bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human Cytomegalovirus Virions Differentially Incorporate Viral and Host Cell RNA during the Assembly Process
Authors: Greijer Astrid E. , Dekkers Chantal A. J. , Middeldorp Jaap M. 
Published: July 2002

ABSTRACT
While analyzing human cytomegalovirus (HCMV) gene expression in infected cells by RNA-specific nucleic acid sequence-based amplification (NASBA), positive results were observed for HCMV RNA encoded by several viral genes immediately after the addition of the virus. UV-inactivated virus also gave a positive NASBA result without establishing active infection, suggesting that RNA was associated with the inoculum. Highly purified virions devoid of cellular contamination proved to be positive for viral RNA encoding both immediate-early (UL123) and late (UL65) gene products. Virion-associated RNA might be incorporated specifically or without selection during the virion assembly. In the latter case, cellular RNA would also be present in the virion. A high-abundant cellular RNA encoded by GAPDH and even U1A RNA, which is expressed at low levels, were detected in the virion fraction, whereas cellular DNA was absent. Virion fractionation revealed that cellular RNA was absent in purified de-enveloped capsids. In conclusion, cellular and viral RNA was present between the capsid and envelope of the virion, whereas in the capsid only viral RNA could be detected. The results suggest that virion-associated viral and cellular RNA is incorporated nonspecifically during virion assembly.
Increased Expression and Immunogenicity of Sequence-Modified Human Immunodeficiency Virus Type 1
gag
Gene
Authors: zur Megede Jan , Chen Min-Chao , Doe Barbara , Schaefer Mary , Greer Catherine E. , Selby Mark , Otten Gillis R. , Barnett Susan W. 
Published: July 2002

ABSTRACT

A major challenge for the next generation of human immunodeficiency virus (HIV) vaccines is the induction of potent, broad, and durable cellular immune responses. The structural protein Gag is highly conserved among the HIV type 1 (HIV-1) gene products and is believed to be an important target for the host cell-mediated immune control of the virus during natural infection. Expression of Gag proteins for vaccines has been hampered by the fact that its expression is dependent on the HIV Rev protein and the Rev-responsive element, the latter located on the
env
transcript. Moreover, the HIV genome employs suboptimal codon usage, which further contributes to the low expression efficiency of viral proteins. In order to achieve high-level Rev-independent expression of the Gag protein, the sequences encoding HIV-1
SF2
p55
Gag
were modified extensively. First, the viral codons were changed to conform to the codon usage of highly expressed human genes, and second, the residual inhibitory sequences were removed. The resulting modified
gag
gene showed increases in p55
Gag
protein expression to levels that ranged from 322- to 966-fold greater than that for the native gene after transient expression of 293 cells. Additional constructs that contained the modified
gag
in combination with modified
protease
coding sequences were made, and these showed high-level Rev-independent expression of p55
Gag
and its cleavage products. Density gradient analysis and electron microscopy further demonstrated that the modified
gag
and
gagprotease
genes efficiently expressed particles with the density and morphology expected for HIV virus-like particles. Mice immunized with DNA plasmids containing the modified
gag
showed Gag-specific antibody and CD8
+
cytotoxic T-lymphocyte (CTL) responses that were inducible at doses of input DNA 100-fold lower than those associated with plasmids containing the native
gag
gene. Most importantly, four of four rhesus monkeys that received two or three immunizations with modified
gag
plasmid DNA demonstrated substantial Gag-specific CTL responses. These results highlight the useful application of modified
gag
expression cassettes for increasing the potency of DNA and other gene delivery vaccine approaches against HIV.
Fatty Acid-Depleted Albumin Induces the Formation of Echovirus A Particles
Authors: Ward Trevor , Powell Robert M. , Chaudhry Yasmin , Meredith Janet , Almond Jeffrey W. , Kraus Werner , Nelsen-Salz Birgit , Eggers Hans J. , Evans David J. 
Published: July 2002

ABSTRACT
Picornavirus infection requires virus uncoating, associated with the production of 135S “A” particles and 80S empty particles from 160S mature virions, to release the RNA genome into the cell cytoplasm. Normal albumin inhibits this process. We now show that when depleted of fatty acids, albumin induces the formation of echovirus A particles.
Functional and Selective Targeting of Adenovirus to High-Affinity Fcγ Receptor I-Positive Cells by Using a Bispecific Hybrid Adapter
Authors: Ebbinghaus Christina , Al-Jaibaji Ahmed , Operschall Elisabeth , Schöffel Angelika , Peter Isabelle , Greber Urs F. , Hemmi Silvio 
Published: July 2002

ABSTRACTAdenovirus (Ad) efficiently delivers its DNA genome into a variety of cells and tissues, provided that these cells express appropriate receptors, including the coxsackie-adenovirus receptor (CAR), which binds to the terminal knob domain of the viral capsid protein fiber. To render CAR-negative cells susceptible to Ad infection, we have produced a bispecific hybrid adapter protein consisting of the amino-terminal extracellular domain of the human CAR protein (CARex) and the Fc region of the human immunoglobulin G1 protein, comprising the hinge and the CH2 and CH3 regions. CARex-Fc was purified from COS7 cell supernatants and mixed with Ad particles, thus blocking Ad infection of CAR-positive but Fc receptor-negative cells. The functionality of the CARex domain was further confirmed by successful immunization of mice with CARex-Fc followed by selection of a monoclonal anti-human CAR antibody (E1-1), which blocked Ad infection of CAR-positive cells. When mixed with Ad expressing eGFP, CARex-Fc mediated an up to 250-fold increase of transgene expression in CAR-negative human monocytic cell lines expressing the high-affinity Fcγ receptor I (CD64) but not in cells expressing the low-affinity Fcγ receptor II (CD32) or III (CD16). These results open new perspectives for Ad-mediated cancer cell vaccination, including the treatment of acute myeloid leukemia.
Susceptibility of Rat-Derived Cells to Replication by Human Immunodeficiency Virus Type 1
Authors: Keppler Oliver T. , Yonemoto Wesley , Welte Frank J. , Patton Kathryn S. , Iacovides Demetris , Atchison Robert E. , Ngo Tuan , Hirschberg David L. , Speck Roberto F. , Goldsmith Mark A. 
Published: July 2002

ABSTRACT
Progress in developing a small animal model of human immunodeficiency virus type 1 (HIV-1) disease would greatly facilitate studies of transmission, pathogenesis, host immune responses, and antiviral strategies. In this study, we have explored the potential of rats as a susceptible host. In a single replication cycle, rat cell lines Rat2 and Nb2 produced infectious virus at levels 10- to 60-fold lower than those produced by human cells. Rat-derived cells supported substantial levels of early HIV-1 gene expression, which was further enhanced by overexpression of human cyclin T1. Rat cells displayed quantitative, qualitative, and cell-type-specific limitations in the late phase of the HIV-1 replication cycle including relative expression levels of HIV-1 Gag proteins, intracellular Gag processing, and viral egress. Nb2 cells were rendered permissive to HIV-1 R5 viruses by coexpression of human CD4 and CCR5, indicating that the major restriction on HIV-1 replication was at the level of cellular entry. We also found that primary rat lymphocytes, macrophages, and microglia expressed considerable levels of early HIV-1 gene products following infection with pseudotyped HIV-1. Importantly, primary rat macrophages and microglia, but not lymphocytes, also expressed substantial levels of HIV-1 p24 CA and produced infectious virions. Collectively, these results identify the rat as a promising candidate for a transgenic small animal model of HIV-1 infection and highlight pertinent cell-type-specific restrictions that are features of this species.
In Vitro Assembly of Sindbis Virus Core-Like Particles from Cross-Linked Dimers of Truncated and Mutant Capsid Proteins
Authors: Tellinghuisen Timothy L. , Perera Rushika , Kuhn Richard J. 
Published: July 2002

ABSTRACT
A nucleic acid-bound capsid protein dimer was previously identified using a Sindbis virus in vitro nucleocapsid assembly system and cross-linking reagents. Cross-link mapping, in combination with a model of the nucleocapsid core, suggested that this dimer contained one monomer from each of two adjacent capsomeres. This intercapsomere dimer is believed to be the initial intermediate in the nucleocapsid core assembly mechanism. This paper presents the purification of cross-linked dimers of a truncated capsid protein and the partial purification of cross-linked dimers of a full-length assembly-defective mutant. The assembly of core-like particles from these cross-linked capsid protein dimers is demonstrated. Core-like particles generated from cross-linked full-length mutant CP(19-264)L52D were examined by electron microscopy and appeared to have a morphology similar to that of wild-type in vitro-assembled core-like particles, although a slight size difference was often visible. Truncated cross-linked CP(81-264) dimers generated core-like particles as well. These core-like particles could subsequently be disassembled when reversible cross-linking reagents were used to form the dimers. The ability of the covalent intercapsomere cross-link to rescue capsid proteins with assembly defects or truncations in the amino-terminal region of the capsid protein supports the previous model of assembly and suggests a possible role for the amino-terminal region of the protein.
The Initiator Element in a Herpes Simplex Virus Type 1 Late-Gene Promoter Enhances Activation by ICP4, Resulting in Abundant Late-Gene Expression
Authors: Kim Dool-Bboon , Zabierowski Susan , DeLuca Neal A. 
Published: July 2002

ABSTRACT

The start site regions of late genes of herpes simplex virus type 1 are similar to the eukaryotic initiator sequence (Inr), have been shown to affect the levels of expression, and may also play a role in transcription activation by the viral activator ICP4. A series of linker-scanning mutations spanning the start site of transcription and several downstream mutations in the true late gC promoter were analyzed in reconstituted in vitro transcription reactions with and without ICP4, as well as in the context of the viral genome during infection. The nucleotide contacts previously found to be important for Inr function were also found to be important for optimal induction by ICP4. While the Inr had a substantial effect on the accumulation of gC RNA during infection, no other sequence downstream of the TATA box to +124 had a significant effect on levels of expression during infection. Therefore, these studies suggest that TATA box and the Inr are the only
cis
-acting elements required to achieve optimal expression of gC, and that the high levels of late-gene transcription may be largely due to the induction by ICP4, functioning through the Inr element.
Amino-Terminal Precursor Sequence Modulates Canine Distemper Virus Fusion Protein Function
Authors: von Messling Veronika , Cattaneo Roberto 
Published: July 2002

ABSTRACT

The fusion (F) proteins of most paramyxoviruses are classical type I glycoproteins with a short hydrophobic leader sequence closely following the translation initiation codon. The predicted reading frame of the canine distemper virus (CDV) F protein is more complex, with a short hydrophobic sequence beginning 115 codons downstream of the first AUG. To verify if the sequence between the first AUG and the hydrophobic region is translated, we produced a specific antiserum that indeed detected a short-lived F protein precursor that we named PreF
0
. A peptide resulting from PreF
0
cleavage was identified and named Pre, and its half-life was measured to be about 30 min. PreF
0
cleavage was completed before proteolytic activation of F
0
into its F
1
and F
2
subunits by furin. To test the hypothesis that the Pre peptide may influence protein activity, we compared the function of F proteins synthesized with that peptide to that of F proteins synthesized with a shorter amino-terminal signal sequence. F proteins synthesized with the Pre peptide were more stable and less active. Thus, the Pre peptide modulates the function of the CDV F protein. Interestingly, a distinct two-hit activation process has been recently described for human respiratory syncytial virus, another paramyxovirus.
Synthesis of Bis(diphenylphosphinio)octahydro-closo-decaborates L2B10H8 (L = Ph2PH) and 1-(Diphenylphosphinio)nonahydro-closo-decaborates(1-) [1-LB10H9]- (L = Ph2PH, Ph2P(OH)) by the Palladium-Catalyzed Reaction of Ph2PH with 1-Diazononahydro-closo-decaborate(1-) [1-N2B10H9]-
Authors: Naoufal Daoud , Bonnetot Bernard , Mongeot Henri , Grüner Bohumír 
Published: July 2002

(PPh3)2PdCl2 and CuI, used in low concentration as catalysts, favour the replacement of the diazo group of [1-N2B10H9]- by Ph2PH. Owing to its instability [1-(Ph2PH)B10H9]- could not be isolated in a pure form and was obtained as a mixture with [1-Ph2P(OH)B10H9]-, but pure samples of [1-Ph2P(OH)B10H9]- were easily obtainable. (PPh3)2PdCl2 also acted as a reactant, the reduction of Pd(II) to Pd(0) allowing the formation of the neutral substituted boranes 1,6-(Ph2PH)2B10H8 and 1,10-(Ph2PH)2B10H8. These two isomers were separated by chromatography. All the products were characterized by 11B and 31P NMR and mass spectrometry techniques.
Bone status in cystic fibrosis
Authors: Sood M , Hambleton G , Super M , Fraser W D , Adams J E , Mughal M Z 
Published: July 2002

AIMTo investigate bone mineral status of children with cystic fibrosis (CF).METHODSIn 29 children with CF and 49 matched controls, bone mineral content (BMC), projected bone area (BA), and areal bone mineral density (BMD) of the whole body, total hip, and lumbar spine (L1–L4) were measured using dual energyxray absorptiometry. The BMC values at each site were adjusted for BA, height, and weight. At the lumbar spine, the bone mineral apparent density (BMAD) was calculated by dividing the BMC by the estimated volume, derived from BA. Vertebral (T12–L3) trabecular bone mineral density (vTBMD) was measured using quantitative computed tomography in children with CF. Calcaneal broadband ultrasound attenuation (BUA) was measured in CF patients and controls using quantitative ultrasound. The disease severity of CF children was evaluated by the Shwachman–Kulczycki (SK) score.RESULTSThe mean BUA, whole body and regional BA, adjusted BMC, and areal BMD of children with CF were not different from those of controls. The mean BMAD of the lumbar spine was reduced in CF patients compared with controls, whereas the mean vTBMD standard deviation scores were significantly higher in CF patients. The median SK score of the CF group was 81 (range 42–100), indicating that as a group our CF patient population had relatively mild disease.CONCLUSIONThe normal vertebral BMC, decreased BMAD, and higher vTBMD suggests that the vertebral cortical thickness or density might be reduced in CF subjects. The overall bone mineral status of CF children with relatively mild disease was not different from size matched controls.
The epidemiology of hepatitis C in a UK health regional population of 5.12 million
Authors: Mohsen A H , Group Trent HCV Study 
Published: July 2002

BACKGROUNDThe epidemiology and natural history of hepatitis C virus (HCV) infection in the UK are uncertain. Previous reports are from small or selected populations such as blood donors or tertiary referral centres.AIMSTo study the epidemiology and natural history of HCV infection.METHODSProspective study incorporating five centres within the Trent region. Patients were managed and followed up according to a commonly agreed protocol.SUBJECTSA total of 1128 HCV positive patients. Patients with haemophilia, human immunodeficiency virus, and chronic renal failure were excluded.RESULTSBetween September 1991 and December 1998, 2546 anti-HCV positive patients were identified of whom 1128 (44%) were enrolled in the cohort. A risk factor(s) for infection was identified in 93.4% of patients who completed the questionnaire; 81% of patients were HCV RNA positive. A total of 397 initial liver biopsies were scored by a single pathologist. These showed a correlation between high alcohol intake and fibrosis score. Multivariate analysis showed fibrosis to be associated with age over 40, past evidence of hepatitis B virus infection, and higher necroinflammatory grade but not with sex, viral genotype, maximum known alcohol intake, estimated duration of infection, or mode of transmission. Twelve (7.8%) of 153 patients who received interferon therapy had sustained serum virus clearance. Sixty six patients have died during the follow up period, 31 with a liver related cause of death. This represents a considerable excess over the expected death rate for a cohort of this age and sex distribution.CONCLUSIONSHCV infection is an emerging health problem in the Trent region. Identifying risk factors for infection and disease severity will enhance understanding and facilitate improved intervention. An excess mortality in infected individuals is already evident in this unselected cohort.
Dysphagia and thoracoabdominal aneurysm
Authors: Taylor C W , Sinha A , Nightingale J M D 
Published: July 2002

Abstract
Two elderly patients who presented with gradually progressive dysphagia are described. Investigations excluded an intraluminal obstruction and showed extrinsic compression of the oesophagus by an aneurysmal aorta. Surgery was not performed and they were successfully managed with a liquid diet.
It could only happen to a doctor—Haemophilus aphrophilus septicaemia complicated by a prevertebral infection after dental work
Authors: Poullis A , Gould S R , Lim A G 
Published: July 2002

Abstract
A 53 year old man presented with severe neck pain and a flu-like illness; he had recently returned from Sri Lanka and had had dental treatment six days before illness onset. Blood culture showed infection by Haemophilus aphrophilus. Magnetic resonance imaging was performed and exploratory surgery undertaken. The prevertebral cervical fascia was inflamed but no abscess identified. He was treated with antibiotics and made an uneventful recovery.
Index structures for selective dissemination of information under the Boolean model
Authors: Yan Tak W. , García-Molina Héctor 
Published: July 2002

The number, size, and user population of bibliographic and full-text document databases are rapidly growing. With a high document arrival rate, it becomes essential for users of such databases to have access to the very latest documents; yet the high document arrival rate also makes it difficult for users to keep themselves updated. It is desirable to allow users to submit profiles, i.e., queries that are constantly evaluated, so that they will be automatically informed of new additions that may be of interest. Such service is traditionally called Selective Dissemination of Information (SDI).
The high document arrival rate, the huge number of users, and the timeliness requirement of the service pose a challenge in achieving efficient SDL. In this article, we propose several index structures for indexing profiles and algorithms that efficiently match documents against large number of profiles. We also present analysis and simulation results to compare their performance under different scenarios.
Polymorphism and type inference in database programming
Authors: Buneman Peter , Ohori Atsushi 
Published: July 2002

In order to find a static type system that adequately supports database languages, we need to express the most general type of a program that involves database operations. This can be achieved through an extension to the type system of ML that captures the polymorphic nation of field selection, together with a techniques that generalizes relational operators to arbitrary data structures. The combination provides a statically typed language in which generalized relational databases may be cleanly represented as typed structures. As in ML types are inferred, which relieves the programmer of making the type assertions that may be required in a complex database environment.
These extensions may also be used to provide static polymorphic typechecking in object-oriented languages and databases. A problem that arises with object-oriented databases is the apparent need for dynamic typechecking when dealing queries on heterogeneous collections of objects. An extension of the type system needed for generalized relational operations can also be used for manipulating collections of dynamically typed values in a statically typed language. A prototype language based on these ideas has been implemented. While it lacks a proper treatment of persistent data, it demonstrates that a wide variety of database structures can be cleanly represented in a polymorphic programming language.
On the completeness of object-creating database transformation languages
Authors: Van Den Bussche Jan , Van Gucht Dirk , Andries Marc , Gyssens Marc 
Published: July 2002

Object-oriented applications of database systems require database transformations involoving nonstandard functionalities such as set manipulation and object creation, that is, the introduction of new domain elements. To deal with thse functionalities, Abiteboul and Kanellakis [1989] introduced the “determinate” transformations as a generalization of the standard domain-preserving transformations. The obvious extensions of complete standard database programming languages, however, are not complete for the determinate transformations. To remedy this mismatch, the “constructive” transformations are proposed. It is shown that the constructive transformations are precisely the transformations that can be expressed in said extensions of complete standard languages. Thereto, a close correspondence between object creation and the construction of hereditarily finite sets is established.A restricted version of the main completeness result for the case where only list manipulations are involved is also presented.
Relational expressive power of constraint query languages
Authors: Benedikt Michael , Dong Guozhu , Libkin Leonid , Wong Limsoon 
Published: July 2002

The expressive power of first-order query languages with several classes of equality and inequality constraints is studied in this paper. We settle the conjecture that recursive queries such as parity test and transitive closure cannot be expressed in the relational calculus augmented with polynomial inequality constraints over the reals. Furthermore, noting that relational queries exhibit several forms of genericity, we establish a number of collapse results of the following form: The class of generic Boolean queries expressible in the relational calculus augmented with a given class of constraints coincides with the class of queries expressible in the relational calculus (with or without an order relation). We prove such results for both the natural and active-domain semantics. As a consequence, the relational calculus augmented with polynomial inequalities expresses the same classes of generic Boolean queries under both the natural and active-domain semantics.In the course of proving these results for the active-domin semantics, we establish Ramsey-type theorems saying that any query involving certain kinds of constraints coincides with a constraint-free query on databases whose elements come from a certain infinite subset of the domain. To prove the collapse results for the natural semantics, we make use of techniques from nonstandard analysis and from the model theory of ordered structures.