bluuebunny/crossref_metadata_2025 huggingface dataset:
Base-Pair Substitutions in Avian Sarcoma Virus U5 and U3 Long Terminal Repeat Sequences Alter the Process of DNA Integration In Vitro
Authors: Hindmarsh Patrick , Johnson Michael , Reeves Ray , Leis Jonathan
Published: July 2002

We have described a reconstituted avian sarcoma virus (ASV) concerted DNA integration system with specially designed mini-donor DNA containing a
supF
transcription unit, a supercoiled plasmid acceptor, purified bacterially expressed ASV integrase (IN), and human high-mobility-group protein I(Y). Integration in this system is dependent upon the mini-donor DNA having IN recognition sequences at both ends and upon both ends of the same donor integrating into the acceptor DNA. The integrated DNA product exhibits all of the features associated with integration of viral DNA in vivo (P. Hindmarsh et al., J. Virol., 73:2994–3003, 1999). Individual integrants are isolated from bacteria containing drug-resistant markers with amber mutations. This system was used to evaluate the importance of sequences in the terminal U5 and U3 long terminal repeats at positions 5 and/or 6, adjacent to the conserved CA dinucleotide. Base-pair substitutions introduced at these positions in U5 result in significant reductions in recovered integrants from bacteria, due to increases in one-ended insertion events. Among the recovered integrants from reactions with mutated U5 but not U3 IN recognition sequences were products that contain large deletions in the acceptor DNA. Base-pair substitutions at positions 5 and 6 in U3 mostly reduce the efficiency of integration of the modified donor. Together, these results indicate that sequences directly 5′ to the conserved CA dinucleotide are very important for the process of concerted DNA integration. Furthermore, IN interacts with U3 and U5 termini differently, and aberrant end-processing events leading to nonconcerted DNA integration are more common in U5 than in U3.
Reverse Genetics System for Uukuniemi Virus (
Bunyaviridae
): RNA Polymerase I-Catalyzed Expression of Chimeric Viral RNAs
Authors: Flick Ramon , Pettersson Ralf F.
Published: July 2002

We describe here the development of a reverse genetics system for the phlebovirus Uukuniemi virus, a member of the
Bunyaviridae
family, by using RNA polymerase I (pol I)-mediated transcription. Complementary DNAs containing the coding sequence for either chloramphenicol acetyltransferase (CAT) or green fluorescent protein (GFP) (both in antisense orientation) were flanked by the 5′- and 3′-terminal untranslated regions of the Uukuniemi virus sense or complementary RNA derived from the medium-sized (M) RNA segment. This chimeric cDNA (pol I expression cassette) was cloned between the murine pol I promoter and terminator and the plasmid transfected into BHK-21 cells. When such cells were either superinfected with Uukuniemi virus or cotransfected with expression plasmids encoding the L (RNA polymerase), N (nucleoprotein), and NSs (nonstructural protein) viral proteins, strong CAT activity or GFP expression was observed. CAT activity was consistently stronger in cells expressing L plus N than following superinfection. No activity was seen without superinfection, nor was activity detected when either the L or N expression plasmid was omitted. Omitting NSs expression had no effect on CAT activity or GFP expression, indicating that this protein is not needed for viral RNA replication or transcription. CAT activity could be serially passaged to fresh cultures by transferring medium from CAT-expressing cells, indicating that recombinant virus containing the reporter construct had been produced. In summary, we demonstrate that the RNA pol I system, originally developed for influenza virus, which replicates in the nucleus, has strong potential for the development of an efficient reverse genetics system also for
Bunyaviridae
members, which replicate in the cytoplasm.
Cellular Splicing Factor RAF-2p48/NPI-5/BAT1/UAP56 Interacts with the Influenza Virus Nucleoprotein and Enhances Viral RNA Synthesis
Authors: Momose Fumitaka , Basler Christopher F. , O'Neill Robert E. , Iwamatsu Akihiro , Palese Peter , Nagata Kyosuke
Published: July 2002

Previous biochemical data identified a host cell fraction, designated RAF-2, which stimulated influenza virus RNA synthesis. A 48-kDa polypeptide (RAF-2p48), a cellular splicing factor belonging to the DEAD-box family of RNA-dependent ATPases previously designated BAT1 (also UAP56), has now been identified as essential for RAF-2 stimulatory activity. Additionally, RAF-2p48 was independently identified as an influenza virus nucleoprotein (NP)-interacting protein, NPI-5, in a yeast two-hybrid screen of a mammalian cDNA library. In vitro, RAF-2p48 interacted with free NP but not with NP bound to RNA, and the RAF-2p48–NP complex was dissociated following addition of free RNA. Furthermore, RAF-2p48 facilitated formation of the NP-RNA complexes that likely serve as templates for the viral RNA polymerase. RAF-2p48 was shown, in both in vitro binding assays and the yeast two-hybrid system, to bind to the amino-terminal region of NP, a domain essential for RNA binding. Together, these observations suggest that RAF-2p48 facilitates NP-RNA interaction, thus leading to enhanced influenza virus RNA synthesis.
Direct and Indirect Regulation of Cytokine and Cell Cycle Proteins by EBNA-2 during Epstein-Barr Virus Infection
Authors: Spender Lindsay C. , Cornish Georgina H. , Rowland Benjamin , Kempkes Bettina , Farrell Paul J.
Published: July 2002

We have studied the pathways of regulation of cytokine and cell cycle control proteins during infection of human B lymphocytes by Epstein-Barr virus (EBV). Among 30 cytokine RNAs analyzed by the RNase protection assay, tumor necrosis factor alpha (TNF-α), granulocyte colony-stimulating factor, lymphotoxin (LT), and LTβ were found to be regulated within 20 h of EBV infection of primary B cells. Similar results were obtained using the estrogen-regulated EBNA-2 cell line EREB2.5, in which RNAs for LT and TNF-α were induced within 6 h of activation of EBNA-2. Expression of Notch also caused an induction of TNF-α RNA. The induction of TNF-α RNA by EBNA-2 was indirect, and constitutive expression of either LMP-1 or c-myc proteins did not substitute for EBNA-2 in induction of TNF-α RNA. Cyclin D2 is also an indirect target of EBNA-2-mediated transactivation. EBNA-2 was found to activate the cyclin D2 promoter in a transient-transfection assay. A mutant of EBNA-2 that does not bind RBP-Jκ retained some activity in this assay, and activation did not depend on the presence of B-cell-specific factors. Deletion analysis of the cyclin D2 promoter revealed that removal of sequences containing E-box c-myc consensus DNA binding sequences did not reduce EBNA-2-mediated activation of the cyclin D2 promoter in the transient-transfection assay. The results indicate that cytokines are an early target of EBNA-2 and that EBNA-2 can regulate cyclin D2 transcription in EBV-infected cells by mechanisms additional to the c-myc pathway.
Measles Viruses on Throat Swabs from Measles Patients Use Signaling Lymphocytic Activation Molecule (CDw150) but Not CD46 as a Cellular Receptor
Authors: Ono Nobuyuki , Tatsuo Hironobu , Hidaka Yasufumi , Aoki Tomonobu , Minagawa Hiroko , Yanagi Yusuke
Published: July 2002

Both CD46 and signaling lymphocytic activation molecule (SLAM) have been shown to act as cellular receptors for measles virus (MV). The viruses on throat swabs from nine patients with measles in Japan were titrated on Vero cells stably expressing human SLAM. Samples from all but two patients produced numerous plaques on SLAM-expressing Vero cells, whereas none produced any plaques on Vero cells endogenously expressing CD46. The Edmonston strain of MV, which can use either CD46 or SLAM as a receptor, produced comparable titers on these two types of cells. The results strongly suggest that the viruses in the bodies of measles patients use SLAM but probably not CD46 as a cellular receptor.
Macaques with Rapid Disease Progression and Simian Immunodeficiency Virus Encephalitis Have a Unique Cytokine Profile in Peripheral Lymphoid Tissues
Authors: Orandle Marlene S. , Williams Kenneth C. , MacLean Andrew G. , Westmoreland Susan V. , Lackner Andrew A.
Published: July 2002

The influence of host cytokine response on viral load, disease progression, and neurologic lesions was investigated in the simian immunodeficiency virus (SIV)-infected macaque model of AIDS. Cytokine gene expression (interleukin-1β [IL-1β], IL-2, IL-6, IL-10, gamma interferon [IFN-γ], and tumor necrosis factor alpha [TNF-α]) and viral loads were evaluated by semiquantitative reverse transcription-PCR in lymph nodes of 5 control animals and 28 animals infected with SIVmac251 at the terminal stages of AIDS. Infected animals showed higher expression of IFN-γ, IL-6, and IL-10 mRNAs compared with controls. Levels of all cytokines were comparable between animals with rapid (survival, <200 days) or slow/normal (survival, >200 days) disease progression. However, among rapid progressors, the eight animals with SIV encephalitis had a unique cytokine profile (increased IL-2, IL-6, and IFN-γ) that was associated with higher viral loads. These observations provide evidence that host cytokine responses may influence SIV neuropathogenesis independent of disease progression.
Ebola Virus VP40 Drives the Formation of Virus-Like Filamentous Particles Along with GP
Authors: Noda Takeshi , Sagara Hiroshi , Suzuki Emiko , Takada Ayato , Kida Hiroshi , Kawaoka Yoshihiro
Published: July 2002

Using biochemical assays, it has been demonstrated that expression of Ebola virus VP40 alone in mammalian cells induced production of particles with a density similar to that of virions. To determine the morphological properties of these particles, cells expressing VP40 and the particles released from the cells were examined by electron microscopy. VP40 induced budding from the plasma membrane of filamentous particles, which differed in length but had uniform diameters of approximately 65 nm. When the Ebola virus glycoprotein (GP) responsible for receptor binding and membrane fusion was expressed in cells, we found pleomorphic particles budding from the plasma membrane. By contrast, when GP was coexpressed with VP40, GP was found on the filamentous particles induced by VP40. These results demonstrated the central role of VP40 in formation of the filamentous structure of Ebola virions and may suggest an interaction between VP40 and GP in morphogenesis.
Interaction of the Coronavirus Nucleoprotein with Nucleolar Antigens and the Host Cell
Authors: Chen Hongying , Wurm Torsten , Britton Paul , Brooks Gavin , Hiscox Julian A.
Published: July 2002

Coronavirus nucleoproteins (N proteins) localize to the cytoplasm and the nucleolus, a subnuclear structure, in both virus-infected primary cells and in cells transfected with plasmids that express N protein. The nucleolus is the site of ribosome biogenesis and sequesters cell cycle regulatory complexes. Two of the major components of the nucleolus are fibrillarin and nucleolin. These proteins are involved in nucleolar assembly and ribosome biogenesis and act as chaperones for the import of proteins into the nucleolus. We have found that fibrillarin is reorganized in primary cells infected with the avian coronavirus infectious bronchitis virus (IBV) and in continuous cell lines that express either IBV or mouse hepatitis virus N protein. Both N protein and a fibrillarin-green fluorescent protein fusion protein colocalized to the perinuclear region and the nucleolus. Pull-down assays demonstrated that IBV N protein interacted with nucleolin and therefore provided a possible explanation as to how coronavirus N proteins localize to the nucleolus. Nucleoli, and proteins that localize to the nucleolus, have been implicated in cell growth-cell cycle regulation. Comparison of cells expressing IBV N protein with controls indicated that cells expressing N protein had delayed cellular growth. This result could not to be attributed to apoptosis. Morphological analysis of these cells indicated that cytokinesis was disrupted, an observation subsequently found in primary cells infected with IBV. Coronaviruses might therefore delay the cell cycle in interphase, where maximum translation of viral mRNAs can occur.
Association of the Caveola Vesicular System with Cellular Entry by Filoviruses
Authors: Empig Cyril J. , Goldsmith Mark A.
Published: July 2002

The filoviruses Ebola Zaire virus and Marburg virus are believed to infect target cells through endocytic vesicles, but the details of this pathway are unknown. We used a pseudotyping strategy to investigate the cell biology of filovirus entry. We observed that specific inhibitors of the caveola system, including cholesterol-sequestering drugs and phorbol esters, inhibited the entry of filovirus pseudotypes into human cells. We also measured slower cell entry kinetics for both filovirus pseudotypes than for pseudotypes of vesicular stomatitis virus (VSV), which has been recognized to exploit the clathrin-mediated entry pathway. Finally, visualization by immunofluorescence and confocal microscopy revealed that the filovirus pseudotypes colocalized with the caveola protein marker caveolin-1 but that VSV pseudotypes did not. Collectively, these results provide evidence suggesting that filoviruses use caveolae to gain entry into cells.
Folding and Dimerization of Tick-Borne Encephalitis Virus Envelope Proteins prM and E in the Endoplasmic Reticulum
Authors: Lorenz Ivo C. , Allison Steven L. , Heinz Franz X. , Helenius Ari
Published: July 2002

Flavivirus envelope proteins are synthesized as part of large polyproteins that are co- and posttranslationally cleaved into their individual chains. To investigate whether the interaction of neighboring proteins within the precursor protein is required to ensure proper maturation of the individual components, we have analyzed the folding of the flavivirus tick-borne encephalitis (TBE) virus envelope glycoproteins prM and E by using a recombinant plasmid expression system and virus-infected cells. When expressed in their polyprotein context, prM and E achieved their native folded structures with half-times of approximately 4 min for prM and about 15 min for E. They formed heterodimeric complexes within a few minutes after synthesis that were required for the final folding of E but not for that of prM. Heterodimers could also be formed in
trans
when these proteins were coexpressed from separate constructs. When expressed without prM, E could form disulfide bonds but did not express a specific conformational epitope and remained sensitive to reduction by dithiothreitol. This is consistent with a chaperone-like role for prM in the folding of E. PrM was able to achieve its native folded structure without coexpression of E, but signal sequence cleavage at the N terminus was delayed. Our results show that prM is an especially rapidly folding viral glycoprotein, that polyprotein cleavage and folding of the TBE virus envelope proteins occurs in a coordinated sequence of processing steps, and that proper and efficient maturation of prM and E can only be achieved by cosynthesis of these two proteins.
Inhibition of Tumor Necrosis Factor Alpha-Induced NF-κB Activation by the Adenovirus E3-10.4/14.5K Complex
Authors: Friedman Joshua M. , Horwitz Marshall S.
Published: July 2002

Recombinant adenoviruses (Ads) are useful tools in gene transfer because they are able to infect a wide variety of tissues and cell types and do not require a replicating target cell. However, transgene expression is only transient due to host innate and acquired immune responses to the virus. Most recombinant Ads have deletions of early region 3 (E3) genes, allowing more space for insertion of the transgene. Although the E3 region is not necessary for infection, it has been observed that these “nonessential” genes have immunomodulatory properties. We demonstrate here that the E3 region of Ad inhibits the activation of NF-κB induced by tumor necrosis factor alpha (TNF-α) and interleukin-1. Ad E3 is able to prevent NF-κB from entering the nucleus, where it is normally active. Ad E3 also appears to function by preventing the activation of the kinase complex, IKK, which is responsible for phosphorylation of IκB that retains NF-κB in the cytoplasm in an inactive state. The prevention of NF-κB activation has been mapped to a complex of two of the seven E3 products, E3-10.4K and E3-14.5K (RIDα/β). These and other studies indicate that, by using Ad vectors containing the E3 region, it may be possible to reduce the harmful proinflammatory effects of TNF-α and other cytokines that compromise the use of Ad gene therapy vectors in vivo.
Enhanced Expression of Proinflammatory Cytokines in the Central Nervous System Is Associated with Neuroinvasion by Simian Immunodeficiency Virus and the Development of Encephalitis
Authors: Orandle Marlene S. , MacLean Andrew G. , Sasseville Vito G. , Alvarez Xavier , Lackner Andrew A.
Published: July 2002

Inflammatory cytokines are believed to play an important role in the pathogenesis of human immunodeficiency virus type 1-associated encephalitis. To examine this in the simian immunodeficiency virus (SIV)-infected macaque model of neuroAIDS, inflammatory cytokine gene expression was evaluated in the brains of macaques infected with pathogenic SIVmac251by reverse transcriptase PCR. Interleukin-1 beta was readily detected in the brains of all animals evaluated, regardless of infection status or duration of infection. Tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) transcripts were undetectable in the brains of uninfected control animals but were upregulated at 7 and 14 days postinoculation. At the terminal stage of infection, TNF-α and IFN-γ transcripts were coexpressed in the brains of four of five animals with SIV encephalitis (SIVE). Within an encephalitic brain, TNF-α and IFN-γ transcripts were detected in six of seven regions with histologic evidence of SIVE, suggesting a direct relationship between neuropathology and altered cytokine gene expression. With combined fluorescent in situ hybridization and immunofluorescence, TNF-α-expressing cells were frequently identified as CD68-positive macrophages within perivascular lesions. These observations provide evidence that cytokines produced by activated inflammatory macrophages are an important element in the pathogenesis of SIVE.
VP40, the Matrix Protein of Marburg Virus, Is Associated with Membranes of the Late Endosomal Compartment
Authors: Kolesnikova Larissa , Bugany Harald , Klenk Hans-Dieter , Becker Stephan
Published: July 2002

Localization of VP40 in Marburg virus (MBGV)-infected cells was studied by using immunofluorescence and immunoelectron microscopic analysis. VP40 was detected in association with nucleocapsid structures, present in viral inclusions and at sites of virus budding. Additionally, VP40 was identified in the foci of virus-induced membrane proliferation and in intracellular membrane clusters which had the appearance of multivesicular bodies (MVBs). VP40-containing MVBs were free of nucleocapsids. When analyzed by immunogold labeling, the concentration of VP40 in MVBs was six times higher than in nucleocapsid structures. Biochemical studies showed that recombinant VP40 represented a peripheral membrane protein that was stably associated with membranes by hydrophobic interaction. Recombinant VP40 was also found in association with membranes of MVBs and in filopodia- or lamellipodia-like protrusions at the cell surface. Antibodies against marker proteins of various cellular compartments showed that VP40-positive membranes contained Lamp-1 and the transferrin receptor, confirming that they belong to the late endosomal compartment. VP40-positive membranes were also associated with actin. Western blot analysis of purified MBGV structural proteins demonstrated trace amounts of actin, Lamp-1, and Rab11 (markers of recycling endosomes), while markers for other cellular compartments were absent. Our data indicate that MBGV VP40 was able to interact with membranes of late endosomes in the course of viral infection. This capability was independent of other MBGV proteins.
Herpes Simplex Virus ICP0 and ICP34.5 Counteract Distinct Interferon-Induced Barriers to Virus Replication
Authors: Mossman Karen L. , Smiley James R.
Published: July 2002

Interferon inhibits virus replication through multiple mechanisms. Here we show that herpes simplex virus proteins ICP0 and ICP34.5 overcome interferon-induced barriers to viral transcription and translation, respectively. These cytokine-induced antiviral mechanisms are differentially expressed in established cell lines: U2OS cells do not mount the IFN-induced mechanism targeted by ICP0, and Vero cells may be defective for the mechanism targeted by ICP34.5.
Truncation of the Cytoplasmic Domain Induces Exposure of Conserved Regions in the Ectodomain of Human Immunodeficiency Virus Type 1 Envelope Protein
Authors: Edwards Terri G. , Wyss Stéphanie , Reeves Jacqueline D. , Zolla-Pazner Susan , Hoxie James A. , Doms Robert W. , Baribaud Frédéric
Published: July 2002

We have described a CD4-independent variant of HXBc2, termed 8x, that binds directly to CXCR4 and mediates CD4-independent virus infection. Determinants for CD4 independence map to residues in the V3 and V4-C4 domains together with a single nucleotide deletion in the transmembrane domain which introduces a frameshift (FS) at position 706. This FS results in a truncated cytoplasmic domain of 27 amino acids. We demonstrate here that while introduction of the 8x FS mutation into heterologous R5, X4, or R5X4 Env proteins did not impart CD4 independence, it did affect the conformation of the gp120 surface subunit, exposing highly conserved domains involved in both coreceptor and CD4 binding. In addition, antigenic changes in the gp41 ectodomain were also observed, consistent with the idea that the effects of cytoplasmic domain truncation must in some way be transmitted to the external gp120 subunit. Truncation of gp41 also resulted in the marked neutralization sensitivity of all Env proteins tested to human immunodeficiency virus-positive human sera and monoclonal antibodies directed against the CD4 or coreceptor-binding sites. These results demonstrate a structural interdependence between the cytoplasmic domain of gp41 and the ectodomain of the Env protein. They also may help explain why the length of the gp41 cytoplasmic domain is retained in vivo and may provide a way to genetically trigger the exposure of neutralization determinants in heterologous Env proteins that may prove useful for vaccine development.
Effects of Promyelocytic Leukemia Protein on Virus-Host Balance
Authors: Bonilla Weldy V. , Pinschewer Daniel D. , Klenerman Paul , Rousson Valentin , Gaboli Mirella , Pandolfi Pier P. , Zinkernagel Rolf M. , Salvato Maria S. , Hengartner Hans
Published: July 2002

The cellular promyelocytic leukemia protein (PML) associates with the proteins of several viruses and in some cases reduces viral propagation in cell culture. To examine the role of PML in vivo, we compared immune responses and virus loads of PML-deficient and control mice infected with lymphocytic choriomeningitis virus (LCMV) and vesicular stomatitis virus (VSV). PML−/−mice exhibited accelerated primary footpad swelling reactions to very-low-dose LCMV, higher swelling peaks upon high-dose inoculation, and higher viral loads in the early phase of systemic LCMV infection. T-cell-mediated hepatitis and consequent mortality upon infection with a hepatotropic LCMV strain required 10- to 100-times-lower inocula despite normal cytotoxic T-lymphocyte reactivity in PML−/−mice. Furthermore, PML deficiency rendered mice 10 times more susceptible to lethal immunopathology upon intracerebral LCMV inoculation. Accordingly, 10-times-lower VSV inocula elicited specific neutralizing-antibody responses, a replication-based effect not observed with inactivated virus or after immunization with recombinant VSV glycoprotein. These in vivo observations corroborated our results showing more virus production in PML−/−fibroblasts. Thus, PML is a contributor to innate immunity, defining host susceptibility to viral infections and to immunopathology.
Long-Distance Base Pairing in Flock House Virus RNA1 Regulates Subgenomic RNA3 Synthesis and RNA2 Replication
Authors: Lindenbach Brett D. , Sgro Jean-Yves , Ahlquist Paul
Published: July 2002

Replication of flock house virus (FHV) RNA1 and production of subgenomic RNA3 in the yeast
Saccharomyces cerevisiae
provide a useful tool for the dissection of FHV molecular biology and host-encoded functions involved in RNA replication. The replication template activity of RNA1 can be separated from its coding potential by supplying the RNA1-encoded replication factor protein A in
trans
. We constructed a
trans
-replication system in yeast to examine
cis
-acting elements in RNA1 that control RNA3 production, as well as RNA1 and RNA2 replication. Two
cis
elements controlling RNA3 production were found. A proximal subgenomic control element was located just upstream of the RNA3 start site (nucleotides [nt] 2282 to 2777). A short distal element also controlling RNA3 production (distal subgenomic control element) was identified 1.5 kb upstream, at nt 1229 to 1239. Base pairing between these distal and proximal elements was shown to be essential for RNA3 production by covariation analysis and in vivo selection of RNA3-expressing replicons from plasmid libraries containing random sequences in the distal element. Two distinct RNA1 replication elements (RE) were mapped within the 3′ quarter of RNA1: the intRE (nt 2322 to 2501) and the 3′RE (nt 2735 to 3011). The 3′RE significantly overlaps the RNA3 region in RNA1, and this information was applied to produce improved RNA3-based vectors for foreign-gene expression. In addition, replication of an RNA2 derivative was dependent on RNA1 templates capable of forming the long-distance interaction that controls RNA3 production.
Density of Aqueous Solutions of Na2CO3-NAHCO3
Authors: Palatý Zdeněk
Published: July 2002

The paper deals with a correlation of the ternary systems H2O - Na2CO3 - NaHCO3. The corresponding data have been correlated with an equation presuming the additivity of partial molar volumes, the components being water and the so-called basic solutions of Na2CO3 and NaHCO3. From the comparison of experimental and calculated density values of the solutions of Na2CO3 - NaHCO3, Na2CO3, and NaHCO3 at 20 °C it follows that the given procedure provides very precise results.
Reliability of DFT Methods for Description of Cu Sites and Their Interaction with NO in Zeolites
Authors: Nachtigallová Dana , Davidová Markéta , Nachtigall Petr
Published: July 2002

The reliability of various DFT functionals for description of Cu sites and their interaction with NO in zeolites is tested. The dissociation energies of Cun+H2O and Cun+NO systems calculated with various DFT functionals are compared with those obtained at the MP2 and CCSD(T) levels of theory. It is concluded that hybrid density functional (B3LYP) gives reliable description of studied systems, while LDA seriously overestimates dissociation energies.
Mass-Transfer Efficiency of a Small-Size Teflon Bubble-Cap Tray
Authors: Petrov Peter S. , Genkova Penka V.
Published: July 2002

The combined effect of flow conditions, geometry and physical properties on distillation efficiency of a newly constructed small-size Teflon bubble-cap tray for production of high-purity substances is experimentally investigated. The limits of vapour loading required for a steady hydrodynamic tray operation are found. The results evidence an influence of the liquid entrainment on plate efficiency at elevated superficial vapour velocities and higher downcomers. The comparison of the plate efficiency values determined experimentally with those from different correlations for large columns shows that the equation of MacFarland et al. and the point AIChE theoretical method are the best for predicting mass-transfer efficiency of the small-size bubble-cap Teflon tray used.
Visible Absorption Spectrum of Benzophenone Radical Anion in Dipolar Aprotic Solvents
Authors: Wagner-Czauderna Elżbieta , Kalinowski Marek K.
Published: July 2002

Two-parameter regression including the acceptor number (AN) and permittivity (ε) of the solvent explains to some extent the solvatochromic shift of the absorption band of benzophenone radical anion (Ph2C•-O-) in the visible region. In 11 dipolar aprotic solvents characterized by ε > 10, in which the Ph2C•-O- anions are not associated with (C2H5)4N+ cations (the radicals were prepared by cathodic reduction of benzophenone in the presence of (C2H5)4N+ClO4- as electrolyte) a correlation equation has the form νmax (in cm-1) = 86.2(AN) - 19.7 · 103[(ε - 1)/(2ε + 1)] + 21.32 · 103. It reflects the relative stabilization of the ground state in a medium with a high acceptor number and an increase in the dipole moment of Ph2C•-O- during excitation.
Effects of exercise on lymphocytes and cytokines
Authors: Pedersen Bente Klarlund , Toft Anders Dyhr
Published: July 2002

Objectives—To review results on exercise induced changes in the immune system following strenuous and moderate exercise.

Methods—A literature search over the past 15 years was conducted using Medline and selected papers.

Results—After intense long term exercise, the immune system is characterised by concomitant impairment of the cellular immune system and increased inflammation. Thus low concentrations of lymphocytes, suppressed natural immunity, suppressed lymphocyte proliferation, and suppressed levels of secretory IgA in saliva are found simultaneously with high levels of circulating proinflammatory and anti-inflammatory cytokines. The underlying mechanisms are multifactorial and include neuroendocrinological and metabolic factors. The clinical consequences of the exercise induced immune changes have not formally been identified, but the exercise effect on lymphocyte dynamics and immune function may be linked to the exercise effects on resistance to infections and malignancy and the cytokine response may be linked to muscle damage or muscle cell growth.

Conclusions—Moderate exercise across the life span seems to increase resistance to upper respiratory tract infections, whereas repeated strenuous exercise suppresses immune function. It is premature to offer advice on nutrition to athletes in order to alter the exercise induced immunosuppression found after exercise.
Is exercise effective treatment for osteoarthritis of the knee?
Authors: Petrella Robert J
Published: July 2002

Objective—To review and determine the effectiveness of exercise treatment in osteoarthritis of the knee.

Methods—A computerised literature search of Medline was carried out searching between June 1966 and January 2000.

Results—Twenty three randomised controlled trials were identified from the literature. Only three trials were sufficiently powered. Small to moderate beneficial effects of exercise treatment were found for pain, small beneficial effects on disability outcome measures, and moderate to great beneficial effects were observed according to patient global assessment of effect. It was not possible to obtain evidence on the content of exercise interventions, as studies were hampered by lack of attention to proper concealment, reporting of adverse effects, and long term effects of exercise treatment. The lack of standard outcomes measures is also noted.

Conclusions—The available evidence indicates beneficial short term effects of exercise treatment in patients with osteoarthritis of the knee. However, the number of available studies is limited, and more research is needed to expand this recommendation. Specifically, additional trials should provide information on adherence, home based interventions, interaction with pharmacological treatments, functional outcomes measures relevant to exercise treatment in these patients, and long term effects. At present, doctors should recommend exercise to all patients with mild/moderate disease. Further study should be encouraged and exercise should be continued to be recommended as a mainstay of non-pharmacological treatment of osteoarthritis of the knee.
Benefits from aerobic exercise in patients with major depression: a pilot study
Authors: Dimeo F , Bauer M , Varahram I , Proest G , Halter U
Published: July 2002

Background—Several reports indicate that physical activity can reduce the severity of symptoms in depressed patients. Some data suggest that even a single exercise bout may result in a substantial mood improvement.

Objective—To evaluate the short term effects of a training programme on patients with moderate to severe major depression.

Methods—Twelve patients (mean (SD) age 49 (10) years; five men, seven women) with a major depressive episode according to the Diagnostic and Statistical Manual of the American Society of Psychiatry (DSM IV) criteria participated. The mean (SD) duration of the depressive episode was 35 (21) weeks (range 12–96). Training consisted of walking on a treadmill following an interval training pattern and was carried out for 30 minutes a day for 10 days.

Results—At the end of the training programme, there was a clinically relevant and statistically significant reduction in depression scores (Hamilton Rating Scale for Depression: before, 19.5 (3.3); after, 13 (5.5); p = 0.002. Self assessed intensity of symptoms: before, 23.2 (7); after, 17.7 (8.1); p = 0.006. Values are mean (SD)). Subjective and objective changes in depression scores correlated strongly (r= 0.66, p = 0.01).

Conclusions—Aerobic exercise can produce substantial improvement in mood in patients with major depressive disorders in a short time.
Pectoralis major tears: comparison of surgical and conservative treatment
Authors: Hanna C M , Glenny A B , Stanley S N , Caughey M A
Published: July 2002

Objectives—To compare objective measures of strength and subjective functional outcomes in complete distal pectoralis major tears treated either surgically or non-surgically.

Methods—Twenty two pectoralis major tears were included in 21 patients. Ten were surgically repaired and 12 were managed non-surgically. Patients completed a standard questionnaire, and clinical examination and isokinetic dynamometry were carried out.

Results—In patients who had surgical repair, peak torque returned to 99% of that of the uninjured side and work performed returned to 97%. For those managed conservatively, peak torque and work performed returned to only 56% of that of the uninjured side (p = 0.003 for the difference in peak torque, and p = 0.01 for work performed). Findings were independent of the strength of the patient, whether or not the dominant arm was involved, the age of the patient, and the length of time from injury or surgery to testing. Patients were grouped into one of three subjective functional outcome groups, and those who had a surgical repair had a better functional outcome.

Conclusions—Surgical repair results in greater recovery of peak torque and work performed than conservative management of patients with rupture of the pectoralis major.
Clinical risk factors for hamstring muscle strain injury: a prospective study with correlation of injury by magnetic resonance imaging
Authors: Verrall G M , Slavotinek J P , Barnes P G , Fon G T , Spriggins A J
Published: July 2002

Objective—To prospectively establish risk factors for hamstring muscle strain injury using magnetic resonance imaging (MRI) to define the diagnosis of posterior thigh injury.

Method—In a prospective cohort study using two elite Australian Rules football clubs, the anthropometric characteristics and past clinical history of 114 athletes were recorded. Players were followed throughout the subsequent season, with posterior thigh injuries being documented. Hamstring intramuscular hyperintensity on T2 weighted MRI was required to meet our criteria for a definite hamstring injury. Statistical associations were sought between anthropometric and previous clinical characteristics and hamstring muscle injury.

Results—MRI in 32 players showed either hamstring injury (n = 26) or normal scans (n = 6). An association existed between a hamstring injury and each of the following: increasing age, being aboriginal, past history of an injury to the posterior thigh or knee or osteitis pubis (all p<0.05). These factors were still significant when players with a past history of posterior thigh injury (n = 26) were excluded. Previous back injury was associated with a posterior thigh injury that looked normal on MRI scan, but not with an MRI detected hamstring injury.

Conclusions—Hamstring injuries are common in Australian football, and previous posterior thigh injury is a significant risk factor. Other factors, such as increasing age, being of aboriginal descent, or having a past history of knee injury or osteitis pubis, increase the risk of hamstring strain independently of previous posterior thigh injury. However, as the numbers in this study are small, further research is needed before definitive statements can be made.
Does rugby headgear prevent concussion? Attitudes of Canadian players and coaches
Authors: Pettersen J A
Published: July 2002

Objectives: To examine the attitudes of players and coaches to the use of protective headgear, particularly with respect to the prevention of concussion.

Methods: A questionnaire designed to assess attitudes to headgear was administered to 63 players from four different Canadian teams, each representing a different level of play (high school, university, community club, national). In addition, coaches from all four levels were questioned about team policies and their personal opinions about the use of headgear to prevent concussion.

Results: Although the players tended to believe that the headgear could prevent concussion (62%), the coaches were less convinced (33%). Despite the players' belief that headgear offers protection against concussion, only a minority reported wearing headgear (27%) and few (24%) felt that its use should be made mandatory. Common reasons for not wearing headgear were “its use is not mandatory”, “it is uncomfortable”, and “it costs too much”.

Conclusion: Although most players in the study believe that rugby headgear may prevent concussion, only a minority reported wearing it. Coaches tended to be less convinced than the players that rugby headgear can prevent concussion.
Identifying some determinants of “jet lag” and its symptoms: a study of athletes and other travellers
Authors: Waterhouse J , Edwards B , Nevill A , Carvalho S , Atkinson G , Buckley P , Reilly T , Godfrey R , Ramsay R
Published: July 2002

Background: Travelling across multiple time zones disrupts normal circadian rhythms and induces “jet lag”. Possible effects of this on training and performance in athletes were concerns before the Sydney Olympic Games.

Objective: To identify some determinants of jet lag and its symptoms.

Methods: A mixture of athletes, their coaches, and academics attending a conference (n = 85) was studied during their flights from the United Kingdom to Australia (two flights with a one hour stopover in Singapore), and for the first six days in Australia. Subjects differed in age, sex, chronotype, flexibility of sleeping habits, feelings of languor, fitness, time of arrival in Australia, and whether or not they had previous experience of travel to Australia. These variables and whether the body clock adjusted to new local time by phase advance or delay were tested as predictors for jet lag and some of its symptoms by stepwise multiple regression analyses.

Results: The amount of sleep in the first flight was significantly greater in those who had left the United Kingdom in the evening than the morning (medians of 5.5 hours and 1.5 hours respectively; p = 0.0002, Mann-Whitney), whereas there was no significant difference on the second flight (2.5 hoursv2.8 hours; p = 0.72). Only the severity of jet lag and assessments of sleep and fatigue were commonly predicted significantly (p<0.05) by regression analysis, and then by only some of the variables. Thus increasing age and a later time of arrival in Australia were associated with less jet lag and fatigue, and previous experience of travel to Australia was associated with an earlier time of getting to sleep. Subjects who had adjusted by phase advance suffered worse jet lag during the 5th and 6th days in Australia.

Conclusions: These results indicate the importance of an appropriate choice of itinerary and lifestyle for reducing the negative effects of jet lag in athletes and others who wish to perform optimally in the new time zone.
An ergonomic comparison of rowing machine designs: possible implications for safety
Authors: Bernstein I A , Webber O , Woledge R
Published: July 2002

Objectives: Ergometer training is a common cause of injuries in rowers. A randomised crossover study comparing two power head designs was carried out to examine ergonomic risk factors.

Methods: Six elite male rowers undertook 20 minute fatiguing rowing pieces with both fixed and floating power heads. A CODA MPX infrared telemetric motion analysis detector and the ergometer's interface were used to measure displacement, force, work performed, and power output.

Results: There was no significant difference in the total work performed, power per stroke, or metabolic load between the two ergometer designs. Fatigue was shown by a mean (SEM) fall of 9.7 (0.79) W/stroke (95% confidence interval (CI) 8.0 to 11.5) between minutes 8–10 and minutes 16–18 (p<0.001). The stroke length was 53 (13) mm (95% CI 18 to 89) longer with the fixed power head (p<0.02). With fatigue, the stroke with the fixed power head lengthened at the “catch” (beginning of the stroke) by 19.5 mm (p<0.01) and shortened at the finish of the stroke by 7.2 mm (p<0.05). No significant changes in stroke length were seen with the floating power head. The mean force per stroke was 12.1% (95% CI 3.0 to 21.2) (27.3 (8.0) N) higher with the power head fixed versus floating (p<0.02).

Conclusions: It is postulated that longer stroke lengths and greater forces are risk factors for soft tissue injuries. Further research into whether floating power head rowing ergometers are associated with lower injury rates than fixed power head designs is now needed.
Blood transfusion increases radical promoting non-transferrin bound iron in preterm infants
Authors: Hirano K , Morinobu T , Kim H , Hiroi M , Ban R , Ogawa S , Ogihara H , Tamai H , Ogihara T
Published: July 2002

BACKGROUND

Blood transfusion has been recognised as a risk factor for the development of retinopathy of prematurity (ROP) or chronic lung disease (CLD) in preterm infants, but the precise mechanism involved is not understood.

AIM

To investigate the level of non-transferrin bound “free” iron, which has the potential to promote the generation of reactive oxygen species, and its redox status in the plasma of preterm infants immediately before and after blood transfusion.

METHODS

Twenty one preterm infants with a median gestational age and birth weight of 27 weeks and 1021 g respectively were prospectively enrolled in the study. Sixteen of the 21 infants developed ROP and/or CLD. The infants were transfused with concentrated red blood cells at a median age of 32 days. The plasma concentration of total bleomycin detectable iron (BDI) was measured and also the ferrous iron (Fe2+) activity by bleomycin-iron complex dependent degradation of DNA.

RESULTS

Even before blood transfusion, BDI was detectable in one third of the blood samples, and all but one sample had ferrous iron activity. After transfusion, both BDI and ferrous iron activity were significantly increased, in contrast with the situation in full term infants. Plasma ascorbic acid (AA) concentration was significantly decreased after blood transfusion, whereas the level of its oxidation product, dehydroascorbic acid (DHAA), and the DHAA/AA ratio were significantly increased compared with before the transfusion. The activity of plasma ferroxidase, which converts iron from the ferrous to the ferric state, was appreciably decreased in preterm infants, as expected from their very low plasma caeruloplasmin concentration.

CONCLUSIONS

Plasma non-transferrin bound iron was significantly increased in preterm infants after blood transfusion and existed partly in the ferrous form, because of the low ferroxidase activity and the reduction of ferric iron (Fe3+) by ascorbic acid. This finding was specific to preterm infants and was not observed in full term infants after blood transfusion. Non-transferrin bound “free” iron may catalyse the generation of reactive oxygen species, which may be responsible for the clinical association of blood transfusion with ROP and CLD.

Key messages

Plasma non-transferrin bound iron was significantly increased in preterm infants after blood transfusion and existed partly in the ferrous pro-oxidant form

The increase in plasma non-transferrin bound iron after blood transfusion was not observed in full term infants
An ethical paradox: the effect of unethical conduct on medical students' values
Authors: Satterwhite Robert C , Satterwhite William M , Enarson Cam
Published: July 2002

Objective—To report the ethical development of medical students across four years of education at one medical school.

Design and setting—A questionnaire was distributed to all four classes at the Wake Forest University School of Medicine during the Spring of 1996.

Participants—Three hundred and three students provided demographic information as well as information concerning their ethical development both as current medical students and future interns.

Main measurements—Results were analyzed using cross-tabulations, correlations, and analysis of variance.

Results—Results suggested that the observation of and participation in unethical conduct1may have disparaging effects on medical students' codes of ethics with 35% of the total sample (24% of first years rising to 55% of fourth years) stating that derogatory comments made by residents/attendings, either in the patient's presence or absence, were “sometimes” or “often” appropriate. However, approximately 70% of the sample contended that their personal code of ethics had not changed since beginning medical school and would not change as a resident.

Conclusions—Results may represent an internal struggle that detracts from the medical school experience, both as a person and as a doctor. Our goal as educators is to alter the educational environment so that acceptance of such behaviour is not considered part of becoming a physician.
Is it possible to assess the “ethics” of medical school applicants?: Table 1
Authors: Lowe Michael , Kerridge Ian , Bore Miles , Munro Don , Powis David
Published: July 2002

Questions surrounding the assessment of medical school applicants' morality are difficult but they are nevertheless important for medical schools to consider. It is probably inappropriate to attempt to assess medical school applicants' ethical knowledge, moral reasoning, or beliefs about ethical issues as these all may be developed during the process of education. Attitudes towards ethical issues and ethical sensitivity, however, might be tested in the context of testing for personality attributes. Before any “ethics” testing is introduced as part of screening for admission to medical school it would require validation. We suggest a number of ways in which this might be achieved.