bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantification of myoglobin deoxygenation and intracellular partial pressure of O2 during muscle contraction during haemoglobin‐free medium perfusion
Authors: Takakura Hisashi , Masuda Kazumi , Hashimoto Takeshi , Iwase Satoshi , Jue Thomas 
Published: January 2010

Although the O2 gradient regulates O2 flux from the capillary into the myocyte to meet the energy demands of contracting muscle, intracellular O2 dynamics during muscle contraction remain unclear. Our hindlimb perfusion model allows the determination of intracellular myoglobin (Mb) saturation (

) and intracellular oxygen tension of myoglobin (

) in contracting muscle using near infrared spectroscopy (NIRS). The hindlimb of male Wistar rats was perfused from the abdominal aorta with a well‐oxygenated haemoglobin‐free Krebs–Henseleit buffer. The deoxygenated Mb (Δ[deoxy‐Mb]) signal was monitored by NIRS. Based on the value of Δ[deoxy‐Mb],
and
were calculated, and the time course was evaluated by an exponential function model. Both
and
started to decrease immediately after the onset of contraction. The steady‐state values of
and
progressively decreased with relative work intensity or muscle oxygen consumption. At the maximal twitch rate,
and
were 49% and 2.4 mmHg, respectively. Moreover, the rate of release of O2 from Mb at the onset of contraction increased with muscle oxygen consumption. These results suggest that at the onset of muscle contraction, Mb supplies O2 during the steep decline in
, which expands the O2 gradient to increase the O2 flux to meet the increased energy demands.
Staphylococcal Cassette Chromosome
mec
-Like Element in
Macrococcus caseolyticus
Authors: Tsubakishita Sae , Kuwahara-Arai Kyoko , Baba Tadashi , Hiramatsu Keiichi 
Published: January 2010

ABSTRACT

Macrococcus
is a bacterial genus that is closely related to
Staphylococcus
, which typically is isolated from animal skin and products. The genome analysis of multidrug-resistant
Macrococcus caseolyticus
strain JCSC5402, isolated from chicken, previously led to the identification of plasmid pMCCL2, which carries a transposon containing an unusual form of the
Macrococcus mec
gene complex (

mecA
m

-

mecR1
m

-

mecI
m

-

blaZ
m

). In
M. caseolyticus
strain JCSC7096, this
mec
transposon containing the
mec
gene complex (designated Tn
6045
in this study) was found integrated downstream of
orfX
on the chromosome. Tn
6045
of JCSC7096 was bracketed by the direct repeat sequences (DR) specifically recognized by cassette chromosome recombinase (CCR). A non-
mecA
-containing staphylococcal cassette chromosome (SCC) element, designated SCC
7096
, was integrated next to the
mec
transposon and separated from the latter by a DR. Nested PCR experiments showed that the
mec
transposon not only was excised singly but also coexcised with SCC
7096
from the chromosome at the DRs. The coexcised elements formed the extrachromosomal closed circular DNA of the SCC
mec
-like element. SCC
mec
is known to be the mobile element conveying methicillin (meticillin) resistance in staphylococci. However, its origin has been unknown. Our observation revealed a potential mechanism of the generation of a new SCC
mec
-like element in
M. caseolyticus
, a commensal bacterium of food animals.
Epidemiology of Invasive Meningococcal Disease with Decreased Susceptibility to Penicillin in Ontario, Canada, 2000 to 2006
Authors: Brown Elizabeth M. , Fisman David N. , Drews Steven J. , Dolman Sharon , Rawte Prasad , Brown Shirley , Jamieson Frances 
Published: January 2010

ABSTRACT

Neisseria meningitidis
has been relatively slow to acquire resistance to penicillin. We previously reported an increase in the incidence of invasive meningococcal disease (IMD) strains with decreased susceptibility to penicillin (DSP) in Ontario. Our objectives were to evaluate trends in IMD with DSP, to identify case-level predictors of IMD with DSP, and to evaluate the relationship among DSP, bacterial phenotype, and the likelihood of a fatal outcome. All IMD isolates received in Ontario between 2000 and 2006 were submitted to the Public Health Laboratories, Toronto, for confirmation of the species, serogroup determination, and susceptibility testing. Isolates were considered to be IMD strains with DSP if the penicillin MIC was ≥0.125 μg/ml. Temporal trends were evaluated using multivariable Poisson regression models. Correlates of diminished susceptibility and fatal outcome were evaluated with multivariable logistic regression models. The overall rate of IMD caused by strains with DSP in Ontario was approximately 1.20 cases per million population annually (95% confidence interval [95% CI], 0.99 to 1.46). Seventy-nine strains (21.7%) were IMD strains with DSP. There was no year-to-year trend in the incidence of IMD with DSP. IMD with DSP was strongly associated with strains of serogroups Y (odds ratio [OR], 6.3; 95% CI, 3.6 to 11.1) and W-135 (OR, 8.2; 95% CI, 4.0 to 16.7). Infection with serogroup B or C strains was associated with a marked increase in the risk of mortality (OR, 3.07; 95% CI, 1.39 to 6.75); however, no association between IMD with DSP and mortality was observed. In contrast to trends of the 1990s, the incidence of IMD with DSP was stable in Ontario between 2000 and 2006. In Ontario, the serogroup rather than the penicillin MIC is the microbiological parameter most predictive of mortality.
Spread of OXA-48-Encoding Plasmid in Turkey and Beyond
Authors: Carrër Amélie , Poirel Laurent , Yilmaz Mesut , Akan Özay Arikan , Feriha Cilli , Cuzon Gaëlle , Matar Ghassan , Honderlick Patrick , Nordmann Patrice 
Published: January 2010

ABSTRACT

Eighteen carbapenem-resistant, OXA-48-positive enterobacterial isolates recovered from Turkey, Lebanon, Egypt, France, and Belgium were analyzed. In most isolates, similar 70-kb plasmids carrying the carbapenemase gene
bla
OXA-48
were identified. That gene was located within either transposon Tn
1999
or transposon Tn
1999.2
, which was always inserted within the same gene. This work highlights the current plasmid-mediated dissemination of the OXA-48 carbapenemase worldwide.
New Susceptibility Breakpoints for First-Line Antituberculosis Drugs Based on Antimicrobial Pharmacokinetic/Pharmacodynamic Science and Population Pharmacokinetic Variability
Authors: Gumbo Tawanda 
Published: January 2010

ABSTRACT

Arguably, one of the most common and consequential laboratory tests performed in the world is
Mycobacterium tuberculosis
susceptibility testing.
M. tuberculosis
resistance is defined by growth of ≥1% of a bacillary inoculum on the critical concentration of an antibiotic. The critical concentration was chosen based on inhibition of ≥95% of wild-type isolates. The critical concentration of isoniazid is either 0.2 or 1.0 mg/liter, that of rifampin is 1.0 mg/liter, that of pyrazinamide is 100 mg/liter, that of ethambutol is 5.0 mg/liter, and that of fluoroquinolones is 1.0 mg/liter. However, the relevance of these concentrations to microbiologic and clinical outcomes is unclear. Critical concentrations were identified using the ability to achieve the antibiotic area under the concentration-time curve/MIC ratio associated with ≥90% of maximal kill (EC
90
) of
M. tuberculosis
in ≥90% of patients. Population pharmacokinetic parameters and their variability encountered in tuberculosis patients were utilized in Monte Carlo simulations to determine the probability that particular daily doses of the drugs would achieve or exceed the EC
90
in the epithelial lining fluid of 10,000 tuberculosis patients. Failure to achieve EC
90
in ≥90% of patients at a particular MIC was defined as drug resistance. The critical concentrations of moxifloxacin and ethambutol remained unchanged, but a critical concentration of 50 mg/liter was identified for pyrazinamide, 0.0312 mg/liter and 0.125 mg/liter were defined for low- and high-level isoniazid resistance, respectively, and 0.0625 mg/liter was defined for rifampin. Thus, current critical concentrations of first-line antituberculosis drugs are overoptimistic and should be set lower. With the proposed breakpoints, the rates of multidrug-resistant tuberculosis could become 4-fold higher than currently assumed.
Genetic Dissection of Azole Resistance Mechanisms in
Candida albicans
and Their Validation in a Mouse Model of Disseminated Infection
Authors: MacCallum Donna M. , Coste Alix , Ischer Françoise , Jacobsen Mette D. , Odds Frank C. , Sanglard Dominique 
Published: January 2010

ABSTRACT

Principal mechanisms of resistance to azole antifungals include the upregulation of multidrug transporters and the modification of the target enzyme, a cytochrome P450 (Erg11) involved in the 14α-demethylation of ergosterol. These mechanisms are often combined in azole-resistant
Candida albicans
isolates recovered from patients. However, the precise contributions of individual mechanisms to
C. albicans
resistance to specific azoles have been difficult to establish because of the technical difficulties in the genetic manipulation of this diploid species. Recent advances have made genetic manipulations easier, and we therefore undertook the genetic dissection of resistance mechanisms in an azole-resistant clinical isolate. This isolate (DSY296) upregulates the multidrug transporter genes
CDR1
and
CDR2
and has acquired a G464S substitution in both
ERG11
alleles. In DSY296, inactivation of
TAC1
, a transcription factor containing a gain-of-function mutation, followed by sequential replacement of
ERG11
mutant alleles with wild-type alleles, restored azole susceptibility to the levels measured for a parent azole-susceptible isolate (DSY294). These sequential genetic manipulations not only demonstrated that these two resistance mechanisms were those responsible for the development of resistance in DSY296 but also indicated that the quantitative level of resistance as measured
in vitro
by MIC determinations was a function of the number of genetic resistance mechanisms operating in any strain. The engineered strains were also tested for their responses to fluconazole treatment in a novel 3-day model of invasive
C. albicans
infection of mice. Fifty percent effective doses (ED
50
s) of fluconazole were highest for DSY296 and decreased proportionally with the sequential removal of each resistance mechanism. However, while the fold differences in ED
50
were proportional to the fold differences in MICs, their magnitude was lower than that measured
in vitro
and depended on the specific resistance mechanism operating.
Revisiting with a Relative-Density Calibration Approach the Determination of Growth Rates of Microorganisms by Use of Optical Density Data from Liquid Cultures
Authors: Lin Hsiu-Li , Lin Chien-Chung , Lin Yi-Jen , Lin Hsiu-Chen , Shih Chwen-Ming , Chen Chi-Rong , Huang Rong-Nan , Kuo Tai-Chih 
Published: January 2010

ABSTRACT

To solve the problems of measuring the growth rates of microorganisms from optical density (OD)-growth time plots, we used relative-density (RD) plots. The relationship of OD and RD was built from the diluted grown cultures. This method was satisfactorily applied to study the growth of
Escherichia coli
and the cyanobacterium
Anabaena spiroides
.
Biofilm Formation by and Multicellular Behavior of
Escherichia coli
O55:H7, an Atypical Enteropathogenic Strain
Authors: Weiss-Muszkat Michal , Shakh Dana , Zhou Yizhou , Pinto Riky , Belausov Eddy , Chapman Matthew R. , Sela Shlomo 
Published: January 2010

ABSTRACT

Enteropathogenic
Escherichia coli
(EPEC) is an important causal agent of diarrheal illness throughout the world. Nevertheless, researchers have only recently begun to explore its capacity to form biofilms. Strain O55:H7 (DMS9) is a clinical isolate belonging to the atypical EPEC (aEPEC) group, which displays a high degree of genetic relatedness to enterohemorrhagic
E. coli
. Strain DMS9 formed a robust biofilm on an abiotic surface at 26°C, but not at 37°C. It also formed a dense pellicle at the air-liquid interface and developed a red, rough, and dry (RDAR) morphotype on Congo red agar. Unlike a previously described
E. coli
O157:H7 strain, the aEPEC strain seems to express cellulose. Transposon mutagenesis was used to identify biofilm-deficient mutants. One of the mutants was inactivated in the
csgFG
genes, required for assembly and secretion of curli fimbriae, while a second mutant had a mutation in
crl
, a thermosensitive global regulator that modulates σ
S
activity and downstream expression of curli and cellulose. The two mutants were deficient in their biofilm formation capabilities and did not form a pellicle at the air-liquid interface. Unlike in
Salmonella
, the
csgFG
mutant in aEPEC completely lost the RDAR phenotype, while the
crl
mutant displayed a unique RDAR “pizza”-like morphotype. Genetic complementation of the two mutants resulted in restoration of the wild-type phenotype. This report is the first to describe and analyze a multicellular behavior in aEPEC and support a major role for curli and the
crl
regulator in biofilm development at low temperatures corresponding to the nonmammalian host environment.
Detection of Infectious Adenoviruses in Environmental Waters by Fluorescence-Activated Cell Sorting Assay
Authors: Li Dan , He Miao , Jiang Sunny C. 
Published: January 2010

ABSTRACT

Methods for rapid detection and quantification of infectious viruses in the environment are urgently needed for public health protection. A fluorescence-activated cell-sorting (FACS) assay was developed to detect infectious adenoviruses (Ads) based on the expression of viral protein during replication in cells. The assay was first developed using recombinant Ad serotype 5 (rAd5) with the E1A gene replaced by a green fluorescent protein (GFP) gene. Cells infected with rAd5 express GFP, which is captured and quantified by FACS. The results showed that rAd5 can be detected at concentrations of 1 to 10
4
PFU per assay within 3 days, demonstrating a linear correlation between the viral concentration and the number of GFP-positive cells with an
r
2
value of >0.9. Following the same concept, FACS assays using fluorescently labeled antibodies specific to the E1A and hexon proteins, respectively, were developed. Assays targeting hexon showed greater sensitivity than assays targeting E1A. The results demonstrated that as little as 1 PFU Ads was detected by FACS within 3 days based on hexon protein, with an
r
2
value greater than 0.9 over a 4-log concentration range. Application of this method to environmental samples indicated positive detection of infectious Ads in 50% of primary sewage samples and 33% of secondary treated sewage samples, but none were found in 12 seawater samples. The infectious Ads ranged in quantity between 10 and 165 PFU/100 ml of sewage samples. The results indicate that the FACS assay is a rapid quantification tool for detecting infectious Ads in environmental samples and also represents a considerable advancement for rapid environmental monitoring of infectious viruses.
Presence and Characterization of Shiga Toxin-Producing
Escherichia coli
and Other Potentially Diarrheagenic
E. coli
Strains in Retail Meats
Authors: Xia Xiaodong , Meng Jianghong , McDermott Patrick F. , Ayers Sherry , Blickenstaff Karen , Tran Thu-Thuy , Abbott Jason , Zheng Jie , Zhao Shaohua 
Published: January 2010

ABSTRACT

To determine the presence of Shiga toxin-producing
Escherichia coli
(STEC) and other potentially diarrheagenic
E. coli
strains in retail meats, 7,258
E. coli
isolates collected by the U.S. National Antimicrobial Resistance Monitoring System (NARMS) retail meat program from 2002 to 2007 were screened for Shiga toxin genes. In addition, 1,275 of the
E. coli
isolates recovered in 2006 were examined for virulence genes specific for other diarrheagenic
E. coli
strains. Seventeen isolates (16 from ground beef and 1 from a pork chop) were positive for
stx
genes, including 5 positive for both
stx
1
and
stx
2
, 2 positive for
stx
1
, and 10 positive for
stx
2
. The 17 STEC strains belonged to 10 serotypes: O83:H8, O8:H16, O15:H16, O15:H17, O88:H38, ONT:H51, ONT:H2, ONT:H10, ONT:H7, and ONT:H46. None of the STEC isolates contained
eae
, whereas seven carried enterohemorrhagic
E. coli
(EHEC)
hlyA
. All except one STEC isolate exhibited toxic effects on Vero cells. DNA sequence analysis showed that the
stx
2
genes from five STEC isolates encoded mucus-activatable Stx2d. Subtyping of the 17 STEC isolates by pulsed-field gel electrophoresis (PFGE) yielded 14 distinct restriction patterns. Among the 1,275 isolates from 2006, 11 atypical enteropathogenic
E. coli
(EPEC) isolates were identified in addition to 3 STEC isolates. This study demonstrated that retail meats, mainly ground beef, were contaminated with diverse STEC strains. The presence of atypical EPEC strains in retail meat is also of concern due to their potential to cause human infections.
Preparation of Genomic DNA from a Single Species of Uncultured Magnetotactic Bacterium by Multiple-Displacement Amplification
Authors: Arakaki Atsushi , Shibusawa Mie , Hosokawa Masahito , Matsunaga Tadashi 
Published: January 2010

ABSTRACT

Magnetotactic bacteria comprise a phylogenetically diverse group that is capable of synthesizing intracellular magnetic particles. Although various morphotypes of magnetotactic bacteria have been observed in the environment, bacterial strains available in pure culture are currently limited to a few genera due to difficulties in their enrichment and cultivation. In order to obtain genetic information from uncultured magnetotactic bacteria, a genome preparation method that involves magnetic separation of cells, flow cytometry, and multiple displacement amplification (MDA) using φ29 polymerase was used in this study. The conditions for the MDA reaction using samples containing 1 to 100 cells were evaluated using a pure-culture magnetotactic bacterium, “
Magnetospirillum magneticum
AMB-1,” whose complete genome sequence is available. Uniform gene amplification was confirmed by quantitative PCR (Q-PCR) when 100 cells were used as a template. This method was then applied for genome preparation of uncultured magnetotactic bacteria from complex bacterial communities in an aquatic environment. A sample containing 100 cells of the uncultured magnetotactic coccus was prepared by magnetic cell separation and flow cytometry and used as an MDA template. 16S rRNA sequence analysis of the MDA product from these 100 cells revealed that the amplified genomic DNA was from a single species of magnetotactic bacterium that was phylogenetically affiliated with magnetotactic cocci in the
Alphaproteobacteria
. The combined use of magnetic separation, flow cytometry, and MDA provides a new strategy to access individual genetic information from magnetotactic bacteria in environmental samples.
Efficacy of Copper-Silver Ionization in Controlling Biofilm- and Plankton-Associated Waterborne Pathogens
Authors: Shih Hsiu-Yun , Lin Yusen E. 
Published: January 2010

ABSTRACT

The study was to determine the efficacy of copper-silver ionization against the formation of
Pseudomonas aeruginosa
,
Stenotrophomonas maltophilia
, and
Acinetobacter baumannii
in biofilms and planktonic phases. At concentrations below the EPA limits, ionization has potential to control the three waterborne pathogens, in addition to
Legionella
, in hospital water systems for nosocomial infection control.
Detection of 2,4,6-Trinitrotoluene-Utilizing Anaerobic Bacteria by
15
N and
13
C Incorporation
Authors: Gallagher Erin M. , Young Lily Y. , McGuinness Lora M. , Kerkhof Lee J. 
Published: January 2010

ABSTRACT

2,4,6-Trinitrotoluene (
15
N or
13
C labeled) was added to Norfolk Harbor sediments to test whether anaerobic bacteria use TNT for growth. Stable-isotope probing (SIP)-terminal restriction fragment length polymorphism (TRFLP) detected peaks in the [
15
N]TNT cultures (60, 163, and 168 bp). The 60-bp peak was also present in the [
13
C]TNT cultures and was related to
Lysobacter taiwanensis
.
Rapid and Specific Method for Evaluating
Streptomyces
Competitive Dynamics in Complex Soil Communities
Authors: Schlatter Daniel C. , Samac Deborah A. , Tesfaye Mesfin , Kinkel Linda L. 
Published: January 2010

ABSTRACT

Quantifying target microbial populations in complex communities remains a barrier to studying species interactions in soil environments. Quantitative PCR (qPCR) assays were developed for quantifying pathogenic
Streptomyces scabiei
and antibiotic-producing
Streptomyces lavendulae
strains in complex soil communities. This assay will be useful for evaluating the competitive dynamics of streptomycetes in soil.
Mannheimia succiniciproducens
Phosphotransferase System for Sucrose Utilization
Authors: Lee Jeong Wook , Choi Sol , Kim Ji Mahn , Lee Sang Yup 
Published: January 2010

ABSTRACT

The succinic acid producer
Mannheimia succiniciproducens
can efficiently utilize sucrose as a carbon source, but its metabolism has not been understood. This study revealed that
M. succiniciproducens
uses a sucrose phosphotransferase system (PTS), sucrose 6-phosphate hydrolase, and a fructose PTS for the transport and utilization of sucrose.
Efficient Production of 2-Oxobutyrate from 2-Hydroxybutyrate by Using Whole Cells of
Pseudomonas stutzeri
Strain SDM
Authors: Gao Chao , Zhang Wen , Lv Chuanjuan , Li Lixiang , Ma Cuiqing , Hu Chunhui , Xu Ping 
Published: January 2010

ABSTRACT

2-Oxobutyrate is an important intermediate in the chemical, drug, and food industries. Whole cells of
Pseudomonas stutzeri
SDM, containing NAD-independent lactate dehydrogenases, effectively converted 2-hydroxybutyrate into 2-oxobutyrate. Under optimal conditions, the biocatalytic process produced 2-oxobutyrate at a high concentration (44.4 g liter
−1
) and a high yield (91.5%).
Exploiting the Role of TolC in Pathogenicity: Identification of a Bacteriophage for Eradication of
Salmonella
Serovars from Poultry
Authors: Ricci Vito , Piddock Laura J. V. 
Published: January 2010

ABSTRACT

Using a screening procedure, three bacteriophages, ST27, ST29, and ST35, were identified with selective activity for
Salmonella enterica
serovar Typhimurium (SL1344) but not SL1344
tolC
::
aph
. Overproduction of TolC led to a lower efficiency of plating (EOP), further suggesting that TolC was the target receptor. Activity against other serovars of
Salmonella
was observed but not against other species of
Enterobacteriaceae
. This study provides proof of principle that bacteriophages can be active against the outer membrane protein of tripartite resistance-nodulation-division (RND) efflux pumps and so could be used to reduce the numbers of
Salmonella
cells in animals reared for food production.
Effects of Aeration on the Synthesis of Poly(3-Hydroxybutyrate) from Glycerol and Glucose in Recombinant
Escherichia coli
Authors: de Almeida Alejandra , Giordano Andrea M. , Nikel Pablo I. , Pettinari M. Julia 
Published: January 2010

ABSTRACT

Bioreactor cultures of
Escherichia coli
recombinants carrying
phaBAC
and
phaP
of
Azotobacter
sp. FA8 grown on glycerol under low-agitation conditions accumulated more poly(3-hydroxybutyrate) (PHB) and ethanol than at high agitation, while in glucose cultures, low agitation led to a decrease in PHB formation. Cells produced smaller amounts of acids from glycerol than from glucose. Glycerol batch cultures stirred at 125 rpm accumulated, in 24 h, 30.1% (wt/wt) PHB with a relative molecular mass of 1.9 MDa, close to that of PHB obtained using glucose.