neutral pH and ≥22°C is sufficient to activate Env for fusion. A recent study suggested that two steps are necessary to activate avian retroviral Envs: receptor binding at neutral pH, followed by exposure to low pH (W. Mothes et al., Cell
103:
679-689, 2000). Therefore, we evaluated the requirements for intact ASLV-A particles to bind to target bilayers and fuse with cells. We found that ASLV-A particles bind stably to liposomes in a receptor- and temperature-dependent manner at neutral pH. Using ASLV-A particles biosynthetically labeled with pyrene, we found that ASLV-A mixes its lipid envelope with cells within 5 to 10 min at 37°C. Lipid mixing was neither inhibited nor enhanced by incubation at low pH. Lipid mixing of ASLV-A was inhibited by a peptide designed to prevent six-helix bundle formation in EnvA; the same peptide inhibits virus infection and EnvA-mediated cell-cell fusion (at both neutral and low pHs). Bafilomycin and dominant-negative dynamin inhibited lipid mixing of Sindbis virus (which requires low pH for fusion), but not of ASLV-A, with host cells. Finally, we found that, although EnvA-induced cell-cell fusion is enhanced at low pH, a mutant EnvA that is severely compromised in its ability to support infection still induced massive syncytia at low pH. Our results indicate that receptor binding at neutral pH is sufficient to activate EnvA, such that ASLV-A particles bind hydrophobically to and merge their membranes with target cells. Possible roles for low pH at subsequent stages of viral entry are discussed.
Antibiotika‐Resistenz: Struktur eines Transporterproteins
Authors: Groß Michael 
Published: February 2003

AbstractBakterienstämme, die gegen zahlreiche Medikamente resistent sind, stellen die Medizin vor immer größere Herausforderungen. Seit den 1990er Jahren weiß man, dass die dafür verantwortlichen Resistenzgene nicht nur zwischen Stämmen sondern sogar zwischen verschiedenen Arten leichter weitergereicht werden können, als man vermutet hatte. Um so dringender wird die Aufgabe, die in der Natur existierenden Resistenzen umfassend zu verstehen und direkt bei der Entwicklung neuer Antibiotika zu berücksichtigen.
Highlights aus Liebigs Experimentalvorlesung
Authors: Schwedt Georg 
Published: February 2003

AbstractLiebigs Geburtstag jährt sich am 12. Mai 2003 zum 200. Mal. Aus diesem Anlass werden einzelne Experimente bzw. Versuchsreihen, die noch heute eine grundlegende Bedeutung haben, aus seiner in Gießen entwickelten Experimentalvorlesung vorgestellt. Sie stammen aus dem im Nachlass seines Sohnes, des Arztes Georg von Liebig (1827—1903), im Jahre 1906 aufgefundenen Vorlesungsbuch, das 1983 veröffentlicht wurde.
PDP: protein domain parser
Authors: Alexandrov Nickolai , Shindyalov Ilya 
Published: February 2003

Abstract
Summary: We have developed a program for automatic identification of domains in protein three-dimensional structures. Performance of the program was assessed by three different benchmarks: (i) by comparison with the expert-curated SCOP database of structural domains; (ii) by comparison with a collection of manual domain assignments; and (iii) by comparison with a set of 55 proteins, frequently used as a benchmark for automatic domain assignment. In all these benchmarks PDP identified domains correctly in more than 80% of proteins.
Availability: http://123d.ncifcrf.gov/
Contact: nicka@ceres-inc.comshindyal@sdsc.edu
* To whom correspondence should be addressed.
Nucleocapsid-Independent Specific Viral RNA Packaging via Viral Envelope Protein and Viral RNA Signal
Authors: Narayanan Krishna , Chen Chun-Jen , Maeda Junko , Makino Shinji 
Published: February 2003

ABSTRACT

For any of the enveloped RNA viruses studied to date, recognition of a specific RNA packaging signal by the virus's nucleocapsid (N) protein is the first step described in the process of viral RNA packaging. In the murine coronavirus a selective interaction between the viral transmembrane envelope protein M and the viral ribonucleoprotein complex, composed of N protein and viral RNA containing a short
cis
-acting RNA element, the packaging signal, determines the selective RNA packaging into virus particles. In this report we show that expressed coronavirus envelope protein M specifically interacted with coexpressed noncoronavirus RNA transcripts containing the short viral packaging signal in the absence of coronavirus N protein. Furthermore, this M protein-packaging signal interaction led to specific packaging of the packaging signal-containing RNA transcripts into coronavirus-like particles in the absence of N protein. These findings not only highlight a novel RNA packaging mechanism for an enveloped virus, where the specific RNA packaging can occur without the core or N protein, but also point to a new, biologically important general model of precise and selective interaction between transmembrane proteins and specific RNA elements.
Simian-Human Immunodeficiency Virus SHIV89.6-Induced Protection against Intravaginal Challenge with Pathogenic SIVmac239 Is Independent of the Route of Immunization and Is Associated with a Combination of Cytotoxic T-Lymphocyte and Alpha Interferon Responses
Authors: Abel Kristina , Compton Lara , Rourke Tracy , Montefiori David , Lu Ding , Rothaeusler Kristina , Fritts Linda , Bost Kristen , Miller Christopher J. 
Published: February 2003

ABSTRACTAttenuated primate lentivirus vaccines provide the most consistent protection against challenge with pathogenic simian immunodeficiency virus (SIV). Thus, they provide an excellent model to examine the influence of the route of immunization on challenge outcome and to study vaccine-induced protective anti-SIV immune responses. In the present study, rhesus macaques were immunized with live nonpathogenic simian-human immunodeficiency virus (SHIV) 89.6 either intravenously or mucosally (intranasally or intravaginally) and then challenged intravaginally with pathogenic SIVmac239. The route of immunization did not affect mucosal challenge outcome after a prolonged period of systemic infection with the nonpathogenic vaccine virus. Further, protection from the SIV challenge was associated with the induction of multiple host immune effector mechanisms. A comparison of immune responses in vaccinated-protected and vaccinated-unprotected animals revealed that vaccinated-protected animals had higher frequencies of SIV Gag-specific cytotoxic T lymphocytes and gamma interferon (IFN-γ)-secreting cells during the acute phase postchallenge. Vaccinated-protected animals also had a more pronounced increase in peripheral blood mononuclear cell IFN-α mRNA levels than did the vaccinated-unprotected animals in the first few weeks after challenge. Thus, innate as well as cellular anti-SIV immune responses appeared to contribute to the SHIV89.6-induced protection against intravaginal challenge with pathogenic SIVmac239.
Duplication of U3 Sequences in the Long Terminal Repeat of Mink Cell Focus-Inducing Viruses Generates Redundancies of Transcription Factor Binding Sites Important for the Induction of Thymomas
Authors: DiFronzo Nancy L. , Frieder Marisa , Loiler Scott A. , Pham Quynh N. , Holland Christie A. 
Published: February 2003

ABSTRACT

The ability of mink cell focus-inducing (MCF) viruses to induce thymomas is determined, in part, by transcriptional enhancers in the U3 region of their long terminal repeats (LTRs). To elucidate sequence motifs important for enhancer function in vivo, we injected newborn mice with MCF 1dr (supF), a weakly pathogenic, molecularly tagged (supF) MCF virus containing only one copy of a sequence that is present as two copies (known as the directly repeated [DR] sequence) in the U3 region of MCF 247 and analyzed LTRs from supF-tagged proviruses in two resulting thymomas. Tagged proviruses integrated upstream and in the reverse transcriptional orientation relative to c
-myc
provided the focus of our studies. These proviruses are thought to contribute to thymoma induction by enhancer-mediated deregulation of c-
myc
expression. The U3 region in a tagged LTR in one thymoma was cloned and sequenced. Relative to MCF 1dr (supF), the cloned U3 region contained an insertion of 140 bp derived predominantly from the DR sequence of the injected virus. The inserted sequence contains predicted binding sites for transcription factors known to regulate the U3 regions of various murine leukemia viruses. Similar constellations of binding sites were duplicated in two proviral LTRs integrated upstream from c-
myc
in a second thymoma. We replaced the U3 sequences in an infectious molecular clone of MCF 247 with the cloned proviral U3 sequences from the first thymoma and generated an infectious chimeric virus, MCF ProEn. When injected into neonatal AKR mice, MCF ProEn was more pathogenic than the parental virus, MCF 1dr (supF), as evidenced by the more rapid onset and higher incidence of thymomas. Molecular analyses of the resultant thymomas indicated that the U3 region of MCF ProEn was genetically stable. These data suggest that the arrangement and/or redundancy of transcription factor binding sites generated by specific U3 sequence duplications are important to the biological events mediated by MCF proviruses integrated near c-
myc
that contribute to transformation.
TCL1 expression in plasmacytoid dendritic cells (DC2s) and the related CD4+ CD56+ blastic tumors of skin
Authors: Herling Marco , Teitell Michael A. , Shen Rhine R. , Medeiros L. Jeffrey , Jones Dan 
Published: February 2003

AbstractInitially considered to be of natural killer (NK)–cell origin, CD4+ CD56+ blastic tumors (BTs) of skin have recently been proposed to be of dendritic cell lineage. We have previously described BTs with transformation to myelomonocytic leukemia. Here we report expression of the lymphoid proto-oncogene TCL1 in 10 (83%) of 12 BTs and in lymph node plasmacytoid dendritic cells (DC2s). TCL1 was also expressed in myelomonocytic blasts of 3 transformed BT cases but not in true NK-cell tumors (n = 18), de novo acute myelomonocytic leukemias (1 of 14, 7%), or mature T-cell malignancies (1 of 112, &lt; 1%), with the exception of T-prolymphocytic leukemia (T-PLL). All BT cases were also positive for the DC2-associated marker CD123. These results further support derivation of BTs from DC2s, and demonstrate that TCL1 expression in this tumor is common to the immature blastoid, lymphoid-appearing, and subsequent myelomonocytic phases of this disease.
Cell surface peptidase CD26/DPPIV mediates G-CSF mobilization of mouse progenitor cells
Authors: Christopherson Kent W. , Cooper Scott , Broxmeyer Hal E. 
Published: February 2003

AbstractCXC ligand 12 (CXCL12; also known as stromal cell–derived factor 1α/SDF-1α) chemoattracts hematopoietic stem and progenitor cells (HSCs/HPCs) and is thought to play a crucial role in the mobilization of HSCs/HPCs from the bone marrow. CD26 (dipeptidylpeptidase IV [DPPIV]) is a membrane-bound extracellular peptidase that cleaves dipeptides from the N-terminus of polypeptide chains. CD26 has the ability to cleave CXCL12 at its position-2 proline. We found by flow cytometry that CD26 is expressed on a subpopulation of normal Sca-1+c-kit+lin— hematopoietic cells isolated from mouse bone marrow, as well as Sca-1+c-kit—lin— cells, and that these cells possess CD26 peptidase activity. To test the functional role of CD26 in CXCL12-mediated normal HSC/HPC migration, chemotaxis assays were performed. The CD26 truncated CXCL12(3-68) showed an inability to induce the migration of sorted Sca-1+c-kit+lin— or Sca-1+c-kit—lin— mouse marrow cells compared with the normal CXCL12. In addition, CXCL12(3-68) acts as an antagonist, resulting in the reduction of migratory response to normal CXCL12. Treatment of Sca-1+c-kit+lin— mouse marrow cells, and myeloid progenitors within this population, or Sca-1+c-kit—lin— cells with a specific CD26 inhibitor, enhanced the migratory response of these cells to CXCL12. Finally, to test for potential in vivo relevance of these in vitro observations, mice were treated with CD26 inhibitors during granulocyte colony-stimulating factor (G-CSF)–induced mobilization. This treatment resulted in a reduction in the number of progenitor cells in the periphery as compared with the G-CSF regimen alone. This suggests that a mechanism of action of G-CSF mobilization involves CD26.
X‐ray powder diffraction structural characterization of iron(III) chloro‐ and bromo‐complexes of triphenylphosphine oxide
Authors: Jorík V. , Ondrejkovicová I. , von Dreele R. B. , Ehrenberg H. 
Published: February 2003

AbstractIron (III) complexes of the composition [FeX2(OPPh3)4][FeX4], where X is Cl or Br were synthesised by several methods. It was found that each particular synthesis has yielded solids with slightly different powder patterns and also their comparison to those of calculated from single crystal data showed remarkable differences. A series of constrained Rietveld refinements has been performed on the title complexes to explain these differences. In a course of Rietveld refinement it was found that preferred orientation is not the only factor affecting the shape of the pattern and atoms parameters were included into refinement too. The results of Rietveld refinement allowed to conclude that the structures of compounds prepared by different methods are identical. In addition, it was shown that also in the case of rather complicated structure like the title complexes the powder diffraction method can lead to reasonable results.
Cover Picture: Eur. J. Org. Chem. 5/2003
Authors: Vries Johannes G. de , Vries André H.M. de 
Published: February 2003

AbstractThe cover picture shows a graphical depiction of an array of homogeneous catalysis experiments that were performed in an automated synthesizer. Using modern high‐throughput screening techniques has tremendously accelerated both the discovery of a catalyst for a desired transformation as well as the development of the process that can be implemented into the plant. The background of the picture shows a reactor in one of the plants of DSM Pharmaceutical Chemicals. Details are discussed in the Microreview by J. G. de Vries and A. H. M. de Vries on p. 799 ff.
On weighted inequalities for martingale transform operators
Authors: Martínez Teresa 
Published: February 2003

AbstractFor 1 < p < ∞, the almost surely finiteness of $ E \left(v ^{- {p^{\prime} \over p}} \vert {\cal F}_{1} \right) $ is a necessary and sufficient condition in order to have almost surely convergence of the sequences {E(f|ℱn)} with f ∈ Lp(v dP). This condition is also equivalent to have weighted inequalities from Lp(v dP) into Lp(u dP) for some weight u for Doob's maximal function, square function and generalized Burkholder martingale transforms. Similarly, E(u|ℱ1) < ∞ turns out to be necessary and sufficient for the above weighted inequalities to hold for some v.
LTR_STRUC: a novel search and identification program for LTR retrotransposons
Authors: McCarthy Eugene M. , McDonald John F. 
Published: February 2003

Abstract
Motivation: Long terminal repeat (LTR) retrotransposons constitute a substantial fraction of most eukaryotic genomes and are believed to have a significant impact on genome structure and function. Conventional methods used to search for LTR retrotransposons in genome databases are labor intensive. We present an efficient, reliable and automated method to identify and analyze members of this important class of transposable elements.
Results: We have developed a new data-mining program, LTR_STRUC (LTR retrotransposon structure program) which identifies and automatically analyzes LTR retrotransposons in genome databases by searching for structural features characteristic of such elements. LTR_STRUC has significant advantages over conventional search methods in the case of LTR retrotransposon families having low sequence homology to known queries or families with atypical structure (e.g. non-autonomous elements lacking canonical retroviral ORFs) and is thus a discovery tool that complements established methods. LTR_STRUC finds LTR retrotransposons using an algorithm that encompasses a number of tasks that would otherwise have to be initiated individually by the user. For each LTR retrotransposon found, LTR_STRUC automatically generates an analysis of a variety of structural features of biological interest.
Availability: The LTR_STRUC program is currently available as a console application free of charge to academic users from the authors.
A Single Amino Acid Substitution in Herpes Simplex Virus Type 1 VP16 Inhibits Binding to the Virion Host Shutoff Protein and Is Incompatible with Virus Growth
Authors: Knez J. , Bilan P. T. , Capone J. P. 
Published: February 2003

ABSTRACT
In addition to its well-established role in the activation of herpes simplex virus immediate-early gene transcription, VP16 interacts with and downregulates the function of the virion host shutoff protein (vhs), thereby attenuating vhs-mediated destruction of viral mRNAs and translational arrest at late times of infection. We have carried out two-hybrid analysis in vivo and protein-protein interaction assays in vitro to identify determinants in VP16 necessary for interaction with vhs. The minimal amino-terminal subfragment of VP16 capable of binding to vhs encompassed residues 1 to 345. Alteration of a single leucine at position 344 to alanine (L344A) in the context of the amino-terminal fragment of VP16 containing residues 1 to 404 was sufficient to abolish interaction with vhs in vitro and in vivo. Leu344 could be replaced with hydrophobic amino acids (Ile, Phe, Met, or Val) but not by Asn, Lys, or Pro, indicating that hydrophobicity is an important property of binding to vhs. VP16 harboring a loss-of-function mutation at L344 was not compromised in its ability to interact with host cell factor (HCF-1) or to activate transcription of viral immediate-early genes in transient-transfection assays. Virus complementation assays using the VP16-null virus 8MA and the VP16/vhs double-mutant virus 8MAΔSma showed that VP16(L344A) was able to complement the growth of 8MAΔSma but not 8MA. Thus, a single point mutation in VP16 uncouples binding to vhs from other functions of VP16 required for virus growth and indicates that direct physical association between VP16 and vhs is necessary to sustain a productive infection.
Envelopment of Human Cytomegalovirus Occurs by Budding into Golgi-Derived Vacuole Compartments Positive for gB, Rab 3, Trans-Golgi Network 46, and Mannosidase II
Authors: Homman-Loudiyi M. , Hultenby K. , Britt W. , Söderberg-Nauclér C. 
Published: February 2003

ABSTRACTAlthough considerable progress has been made towards characterizing virus assembly processes, assignment of the site of tegumentation and envelopment for human cytomegalovirus (HCMV) is still not clear. In this study, we examined the envelopment of HCMV particles in human lung fibroblasts (HF) HL 411 and HL 19, human umbilical vein endothelial cells, human pulmonary arterial endothelial cells, and arterial smooth muscle cells at different time points after infection by electron microscopy (EM), immunohistochemistry, and confocal microscopy analysis. Double-immunofluorescence labeling experiments demonstrated colocalization of the HCMV glycoprotein B (gB) with the Golgi resident enzyme mannosidase II, the Golgi marker TGN (trans-Golgi network) 46, and the secretory vacuole marker Rab 3 in all cell types investigated. Final envelopment of tegumented capsids was observed at 5 days postinfection by EM, when tegumented capsids budded into subcellular compartments located in the cytoplasm, in close proximity to the Golgi apparatus. Immunogold labeling and EM analysis confirmed staining of the budding compartment with HCMV gB, Rab 3, and mannosidase II in HL 411 cells. However, the markers Rab 1, Rab 2, Rab 7, Lamp 1 (late endosomes and lysosomes), and Lamp 2 (lysosomes) neither showed specific staining of the budding compartment in the immunogold labeling experiments nor colocalized with gB in the immunofluorescent colocalization experiments in any cell type studied. Together, these results suggest that the final envelopment of HCMV particles takes place mainly into a Golgi-derived secretory vacuole destined for the plasma membrane, which may release new infectious virus particles by fusion with the plasma membrane.