bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pollen Germinates Precociously in the Anthers of raring-to-go, an Arabidopsis Gametophytic Mutant
Authors: Johnson Sheila A. , McCormick Sheila 
Published: July 2002

Abstract
Pollen hydration is usually tightly regulated and occurs in vivo only when desiccated pollen grains acquire water from the female, thus enabling pollen tube growth. Pollen tubes are easily visualized by staining with decolorized aniline blue, a stain specific for callose. We identified a mutant, raring-to-go, in which pollen grains stained for callose before anther dehiscence. Whenraring-to-go plants are transferred to high humidity, pollen tubes dramatically elongate within the anther. As early as the bicellular stage, affected pollen grains in raring-to-goplants acquire or retain water within the anther, and precociously germinate. Thus, the requirement for contact with the female is circumvented. We used pollen tetrad analysis to show thatraring-to-go is a gametophytic mutation, to our knowledge the first gametophytic mutation in Arabidopsis that affects early events in the pollination pathway. To aid in identifyingraring-to-go alleles, we devised a new technique for screening pollen in bulk with decolorized aniline blue. We screened a new M1 mutagenized population and identified several additional mutants with a raring-to-go-like phenotype, demonstrating the usefulness of this technique. Further, we isolated other mutants (gift-wrapped pollen, polka dot pollen, and emotionally fragile pollen) with unexpected patterns of callose staining. We suggest thatraring-to-go and these other mutants may help dissect components of the pathway that regulates pollen hydration and pollen tube growth.
Expression and Chloroplast Targeting of Cholesterol Oxidase in Transgenic Tobacco Plants
Authors: Corbin David R. , Grebenok Robert J. , Ohnmeiss Thomas E. , Greenplate John T. , Purcell John P. 
Published: July 2002

Abstract
Cholesterol oxidase represents a novel type of insecticidal protein with potent activity against the cotton boll weevil (Anthonomus grandis grandis Boheman). We transformed tobacco (Nicotiana tabacum) plants with the cholesterol oxidasechoM gene and expressed cytosolic and chloroplast-targeted versions of the ChoM protein. Transgenic leaf tissues expressing cholesterol oxidase exerted insecticidal activity against boll weevil larvae. Our results indicate that cholesterol oxidase can metabolize phytosterols in vivo when produced cytosolically or when targeted to chloroplasts. The transgenic plants exhibiting cytosolic expression accumulated low levels of saturated sterols known as stanols, and displayed severe developmental aberrations. In contrast, the transgenic plants expressing chloroplast-targeted cholesterol oxidase maintained a greater accumulation of stanols, and appeared phenotypically and developmentally normal. These results are discussed within the context of plant sterol distribution and metabolism.
Magnetization transfer from laser‐polarized xenon to protons located in the hydrophobic cavity of the wheat nonspecific lipid transfer protein
Authors: Landon Céline , Berthault Patrick , Vovelle Françoise , Desvaux Hervé 
Published: July 2002

AbstractNonspecific lipid transfer protein from wheat is studied by liquid‐state NMR in the presence of xenon. The gas–protein interaction is indicated by the dependence of the protein proton chemical shifts on the xenon pressure and formally confirmed by the first observation of magnetization transfer from laser‐polarized xenon to the protein protons. Twenty‐six heteronuclear nOes have allowed the characterization of four interaction sites inside the wheat ns‐LTP cavity. Their locations are in agreement with the variations of the chemical shifts under xenon pressure and with solvation simulations. The richness of the information obtained by the noble gas with a nuclear polarization multiplied by ∼12,000 makes this approach based on dipolar cross‐relaxation with laser‐polarized xenon promising for probing protein hydrophobic pockets at ambient pressure.
Aerodynamic Response of Turbomachinery Blade Rows to Convecting Density Wakes
Authors: Wijesinghe H. S. , Tan C. S. , Covert E. E. 
Published: July 2002

AbstractA two-dimensional computational study was conducted to characterize the density wake induced force and moment fluctuations on a compressor blade row. The flow simulations indicate unsteady blade excitation generated by: (1) density wake fluid directed to the blade suction surface, (2) axial deflection of the blade passage shock wave position and (3) formation of a separation bubble on the blade suction surface. The blade force and moment fluctuation amplitudes are found to scale with the nondimensional density wake width w/c and a nondimensional density parameter ρ*.
Compressor Discharge Brush Seal for Gas Turbine Model 7EA
Authors: Ingistov Steve 
Published: July 2002

AbstractSingle-shaft, heavy-duty industrial gas turbines are extremely sensitive to compressed air bypassing at compressor discharge plane. This plane represents the highest pressure location in entire gas turbine unit (GTU). Standard method to minimize compressed air leakage is labyrinth seal that is integral part of the cylindrical element here called "inner barrel." The inner barrel is also the part of compressor discharge diffuser. This paper describes the efforts related to conversion of standard labyrinth seal into the hybrid seal that is combination of labyrinth and brush seals.
Desorption studies of hydrogen and carbon monoxide from nickel surfaces using thermal desorption spectroscopy
Authors: Cabrera A. L. 
Published: July 2002

The adsorption of hydrogen and carbon monoxide at room temperature on nickel samples was studied with thermal desorption spectroscopy. Desorption from nickel foil was studied using a mass spectrometric method in an ultrahigh vacuum system, while desorption from nickel powder was studied with a microreactor system using a thermal conductivity detector. Two hydrogen desorption peaks are observed at low heating rates (less than 3 K/s). These peaks correspond to the β1 and β2 states observed in single crystals studies. An activation energy of 7–10 kcal/mol is obtained for the low temperature peak (β1 state), assuming first order kinetics, while an energy of 28–30 kcal/mol is obtained for the higher temperature peak (β2 state) with second order kinetics. Desorption spectra using the two different experimental methods are very similar, and the kinetic data derived from the spectra agree well.
When the heating rate is high (larger than 12 K/s) only one hydrogen desorption peak is observed, indicating that experimental resolution decreases for very fast heating rates. Kinetic analysis of this spectra yields an activation energy similar to the β2 state. The two H2 desorption features (β1 and β2) obtained for Ni powder and foil agree well with previously reported studies on Ni single crystals, indicating that the presence of the two desorption states is insensitive to surface structure. The activation energy and order of the desorption for the β2 state obtained in this work is in general agreement with values reported for single crystals studies. The activation energy and order for the β1 state is in agreement with some studies performed with Ni single crystals, largely due to the assumption in prior work that desorption proceeds as a second order process for this state. Three carbon monoxide desorption peaks are observed for low heating rates (less than 3 K/s). Presumably, the two low temperature peaks which are associated with adsorbed molecular CO correspond to on-top and bridge site adsorption. The activation energy for the weakest bonding (on-top site/dominant peak) was obtained and corresponded to 6–10 kcal/mol. The activation energy for dissociated CO (high temperature peak) corresponded to 30–36 kcal/mol. Our ability to resolve the two types of adsorbed molecular CO is lost when very fast heating rates are used (12 K/s).
Excretion of β-Lactam Antibiotics in Sweat—a Neglected Mechanism for Development of Antibiotic Resistance?
Authors: Høiby Niels , Pers Charlotte , Johansen Helle Krogh , Hansen Hanne ,   The Copenhagen Study Group on Antibiotics in Sweat
Published: July 2002

ABSTRACT
The concentrations of β-lactam antibiotics after standard doses were measured in blood and apocrine (axilla) and eccrine (forearm) sweat from six adult healthy persons. All persons had ceftazidime (axilla, 28.4 μg/ml; forearm, 11 μg/ml) and ceftriaxone (axilla, 8.9 μg/ml; forearm, 2.5 μg/ml) in sweat, and one person had cefuroxime in sweat (axilla, 7.8 μg/ml) (all data are mean peaks). Three persons had benzylpenicillin (axilla, 2.6 to 0.1 μg/ml) and one had phenoxymethylpenicillin (axilla, 0.4 μg/ml) in sweat. Excretion of β-lactam antibiotics in the sweat may explain why staphylococci so rapidly become resistant to these drugs.
Intracellular Penetration and Activity of Gemifloxacin in Human Polymorphonuclear Leukocytes
Authors: García Isabel , Pascual Alvaro , Ballesta Sofía , Joyanes Providencia , Perea Evelio J. 
Published: July 2002

ABSTRACTThe intracellular penetration and activity of gemifloxacin in human polymorphonuclear leukocytes (PMN) were evaluated. Gemifloxacin reached intracellular concentrations eight times higher than extracellular concentrations. The uptake was rapid, reversible, and nonsaturable and was affected by environmental temperature, cell viability, and membrane stimuli. At therapeutic extracellular concentrations, gemifloxacin showed intracellular activity againstStaphylococcus aureus.
Efficacy of Telithromycin (HMR 3647) against Enterococci in a Mouse Peritonitis Model
Authors: Singh Kavindra V. , Zscheck Karen K. , Murray Barbara E. 
Published: July 2002

ABSTRACT

We used a mouse peritonitis model to evaluate the in vivo efficacy of telithromycin (HMR 3647) (TEL) and erythromycin (ERY) against four strains of
Enterococcus faecalis
and three strains of
Enterococcus faecium
with differing susceptibilities to TEL. TEL was highly active in vivo against Ery-susceptible (Ery
s
) and -intermediate (Ery
i
) strains (MIC of TEL = 0.015 to 0.062 μg/ml) and showed less efficacy against Ery-resistant (Ery
r
) isolates (MIC of TEL = 4 to 16 μg/ml), although this was overcome in part by a second subcutaneous dose. Quinupristin-dalfopristin was also noted to have less efficacy against Ery
r
versus Ery
s
or Ery
i
E. faecium
strains, but this difference was reduced by intravenous administration. In conclusion, TEL was more potent in vivo against enterococci than was ERY; its activity was lowered by the presence of
erm
(B)-mediated Ery
r
.
Genotypic and Phenotypic Resistance Patterns of Human Immunodeficiency Virus Type 1 Variants with Insertions or Deletions in the Reverse Transcriptase (RT): Multicenter Study of Patients Treated with RT Inhibitors
Authors: Masquelier Bernard , Race Esther , Tamalet Catherine , Descamps Diane , Izopet Jacques , Buffet-Janvresse Claudine , Ruffault Annick , Mohammed Ali Si , Cottalorda Jacqueline , Schmuck Anne , Calvez Vincent , Dam Elisabeth , Fleury Hervé , Brun-Vézinet Françoise ,   the ANRS AC11 Resistance Study Group
Published: July 2002

ABSTRACTGenomic rearrangements in the 5′ part of the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) have been involved in multidrug resistance to nucleoside RT inhibitors (NRTI). We carried out a retrospective, multicenter study to investigate the prevalence, variability, and phenotypic consequences of such rearrangements. Data concerning the HIV-1 RT genotype and the biological and clinical characteristics of NRTI-treated patients were collected from 10 virology laboratories. Sensitivities of the different HIV-1 variants to RT inhibitors were analyzed in a single-cycle recombinant virus assay. Fifty-two of 2,152 (2.4%) RT sequences had a rearrangement in the 5′ part of the RT, with an extensive molecular variation. The number of codons inserted between positions 68 and 69 ranged from 1 (3 samples) or 2 (41 samples) to 5 and 11 in one case each. In four cases, codon 67 was deleted. High levels of phenotypic resistance to zidovudine (AZT), lamivudine (3TC), stavudine (d4T), abacavir (ABC), and didanosine (ddI) were found in 95, 92, 72, 62, and 15% of the 40 samples analyzed, respectively. Resistance to AZT, d4T, and ABC could be found in the absence of the T215Y/F mutations. Resistance to 3TC could develop in the absence of specific mutations. Low-level resistance to ddI was noticed in 40% of the patients. The deletions of codon 67 seemed to have little effect on NRTI sensitivity. Most of the rearrangements were shown to contribute to cross-resistance to NRTI. The results regarding susceptibility to ddI raise the question of the interpretation of the phenotypic data concerning this drug.
In Vitro Antibiotic Susceptibilities of
Burkholderia mallei
(Causative Agent of Glanders) Determined by Broth Microdilution and E-Test
Authors: Heine Henry S. , England Marilyn J. , Waag David M. , Byrne W. Russell 
Published: July 2002

ABSTRACT

In vitro susceptibilities to 28 antibiotics were determined for 11 strains of
Burkholderia mallei
by the broth microdilution method. The
B. mallei
strains demonstrated susceptibility to aminoglycosides, macrolides, quinolones, doxycycline, piperacillin, ceftazidime, and imipenem. For comparison and evaluation, 17 antibiotic susceptibilities were also determined by the E-test. E-test values were always lower than the broth dilution values. Establishing and comparing antibiotic susceptibilities of specific
B. mallei
strains will provide reference information for assessing new antibiotic agents.
Identification and Minisequencing-Based Discrimination of SHV β-Lactamases in Nosocomial Infection-AssociatedKlebsiella pneumoniaein Brisbane, Australia
Authors: Howard Christopher , van Daal Angela , Kelly Gregory , Schooneveldt Jacqueline , Nimmo Graeme , Giffard Philip M. 
Published: July 2002

ABSTRACTExtended-spectrum β-lactamases (ESBLs) are active against oxyimino cephalosporins and monobactams. Twenty-oneKlebsiella pneumoniaeisolates obtained between 1991 and 1995 at the Princess Alexandra Hospital in Brisbane, Australia, were subject to amplification and sequencing of the SHV β-lactamase-encoding genes. Thirteen strains were phenotypically ESBL positive. Of these, six strains carried theblaSHV-2agene and seven strains carried theblaSHV-12gene. Eight strains were phenotypically ESBL negative. Of these, seven strains carried the non-ESBLblaSHV-11gene and one strain carried the non-ESBLblaSHV-1gene. There was complete correspondence between the ESBL phenotype and the presence or absence of an ESBL-encoding gene(s). In addition, it was determined that of the 13 ESBL-positive strains, at least 4 carried copies of a non-ESBL-encoding gene in addition to theblaSHV-2aorblaSHV12gene. A minisequencing-based assay was developed to discriminate the different SHV classes. This technique, termed “first-nucleotide change,” involves the identification of the base added to a primer in a single-nucleotide extension reaction. The assay targeted polymorphisms at the first bases of codons 238 and 240 and reliably discriminated ESBL-positive strains from ESBL-negative strains and also distinguished strains carryingblaSHV-2afrom strains carryingblaSHV-12. In addition, this method was used to demonstrate an association between the relative copy numbers ofblaSHVgenes in individual strains and the levels of antibiotic resistance.
Pharmacodynamic Activity and Efficacy of Linezolid in a Rat Model of Pneumococcal Pneumonia
Authors: Gentry-Nielsen Martha J. , Olsen Keith M. , Preheim Laurel C. 
Published: July 2002

ABSTRACT

Linezolid is a new oxazolidinone antibiotic with potent activity against gram-positive bacteria, including
Streptococcus pneumoniae
. The pharmacodynamic activity and in vivo efficacy of linezolid were compared to those of ceftriaxone in an immunocompetent rat model of pneumococcal pneumonia. Rats infected intratracheally with 8 × 10
7
CFU of a penicillin-sensitive (MIC, 0.032 μg/ml) strain of
S. pneumoniae
were treated for 5 days beginning 18 h postinfection. Groups of rats were sham treated with oral phosphate-buffered saline or received oral liquid linezolid at 25 or 50 mg/kg of body weight twice a day (b.i.d.) or subcutaneous ceftriaxone at 100 mg/kg once daily. Mortality was monitored for 10 days postinfection; blood culturing was performed on day 1 (pretreatment) and on days 3, 5, and 10 postinfection for the determination of bacteremia. Serum also was collected for the determination of pharmacokinetic and pharmacodynamic parameters at 30 min and at 3, 5, and 12 h (linezolid) or 3, 5, and 24 h (ceftriaxone) postdose. The cumulative mortality rates were 100% for the sham-treated group, 58.3% for the low-dose linezolid group, 8.3% for the high-dose linezolid group, and 0% for the ceftriaxone group. Rats in each of the antibiotic treatment groups had significantly fewer bacteria (
P
< 0.00001) in their bronchoalveolar lavage fluid (BALF) on day 3 postinfection than sham-treated rats. There also were significantly fewer organisms in the BALF of rats treated with ceftriaxone than in the BALF of rats treated with either dose of linezolid. Oral linezolid at 50 mg/kg b.i.d. therefore was as effective as ceftriaxone in experimental pneumococcal pneumonia, whereas the 25-mg/kg b.i.d. dose was significantly less effective. All pharmacodynamic parameters reflected efficacy and were significantly different for the two dosage regimens of linezolid (
P
< 0.01). However, the free-fraction pharmacodynamic parameters predictive of outcome were a value of >39% for the percentage of time in the experimental dosing interval during which the linezolid concentration exceeded the MIC and a value of >147 for the ratio of the area under the serum concentration-time curve to the MIC.
PCR Detection of
Salmonella enterica
Serotype Montevideo in and on Raw Tomatoes Using Primers Derived from
hilA
Authors: Guo Xuan , Chen Jinru , Beuchat Larry R. , Brackett Robert E. 
Published: July 2002

ABSTRACT

Salmonellae have been some of the most frequently reported etiological agents in fresh-produce-associated outbreaks of human infections in recent years. PCR assays using four innovative pairs of primers derived from
hilA
and
sirA
, positive regulators of
Salmonella
invasive genes, were developed to identify
Salmonella enterica
serotype Montevideo on and in tomatoes. Based on examination of 83
Salmonella
strains and 22 non-
Salmonella
strains, we concluded that a pair of
hilA
primers detects
Salmonella
specifically. The detection limits of the PCR assay were 10
1
and 10
0
CFU/ml after enrichment at 37°C for 6 and 9 h, respectively. When the assay was validated by detecting
S. enterica
serotype Montevideo in and on artificially inoculated tomatoes, 10
2
and 10
1
CFU/g were detected, respectively, after enrichment for 6 h at 37°C. Our results suggest that the
hilA
-based PCR assay is sensitive and specific, and can be used for rapid detection of Salmonellae in or on fresh produce.
Uptake and Active Efflux of Polycyclic Aromatic Hydrocarbons by
Pseudomonas fluorescens
LP6a
Authors: Bugg Trevor , Foght Julia M. , Pickard Michael A , Gray Murray R. 
Published: July 2002

ABSTRACT

The mechanism of transport of polycyclic aromatic hydrocarbons (PAHs) by
Pseudomonas fluorescens
LP6a, a PAH-degrading bacterium, was studied by inhibiting membrane transport and measuring the resulting change in cellular uptake. Three cultures were used: wild-type LP6a which carried a plasmid for PAH degradation, a transposon mutant lacking the first enzyme in the pathway for PAH degradation, and a cured strain without the plasmid. Washed cells were mixed with aqueous solutions of radiolabelled PAH; then the cells were removed by centrifugation, and the concentrations of PAH in the supernatant and the cell pellet were measured. The change in the pellet and supernatant concentrations after inhibitors of membrane transport (azide, cyanide, or carbonyl cyanide
m
-chlorophenyl hydrazone) were added indicated the role of active transport. The data were consistent with the presence of two conflicting transport mechanisms: uptake by passive diffusion and an energy-driven efflux system to transport PAHs out of the cell. The efflux mechanism was chromosomally encoded. Under the test conditions used, neither uptake nor efflux of phenanthrene by
P. fluorescens
LP6a was saturated. The efflux mechanism showed selectivity since phenanthrene, anthracene, and fluoranthene were transported out of the cell but naphthalene was not.
Cloning, Nucleotide Sequence, and Expression of the Gene Encoding the Bacteriocin Boticin B from
Clostridium botulinum
Strain 213B
Authors: Dineen Sean S. , Bradshaw Marite , Johnson Eric A. 
Published: July 2002

ABSTRACT

Boticin B is a heat-stable bacteriocin produced by
Clostridium botulinum
strain 213B that has inhibitory activity against various strains of
C. botulinum
and related clostridia. The gene encoding the bacteriocin was localized to a 3.0-kb
Hin
dIII fragment of an 18.8-kb plasmid, cloned, and sequenced. DNA sequencing revealed the boticin B structural gene,
btcB
, to be an open reading frame encoding 50 amino acids. A
C. botulinum
strain 62A transconjugant containing the
Hin
dIII fragment inserted into a clostridial shuttle vector expressed boticin B, although at much lower levels than those observed in
C. botulinum
213B. To our knowledge, this is the first demonstration and characterization of a bacteriocin from toxigenic group I
C. botulinum
.
Ferrous Iron-Dependent Volatilization of Mercury by the Plasma Membrane of
Thiobacillus ferrooxidans
Authors: Iwahori Kenji , Takeuchi Fumiaki , Kamimura Kazuo , Sugio Tsuyoshi 
Published: July 2002

ABSTRACT

Of 100 strains of iron-oxidizing bacteria isolated,
Thiobacillus ferrooxidans
SUG 2-2 was the most resistant to mercury toxicity and could grow in an Fe
2+
medium (pH 2.5) supplemented with 6 μM Hg
2+
. In contrast,
T. ferrooxidans
AP19-3, a mercury-sensitive
T. ferrooxidans
strain, could not grow with 0.7 μM Hg
2+
. When incubated for 3 h in a salt solution (pH 2.5) with 0.7 μM Hg
2+
, resting cells of resistant and sensitive strains volatilized approximately 20 and 1.7%, respectively, of the total mercury added. The amount of mercury volatilized by resistant cells, but not by sensitive cells, increased to 62% when Fe
2+
was added. The optimum pH and temperature for mercury volatilization activity were 2.3 and 30°C, respectively. Sodium cyanide, sodium molybdate, sodium tungstate, and silver nitrate strongly inhibited the Fe
2+
-dependent mercury volatilization activity of
T. ferrooxidans
. When incubated in a salt solution (pH 3.8) with 0.7 μM Hg
2+
and 1 mM Fe
2+
, plasma membranes prepared from resistant cells volatilized 48% of the total mercury added after 5 days of incubation. However, the membrane did not have mercury reductase activity with NADPH as an electron donor. Fe
2+
-dependent mercury volatilization activity was not observed with plasma membranes pretreated with 2 mM sodium cyanide. Rusticyanin from resistant cells activated iron oxidation activity of the plasma membrane and activated the Fe
2+
-dependent mercury volatilization activity of the plasma membrane.
Murine Monoclonal Antibodies Specific for Lipopolysaccharide ofEscherichia coliO26 and O111
Authors: Rivera-Betancourt Mildred , Keen James E. 
Published: July 2002

ABSTRACTMonoclonal antibody (MAb) 12F5 reacted with 35Escherichia coliO26 isolates and cross-reacted with 1 of 365 non-E. coliO26 isolates. MAb 15C4 reacted with 30E. coliO111 strains and 8SalmonellaO35 strains (possessing identical O antigen) but not with 362 other bacterial strains. Lipopolysaccharide immunoblots confirmed MAb O-antigen specificity.