bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Fusion Peptide of Semliki Forest Virus Associates with Sterol-Rich Membrane Domains
Authors: Ahn Anna , Gibbons Don L. , Kielian Margaret 
Published: July 2002

ABSTRACT
Semliki Forest virus (SFV) is an enveloped alphavirus whose membrane fusion is triggered by low pH and promoted by cholesterol and sphingolipid in the target membrane. Fusion is mediated by E1, a viral membrane protein containing the putative fusion peptide. Virus mutant studies indicate that SFV's cholesterol dependence is controlled by regions of E1 outside of the fusion peptide. Both E1 and E1*, a soluble ectodomain form of E1, interact with membranes in a reaction dependent on low pH, cholesterol, and sphingolipid and form highly stable homotrimers. Here we have used detergent extraction and gradient floatation experiments to demonstrate that E1* associated selectively with detergent-resistant membrane domains (DRMs or rafts). In contrast, reconstituted full-length E1 protein or influenza virus fusion peptide was not associated with DRMs. Methyl β-cyclodextrin quantitatively extracted both cholesterol and E1* from membranes in the absence of detergent, suggesting a strong association of E1* with sterol. Monoclonal antibody studies demonstrated that raft association was mediated by the proposed E1 fusion peptide. Thus, although other regions of E1 are implicated in the control of virus cholesterol dependence, once the SFV fusion peptide inserts in the target membrane it has a high affinity for membrane domains enriched in cholesterol and sphingolipid.
The Tat Protein of Human Immunodeficiency Virus Type 1 (HIV-1) Can Promote Placement of tRNA Primer onto Viral RNA and Suppress Later DNA Polymerization in HIV-1 Reverse Transcription
Authors: Kameoka Masanori , Morgan Max , Binette Marc , Russell Rodney S. , Rong Liwei , Guo Xiaofeng , Mouland Andrew , Kleiman Lawrence , Liang Chen , Wainberg Mark A. 
Published: July 2002

ABSTRACT
Human immunodeficiency virus type-1 Tat has been proposed to play a role in the regulation of reverse transcription. We previously demonstrated that wild-type Tat can augment viral infectivity by suppressing the reverse transcriptase (RT) reaction at late stages of the viral life cycle in order to prevent the premature synthesis of potentially deleterious viral DNA products. Here we have performed a detailed analysis of the cell-free reverse transcription reaction to elucidate the mechanism(s) whereby Tat can affect this process. Our results show that Tat can suppress nonspecific DNA elongation while moderately affecting the specific initiation stage of reverse transcription. In addition, Tat has an RNA-annealing activity and can promote the placement of tRNA onto viral RNA. This points to a functional homology between Tat and the viral nucleocapsid (NC) protein that is known to be directly involved in this process. Experiments using a series of mutant Tat proteins revealed that the cysteine-rich and core domains of Tat are responsible for suppression of DNA elongation, while each of the cysteine-rich, core, and basic domains, as well as a glutamine-rich region in the C-terminal domain, are important for the placement of tRNA onto the viral RNA genome. These results suggest that Tat can play at least two different roles in the RT reaction, i.e., suppression of DNA polymerization and placement of tRNA onto viral RNA. We believe that the first of these activities of Tat may contribute to the overall efficiency of reverse transcription of the viral genome during a new round of infection as well as to enhanced production of infectious viral particles. We hypothesize that the second activity, illustrating functional homology between Tat and NC, suggests a potential role for NC in the displacement of Tat during viral maturation.
Selection of RNA Aptamers That Are Specific and High-Affinity Ligands of the Hepatitis C Virus RNA-Dependent RNA Polymerase
Authors: Biroccio Antonino , Hamm Jörg , Incitti Ilario , De Francesco Raffaele , Tomei Licia 
Published: July 2002

ABSTRACT
In order to find small RNA molecules that are specific and high-affinity ligands of nonstructural 5B (NS5B) polymerase, we screened by SELEX (systematic evolution of ligands by exponential amplification) a structurally constrained RNA library with an NS5BΔC55 enzyme carrying a C-terminal biotinylation sequence. Among the selected clones, two aptamers appeared to be high-affinity ligands of NS5B, with apparent dissociation constants in the low nanomolar range. They share a sequence that can assume a stem-loop structure. By mutation analysis, this structure has been shown to correspond to the RNA motif responsible for the tight interaction with NS5B. The aptamers appeared to be highly specific for the hepatitis C virus (HCV) polymerase since interaction with the GB virus B (GBV-B) NS5B protein cannot be observed. This is consistent with the observation that the activity of the HCV NS5B polymerase is efficiently inhibited by the selected aptamers, while neither GBV-B nor poliovirus 3D polymerases are affected. The mechanism of inhibition of the NS5B activity turned out to be noncompetitive with respect to template RNA, suggesting that aptamers and template RNA do not bind to the same site. As a matter of fact, mutations introduced in a basic exposed surface of the thumb domain severely impaired both the binding of and activity inhibition by the RNA aptamers.
Variability in the Human Immunodeficiency Virus Type 1 gp120 Env Protein Linked to Phenotype-Associated Changes in the V3 Loop
Authors: Hoffman Noah G. , Seillier-Moiseiwitsch Francoise , Ahn JaeHyung , Walker Jason M. , Swanstrom Ronald 
Published: July 2002

ABSTRACT
Isolates of human immunodeficiency virus type 1 (HIV-1) are classified according to the chemokine receptor (coreceptor) used in conjunction with CD4 to target and enter cells: viruses using CCR5 and CXCR4 are classified as R5 and X4, respectively. The major determinant of entry-related HIV-1 phenotypes is known to reside in the third variable region of gp120 (V3). It is clear, however, that positions outside of V3 play some role in influencing phenotype, although marked context dependence and extensive variability among HIV-1 isolates have made the identification of these positions difficult. We used the presence of previously described substitutions in V3 to classify a large set of HIV-1 subtype B gp120 sequences available in public databases as X4-like or R5-like. Using these classifications, we searched for positions outside of V3 where either amino acid composition or variability differed significantly among sequences of different inferred phenotypes. Our approach took the epidemiological relationships among sequences into account. A cluster of positions linked to changes in V3 was identified between amino acids 190 and 204 of gp120, immediately C-terminal of V2; changes at position 440 in C4 were also linked to inferred phenotype. Structural data place these positions at the coreceptor-binding face of gp120 in a surface-exposed location. We also noted a significant increase in net positive charge in a highly variable region of V2. This study both confirms previous observations and predicts specific positions that contribute to a functional relationship between V3, V2, and C4.
Avian
bic
, a Gene Isolated from a Common Retroviral Site in Avian Leukosis Virus-Induced Lymphomas That Encodes a Noncoding RNA, Cooperates with c-
myc
in Lymphomagenesis and Erythroleukemogenesis
Authors: Tam Wayne , Hughes Stephen H. , Hayward William S. , Besmer Peter 
Published: July 2002

ABSTRACT

bic
is a novel gene identified at a common retroviral integration site in avian leukosis virus-induced lymphomas and has been implicated as a collaborator with c-
myc
in B lymphomagenesis. It lacks an extensive open reading frame and is believed to function as an untranslated RNA (W. Tam, Gene 274:157-167, 2001; W. Tam, D. Ben-Yehuda, and W. S. Hayward, Mol. Cell. Biol. 17:1490-1502, 1997). The oncogenic potential of
bic
, particularly its ability to cooperate with c-
myc
in oncogenesis, was tested directly by expressing c-
myc
and
bic
, either singly or in pairwise combination, in cultured chicken embryo fibroblasts (CEFs) and in chickens using replication-competent retrovirus vectors. Coexpression of c-
myc
and
bic
in CEFs caused growth enhancement of cells. Most importantly, chick oncogenicity assays demonstrated that
bic
can cooperate with c-
myc
in lymphomagenesis and erythroleukemogenesis. The present study provides direct evidence for the involvement of untranslated RNAs in oncogenesis and provides further support for the role of noncoding RNAs as riboregulators.
Bak and Bax Function To Limit Adenovirus Replication through Apoptosis Induction
Authors: Cuconati Andrea , Degenhardt Kurt , Sundararajan Ramya , Anschel Alan , White Eileen 
Published: July 2002

ABSTRACT
Adenovirus infection and expression of E1A induces both proliferation and apoptosis, the latter of which is blocked by the adenovirus Bcl-2 homologue E1B 19K. The mechanism of apoptosis induction and the role that it plays in productive infection are not known. Unlike apoptosis mediated by death receptors, infection with proapoptotic E1B 19K mutant viruses did not induce cleavage of Bid but nonetheless induced changes in Bak and Bax conformation, Bak-Bax interaction, caspase 9 and 3 activation, and apoptosis. In wild-type-adenovirus-infected cells, in which E1B 19K inhibits apoptosis, E1B 19K was bound to Bak, precluding Bak-Bax interaction and changes in Bax conformation. Infection with E1B 19K mutant viruses induced apoptosis in wild-type and Bax- or Bak-deficient baby mouse kidney cells but not in those deficient for both Bax and Bak. Furthermore, Bax and Bak deficiency dramatically increased E1A expression and virus replication. Thus, Bax- and Bak-mediated apoptosis severely limits adenoviral replication, demonstrating that Bax and Bak function as an antiviral response at the cellular level.
Stabilization of a Full-Length Infectious cDNA Clone of Transmissible Gastroenteritis Coronavirus by Insertion of an Intron
Authors: González José M. , Pénzes Zoltan , Almazán Fernando , Calvo Enrique , Enjuanes Luis 
Published: July 2002

ABSTRACT

The stable propagation of a full-length transmissible gastroenteritis coronavirus (TGEV) cDNA in
Escherichia coli
cells as a bacterial artificial chromosome has been considerably improved by the insertion of an intron to disrupt a toxic region identified in the viral genome. The viral RNA was expressed in the cell nucleus under the control of the cytomegalovirus promoter and the intron was efficiently removed during translocation of this RNA to the cytoplasm. The insertion in two different positions allowed stable plasmid amplification for at least 200 generations. Infectious TGEV was efficiently recovered from cells transfected with the modified cDNAs.
An evidence and consensus based guideline for acute diarrhoea management
Authors: Armon K , Stephenson T , MacFaul R , Eccleston P , Werneke U 
Published: July 2002

OBJECTIVETo develop an evidence and consensus based guideline for the management of the child who presents to hospital with diarrhoea (with or without vomiting), a common problem representing 16% of all paediatric medical attenders at an accident and emergency department. Clinical assessment, investigations (biochemistry and stool culture in particular), admission, and treatment are addressed. The guideline aims to aid junior doctors in recognising children who need admission for observation and treatment and those who may safely go home.EVIDENCEA systematic review of the literature was performed. Selected articles were appraised, graded, and synthesised qualitatively. Statements on recommendation were generated.CONSENSUSAn anonymous, postal Delphi consensus process was used. A panel of 39 selected medical and nursing staff were asked to grade their agreement with the generated statements. They were sent the papers, appraisals, and literature review. On the second and third rounds they were asked to re-grade their agreement in the light of other panellists' responses. Consensus was predefined as 83% of panellists agreeing with the statement.RECOMMENDATIONSClinical signs useful in assessment of level of dehydration were agreed. Admission to a paediatric facility is advised for children who show signs of dehydration. For those with mild to moderate dehydration, estimated deficit is replaced over four hours with oral rehydration solution (glucose based, 200–250 mOsm/l) given “little and often”. A nasogastric tube should be used if fluid is refused and normal feeds started following rehydration. Children at high risk of dehydration should be observed to ensure at least maintenance fluid is tolerated. Management of more severe dehydration is detailed. Antidiarrhoeal medication is not indicated.VALIDATIONThe guideline has been successfully implemented and evaluated in a paediatric accident and emergency department.
Balance control, flexibility, and cardiorespiratory fitness among older Tai Chi practitioners
Authors: Hong Youlian , Li Jing Xian , Robinson P D 
Published: July 2002

Background—Tai Chi Chuan (TTC) exercise has beneficial effects on the components of physical condition and can produce a substantial reduction in the risk of multiple falls. Previous studies have shown that short term TCC exercise did not improve the scores in the single leg stance test with eyes closed and the sit and reach test. There has apparently been no research into the effects of TCC on total body rotation flexibility and heart rate responses at rest and after a three minute step test.Methods—In this cross sectional study, 28 male TCC practitioners with an average age of 67.5 years old and 13.2 years of TCC exercise experience were recruited to form the TCC group. Another 30 sedentary men aged 66.2 were selected to serve as the control group. Measurements included resting heart rate, left and right single leg stance with eyes closed, modified sit and reach test, total body rotation test (left and right), and a three minute step test.Results—Compared with the sedentary group, the TCC group had significantly better scores in resting heart rate, three minute step test heart rate, modified sit and reach, total body rotation test on both right and left side (p<0.01), and both right and left leg standing with eyes closed (p<0.05). According to the American Fitness Standards, the TCC group attained the 90th percentile rank for sit and reach and total body rotation test, right and left.Conclusion—Long term regular TCC exercise has favourable effects on the promotion of balance control, flexibility, and cardiovascular fitness in older adults.
Dietary creatine supplementation does not affect some haematological indices, or indices of muscle damage and hepatic and renal function
Authors: Robinson Tristan M , Sewell Dean A , Casey Anna , Steenge Gery , Greenhaff Paul L 
Published: July 2002

Background—The use of creatine (Cr) as a nutritional supplement to aid athletic performance has gained widespread popularity among athletes. However, concerns have recently been expressed over potentially harmful effects of short and long term Cr supplementation on health.Methods—Forty eight young healthy subjects were randomly allocated to three experimental protocols aimed at elucidating any potential health risks associated with five days (20 g/day) to nine weeks (3 g/day) of Cr supplementation. Venous blood samples were collected before and after periods of Cr supplementation and were analysed for some haematological indices, and for indices of hepatic, muscular, and renal dysfunction.Findings—All measured indices were well within their respective normal range at all times. Serum creatinine concentration tended to be increased the day after Cr supplementation. However, values had returned to baseline six weeks after the cessation of supplementation. These increases were probably attributable to increased creatinine production rather than renal dysfunction. No indication of impairment to the haematological indices measured, hepatic function, or muscle damage was apparent after Cr supplementation.Interpretation—These data provide evidence that there are no obvious adverse effects of acute or more chronic Cr supplementation on the haematological indices measured, nor on hepatic, muscle, and renal function. Therefore there is no apparent health risk associated with Cr supplementation to healthy people when it is ingested in quantities that have been scientifically proven to increase muscle Cr stores.
The New Zealand rugby injury and performance project. VI. A prospective cohort study of risk factors for injury in rugby union football
Authors: Quarrie K L , Alsop J C , Waller A E , Bird Y N , Marshall S W , Chalmers D J 
Published: July 2002

Objectives—Although the nature of rugby injury has been well documented, little is known about key risk factors. A prospective cohort study was undertaken to examine the association between potential risk factors and injury risk, measured both as an injury incidence rate and as a proportion of the playing season missed. The latter measure incorporates a measure of injury severity.Methods—A cohort of 258 male players (mean (SD) age 20.6 (3.7) years) were followed through a full competitive season. At a preseason assessment, basic characteristics, health and lifestyle patterns, playing experience, injury experience, training patterns, and anthropometric characteristics were recorded, and then a battery of fitness tests were carried out.Results—A multiple regression model identified grade and previous injury experience as risk factors for in season injury, measured as an injury incidence rate. A second model identified previous injury experience, hours of strenuous physical activity a week, playing position, cigarette smoking status, body mass index, years of rugby participation, stress, aerobic and anaerobic performance, and number of push ups as risk factors for in season injury, measured as proportion of season missed.Conclusions—The findings emphasise the importance of previous injury as a predictor of injury incidence and of missing play. They also show the importance of considering both the incidence rate and severity of injury when identifying risk factors for injury in sport.
Quantitative heel ultrasound variables in powerlifters and controls
Authors: Jawed S , Horton B , Masud T 
Published: July 2002

Objective—To compare by cross sectional study the quantitative heel ultrasound (QUS) variables broadband ultrasound attenuation (BUA) and velocity of sound (VOS) in male powerlifters and controls.Methods—Twenty four powerlifters and 21 sedentary male controls were recruited to the study. All the powerlifters were members of the British Drug Free Powerlifting Association and actively competing at the time of the study. A questionnaire was completed by all those entered into the study. This included a history of smoking and an estimation of daily intake of alcohol and calcium. For the powerlifters, the number of years spent training and time spent training each week was also recorded. The QUS variables of all powerlifters and controls were measured using a Cubaclinical II (McCue) ultrasound scanner.Results—The powerlifters had been training for a mean (SEM) of 10.6 (1.6) years and they trained for 6.5 (0.4) hours a week. The powerlifters were non-significantly older and had a significantly higher body mass index (BMI) than the controls. Calcium intake and consumption of alcohol and tobacco were similar in the two groups. The mean BUA in the powerlifters was a significant 9.5% (95% confidence interval 0.7 to 18.3%) higher than the controls (105v96 dB/MHZ) and 15.6% (95% confidence interval 6.8 to 24.4%) higher after adjustment using analysis of covariance for age, BMI, and alcohol and tobacco consumption (108v93 dB/MHZ). The mean VOS was similar in the two groups, but after adjustment it was significantly higher in the powerlifters (1671v1651 m/s, p<0.01).Conclusions—The study shows the ability of heel ultrasound to discriminate between QUS variables in powerlifters and controls. The results indicate that the QUS variables BUA and VOS are significantly higher for powerlifters than for controls.
Biliary lipid composition in cholesterol microlithiasis
Authors: Fracchia M , Pellegrino S , Secreto P , Gallo L , Masoero G , Pera A , Galatola G 
Published: July 2002

BACKGROUNDLittle information is available on the pathogenesis of cholesterol microlithiasis, and it is not clear if biliary lipid composition in these patients is similar to changes seen in cholesterol gall stone patients.AIMSTo measure biliary lipid composition in patients with cholesterol microlithiasis.PATIENTSEleven patients with cholesterol microlithiasis, 20 cholesterol gall stone patients, and 17 healthy controls.METHODSDuodenal bile was collected in the fasting state during ceruletide infusion. Biliary cholesterol, phospholipids, and total bile acids were analysed by enzymatic assays, and conjugated bile acids by high pressure liquid chromatography.RESULTSPatients with microlithiasis had a cholesterol saturation index significantly higher than controls (mean value 1.30 (95% confidence interval 1.05–1.54)v0.90 (0.72–1.08)) but similar to gall stone patients (1.51 (1.40–1.63)). This was due to a significant decrease in per cent phospholipid (10.0% (7.1–12.8)) compared with controls (21.4% (18.1–24.6)) and gall stone patients (24.9% (20.5–29.3)). Per cent cholesterol was similar in patients with microlithiasis and controls (5.3% (4.5–6.1) and 5.6 % (4.3–6.8), respectively) but was significantly increased in gall stone patients (10.9% (9.3–12.4)). Bile acid composition in patients with microlithiasis was similar to controls whereas in gall stone patients deoxycholic acid was significantly increased: 27.3% (24.8–29.7)v19.0% (15.7–22.2) in controls and 20.6% (14.9–26.2) in patients with microlithiasis.CONCLUSIONPatients with cholesterol microlithiasis have biliary cholesterol supersaturation, similarly to cholesterol gall stone patients. Whereas in the latter this is due to increased per cent cholesterol, in patients with microlithiasis this is caused by phospholipid deficiency, with normal per cent cholesterol and normal biliary bile acid composition.