bluuebunny/crossref_metadata_2025 huggingface dataset:
Pyridine-2,6-Bis(Thiocarboxylic Acid) Produced by
Pseudomonas stutzeri
KC Reduces and Precipitates Selenium and Tellurium Oxyanions
Authors: Zawadzka Anna M. , Crawford Ronald L. , Paszczynski Andrzej J.
Published: May 2006

The siderophore of
Pseudomonas stutzeri
KC, pyridine-2,6-bis(thiocarboxylic acid) (pdtc), is shown to detoxify selenium and tellurium oxyanions in bacterial cultures. A mechanism for pdtc's detoxification of tellurite and selenite is proposed. The mechanism is based upon determination using mass spectrometry and energy-dispersive X-ray spectrometry of the chemical structures of compounds formed during initial reactions of tellurite and selenite with pdtc. Selenite and tellurite are reduced by pdtc or its hydrolysis product H
2
S, forming zero-valent pdtc selenides and pdtc tellurides that precipitate from solution. These insoluble compounds then hydrolyze, releasing nanometer-sized particles of elemental selenium or tellurium. Electron microscopy studies showed both extracellular precipitation and internal deposition of these metalloids by bacterial cells. The precipitates formed with synthetic pdtc were similar to those formed in pdtc-producing cultures of
P. stutzeri
KC. Culture filtrates of
P. stutzeri
KC containing pdtc were also active in removing selenite and precipitating elemental selenium and tellurium. The pdtc-producing wild-type strain KC conferred higher tolerance against selenite and tellurite toxicity than a pdtc-negative mutant strain, CTN1. These observations support the hypothesis that pdtc not only functions as a siderophore but also is involved in an initial line of defense against toxicity from various metals and metalloids.
Effect of Nutrient Periodicity on Microbial Community Dynamics
Authors: Carrero-Colón Militza , Nakatsu Cindy H. , Konopka Allan
Published: May 2006

When microbes are subjected to temporal changes in nutrient availability, growth rate and substrate affinity can contribute to competitive fitness and thereby affect microbial community structure. This hypothesis was tested using planktonic bacterial communities exposed to nutrient additions at 1-, 3-, 7-, or 14-day intervals. Growth rates after nutrient addition were inversely proportional to the pulse interval and declined from 0.5 h
−1
to 0.15 h
−1
as the pulse interval increased from 1 to 14 days. The dynamics of community structure were monitored by 16S rRNA gene PCR-denaturing gradient gel electrophoresis. At pulse intervals of more than 1 day, the community composition continued to change over 130 days. Although replicate systems exposed to the same pulse interval were physiologically similar, their community compositions could exhibit as much dissimilarity (Dice similarity coefficients of <0.5) as did systems operated at different intervals. Bacteria were cultivated from the systems to determine if the physiological characteristics of individual members were consistent with the measured performance of the systems. The isolates fell into three bacterial divisions,
Bacteroidetes
,
Proteobacteria
, and
Actinobacteria
. In agreement with community results, bacteria isolated from systems pulsed every day with nutrients had higher growth rates and ectoaminopeptidase specific activities than isolates from systems pulsed every 14 days. However, the latter isolates did not survive starvation longer than those provided with nutrients every day. The present study demonstrates the dynamic nature of microbial communities exposed to even simple and regular environmental discontinuities when a substantial pool of species that can catabolize the limiting substrate is present.
Alicyclobacillus acidocaldariusThermophilic Esterase EST2's Activity in Milk and Cheese Models
Authors: Mandrich Luigi , Manco Giuseppe , Rossi Mosè , Floris Esther , Jansen-van den Bosch Tanja , Smit Gerrit , Wouters Jeroen A.
Published: May 2006

The aim of this work was to investigate the behavior of thermophilic esterase EST2 fromAlicyclobacillus acidocaldariusin milk and cheese models. The pure enzyme was used to compare the EST2 hydrolytic activity to the activity of endogenous esterase EstA fromLactococcus lactis. The results indicate that EST2 exhibits 30-fold-higher esterase activity than EstA. As EstA has thioesterase activity, EST2 was assayed for this activity under the optimal conditions determined for EstA (namely, 30°C and pH 7.5). Although it is a thermophilic enzyme, EST2 exhibited eightfold-higher thioesterase activity than EstA withS-methyl thiobutanoate. The abilities of EST2 and EstA to synthesize short-chain fatty acid esters were compared. Two methods were developed to do this. In the first method a spectrophotometric assay was used to monitor the synthesis of esters by the pure enzymes usingp-nitrophenol as the alcohol substrate. The synthetic activities were also evaluated under conditions that mimicked those present in milk and/or cheese. The second method involved evaluation of the synthetic abilities of the enzymes when they were directly added to a model cheese matrix. Substantial ester synthesis by EST2 was observed under both conditions. Finally, esterase and thioesterase activities were evaluated in milk using the purified EST2 enzyme and in the model cheese matrix using a strain ofL. lactisNZ9000 harboring the EST2 gene and thus overproducing EST2. Both the esterase and thioesterase activities measured in milk and in the cheese matrix were much greater than the activities of the controls.
Characterization of the Replication, Maintenance, and Transfer Features of the IncP-7 Plasmid pCAR1, Which Carries Genes Involved in Carbazole and Dioxin Degradation
Authors: Shintani Masaki , Yano Hirokazu , Habe Hiroshi , Omori Toshio , Yamane Hisakazu , Tsuda Masataka , Nojiri Hideaki
Published: May 2006

Isolated from
Pseudomonas resinovorans
CA10, pCAR1 is a 199-kb plasmid that carries genes involved in the degradation of carbazole and dioxin. The nucleotide sequence of pCAR1 has been determined previously. In this study, we characterized pCAR1 in terms of its replication, maintenance, and conjugation. By constructing miniplasmids of pCAR1 and testing their establishment in
Pseudomonas putida
DS1, we show that pCAR1 replication is due to the
repA
gene and its upstream DNA region. The
repA
gene and putative
oriV
region could be separated in
P. putida
DS1, and the
oriV
region was determined to be located within the 345-bp region between the
repA
and
parW
genes. Incompatibility testing using the minireplicon of pCAR1 and IncP plasmids indicated that pCAR1 belongs to the IncP-7 group. Monitoring of the maintenance properties of serial miniplasmids in nonselective medium, and mutation and complementation analyses of the
parWABC
genes, showed that the stability of pCAR1 is attributable to the products of the
parWAB
genes. In mating assays, the transfer of pCAR1 from CA10 was detected in a CA10 derivative that was cured of pCAR1 (CA10dm4) and in
P. putida
KT2440 at frequencies of 3 × 10
−1
and 3 × 10
−3
per donor strain, respectively. This is the first report of the characterization of this completely sequenced IncP-7 plasmid.
Stolbur Phytoplasma Genome Survey Achieved Using a Suppression Subtractive Hybridization Approach with High Specificity
Authors: Cimerman Agnès , Arnaud Guillaume , Foissac Xavier
Published: May 2006

Phytoplasmas are unculturable bacterial plant pathogens transmitted by phloem-feeding hemipteran insects. DNA of phytoplasmas is difficult to purify because of their exclusive phloem location and low abundance in plants. To overcome this constraint, suppression subtractive hybridization (SSH) was modified and used to selectively amplify DNA of the stolbur phytoplasma infecting a periwinkle plant. Plasmid libraries were constructed, and the origins of the DNA inserts were verified by hybridization and PCR screenings. After a single round of SSH, there was still a significant level of contamination with plant DNA (around 50%). However, the modified SSH, which included a second round of subtraction (double SSH), resulted in an increased phytoplasma DNA purity (97%). Results validated double SSH as an efficient way to produce a genome survey for microbial agents unavailable in culture. Assembly of 266 insert sequences revealed 181 phytoplasma genetic loci which were annotated. Comparative analysis of 113 kbp indicated that among 217 protein coding sequences, 83% were homologous to “
Candidatus
Phytoplasma asteris” (OY-M strain) genes, with hits widely distributed along the chromosome. Most of the stolbur-specific SSH sequences were orphan genes, with the exception of two partial coding sequences encoding proteins homologous to a mycoplasma surface protein and riboflavin kinase.
Characterization of Novel Carbazole Catabolism Genes from Gram-Positive Carbazole Degrader
Nocardioides aromaticivorans
IC177
Authors: Inoue Kengo , Habe Hiroshi , Yamane Hisakazu , Nojiri Hideaki
Published: May 2006

Nocardioides aromaticivorans
IC177 is a gram-positive carbazole degrader. The genes encoding carbazole degradation (
car
genes) were cloned into a cosmid clone and sequenced partially to reveal 19 open reading frames. The
car
genes were clustered into the
carAaCBaBbAcAd
and
carDFE
gene clusters, encoding the enzymes responsible for the degradation of carbazole to anthranilate and 2-hydroxypenta-2,4-dienoate and of 2-hydroxypenta-2,4-dienoate to pyruvic acid and acetyl coenzyme A, respectively. The conserved amino acid motifs proposed to bind the Rieske-type [2Fe-2S] cluster and mononuclear iron, the Rieske-type [2Fe-2S] cluster, and flavin adenine dinucleotide were found in the deduced amino acid sequences of
carAa
,
carAc
, and
carAd
, respectively, which showed similarities with CarAa from
Sphingomonas
sp. strain KA1 (49% identity), CarAc from
Pseudomonas resinovorans
CA10 (31% identity), and AhdA4 from
Sphingomonas
sp. strain P2 (37% identity), respectively.
E
s
cherichia coli
cells expressing CarAaAcAd exhibited major carbazole 1,9a-dioxygenase (CARDO) activity. These data showed that the IC177 CARDO is classified into class IIB, while gram-negative CARDOs are classified into class III or IIA, indicating that the respective CARDOs have diverse types of electron transfer components and high similarities of the terminal oxygenase. Reverse transcription-PCR (RT-PCR) experiments showed that the
carAaCBaBbAcAd
and
carDFE
gene clusters are operonic. The results of quantitative RT-PCR experiments indicated that transcription of both operons is induced by carbazole or its metabolite, whereas anthranilate is not an inducer. Biotransformation analysis showed that the IC177 CARDO exhibits significant activities for naphthalene, carbazole, and dibenzo-
p
-dioxin but less activity for dibenzofuran and biphenyl.
Development of a Biofilm Production-Deficient
Escherichia coli
Strain as a Host for Biotechnological Applications
Authors: Sung Bong Hyun , Lee Choong Hoon , Yu Byung Jo , Lee Jun Hyoung , Lee Ju Young , Kim Mi Sun , Blattner Frederick R. , Kim Sun Chang
Published: May 2006

Bacteria form biofilms by adhering to biotic or abiotic surfaces. This phenomenon causes several problems, including a reduction in the transport of mass and heat, an increase in resistance to antibiotics, and a shortening of the lifetimes of modules in bioindustrial fermentors. To overcome these difficulties, we created a biofilm production-deficient
Escherichia coli
strain, BD123, by deleting genes involved in curli biosynthesis and assembly, Δ(
csgG-csgC
); colanic acid biosynthesis and assembly, Δ(
wcaL-wza
); and type I pilus biosynthesis, Δ(
fimB-fimH
).
E. coli
BD123 remained mostly in the form of planktonic cells under the conditions tested and became more sensitive to the antibiotics streptomycin and rifampin than the wild-type
E. coli
MG1655: the growth of BD123 was inhibited by one-fourth of the concentrations needed to inhibit MG1655. In addition, the transformation efficiency of BD123 was about 20 times higher than that of MG1655, and the production and secretion of recombinant proteins were ∼16% and ∼25% greater, respectively, with BD123 than with MG1655. These results indicate that the newly created biofilm production-deficient strain of
E. coli
displays several key properties that substantially enhance its utility in the biotechnology arena.
Modeling for Gellan Gum Production by
Sphingomonas paucimobilis
ATCC 31461 in a Simplified Medium
Authors: Wang Xia , Xu Ping , Yuan Yong , Liu Changlong , Zhang Dezhong , Yang Zhengting , Yang Chunyu , Ma Cuiqing
Published: May 2006

Gellan gum production was carried out by
Sphingomonas paucimobilis
ATCC 31461 in a simplified medium with a short incubation time, and a kinetic model for understanding, controlling, and optimizing the fermentation process was proposed. The results revealed that glucose was the best carbon source and that the optimal concentration was 30 g liter
−1
. As for the fermenting parameters, considerably large amounts of gellan gum were yielded by an 8-h-old culture and a 4% inoculum at 200 rpm on a rotary shaker. Under the optimized conditions, the maximum level of gellan gum (14.75 g liter
−1
) and the highest conversion efficiency (49.17%) were obtained in a 30-liter fermentor in batch fermentation. Logistic and Luedeking-Piret models were confirmed to provide a good description of gellan gum fermentation, which gave some support for the study of gellan gum fermentation kinetics. Additionally, this study is the first demonstration that gellan gum production is largely growth associated by analysis of kinetics in its batch fermentation process. Based on model prediction, higher gellan gum production (17.71 g liter
−1
) and higher conversion efficiency (57.12%) were obtained in fed-batch fermentation at the same total glucose concentration (30 g liter
−1
).
Role of Efflux Pumps in Adaptation and Resistance of
Listeria monocytogenes
to Benzalkonium Chloride
Authors: Romanova N. A. , Wolffs P. F. G. , Brovko L. Y. , Griffiths M. W.
Published: May 2006

In this study, potential mechanisms underlying resistance and adaptation to benzalkonium chloride (BC) in
Listeria monocytogenes
were investigated. Two groups of strains were studied. The first group consisted of strains naturally sensitive to BC which could be adapted to BC. The second group consisted of naturally resistant strains. For all adapted isolates, there was a correlation between the resistance to BC and ethidium bromide, but this was not the case for the naturally resistant isolates. To investigate the role of efflux pumps in adaptation or resistance, reserpine, an efflux pump inhibitor, was added to the strains. Addition of reserpine to the sensitive and adapted strains resulted in a decrease in the MIC for BC, whereas no such decrease was observed for the resistant strains, indicating that efflux pumps played no role in the innate resistance of certain strains of
L. monocytogenes
to this compound. Two efflux pumps (MdrL and Lde) have been described in
L. monocytogenes
. Studies showed low and intermediate levels of expression of the genes encoding the efflux pumps for two selected resistant strains, H7764 and H7962, respectively. Adaptation to BC of sensitive isolates of
L. monocytogenes
resulted in significant increases in expression of
mdrl
(
P
< 0.05), but no such increase was observed for
lde
for two adapted strains of
L. monocytogenes
, LJH 381 (
P
= 0.91) and C719 (
P
= 0.11). This indicates that the efflux pump Mdrl is at least partly responsible for the adaptation to BC.
Auxofuran, a Novel Metabolite That Stimulates the Growth of Fly Agaric, Is Produced by the Mycorrhiza Helper Bacterium
Streptomyces
Strain AcH 505
Authors: Riedlinger Julia , Schrey Silvia D. , Tarkka Mika T. , Hampp Rüdiger , Kapur Manmohan , Fiedler Hans-Peter
Published: May 2006

The mycorrhiza helper bacterium
Streptomyces
strain AcH 505 improves mycelial growth of ectomycorrhizal fungi and formation of ectomycorrhizas between
Amanita muscaria
and spruce but suppresses the growth of plant-pathogenic fungi, suggesting that it produces both fungal growth-stimulating and -suppressing compounds. The dominant fungal-growth-promoting substance produced by strain AcH 505, auxofuran, was isolated, and its effect on the levels of gene expression of
A. muscaria
was investigated. Auxofuran and its synthetic analogue 7-dehydroxy-auxofuran were most effective at a concentration of 15 μM, and application of these compounds led to increased lipid metabolism-related gene expression. Cocultivation of strain AcH 505 and
A. muscaria
stimulated auxofuran production by the streptomycete. The antifungal substances produced by strain AcH 505 were identified as the antibiotics WS-5995 B and C. WS-5995 B completely blocked mycelial growth at a concentration of 60 μM and caused a cell stress-related gene expression response in
A. muscaria
. Characterization of these compounds provides the foundation for molecular analysis of the fungus-bacterium interaction in the ectomycorrhizal symbiosis between fly agaric and spruce.
Unexpected Diversity and Complexity of the Guerrero Negro Hypersaline Microbial Mat
Authors: Ley Ruth E. , Harris J. Kirk , Wilcox Joshua , Spear John R. , Miller Scott R. , Bebout Brad M. , Maresca Julia A. , Bryant Donald A. , Sogin Mitchell L. , Pace Norman R.
Published: May 2006

We applied nucleic acid-based molecular methods, combined with estimates of biomass (ATP), pigments, and microelectrode measurements of chemical gradients, to map microbial diversity vertically on a millimeter scale in a hypersaline microbial mat from Guerrero Negro, Baja California Sur, Mexico. To identify the constituents of the mat, small-subunit rRNA genes were amplified by PCR from community genomic DNA extracted from layers, cloned, and sequenced. Bacteria dominated the mat and displayed unexpected and unprecedented diversity. The majority (1,336) of the 1,586 bacterial 16S rRNA sequences generated were unique, representing 752 species (≥97% rRNA sequence identity) in 42 of the main bacterial phyla, including 15 novel candidate phyla. The diversity of the mat samples differentiated according to the chemical milieu defined by concentrations of O
2
and H
2
S. Bacteria of the phylum
Chloroflexi
formed the majority of the biomass by percentage of bulk rRNA and of clones in rRNA gene libraries. This result contradicts the general belief that cyanobacteria dominate these communities. Although cyanobacteria constituted a large fraction of the biomass in the upper few millimeters (>80% of the total rRNA and photosynthetic pigments),
Chloroflexi
sequences were conspicuous throughout the mat. Filamentous
Chloroflexi
bacteria were identified by fluorescence in situ hybridization within the polysaccharide sheaths of the prominent cyanobacterium
Microcoleus chthonoplastes
, in addition to free living in the mat. The biological complexity of the mat far exceeds that observed in other polysaccharide-rich microbial ecosystems, such as the human and mouse distal guts, and suggests that positive feedbacks exist between chemical complexity and biological diversity.
Improved Methodology for Bioremoval of Black Crusts on Historical Stone Artworks by Use of Sulfate-Reducing Bacteria
Authors: Cappitelli Francesca , Zanardini Elisabetta , Ranalli Giancarlo , Mello Emilio , Daffonchio Daniele , Sorlini Claudia
Published: May 2006

An improved methodology to remove black crusts from stone by usingDesulfovibrio vulgarissubsp.vulgarisATCC 29579, a sulfate-reducing bacterium, is presented. The strain removed 98% of the sulfates of the crust in a 45-h treatment. Precipitation of black iron sulfide was avoided using filtration of a medium devoid of iron. Among three cell carriers, Carbogel proved to be superior to both sepiolite and Hydrobiogel-97, as it allowed an easy application of the bacteria, kept the system in a state where microbial activity was maintained, and allowed easy removal of the cells after the treatment.
Multiniche Screening Reveals the Clinically Relevant Metallo-β-Lactamase VIM-2 in
Pseudomonas aeruginosa
Far from the Hospital Setting: an Ongoing Dispersion Process?
Authors: Quinteira Sandra , Peixe Luísa
Published: May 2006

A screening study of the presence of metallo-β-lactamases (IMP and VIM types and SPM-1) in isolates from different nonhospital sources was conducted, and it revealed the presence of
bla
VIM-2
, associated with the In58 class 1 integron, in two unrelated
Pseudomonas aeruginosa
strains from aquatic habitats. The results suggest that the hospital setting was the possible origin of these
bla
VIM-2
-carrying strains.
Development and Validation of an Oligonucleotide Microarray for Detection of Multiple Virulence and Antimicrobial Resistance Genes in
Escherichia coli
Authors: Bruant Guillaume , Maynard Christine , Bekal Sadjia , Gaucher Isabelle , Masson Luke , Brousseau Roland , Harel Josée
Published: May 2006

An oligonucleotide microarray detecting 189
Escherichia coli
virulence genes or markers and 30 antimicrobial resistance genes was designed and validated using DNA from known reference strains. This microarray was confirmed to be a powerful diagnostic tool for monitoring emerging
E. coli
pathotypes and antimicrobial resistance, as well as for environmental, epidemiological, and phylogenetic studies including the evaluation of genome plasticity.
Comparison of a Conventional Antimicrobial Susceptibility Assay to an Oligonucleotide Chip System for Detection of Drug Resistance in
Mycobacterium tuberculosis
Isolates
Authors: Park Heekyung , Song Eun Ju , Song Eun Sil , Lee Eun Yup , Kim Cheol Min , Jeong Seok Hoon , Shin Jeong Hwan , Jeong Joseph , Kim Sunjoo , Park Young Kil , Bai Gill-Han , Chang Chulhun L.
Published: May 2006

An oligonucleotide chip (Combichip Mycobacteria chip) detecting specific mutations in the
rpoB
,
katG
, and
inhA
genes of
Mycobacterium tuberculosis
was compared with conventional antimicrobial susceptibility results. The probes detecting drug resistance were as follows: 7 wild-type and 13 mutant probes for rifampin and 2 wild-type and 3 mutant probes for isoniazid. Target DNA of
M. tuberculosis
was amplified by PCR, followed by hybridization and scanning. Direct sequencing was performed to verify the results of the oligonucleotide chip. One-hundred seven of 115 rifampin-resistant strains (93%) had mutations in the
rpoB
gene. Eighty-five of 119 isoniazid-resistant strains (71%) had mutations in the
katG
gene or
inhA
gene. The diagnostic oligonucleotide chip with mutation-specific probes is a reliable and useful tool for the rapid and accurate diagnosis of resistance against rifampin and isoniazid in
M. tuberculosis
isolates.
Emergence of an Invasive Clone of Nontoxigenic
Corynebacterium diphtheriae
in the Urban Poor Population of Vancouver, Canada
Authors: Romney M. G. , Roscoe D. L. , Bernard K. , Lai S. , Efstratiou A. , Clarke A. M.
Published: May 2006

Invasive disease due to
Corynebacterium diphtheriae
is rare in North America. Here we describe the emergence of a predominant clone of a nontoxigenic strain of
C. diphtheriae
in the impoverished population of Vancouver's downtown core. This clone has caused significant morbidity and contributed to at least two deaths. Over a 5-year period, seven cases of bacteremia due to
C. diphtheriae
were detected in patients admitted to Vancouver hospitals. Injection drug use, diabetes mellitus, skin colonization/infection with
C. diphtheriae
, and homelessness all appeared to be related to the development of bacteremia with the organism. Ribotyping of isolates recovered from blood culture revealed a predominant ribotype pattern that has not previously been reported in North America.
Pulsed-Field Gel Electrophoresis Typing of
Escherichia coli
Strains from Samples Collected before and after Pivmecillinam or Placebo Treatment of Uncomplicated Community-Acquired Urinary Tract Infection in Women
Authors: Ejrnaes Karen , Sandvang Dorthe , Lundgren Bettina , Ferry Sven , Holm Stig , Monsen Tor , Lundholm Rolf , Frimodt-Moller Niels
Published: May 2006

The primary infecting
Escherichia coli
strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or placebo and the
E. coli
strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE). In the pivmecillinam treatment group PFGE showed that among patients having a negative urine culture at the first follow-up 77% (46/60) had a relapse with the primary infecting
E. coli
strain and 23% (14/60) had reinfection with a new
E. coli
strain at the second follow-up. Among patients having
E. coli
at the first follow-up PFGE showed that 80% (32/40) had persistence with the primary infecting
E. coli
strain, 15% (6/40) had reinfection with a new
E. coli
strain, and 5% (2/40) had different
E. coli
strains at the two follow-up visits (one had reinfection followed by relapse, and the other had persistence followed by reinfection). In the placebo group the majority had
E. coli
at the first follow-up. PFGE showed that among these patients 96% (50/52) had persistence with the primary infecting
E. coli
strain and 4% (2/50) had different
E. coli
strains at the two follow-up visits (both had persistence followed by reinfection). The finding that the majority of UTIs at follow-up are caused by the primary infecting
E. coli
strain supports the theory of a vaginal and rectal reservoir but could also support the recent discovery that
E. coli
strains are able to persist in the bladder epithelium despite appropriate antibiotic treatment, constituting a reservoir for recurrent UTI.
International Surveillance of
Candida
spp. and
Aspergillus
spp.: Report from the SENTRY Antimicrobial Surveillance Program (2003)
Authors: Messer Shawn A. , Jones Ronald N. , Fritsche Thomas R.
Published: May 2006

During 2003, a total of 1,397
Candida
isolates, 73
Aspergillus
isolates, 53
Cryptococcus neoformans
isolates, and 25 other fungal isolates from infected, normally sterile, body sites in patients hospitalized in North America, Europe, and Latin America were studied as a component of the longitudinal SENTRY Antimicrobial Surveillance Program. The MICs for seven antifungal agents were determined in a central laboratory (JMI Laboratories, North Liberty, IA) using testing methods promulgated by the Clinical and Laboratory Standards Institute (formerly the National Committee for Clinical Laboratory Standards). The rank order of
Candida
spp. occurrence was as follows:
C. albicans
(48.7%),
C. parapsilosis
(17.3%),
C. glabrata
(17.2%),
C. tropicalis
(10.9%),
C. krusei
(1.9%), and other
Candida
spp. (4.0%).
C. albicans
accounted for 51.5, 47.8, and 36.5% of candidal infections in North America, Europe, and Latin America, respectively. Ravuconazole, voriconazole, and fluconazole were highly active against
C. albicans
,
C. parapsilosis
, and
C. tropicalis
, with both former agents being more potent (MIC at which 90% of the isolates tested are inhibited [MIC
90
] of ≤0.008 to 0.12 μg/ml) than fluconazole (MIC
90
of 0.5 to 2 μg/ml).
C. glabrata
isolates were less susceptible to these agents, with MIC
90
s of 1, 1, and 64 μg/ml, respectively. Ravuconazole and voriconazole were the most active agents tested against
C. krusei
(MIC
90
of 0.5 μg/ml). Among
Aspergillus
spp.,
A. fumigatus
was the most commonly (71.2% of isolates) recovered species; 96.2, 96.2, 84.6, and 11.5% of strains were inhibited by ≤1 μg/ml of ravuconazole, voriconazole, itraconazole, and amphotericin B, respectively. Of the antifungal agents tested, ravuconazole and voriconazole displayed the greatest spectrum of activity against pathogenic
Candida
and
Aspergillus
spp., regardless of geographic origin. These results extend upon previous findings from SENTRY Program reports (1997 to 2000), further characterizing species composition as seen in local clinical practice and demonstrating the potent activity of selected, newer triazole antifungal agents.
Cytolethal Distending Toxin in
Escherichia coli
O157:H7: Spectrum of Conservation, Structure, and Endothelial Toxicity
Authors: Friedrich Alexander W. , Lu Shan , Bielaszewska Martina , Prager Rita , Bruns Phillip , Xu Jian-Guo , Tschäpe Helmut , Karch Helge
Published: May 2006

We identified the cytolethal distending toxin V (CDT-V) gene cluster in 19 (4.9%) of 391 enterohemorrhagic
Escherichia coli
O157:H7.
cdt-V

+

strains belonged to five phage types (PTs) and were most frequent within PTs 14 and 34. CDT-V was expressed in all but two
cdt-V

+

strains and was lethal to cultured endothelial cells. Subtyping schemes should include
cdt-V
as a marker to differentiate
E. coli
O157:H7 even within the same phage type.
Evaluation of a Commercial Latex Agglutination Assay for Serological Diagnosis of Leptospirosis
Authors: Hull-Jackson C. , Glass M. B. , Ari M. D. , Bragg S. L. , Branch S. L. , Whittington C. U. , Edwards C. N. , Levett P. N.
Published: May 2006

Leptospirosis is a febrile zoonosis of worldwide distribution. A latex agglutination assay was evaluated in two studies, the first using a panel of well-characterized sera from patients with leptospirosis and from patients with other disease states and the second, a prospective hospital-based study, evaluating sera from 186 consecutive patients admitted to hospital with acute febrile illness. The confirmed leptospirosis serum panel included paired acute- and convalescent-phase specimens from 40 cases, of which 34 gave positive latex tests (case sensitivity, 85%; 95% confidence interval [95% CI], 70 to 94%). The other diseases represented in the panel of 112 specimens from nonleptospirosis patients included autoimmune diseases, brucellosis, dengue, melioidosis, malaria, syphilis, toxoplasmosis, viral hepatitis, and a number of other viral infections. The specificity of latex agglutination using this panel was 81% (95% CI, 73 to 87%). Among the patients with acute febrile illness, there were 25 cases of leptospirosis and 161 patients with other diagnoses. The sensitivity and specificity of latex agglutination in this group were 88% (95% CI, 72 to 97%) and 98% (95% CI, 95 to 100%), respectively. In this evaluation, the two distinct groups of specimens gave similar results for sensitivity, but specificity was different in each study. The sensitivity and specificity observed for the hospital study were similar to those obtained in evaluations of other rapid tests in the same population. The results of this study suggest that multiple evaluations of new diagnostic assays should be performed, because performance characteristics may vary in different populations.
Native Valve Endocarditis Due to
Gordonia polyisoprenivorans
: Case Report and Review of Literature of Bloodstream Infections Caused by
Gordonia
Species
Authors: Verma Punam , Brown June M. , Nunez Victor H. , Morey Roger E. , Steigerwalt Arnold G. , Pellegrini Gerald J. , Kessler Harold A.
Published: May 2006

We report the first case of endocarditis caused by
Gordonia polyisoprenivorans
and concisely review the English literature regarding bloodstream infections caused by
Gordonia
species.
Central Venous Catheter Colonization by Linezolid-Resistant, Vancomycin-Susceptible
Enterococcus faecalis
Authors: Marra Alexandre R. , Major Yvette , Edmond Michael B.
Published: May 2006

Resistance to linezolid is rare in clinical isolates of
Enterococcus faecalis
. A strain resistant to this antimicrobial but susceptible to vancomycin was found to cause central venous catheter colonization in a patient who never received linezolid.
Normal coordinate analysis of titanium(IV) halide: monoethylenediamine complexes
Authors: Ashley P. J. , Torrible E. G.
Published: May 2006

A partial normal coordinate analysis was performed for the Ti(en)X4 complexes, assuming gauche configuration of the ligand and overall symmetry of C2 for the complex. Comparison of the calculated frequencies with the available experimental data supports the assumption of the chelate structure for the complexes and also confirms the previous assignments for the Ti—N stretching frequencies. Some new assignments are proposed in the 900–300 cm−1 region.
Gallium(III) isothiocyanate and its addition compounds
Authors: Patel S. J. , Tuck D. G.
Published: May 2006

Gallium(III) tris-isothiocyanate trihydrate has been prepared, together with a series of compounds with monodentate ligands of the type Ga(NCS)3L3. Bidentate donors gave either Ga(NCS)3L3 or Ga(NCS)3L1.5. The structure and properties of these species are compared with those of other gallium(III) addition compounds, and of the corresponding indium(III) complexes.
Effect of pH and phosphate ions on the polarographic behavior of D-glucuronolactone
Authors: Thibert R. J. , Johnston J. R.
Published: May 2006

The polarographic determination of D-glucuronolactone in aqueous solution was shown to be feasible up to a concentration of 6 mg per ml in KCl, NaCl, and LiCl with gelatin as the maximum suppressor. The effect of pH and phosphate ions on the polarographic wave of D-glucuronolactone is discussed and compared to the reaction of dialkyl hydrogen phosphites and trialkyl phosphites with β-propiolactones. The effect of pH and phosphate ions on the polarographic wave of D-glucuronic acid was also investigated.
Studies of specifically fluorinated carbohydrates. Part III. A new method for the addition of the elements of "BrF" and of "IF" to unsaturated carbohydrate derivatives
Authors: Hall L. D. , Manville J. F.
Published: May 2006

A smooth addition of the elements of "BrF", to D-glucal triacetate (1), occurs when bromine is reacted with 1 in the presence of silver monofluoride and a suitable solvent. This reaction affords a major product 2-bromo-2-deoxy-α-D-mannopyranosyl fluoride triacetate, together with smaller quantities of 2-bromo-2-deoxy-α-D-glucopyranosyl fluoride triacetate and the corresponding β-D-anomer. The structures of these products have been elucidated by fluorine and proton magnetic resonance studies, and confirmed by several independent syntheses. The same three products are obtained when "BrF" is generated insitu from N-bromosuccinimide and HF; however, under these conditions 2-deoxy-α-D-arabino-hexopyranosyl fluoride triacetate is also formed in ca. 7% yield. The Br2/AgF reagent has also been reacted with several 3,4-dihydro-2H-pyran derivatives and with other glycals. In all cases the major product(s) corresponds to the trans addition of "BrF". Similar results are obtained for the addition of the elements of "IF" to all of the above derivatives.
Studies of specifically fluorinated carbohydrates. Part IV. Addition of the elements of "CIF" to D-glucal triacetate
Authors: Hall L. D. , Manville J. F.
Published: May 2006

Reaction of chlorine with a suspension of D-glucal triacetate and silver monofluoride in an acetonitrile/benzene solution, affords a mixture of the four possible 2-chloro-2-deoxy-D-glycopyranosyl fluoride triacetates. The structures of these derivatives have been established by nuclear magnetic resonance studies and confirmed by independent syntheses. The major product is 2-chloro-2-deoxy-β-D-glucopyranosyl fluoride triacetate. These results are compared with those from the related "BrF" and "IF" additions.
Stereochemical dependence of vicinal H—C—O—H coupling constants
Authors: Fraser Robert R. , Kaufman M. , Morand Peter , Govil G.
Published: May 2006

The exact analysis of the ABC type absorption due to the —CH2OH group of 3β-acetoxy-5β,6β-oxidocholestan-19-ol provides two vicinal HCOH coupling constants for dihedral angles of 80° and 160°. A least squares fit of these and previous data in the literature to a "Karplus" relation provides values for the coefficients in such an equation. The theoretical justification for such a relation has been obtained by extended Hückel molecular orbital calculations for methanol with different dihedral angles. The practical limitations in, and applications of the relation are discussed. An effect of solvent on the vicinal coupling constants is also noted and discussed.
New synthesis of formaldehyde-d2
Authors: Atkinson J. G. , Cillis D. W. , Stuart R. S.
Published: May 2006

A new and improved synthesis of formaldehyde-d2 on a molar scale has been developed via the reactions:[Formula: see text]The yield from deuterated methylene bromide is 50%, and the deuterium content is over 98%.
Facile elimination accompanying some methyl sulfoxide oxidations. Formation of unsaturated carbohydrates
Authors: Cree G. M. , Mackie D. W. , Perlin A. S.
Published: May 2006

Oxidation of some partially-acetylated carbohydrated with methyl sulfoxide, activated by sulfur trioxide–pyridine and triethylamine, leads to facile elimination of the elements of acetic acid and the formation of novel, unsaturated, derivatives.
Heats of formation of RuO4, RuO42−, and related compounds
Authors: Mercer E. E. , Farrar D. T.
Published: May 2006

The heat of reaction of ruthenium metal with bromine in basic solution, according to the equation[Formula: see text]has been measured calorimetrically. In addition, the heat of oxidation of barium ruthenate hydrate by sodium periodate to form RuO4(aq) has been determined. From these heats of reaction, and several other heats measured here, the heats of formation of several ruthenium species have been calculated. The more important of these are: Na2RuO4(aq), ΔHf = −224.1 ± 0.8; RuO42−(aq), ΔHf = −109.4 ± 1.0; RuO4(aq), ΔHf = −57.5 ± 1.1; RuO4(l), ΔHf = −57.0 ± 1.1 kcal/mole.
Ion–molecule reactions in vinyl chloride and vinyl bromide
Authors: Herman J. A. , Myher J. J. , Harrison A. G.
Published: May 2006

The following ion–molecule reactions involving fragment ions in vinyl chloride have been studied and rate constants measured for ions of 2.4 eV exit energy.[Formula: see text]The reaction of the C2H3Cl+ molecule-ion produces C3H4Cl+, C4H5Cl+, and C4H6Cl+ both in a second order and a third order reaction. The apparent rate coefficient for the second order reaction is approximately 1 × 10−11 cm3 molecule−1 s−1 while that for the third order reaction is approximately 1 × 10−25 cm6 molecule−2 s−1. The product distributions from both the second and third order reactions have been determined.In vinyl bromide the C2H3+ ion produces C4H5+, C4H6+, and C2H4Br+ while the C2H3Br+ ion reacts to form C4H6Br+ both in a second order and a third order reaction.
Dielectric studies. Part XXIII. Relaxation data and apparent dipole moments of aniline and some disubstituted aromatic amines
Authors: Tucker S. W. , Walker S.
Published: May 2006

Dielectric studies have been carried out at microwave frequencies on dilute solutions of aniline, p-chloro-, p-bromo-, and m-chloro-anilines, and o-, m-, and p-toluidines at 25 °C in cyclohexane and p-xylene. The static dielectric constant has also been measured at 2 MHz. In addition o- and m-toluidines have been measured at 50 °C and p-toluidine at 15, 35, and 50 °C.The dielectric results, particularly those at 70.01 GHz, establish that there is more than one relaxation process present and the data have been analyzed on a two relaxation time model, the longer of which τ1, is identified as molecular relaxation. The cause of the lower electric dipole moments found from this method as opposed to the non-dielectric absorption methods is discussed. It follows that there is either an additional higher frequency dispersion or (and) a high atomic polarization for aniline and o-, m-, and p-toluidines. Work at still higher frequencies is required to study this further and to establish more precise values of τ2.
Hydrodynamically induced crystallization of isotactic polystyrene
Authors: Wikjord A. G. , Manley R. St. John
Published: May 2006

This report provides a brief preliminary account of the solution crystallization of isotactic polystyrene under the influence of velocity gradients. During crystallizations from 1,3,5-trimethylbenzene and cyclohexanol solutions, the polymer appears in a number of morphological forms which are composed of microfibrillar units. In isotactic polystyrene produced by heterogeneous Ziegler–Natta catalysis, similar microfibrillar units are observed. It is suggested, therefore, that these two apparently different processes have a common underlying mechanism in the formation of the microfibrils. The possible mechanisms of fibril formation are discussed.
The crystal structure of tetraphenylcyclobutadiene molybdenum dicarbonyl bromide
Authors: Mathew M. , Palenik Gus J.
Published: May 2006

The crystal structure of tetraphenylcyclobutadiene molybdenum dicarbonyl bromide has been determined by X-ray diffraction. Previously, the compound has been formulated incorrectly as tetraphenylcyclobutadiene molybdenum tricarbonyl bromide.
Luminescence in the thermal decomposition of 3,3,4-trimethyl-1,2-dioxetane
Authors: Kopecky Karl R. , Mumford Cedric
Published: May 2006

Luminescence is observed during the thermal decomposition of 3,3,4-trimethyl-1,2-dioxetane to acetone and acetaldehyde. The wavelength maximum of the luminescence is at 430–440 mμ when the decomposition is carried out at 60° in benzene solution. This shows that the decomposition of the dioxetane is a concerted electrocyclic reaction which forms a carbonyl compound in the excited singlet state, and confirms the suggestion that bioluminescence is due to the decomposition of 1,2-dioxetanes.
Lignin and related compounds. I. A comparative study of catalysts for lignin hydrogenolysis
Authors: Pepper J. M. , Lee Y. W.
Published: May 2006

A detailed comparative study has been made of the effectiveness of various catalysts for the hydrogenolysis of spruce wood lignin. The catalysts studied were Raney nickel, 10% palladium–charcoal, 5% rhodium–charcoal, 5% rhodium–alumina, 5% ruthenium–charcoal, and 5% ruthenium–alumina. Lignin degradation products were obtained initially as a chloroform-soluble fraction which was then divided and studied as diethyl ether-soluble and -insoluble fractions. Gas–liquid chromatographic separation of the ether-soluble fraction made possible the characterization and quantitative estimation of many of the lower molecular weight lignin degradation products.The data indicate that rhodium, palladium, and a limited amount of Raney nickel produce similar results as do ruthenium and an excess of Raney nickel; however, with the latter catalysts the degradation is more severe. In particular, rhodium–charcoal and palladium–charcoal appear to offer interesting advantages as catalysts for lignin hydrogenolysis.
Structure of crotonic acid dimers and higher polymers with partial stereochemistry of the dimers
Authors: Hocking Martin B.
Published: May 2006

Heating trans-crotonic acid (CH3—CH=CH—CO2H) yields labile high boiling compounds which have received some attention in the past. These have now been conclusively characterized as the two geometric isomers of a dimer of crotonic acid. In addition trimers and tetramers discovered in the thermally polymerized crotonic acid were isolated as their methyl esters and positively identified.
cis-Crotonaldehyde and related compounds
Authors: McGreer D. E. , Page B. D.
Published: May 2006

cis-Crotonaldehyde (1) has been prepared as a mixture with trans-crotonaldehyde (2) by irradiation of 2 with 3000 Å light. The thermodynamic equilibrium value for 1 to 2 was determined to be 1:50. Conditions for attaining this equilibrium and the structural factors contributing to its position are discussed.
Nucleophilic decomposition of α-disulfones
Authors: Allen Jr. Paul , Conway Patrick J.
Published: May 2006

The sulfur–sulfur bond of α-disulfones is attacked by hydroxide ion in alcohol to yield sulfinate and sulfonate ion by a second-order reaction, first order in each of the reactants. With aromatic disulfones the ρ value of the Hammett equation is 0.2. The Arrhenius activation energy of the reaction of p-tolyl disulfone is 7.95 kcal/mole.
Circular dichroism of some bis(halogenoacetato)bis(ethylenediamine)cobalt(III) complexes
Authors: Haines Roland A. , Kipp Edward B.
Published: May 2006

Compounds of the general type cis-bis(halogenoacetato)bis(ethylenediamine)cobalt(III) are discussed for the cases where the halogenoacetate ion is monochloroacetate, dichloroacetate, trichloroacetate, or dibromoacetate. For the first time these complexes have been resolved into their optical isomers and a study has been made of the circular dichroism data obtained.The positions of circular dichroism and absorption bands have been interpreted by calculating relative values of the σ and π interactions for the halogenoacetate ligands.
Electromotive force studies of liquid uranium–zinc alloys
Authors: Hoshino Y. , Plambeck J. A.
Published: May 2006

The electromotive force of cells of the type U(s)/LiCl–KCl (eutectic) + UCl3/(U + Zn) (liquid alloy) have been measured over the temperature range 450–550 °C, in the zinc-rich region of alloy composition. Thermodynamic functions for the limiting uranium–zinc intermetallic compound existing in this region are: ΔGf0, −23.0 kcal/mole; ΔSf0, −37.1 cal/deg mole; ΔHf0, −52.9 kcal/mole at 535 °C. These values are compared with those previously reported by other workers.
Pyrochlores. V. Thermoanalytic, X-ray, neutron, infrared, and dielectric studies of A2Ti2O7 titanates
Authors: Knop Osvald , Brisse François , Castelliz Lotte
Published: May 2006

A number of compositions A23+Ti24+O7 and of related mixed phases were prepared and investigated. For the trivalent lanthanons from Sm to Lu, and for Y, the homogeneous A2Ti2O7 phases were of the cubic pyrochlore type. Their lattice parameters gave a very good linear relationship when plotted against the Templeton–Dauben radii of A3+. The room-temperature stability region of the pyrochlore titanates at ordinary pressures extends from an Ahrens radius ratio, r(A3+):r(Ti4+), of about 1.22 to about 1.50, taking into account homogeneous mixed phases. The compositions Bi2Ti2O7, In2Ti2O7, and Cr2Ti2O7 were not cubic pyrochlores; the results of an X-ray and neutron examination of Sc2Ti2O7 indicate that further work is needed to clarify its structural properties.The structures of Lu, Y, Gd, and Sm titanates were refined from X-ray powder data and that of Y2(Ti0.64Zr0.36)2O7, from neutron powder data. The structure of Er2Ti2O7 was re-refined from previously published data without significant improvement. The positional parameter of the majority oxygen atom, x(O2), in A2B2O7 pyrochlores has been found to increase, and the distortion of the BO6 octahedra to decrease, with the increasing r(A3+):r(B4+) ratio. This is in agreement with a similar result obtained earlier from Mössbauer spectra for A2FeSbO7 pyrochlores.The variation of the frequencies of the principal absorption bands in the infrared spectra of the titanates has been correlated with r(A3+). No evidence of ferroelectricity was found in Sm and Er titanates between room temperature and 4.2 °K.The Templeton–Dauben set of empirical crystal radii for trivalent lanthanons has been supplemented by values for Sc, In, Tl, and Bi derived from the C-type sesquioxides and the pyrochlores. The self-consistency and applicability of the expanded set have been tested on several series of isostructural compounds.
The CdO–CdCl2 reaction studied by thermal analysis and X-ray diffraction: X-ray diffractogram and infrared spectrum of CdCl2•2CdO
Authors: Ramamurthy P. , Secco E. A.
Published: May 2006

CdO and molten CdCl2 react to form CdCl2•2CdO according to the equation:[Formula: see text]The compound CdCl2•2CdO dissociates to the oxide and chloride at 680 °C. CdO and CdCl2 form a solid solution of partial miscibility of 15% by weight of CdO.The X-ray diffractogram of CdCl2•2CdO was indexed to the orthorhombic system. The unit cell dimensions are calculated to be a = 4.38 Å, b = 11.47 Å, c = 9.93 Å with 4 molecules in the unit cell. The infrared spectrum shows a band structure of two doublets and a well-defined band in the region 370–550 cm−1.
Infrared studies of cis- and trans-bis(halogenoacetato)bis(ethylenediamine)-cobalt(III) complexes
Authors: Kipp Edward B. , Haines Roland A.
Published: May 2006

The infrared spectra have been studied for cis- and trans-isomers of complexes of the type [Co(en)2(halac)2]ClO4, where en = ethylenediamine and halac = CH3CO2−, CH2ClCO2−, CHCl2CO2−, CCl3CO2−, CHBr2CO2−, and CF3CO2−. Characteristic differences between the spectra of cis- and trans-isomers have been examined and correlated with data for similar complexes. The most consistent variations are in the 500–610 cm−1 region where Co—N stretching modes occur.