bluuebunny/crossref_metadata_2025_split huggingface dataset:
ENVIRONMENTAL MODULATION OF αv, α2AND β1INTEGRIN SUBUNIT EXPRESSION IN HUMAN OESOPHAGEAL SQUAMOUS CELL CARCINOMAS
Authors: Miller Sharon E. , Veale Rob B. 
Published: September 2002

AbstractIntegrins are cell adhesion molecules pivotal in regulating normal cell behaviour. Ectopic expression of integrins, characteristic of transformed cells, is instrumental in differentiation, proliferation, apoptosis, angiogenesis, matrix degradation and migration. Oesophageal squamous cell carcinoma (SCC) has a propensity to metastasize and hence an extremely poor prognosis. It is shown here that oesophageal SCCs express αvstrongly and that normal oesophageal tissue does not express αv. This makes αva significant indicator of the transformed phenotype. α2and β1integrin subunits are down‐regulated in oesophageal SCCs compared to normal oesophagus. Dominance of the α2β1heterodimer is symptomatic of potential loss of other β1binding integrins in oesophageal SCCs. These results suggest a decrease in rigid cell adhesion possibly increasing migratory potential, whilst simultaneously permitting the adhesion and migration of SCC cells on a large repertoire of ligands due to de novo αvexpression.
Science Goals for Antarctic Infrared Telescopes
Authors: Burton Michael G. , Storey John W. V. , Ashley Michael C. B. 
Published: September 2002

AbstractOver the past few years, site-testing at the South Pole has revealed conditions that are uniquely favourable for infrared astronomy. In particular, the exceptionally low sky brightness throughout the near and mid-infrared leads to the possibility of a modest-sized telescope achieving comparable sensitivity to that of existing 8–10 metre class telescopes. An 8 metre Antarctic telescope, if constructed, would yield performance that would be unrivalled until the advent of the NGST. In this paper we review the scientific potential of infrared telescopes in Antarctica, and discuss their complementarity with existing 8–10 metre class telescopes and future proposed space telescopes. In particular, we discuss the role that a 2 metre class infrared telescope plays in future plans for the development of an observatory on the Antarctic plateau.
Total Magnitudes of Virgo Galaxies. I. Construction of a Self-Consistent Reference Dataset Spanning 8th to 18th Magnitude
Authors: Ke-shih Young Christopher 
Published: September 2002

AbstractThe main objectives of this series of papers are: (1) to demonstrate the existence of serious mutual disagreements between established total (and other integrated) magnitude scales forVirgo galaxies; (2) to attempt to quantify both the systematic and random errors present within these magnitude scales; (3) to investigate the origins of any large error uncovered; and thereby (4) to encourage the general adoption of rigorous total-magnitude measurement procedures by the astronomical community. The ramifications of the findings presented in this series of papers will be discussed in detail at a later date.In this paper, the first in the series, a self-consistent dataset of trustworthy total-magnitude measurements is compiled for a sample of Virgo galaxies spanning a range of 10 000 in apparent brightness, based on only the most reliable measurements and photometry currently available. This reference dataset, which includes luminosity profile shape information, will be used in subsequent papers as one of the bases for assessing existing magnitude scales forVirgo galaxies. As most published magnitudes are based on B–band observations, this series of papers will also focus primarily on B–bnd measurements.
Evolution of the Radio Remnant of SN 1987A: 1990-2001
Authors: Manchester R. N. , Gaensler B. M. , Wheaton V. C. , Staveley-Smith L. , Tzioumis A. K. , Bizunok N. S. , Kesteven M. J. , Reynolds J. E. 
Published: September 2002

AbstractThe development of the radio remnant of SN 1987A has been followed using the Australia Telescope Compact Array since its first detection in 1990 August. The remnant has been observed at four frequencies, 1.4, 2.4, 4.8, and 8.6 GHz, at intervals of 4–6 weeks since the first detection. These data are combined with the 843 MHz data set of Ball et al. (2001) obtained at Molonglo Observatory to study the spectral and temporal variations of the emission. These observations show that the remnant continues to increase in brightness, with a larger rate of increase at recent times. They also show that the radio spectrum is becoming flatter, with the spectral index changing from −0.97 to −0.88 over the 11 years. In addition, at roughly yearly intervals since 1992, the remnant has been imaged at 9 GHz using super-resolution techniques to obtain an effective synthesised beamwidth of about 0″.5. The imaging observations confirm the shell morphology of the radio remnant and show that it continues to expand at ˜3000 km s−1. The bright regions of radio emission seen on the limb of the shell do not appear to be related to the optical hot spots which have subsequently appeared in surrounding circumstellar material.
The Source Energy Spectrum of Cosmic Rays
Authors: Clay R. W. 
Published: September 2002

AbstractAn examination is made of the relationship between the observed energy spectrum of cosmic rays and the averaged spectrum of the cosmic rays at their sources. These spectra differ greatly, due to propagation effects. A form of the source spectrum is deduced which is a rather featureless power law over the full range of observations from 1010 eV to 1020 eV. We suggest that this lack of features is indicative of a common source for all cosmic rays over the full energy range, as opposed to lower energy Galactic and higher energy intergalactic components such as is often suggested.
The Structure of Accretion Flow at the Base of Jets in AGN
Authors: Donea Alina-C. , Biermann Peter L. 
Published: September 2002

AbstractThis paper discusses the boundary layer and the emission spectrum from an accretion disk having a jet anchored at its inner radius, close to the black hole. We summarise our earlier work and apply it to the accretion disks of some blazars. We suggest that the ‘accretion disk with jet’ (ADJ) model could make the bridge between standard accretion disk models (suitable for quasars and FRiisources) and low-power advection dominated accretion disk models (suitable for some of the low-power BL Lacs and FRisources).The jet is collimated within a very narrow region close to the black hole (nozzle). In our model it is assumed that the boundary layer of the disk is the region between radius Rms— the last marginally stable circular orbit calculated for a Kerr geometry — and the radius Rjet, which gives the thickness of the ‘footring’, i.e. the base of the jet. We analyse the size of the boundary layer of the disk where the jet is fed with energy, mass, and angular momentum. As a consequence of the angular momentum extraction, the accretion disk beyond Rjetno longer has a Keplerian flow. A hot corona usually surrounds the disk, and entrainment of the corona along the flow could also be important for the energy and mass budget of the jet.We assume that the gravitational energy available at the footring of the jet goes into the jet, and so the spectrum from the accretion disk gives a total luminosity smaller than that of a ‘standard’ accretion disk, and our ADJ model should apply for blazars with low central luminosities. Variations of the boundary layer and nozzle may account for some of the variability observed in active galactic nuclei.
AGN Variability from the USNO Radio Reference Frame Image Database
Authors: Fey Alan L. 
Published: September 2002

AbstractWe present results from preliminary analysis of radio interferometric data taken from the US Naval Observatory Radio Reference Frame Image Database. The results presented here reveal valuable insight into the structural variability of the two extragalactic radio sources 0552+398 and 1308+326. We are actively pursuing analysis of additional objects.
Near Infrared Micro-variability of Radio-loud Quasars
Authors: Whiting Matthew , Oshlack Alicia , Webster Rachel 
Published: September 2002

AbstractWe observed three AGN from the Parkes Half-Jansky Flat-spectrum Sample at near infrared (NIR) wavelengths to search for micro-variability. In one source, the blue quasar PKS 2243–123, good evidence for NIR micro-variability was found. In the other two sources, PKS 2240–260 and PKS 2233–148, both BL Lacertae objects, no such evidence of variability was detected. We discuss the implications of these observations for the various mechanisms that have been proposed for micro-variability.
Intraday Optical Variability of S5 0716+714
Authors: Nesci Roberto , Massaro Enrico , Montagni Franco 
Published: September 2002

AbstractWe present an optical intraday variability (IDV) study of S5 0716+714 carried out over 52 nights. The source showed detectable variations (>0.05 mag) in 80% of the nights. Typical variation rates of 0.02 mag/hour have been found to last on average 4 hours, with the average rising rate faster than the decreasing one. A maximum rising rate of 0.16 mag/hour has been observed. If the luminosity variation is due to jittering in the jet direction, a comoving dθ/dt rate of ∼100 arcsec/hour is required, assuming for the jet θ ∼ 7° and Γ ∼ 14.
The 2001 Australian Galaxy Cluster Workshop
Authors: Drinkwater Michael J. 
Published: September 2002

AbstractThe first ‘Australian Cluster Workshop’ was held at the Australia Telescope National Facility in Sydney on 2001 February 6. The aim of the workshop was to bring together the many and varied groups working on clusters of galaxies in Australia, to forge new multi-disciplinary links, and to generate enthusiasm and support for new cluster work and further cluster meetings in Australia. In this paper I present a summary of the workshop as well as some additional review material intended to place current Australian research in a broader perspective, looking ahead to the major issues still to be addressed.
Variability of Water Megamasers in AGN
Authors: Maloney Philip 
Published: September 2002

AbstractPowerful water masers have been detected in 23 active galactic nuclei (AGN) to date. Most of the sources that have been monitored show evidence for variability, which may be either intrinsic (response of the masers to a time-varying pump or background source) or extrinsic (the effects of scintillation in the interstellar medium of the Galaxy). I briefly review the examples in which these mechanisms may be operating (interstellar scintillation in the Circinus galaxy, a time-varying background source in Mrk 348, and a time-varying AGN luminosity in NGC 1068).
The Parsec-scale Jets of Extragalactic TeV Gamma-ray Sources
Authors: Piner B. G. , Edwards P. G. , Fodor S. , Rector T. A. 
Published: September 2002

AbstractWe present results of VLBI monitoring observations of the blazars detected by ground-based TeV gamma-ray telescopes. Preliminary results have shown that the apparent speeds of the parsec-scale jet features in these sources are predominantly subluminal, and significantly slower than those in the GeV-peaked (EGRET) gamma-ray blazars. Here we add results from additional sources and additional epochs that increase the statistical significance of this comparison. These slower speeds may indicate rapid deceleration of the jets in TeV blazars between the TeV gamma-ray emitting scales and VLBI scales.
Interstellar Scintillation Explains the Intraday Variations in the Linear Polarisation of Quasar PKS 0405-385 at cm-wavelengths
Authors: Rickett Barney , Kedziora-Chudczer Lucyna , Jauncey David L. 
Published: September 2002

AbstractDuring its burst of intraday variation (IDV) in June 1996 quasar PKS 0405–385 exhibited rapid changes in the Stokes parameters Q and U that were even faster than the 1 hr timescale changes in I. Auto- and cross-correlation analyses of I,Q, and U at 8.6 GHz show systematic relations between the variations in I,Q, and U. These are well modelled by interstellar scintillation (ISS) of a 14 × 20 μ as source, with about 180 degree rotation of the polarisation angle along its long dimension. This success in explaining the remarkable IDV in polarisation confirms that ISS gives rise to the IDV in this quasar.
Molecular Hydrogen in the Lagoon: H2 Line Emission from Messier 8
Authors: Burton Michael G. 
Published: September 2002

AbstractThe 2.12 μm v = 1−0 S(1) line of molecular hydrogen has been imaged in the Hourglass region of M8. The line is emitted from a roughly bipolar region, centred around the O7 star Herschel 36. The peak H2 1−0 S(1) line intensity is 8.2 × 10−15 erg s−1 cm−2arcsec−2. The line centre emission velocity varies from −25 kms−1 in the SE lobe to +45 kms−1 in the NW lobe. The distribution is similar to that of the CO J = 3−2 line. The H2 line appears to be shock-excited when a bipolar outflow from Herschel 36 interacts with the ambient molecular cloud. The total luminosity of all H2 lines is estimated to be ˜16 L⊙ and the mass of the hot molecular gas ˜9 × 10−4 M⊙ (without any correction for extinction).
AAT/WFI Observations of the Extragalactic HI Cloud HIPASS J1712-64
Authors: Lewis Geraint F. , Irwin Michael J. , Ibata Rodrigo A. , Gibson Brad K. 
Published: September 2002

AbstractAAT/WFI optical images of a candidate extragalactic HI cloud, HIPASS J1712–64, are presented. The g and r band CCD mosaic camera frames were processed using a new data pipeline recently installed at the AAO. The resultant stacked images reach significantly deeper levels than those of previous published optical imaging of this candidate, providing a detection limit Mg ˜ −7 at a distance of 3 Mpc, the inferred distance to HIPASS J1712–64. However, detailed analysis of the images fails to uncover any stellar population associated with the HI emission. If this system is a member of the Local Group then it is pathologically different to other members. Hence, our observations reinforce earlier suggestions that this HI cloud is most likely Galactic in origin and not a Local Volume dwarf galaxy.
Multidrug Pump Inhibitors Uncover Remarkable Activity of Plant Antimicrobials
Authors: Tegos George , Stermitz Frank R. , Lomovskaya Olga , Lewis Kim 
Published: September 2002

ABSTRACT

Plant antimicrobials are not used as systemic antibiotics at present. The main reason for this is their low level of activity, especially against gram-negative bacteria. The reported MIC is often in the range of 100 to 1,000 μg/ml, orders of magnitude higher than those of common broad-spectrum antibiotics from bacteria or fungi. Major plant pathogens belong to the gram-negative bacteria, which makes the low level of activity of plant antimicrobials against this group of microorganisms puzzling. Gram-negative bacteria have an effective permeability barrier, comprised of the outer membrane, which restricts the penetration of amphipathic compounds, and multidrug resistance pumps (MDRs), which extrude toxins across this barrier. It is possible that the apparent ineffectiveness of plant antimicrobials is largely due to the permeability barrier. We tested this hypothesis in the present study by applying a combination of MDR mutants and MDR inhibitors. A panel of plant antimicrobials was tested by using a set of bacteria representing the main groups of plant pathogens. The human pathogens
Pseudomonas aeruginosa
,
Escherichia coli
, and
Salmonella enterica
serovar Typhimurium were also tested. The results show that the activities of the majority of plant antimicrobials were considerably greater against the gram-positive bacteria
Staphylococcus aureus
and
Bacillus megaterium
and that disabling of the MDRs in gram-negative species leads to a striking increase in antimicrobial activity. Thus, the activity of rhein, the principal antimicrobial from rhubarb, was potentiated 100- to 2,000-fold (depending on the bacterial species) by disabling the MDRs. Comparable potentiation of activity was observed with plumbagin, resveratrol, gossypol, coumestrol, and berberine. Direct measurement of the uptake of berberine, a model plant antimicrobial, confirmed that disabling of the MDRs strongly increases the level of penetration of berberine into the cells of gram-negative bacteria. These results suggest that plants might have developed means of delivering their antimicrobials into bacterial cells. These findings also suggest that plant antimicrobials might be developed into effective, broad-spectrum antibiotics in combination with inhibitors of MDRs.
Mutations in 23S rRNA Account for Intrinsic Resistance to Macrolides in
Mycoplasma hominis
and
Mycoplasma fermentans
and for Acquired Resistance to Macrolides in
M. hominis
Authors: Pereyre S. , Gonzalez P. , de Barbeyrac B. , Darnige A. , Renaudin H. , Charron A. , Raherison S. , Bébéar C. , Bébéar C. M. 
Published: September 2002

ABSTRACT

The mechanisms of intrinsic resistance of
Mycoplasma hominis
to 14- and 15-membered macrolides were investigated in comparison with those of
M. pneumoniae
, which is naturally susceptible to macrolides. Radiolabeled erythromycin was not accumulated by
M. hominis
PG21, but addition of an ABC transporter inhibitor increased the level of erythromycin uptake more than two times, suggesting the existence of an active efflux process. The affinity of [
14
C]erythromycin to ribosomes isolated from
M. hominis
was dramatically reduced relative to that to ribosomes isolated from
M. pneumoniae.
The nucleotide sequences of 23S rRNA of both ribosomal operons
rrnA
and
rrnB
and ribosomal proteins L4 and L22 of
M. hominis
were obtained. Compared to the sequence of
M. pneumoniae
,
M. hominis
harbored a G2057A transition in its 23S rRNA sequence, as did
M. fermentans
, another mycoplasma that is erythromycin resistant. An additional C2610U change was also found in the sequence of
M. hominis
. Moreover, two
M. hominis
clinical isolates with acquired resistance to 16-membered macrolides were examined for mutations in domain II and domain V of 23S rRNA and in ribosomal proteins L4 and L22. Compared to the sequence of reference strain PG21, one isolate harbored a A2059G transition and a C2611U transition in one of the two
rrn
operons, while the other one was mutated only at position 2059, also on the same operon. No mutation was found in the two ribosomal protein sequences. Overall, the present study is an exhaustive characterization of the intrinsic resistance of
M. hominis
to 14- and 15-membered macrolides and the first description of mycoplasma clinical isolates resistant to macrolide, lincosamide, and streptogramin antibiotics harboring a mutation at position 2611 in the 23S rRNA.
Bactericidal Activity of Rifampin-Amikacin against
Mycobacterium ulcerans
in Mice
Authors: Dega Herve , Bentoucha Abdelhalim , Robert Jerome , Jarlier Vincent , Grosset Jacques 
Published: September 2002

ABSTRACT

To identify the most active curative treatment of Buruli ulcer, two regimens incorporating the use of rifampin (RIF) were compared with the use of RIF alone in a mouse footpad model of
Mycobacterium ulcerans
infection. Treatments began after footpad swelling from infection and continued for 12 weeks with five doses weekly of one of the following regimens: (i) 10 mg of RIF/kg alone; (ii) 10 mg of RIF/kg and 100 mg of amikacin (AMK)/kg; and (iii) 10 mg of RIF/kg, 100 mg of clarithromycin (CLR)/kg, and 50 mg of sparfloxacin (SPX)/kg. The activity of each regimen was assessed in terms of the reduction of the average lesion index and acid-fast bacillus (AFB) and CFU counts. All three regimens displayed various degrees of bactericidal activity against
M. ulcerans
. The ranking of bactericidal activity was found to be as follows: RIF-AMK > RIF-CLR-SPX > RIF. RIF-AMK was able to cure
M. ulcerans
-infected mice and prevent relapse 26 weeks after completion of treatment. To determine the impact of different rhythms of administration of RIF-AMK on the suppression of
M.ulcerans
growth, mice were given the RIF-AMK combination for 4 weeks but doses were administered either 5 days a week or twice or once weekly. After completion of treatment, the mice were kept under supervision for 30 additional weeks.
M. ulcerans
was considered to have grown in the footpad if swelling was visually observed and harvests contained more than 5 × 10
5
AFB per footpad. The proportion of mice in which growth of
M. ulcerans
occurred, irrespective of drug dosage, was compared with the control mice to determine the proportion of
M. ulcerans
killed. Each dosage of RIF-AMK was bactericidal for
M. ulcerans
(
P
< 0.001), but the effect was significantly stronger in mice treated 5 days per week. The promising results of RIF-AMK treatment in
M. ulcerans
-infected mice support the clinical trial that is currently in progress under World Health Organization auspices in Ghana.
Biochemical-Genetic Analysis and Distribution of DES-1, an Ambler Class A Extended-Spectrum β-Lactamase from
Desulfovibrio desulfuricans
Authors: Morin Anne-Sophie , Poirel Laurent , Mory Francine , Labia Roger , Nordmann Patrice 
Published: September 2002

ABSTRACT

Desulfovibrio
spp. are gram-negative anaerobes phylogenetically related to
Bacteroides
spp., which are rarely isolated and which are mostly isolated from intra-abdominal abscesses.
Desulfovibrio desulfuricans
clinical isolate D3 had a clavulanic acid-inhibited β-lactam resistance profile and was resistant to some expanded-spectrum cephalosporins. A β-lactamase gene,
bla
DES-1
, was cloned from whole-cell DNA of isolate D3 and expressed in
Escherichia coli
. Purified β-lactamase DES-1, with a pI value of 9.1, had a relative molecular mass of ca. 31 kDa and a mature protein of 288 amino acids. DES-1 was distantly related to Ambler class A β-lactamases and most closely related to PenA from
Burkholderia pseudomallei
(48% amino acid identity). It was weakly related to class A β-lactamases CblA, CepA, CfxA, and CfxA2 from other anaerobic species,
Bacteroides
spp. and
Prevotella intermedia
. Its hydrolysis spectrum included amino- and ureidopenicillins, narrow-spectrum cephalosporins, ceftriaxone, and cefoperazone.
bla
DES-1
-like genes were not identified in phylogenetically related
Desulfovibrio fairfieldensis
isolates. However, they were found in some but not all
D. desulfuricans
strains, thus suggesting that these genes may be present in a given
D. desulfuricans
subspecies.
Intracellular Accumulation of Human Immunodeficiency Virus Protease Inhibitors
Authors: Khoo Saye H. , Hoggard Patrick G. , Williams Ian , Meaden E. Rhiannon , Newton Philippa , Wilkins Edmund G. , Smith Alan , Tjia John F. , Lloyd Judy , Jones Kevin , Beeching Nick , Carey Peter , Peters Barry , Back David J. 
Published: September 2002

ABSTRACT

Intracellular accumulation of the protease inhibitors (PIs) saquinavir (SQV), ritonavir (RTV), and indinavir (IDV) was determined in 50 human immunodeficiency virus-positive patients. Following extraction, PIs were quantified by mass spectrometry. Paired plasma and intracellular samples were collected over a full dosing interval from patients (13 on SQV, 6 on RTV, 8 on IDV, 16 on SQV plus RTV, 7 on IDV plus RTV) with a plasma viral load of <400 copies/ml. Data were expressed as intracellular/plasma drug concentration ratios. A hierarchy of intracellular accumulation was demonstrated by the following medians: 9.45 for SQV > 1.00 for RTV > 0.51 for IDV. Coadministration of RTV did not boost ratios of SQV or IDV within the cell or in plasma, although absolute plasma and intracellular SQV concentrations were increased by RTV. Seven individuals receiving SQV in hard-gel capsule form (median, 32 months) had higher intracellular/plasma drug ratios than all other patients receiving SQV (median, 17.62 versus 4.83;
P
= 0.04), despite consistently low plasma SQV concentrations. How this occurs may provide insight into the mechanisms that limit adequate drug penetration into sanctuary sites.