bluuebunny/crossref_metadata_2025_split huggingface dataset:
Meropenem Pharmacokinetics in the Newborn
Authors: van den Anker John N. , Pokorna Pavla , Kinzig-Schippers Martina , Martinkova Jirina , de Groot Ronald , Drusano G. L. , Sorgel Fritz 
Published: July 2009

ABSTRACT

We studied meropenem in 23 pre-term (gestational age, 29 to 36 weeks) and 15 full-term (gestational age, 37 to 42 weeks) neonates. Meropenem doses of 10, 20, and 40 mg/kg were administered as single doses (30-min intravenous infusion) on a random basis. Blood was obtained for determining the meropenem concentration nine times. Each child required other antimicrobials for proven/suspected bacterial infections. Samples were assayed by high-performance liquid chromatography analysis. Population pharmacokinetic parameter values were obtained by employing the BigNPAG program. Model building was performed by the likelihood ratio test. The final model included estimated creatinine clearance (CL
cr
) (Schwartz formula) and weight (Wt) in the calculation of clearance (meropenem clearance = 0.00112 × CL
cr
+ 0.0925 × Wt + 0.156 liter/hr). The overall fit of the model to the data was good (observed = 1.037 × predicted − 0.096; r
2
= 0.977). Given the distributions of estimated creatinine clearance and weight between pre-term and full-term neonates, meropenem clearance was substantially higher in the full-term group. A Monte Carlo simulation was performed using the creatinine clearance and weight distributions for pre-term and full-term populations separately, examining 20- and 40-mg/kg doses, 8- and 12-h dosing intervals, and 0.5-h and 4-h infusion times. The 8-h interval produced robust target attainments (both populations). If more resistant organisms were to be treated (MIC of 4 to 8 mg/liter), the 40-mg/kg dose and a prolonged infusion was favored. Treating clinicians need to balance dose choices for optimizing target attainment against potential toxicity. These findings require validation in clinical circumstances.
CraA, a Major Facilitator Superfamily Efflux Pump Associated with Chloramphenicol Resistance in
Acinetobacter baumannii
Authors: Roca I. , Marti S. , Espinal P. , Martínez P. , Gibert I. , Vila J. 
Published: July 2009

ABSTRACT

Acinetobacter baumannii
has been increasingly associated with hospital-acquired infections, and the presence of multidrug resistance strains is of great concern to clinicians.
A. baumannii
is thought to possess a great deal of intrinsic resistance to several antimicrobial agents, including chloramphenicol, although the mechanisms involved in such resistance are not well understood. In this work, we have identified a major facilitator superfamily efflux pump present in most
A. baumannii
strains, displaying strong substrate specificity toward chloramphenicol.
Role of Porins in the Susceptibility of
Mycobacterium smegmatis
and
Mycobacterium chelonae
to Aldehyde-Based Disinfectants and Drugs
Authors: Svetlíková Zuzana , Škovierová Henrieta , Niederweis Michael , Gaillard Jean-Louis , McDonnell Gerald , Jackson Mary 
Published: July 2009

ABSTRACT

Nosocomial outbreaks attributable to glutaraldehyde-resistant, rapidly growing mycobacteria are increasing. Here, evidence is provided that defects in porin expression dramatically increase the resistance of
Mycobacterium smegmatis
and
Mycobacterium chelonae
to glutaraldehyde and another aldehyde disinfectant,
ortho
-phthalaldehyde. Since defects in porin activity also dramatically increased the resistance of
M. chelonae
to drugs, there is thus some concern that the widespread use of glutaraldehyde and
ortho
-phthalaldehyde in clinical settings may select for drug-resistant bacteria.
Metabolism and Cometabolism of Cyclic Ethers by a Filamentous Fungus, aGraphiumsp
Authors: Skinner Kristin , Cuiffetti Lynda , Hyman Michael 
Published: July 2009

ABSTRACTThe filamentous fungusGraphiumsp. (ATCC 58400) grows on gaseousn-alkanes and diethyl ether.n-Alkane-grown mycelia of this strain also cometabolically oxidize the gasoline oxygenate methyltert-butyl ether (MTBE). In this study, we characterized the ability of this fungus to metabolize and cometabolize a range of cyclic ethers, including tetrahydrofuran (THF) and 1,4-dioxane (14D). This strain grew on THF and other cyclic ethers, including tetrahydropyran and hexamethylene oxide. However, more vigorous growth was consistently observed on the lactones and terminal diols potentially derived from these ethers. Unlike the case in all previous studies of microbial THF oxidation, a metabolite, γ-butyrolactone, was observed during growth of this fungus on THF. Growth on THF was inhibited by the samen-alkenes andn-alkynes that inhibit growth of this fungus onn-alkanes, while growth on γ-butyrolactone or succinate was unaffected by these inhibitors. Propane and THF also behaved as mutually competitive substrates, and propane-grown mycelia immediately oxidized THF, without a lag phase. Mycelia grown on propane or THF exhibited comparable high levels of hemiacetal-oxidizing activity that generated methyl formate from mixtures of formaldehyde and methanol. Collectively, these observations suggest that THF andn-alkanes may initially be oxidized by the same monooxygenase and that further transformation of THF-derived metabolites involves the activity of one or more alcohol dehydrogenases. Both propane- and THF-grown mycelia also slowly cometabolically oxidized 14D, although unlike THF oxidation, this reaction was not sustainable. Specific rates of THF, 14D, and MTBE degradation were very similar in THF- and propane-grown mycelia.
SomeListeria monocytogenesOutbreak Strains Demonstrate Significantly Reduced Invasion,inlATranscript Levels, and Swarming Motility In Vitro
Authors: Roberts A. J. , Williams S. K. , Wiedmann M. , Nightingale K. K. 
Published: July 2009

ABSTRACTListeria monocytogenescan cause a severe invasive food-borne disease known as listeriosis, and large outbreaks of this disease occur occasionally. Based on molecular-subtype data, epidemic clone (EC) strains have been defined, including ECI and ECIa, which have caused listeriosis outbreaks on different continents. While a number of molecular-subtyping studies of outbreak strains have been reported, few comprehensive data sets of virulence-associated characteristics of these strains are available. We assembled a set of human clinical isolates from 15 outbreaks that occurred worldwide between 1975 and 2002. Initial characterization of these strains showed significant variation in the ability to invade human Caco-2 intestinal epithelial cells and HepG2 hepatic cells; four strains showed consistently reduced invasion in both cell lines. DNA sequencing ofinlA, which encodes a protein required for efficient Caco-2 and HepG2 invasion, showed that none of the invasion-attenuated strains contained known virulence-attenuating mutations ininlA. Phylogenetic analyses ofinlAsequences revealed a well-supported clade containing a fully invasive ECI strain and three invasion-attenuated ECI strains, along with a fully invasive ECIa strain and an invasion-attenuated ECIa strain. Of the four invasion-attenuated strains, one strain showed both reducedinlAtranscript levels and impaired swarming, one strain showed reducedinlAtranscript levels, and two strains showed reduced swarming. Overall, our data show that (i)L. monocytogenesstrains from outbreaks vary significantly in invasion efficiency and (ii) different mechanisms may contribute to reduced invasion efficiency. Association between EC strains and listeriosis outbreaks may involve characteristics other than virulence phenotypes, including survival and growth in food-associated environments.
Pulsed-Field Gel Electrophoresis Profile Changes Resulting from Spontaneous Chromosomal Deletions in Enterohemorrhagic
Escherichia coli
O157:H7 during Passage in Cattle
Authors: Yoshii Noriyo , Ogura Yoshitoshi , Hayashi Tetsuya , Ajiro Takashi , Sameshima Toshiya , Nakazawa Muneo , Kusumoto Masahiro , Iwata Taketoshi , Akiba Masato 
Published: July 2009

ABSTRACT

A total of 905 enterohemorrhagic
Escherichia coli
(EHEC) O157:H7 isolates that were recovered from experimentally infected cattle, in addition to the inoculated strain, were analyzed by pulsed-field gel electrophoresis (PFGE). Twelve PFGE profiles other than that of the inoculated strain were observed. We successfully identified five distinct chromosomal deletions that affected the PFGE profiles using whole-genome PCR scanning and DNA sequencing analysis. The changes in PFGE profiles of EHEC O157:H7 isolates after passage through the intestinal tract of cattle were partially generated by deletion of chromosomal regions.
Development of an Improved Isolation Approach and Simple Sequence Repeat Markers To Characterize
Phytophthora capsici
Populations in Irrigation Ponds in Southern Georgia
Authors: Wang Ziying , Langston David B. , Csinos Alexander S. , Gitaitis Ronald D. , Walcott Ronald R. , Ji Pingsheng 
Published: July 2009

ABSTRACT

Phytophthora capsici
, the causal agent of
Phytophthora
blight, is a major concern in vegetable production in Georgia and many other states in the United States. Contamination of irrigation water sources by
P. capsici
may be an important source of inoculum for the pathogen. A simple method was developed in this study to improve the efficiency of recovering
P. capsici
from fruits used as baits in irrigation ponds. In contrast to direct isolation on agar plates, infected fruit tissues were used to inoculate stems of pepper seedlings, and the infected pepper stems were used for isolation on agar plates. With isolation through inoculation of pepper stems, the frequency of recovering
P. capsici
from infected eggplant and pear fruits increased from 13.9% to 77.7% and 8.1% to 53.5%, respectively, compared with direct isolation on agar plates.
P. capsici
was isolated from seven out of nine irrigation ponds evaluated, with most of the ponds containing both A1 and A2 mating types and a 4:5 ratio of A1 to A2 when isolates from all ponds were calculated. All
P. capsici
isolates were pathogenic on squash plants, and only a small proportion (8.2%) of the isolates were resistant or intermediately sensitive to mefenoxam. Simple sequence repeats (SSRs) were identified through bioinformatics mining of 55,848 publicly available expressed sequence tags of
P. capsici
in dbEST GenBank. Thirty-one pairs of SSR primers were designed, and SSR analysis indicated that the 61
P. capsici
isolates from irrigation ponds were genetically distinct. Cluster analysis separated the isolates into five genetic clusters with no more than two genetic groups in one pond, indicating relatively low
P. capsici
genetic diversity in each pond. The isolation method and SSR markers developed for
P. capsici
in this study could contribute to a more comprehensive understanding of the genetic diversity of this important pathogen.
Protein Engineering of the Transcriptional Activator FhlA To Enhance Hydrogen Production in
Escherichia coli
Authors: Sanchez-Torres Viviana , Maeda Toshinari , Wood Thomas K. 
Published: July 2009

ABSTRACT

Escherichia coli
produces H
2
from formate via the formate hydrogenlyase (FHL) complex during mixed acid fermentation; the FHL complex consists of formate dehydrogenase H (encoded by
fdhF
) for forming 2H
+
, 2e
−
, and CO
2
from formate and hydrogenase 3 (encoded by
hycGE
) for synthesizing H
2
from 2H
+
and 2e
−
. FHL protein production is activated by the σ
54
transcriptional activator FhlA, which activates transcription of
fdhF
and the
hyc
,
hyp
, and
hydN-hypF
operons. Here, through random mutagenesis using error-prone PCR over the whole gene, as well as over the
fhlA
region encoding the first 388 amino acids of the 692-amino-acid protein, we evolved FhlA to increase H
2
production. The amino acid replacements in FhlA133 (Q11H, L14V, Y177F, K245R, M288K, and I342F) increased hydrogen production ninefold, and the replacements in FhlA1157 (M6T, S35T, L113P, S146C, and E363K) increased hydrogen production fourfold. Saturation mutagenesis at the codons corresponding to the amino acid replacements in FhlA133 and at position E363 identified the importance of position L14 and of E363 for the increased activity; FhlA with replacements L14G and E363G increased hydrogen production (fourfold and sixfold, respectively) compared to FhlA. Whole-transcriptome and promoter reporter constructs revealed that the mechanism by which the FhlA133 changes increase hydrogen production is by increasing transcription of all of the genes activated by FhlA (the FHL complex). With FhlA133, transcription of P

fdhF

and P

hyc

is less sensitive to formate regulation, and with FhlA363 (E363G), P

hyc

transcription increases but P

hyp

transcription decreases and hydrogen production is less affected by the repressor HycA.
Application of a Short Intracellular pH Method to Flow Cytometry for Determining
Saccharomyces cerevisiae
Vitality
Authors: Weigert Claudia , Steffler Fabian , Kurz Tomas , Shellhammer Thomas H. , Methner Frank-Jürgen 
Published: July 2009

ABSTRACT

The measurement of yeast's intracellular pH (ICP) is a proven method for determining yeast vitality. Vitality describes the condition or health of viable cells as opposed to viability, which defines living versus dead cells. In contrast to fluorescence photometric measurements, which show only average ICP values of a population, flow cytometry allows the presentation of an ICP distribution. By examining six repeated propagations with three separate growth phases (lag, exponential, and stationary), the ICP method previously established for photometry was transferred successfully to flow cytometry by using the pH-dependent fluorescent probe 5,6-carboxyfluorescein. The correlation between the two methods was good (
r
2
= 0.898,
n
= 18). With both methods it is possible to track the course of growth phases. Although photometry did not yield significant differences between exponentially and stationary phases (
P
= 0.433), ICP via flow cytometry did (
P
= 0.012). Yeast in an exponential phase has a unimodal ICP distribution, reflective of a homogeneous population; however, yeast in a stationary phase displays a broader ICP distribution, and subpopulations could be defined by using the flow cytometry method. In conclusion, flow cytometry yielded specific evidence of the heterogeneity in vitality of a yeast population as measured via ICP. In contrast to photometry, flow cytometry increases information about the yeast population's vitality via a short measurement, which is suitable for routine analysis.
Potentially Pathogenic Bacteria in Shower Water and Air of a Stem Cell Transplant Unit
Authors: Perkins Sarah D. , Mayfield Jennie , Fraser Victoria , Angenent Largus T. 
Published: July 2009

ABSTRACT

Potential pathogens from shower water and aerosolized shower mist (i.e., shower aerosol) have been suggested as an environmental source of infection for immunocompromised patients. To quantify the microbial load in shower water and aerosol samples, we used culture, microscopic, and quantitative PCR methods to investigate four shower stalls in a stem cell transplant unit at Barnes-Jewish Hospital in St. Louis, MO. We also tested membrane-integrated showerheads as a possible mitigation strategy. In addition to quantification, a 16S rRNA gene sequencing survey was used to characterize the abundant bacterial populations within shower water and aerosols. The average total bacterial counts were 2.2 × 10
7
cells/liter in shower water and 3.4 × 10
4
cells/m
3
in shower aerosol, and these counts were reduced to 6.3 × 10
4
cells/liter (99.6% efficiency) and 8.9 × 10
3
cells/m
3
(82.4% efficiency), respectively, after membrane-integrated showerheads were installed. Potentially pathogenic organisms were found in both water and aerosol samples from the conventional showers. Most notable was the presence of
Mycobacterium mucogenicum
(99.5% identity) in the water and
Pseudomonas aeruginosa
(99.3% identity) in the aerosol samples. Membrane-integrated showerheads may protect immunocompromised patients from waterborne infections in a stem cell transplant unit because of efficient capture of vast numbers of potentially pathogenic bacteria from hospital water. However, an in-depth epidemiological study is necessary to investigate whether membrane-integrated showerheads reduce hospital-acquired infections. The microbial load in shower aerosols with conventional showerheads was elevated compared to the load in HEPA-filtered background air in the stem cell unit, but it was considerably lower than typical indoor air. Thus, in shower environments without HEPA filtration, the increase in microbial load due to shower water aerosolization would not have been distinguishable from anticipated variations in background levels.
Bacterial Chemotaxis to Atrazine and Relateds-Triazines
Authors: Liu Xianxian , Parales Rebecca E. 
Published: July 2009

ABSTRACTPseudomonassp. strain ADP utilizes the human-mades-triazine herbicide atrazine as the sole nitrogen source. The results reported here demonstrate that atrazine and the atrazine degradation intermediatesN-isopropylammelide and cyanuric acid are chemoattractants for strain ADP. In addition, the nonmetabolizeds-triazine ametryn was also an attractant. The chemotactic response to theses-triazines was not specifically induced during growth with atrazine, and atrazine metabolism was not required for the chemotactic response. A cured variant of strain ADP (ADP M13-2) was attracted tos-triazines, indicating that the atrazine catabolic plasmid pADP-1 is not necessary for the chemotactic response and that atrazine degradation and chemotaxis are not genetically linked. These results indicate that atrazine and relateds-triazines are detected by one or more chromosomally encoded chemoreceptors inPseudomonassp. strain ADP. We demonstrated thatEscherichia coliis attracted to thes-triazine compoundsN-isopropylammelide and cyanuric acid, and anE. colimutant lacking Tap (the pyrimidine chemoreceptor) was unable to respond tos-triazines. These data indicate that pyrimidines and triazines are detected by the same chemoreceptor (Tap) inE. coli. We showed thatPseudomonassp. strain ADP is attracted to pyrimidines, which are the naturally occurring structures closest to triazines, and propose that chemotaxis towards-triazines may be due to fortuitous recognition by a pyrimidine chemoreceptor inPseudomonassp. strain ADP. In competition assays, the presence of atrazine inhibited chemotaxis ofPseudomonassp. strain ADP to cytosine, and cytosine inhibited chemotaxis to atrazine, suggesting that pyrimidines ands-triazines are detected by the same chemoreceptor.
Carbohydrate Metabolism Differences between Subgroup A1 and B2 Strains of
B
acillus anthracis
as Assessed by Comparative Genomics and Functional Genetics
Authors: Sylvestre Patricia , Moya Mary , Haustant Michel , Vaissaire Josée , Mock Michèle 
Published: July 2009

ABSTRACT

In France,
Bacillus anthracis
subgroup B2 strains do not metabolize starch or glycogen but can use gluconate, whereas subgroup A1 strains show the inverse pattern. Functional genetic analysis revealed that mutations in the
amyS
and
gntK
genes encoding an alpha-amylase and a gluconate kinase, respectively, were responsible for these phenotypes.
Single Nucleotide Polymorphism-Based Diagnostic System for Crop-Associated
Sclerotinia
Species
Authors: Andrew Marion , Kohn Linda M. 
Published: July 2009

ABSTRACT

A molecular diagnostic system using single nucleotide polymorphisms (SNPs) was developed to identify four
Sclerotinia
species:
S. sclerotiorum
(Lib.) de Bary,
S. minor
Jagger,
S. trifoliorum
Erikss., and the undescribed species
Sclerotinia
species 1. DNAs of samples are hybridized with each of five 15-bp oligonucleotide probes containing an SNP site midsequence unique to each species. For additional verification, hybridizations were performed using diagnostic single nucleotide substitutions at a 17-bp sequence of the calmodulin locus. The accuracy of these procedures was compared to that of a restriction fragment length polymorphism (RFLP) method based on Southern hybridizations of EcoRI-digested genomic DNA probed with the ribosomal DNA-containing plasmid probe pMF2, previously shown to differentiate
S. sclerotiorum
,
S. minor
, and
S. trifoliorum.
The efficiency of the SNP-based assay as a diagnostic test was evaluated in a blind screening of 48
Sclerotinia
isolates from agricultural and wild hosts. One isolate of
Botrytis cinerea
was used as a negative control. The SNP-based assay accurately identified 96% of
Sclerotinia
isolates and could be performed faster than RFLP profiling using pMF2. This method shows promise for accurate, high-throughput species identification.
H
2
O
2
Activates the Nuclear Localization of Msn2 and Maf1 through Thioredoxins in
Saccharomyces cerevisiae
Authors: Boisnard Stéphanie , Lagniel Gilles , Garmendia-Torres Cecilia , Molin Mikael , Boy-Marcotte Emmanuelle , Jacquet Michel , Toledano Michel B. , Labarre Jean , Chédin Stéphane 
Published: July 2009

ABSTRACT

The cellular response to hydrogen peroxide (H
2
O
2
) is characterized by a repression of growth-related processes and an enhanced expression of genes important for cell defense. In budding yeast, this response requires the activation of a set of transcriptional effectors. Some of them, such as the transcriptional activator Yap1, are specific to oxidative stress, and others, such as the transcriptional activators Msn2/4 and the negative regulator Maf1, are activated by a wide spectrum of stress conditions. How these general effectors are activated in response to oxidative stress remains an open question. In this study, we demonstrate that the two cytoplasmic thioredoxins, Trx1 and Trx2, are essential to trigger the nuclear accumulation of Msn2/4 and Maf1, specifically under H
2
O
2
treatment. Contrary to the case with many stress conditions previously described for yeast, the H
2
O
2
-induced nuclear accumulation of Msn2 and Maf1 does not correlate with the downregulation of PKA kinase activity. Nevertheless, we show that PP2A phosphatase activity is essential for driving Maf1 dephosphorylation and its subsequent nuclear accumulation in response to H
2
O
2
treatment. Interestingly, under this condition, the lack of PP2A activity has no impact on the subcellular localization of Msn2, demonstrating that the H
2
O
2
signaling pathways share a common route through the thioredoxin system and then diverge to activate Msn2 and Maf1, the final integrators of these pathways.