bluuebunny/crossref_metadata_2025_split huggingface dataset:
Delayed Impact of New Volcanic Ejecta on Ground Water Quality
Authors: Machida Isao , Lee Sun‐Hoon 
Published: June 2008

AbstractWe observed long‐term changes in the concentrations of dissolved ions in ground water caused by leachate from new volcanic ejecta deposited on the ground surface of the volcanic Miyakejima Island, Japan. Water samples were collected from nine wells and two rain collectors over a period of more than 10 years, and samples of runoff water were collected periodically. The samples were analyzed for temperature, pH, alkalinity, Cl−, and SO42−; some of the samples were also analyzed for δ13C. Because the leachate from the volcanic ejecta contained sulfate, we recorded an increase in SO42− concentrations in the (unconfined) well water. The increase in SO42− was initially detected between less than 1.4 and 5.2 years after the eruption, showing peak concentrations from 2.4 to 6.4 years after the eruption. This delayed response reflects the transit time of downward‐moving SO42− in the vadose zone, corresponding to an apparent movement rate of 0.4 to 7.2 cm/d. The rate relates to the mean recharge, represented as a fraction of local mean rainfall, and is calculated using the Cl− balance method. The magnitude of the recorded increases reflects the volume of volcanic mudflow on the ground surface within the basin. For the management of ground water after an eruption, it is therefore important to know the chemical properties of the volcanic ejecta and the spatial distribution of mudflow to estimate the magnitude of the effect of ejecta on ground water quality.
Impact of Simulation Model Solver Performance on Ground Water Management Problems
Authors: Ahlfeld David P. , Hoque Yamen 
Published: June 2008

AbstractGround water management models require the repeated solution of a simulation model to identify an optimal solution to the management problem. Limited precision in simulation model calculations can cause optimization algorithms to produce erroneous solutions. Experiments are conducted on a transient field application with a streamflow depletion control management formulation solved with a response matrix approach. The experiment consists of solving the management model with different levels of simulation model solution precision and comparing the differences in optimal solutions obtained. The precision of simulation model solutions is controlled by choice of solver and convergence parameter and is monitored by observing reported budget discrepancy. The difference in management model solutions results from errors in computation of response coefficients. Error in the largest response coefficients is found to have the most significant impact on the optimal solution. Methods for diagnosing the adequacy of precision when simulation models are used in a management model framework are proposed.
Patterns of Water, Heat, and Solute Flux through Streambeds around Small Dams
Authors: Fanelli Rosemary M. , Lautz Laura K. 
Published: June 2008

AbstractHyporheic exchange, enhanced by complex stream channel morphology, can influence biogeochemical processing in the streambed. These processes chemically alter water passing temporarily through the streambed, which eventually returns to the stream channel and can potentially affect surface water quality. To assess the degree of biogeochemical cycling induced by complex streambed morphology, we instrumented two 20‐m reaches of Red Canyon Creek, Wyoming, each containing a small log dam, with in‐stream minipiezometers and temperature data loggers. We simultaneously observed pore water geochemistry and streambed temperature dynamics in several bedforms located upstream or downstream of the dams. We modeled seepage flux into the streambed using heat transport modeling.Upstream of the dams, low‐permeability sediments have settled out in low‐velocity pools, and enhanced anaerobic biogeochemical cycling occurred in the streambed. Rapid flux into the streambed occurred in glides immediately above the dams, where streambed temperature dynamics and geochemistry were nearly identical to the stream. In riffle sequences downstream of the dams, the streambed was oxygen rich, showed evidence of nitrification, and temperature dynamics indicated high connectivity between the streambed and the stream. Further downstream, streambed pore water geochemistry indicated ground water discharge occurring at the pool‐riffle transition. Assessing streambed biogeochemical cycling may be facilitated by coupling streambed temperature measurements with pore water geochemistry and can aid in understanding how hyporheic exchange contributes to overall stream biogeochemistry.
Pharmacokinetics of Miltefosine in Old World Cutaneous Leishmaniasis Patients
Authors: Dorlo Thomas P. C. , van Thiel Pieter P. A. M. , Huitema Alwin D. R. , Keizer Ron J. , de Vries Henry J. C. , Beijnen Jos H. , de Vries Peter J. 
Published: June 2008

ABSTRACT

The pharmacokinetics of miltefosine in leishmaniasis patients are, to a great extent, unknown. We examined and characterized the pharmacokinetics of miltefosine in a group of patients with Old World (
Leishmania major
) cutaneous leishmaniasis. Miltefosine plasma concentrations were determined in samples taken during and up to 5 months after the end of treatment from 31 Dutch military personnel who contracted cutaneous leishmaniasis in Afghanistan and were treated with 150 mg miltefosine/day for 28 days. Samples were analyzed with a validated liquid chromatography-tandem mass spectrometry assay with a lower limit of quantification (LLOQ) of 4 ng/ml. Population pharmacokinetic modeling was performed with nonlinear mixed-effect modeling, using NONMEM. The pharmacokinetics of miltefosine could best be described by an open two-compartment disposition model, with a first elimination half-life of 7.05 days and a terminal elimination half-life of 30.9 days. The median concentration in the last week of treatment (days 22 to 28) was 30,800 ng/ml. The maximum duration of follow-up was 202 days after the start of treatment. All analyzed samples contained a concentration above the LLOQ. Miltefosine is eliminated from the body much slower than previously thought and is therefore still detectable in human plasma samples taken 5 to 6 months after the end of treatment. The presence of subtherapeutic miltefosine concentrations in the blood beyond 5 months after treatment might contribute to the selection of resistant parasites, and moreover, the measures for preventing the teratogenic risks of miltefosine treatment should be reconsidered.
Restoration of Susceptibility of Intracellular Methicillin-ResistantStaphylococcus aureusto β-Lactams: Comparison of Strains, Cells, and Antibiotics
Authors: Lemaire Sandrine , Olivier Aurélie , Van Bambeke Françoise , Tulkens Paul M. , Appelbaum Peter C. , Glupczynski Youri 
Published: June 2008

ABSTRACTStaphylococcus aureusinvades eukaryotic cells. When methicillin-resistantS. aureus(MRSA) ATCC 33591 is phagocytized by human THP-1 macrophages, complete restoration of susceptibility to cloxacillin and meropenem is shown and the strain becomes indistinguishable from MSSA ATCC 25923 due to the acid pH prevailing in phagolysosomes (S. Lemaire et al., Antimicrob. Agents Chemother. 51:1627-1632, 2007). We examined whether this observation can be extended to (i) strains of current clinical and epidemiological interest (three hospital-acquired MRSA [HA-MRSA] strains, two community-acquired MRSA [CA-MRSA] strains, two HA-MRSA strains with the vancomycin-intermediate phenotype, one HA-MRSA strain with the vancomycin-resistant phenotype, and one animal [porcine] MRSA strain), (ii) activated THP-1 cells and nonprofessional phagocytes (keratinocytes, Calu-3 bronchial epithelial cells), and (iii) other β-lactams (imipenem, oxacillin, cefuroxime, cefepime). All strains showed (i) a marked reduction in MICs in broth at pH 5.5 compared with the MIC at pH 7.4 and (ii) sigmoidal dose-response curves with cloxacillin (0.01× to 100× MIC, 24 h of incubation) after phagocytosis by THP-1 macrophages that were indistinguishable from each other and from the dose-response curve for methicillin-susceptibleS. aureus(MSSA) ATCC 25923 (relative potency [50% effect], 6.09× MIC [95% confidence interval {CI}, 4.50 to 8.25]; relative efficacy [change in bacterial counts over the original inoculum for an infinitely large cloxacillin concentration, or maximal effect], −0.69 log CFU [95% CI, −0.79 to −0.58]). Similar dose-response curves for cloxacillin were also observed with MSSA ATCC 25923 and MRSA ATCC 33591 after phagocytosis by activated THP-1 macrophages, keratinocytes, and Calu-3 cells. By contrast, there was a lower level of restoration of susceptibility of MRSA ATCC 33591 to cefuroxime and cefepime after phagocytosis by THP-1 macrophages, even when the data were normalized for differences in MICs. We conclude that the restoration of MRSA susceptibility to β-lactams after phagocytosis is independent of the strain and the types of cells but varies between β-lactams.
Role of Global Regulators and Nucleotide Metabolism in Antibiotic Tolerance in
Escherichia coli
Authors: Hansen Sonja , Lewis Kim , Vulić Marin 
Published: June 2008

ABSTRACT

Bacterial populations produce a small number of persister cells that exhibit multidrug tolerance. Persister cells are largely responsible for the antibiotic recalcitrance of biofilm infections. The mechanism of persister cell formation largely remains unknown due to the challenges in identifying persister genes. We screened an ordered comprehensive library of 3,985
Escherichia coli
knockout strains to identify mutants with altered antibiotic tolerance. Stationary-state cultures in 96-well plates were exposed to ofloxacin at a concentration which allows only tolerant persister cells to survive. The persister cell level of each culture was determined. A total of 150 mutants with decreased persistence were identified in the initial screen, and subsequent validation confirmed that neither the growth rate nor the ofloxacin MIC was affected for 10 of them. The genes affected in these strains were
dnaJ
and
dnaK
(chaperones),
apaH
(diadenosine tetraphosphatase),
surA
(peptidyl-prolyl
cis
-
trans
isomerase),
fis
and
hns
(global regulators),
hnr
(response regulator of RpoS),
dksA
(transcriptional regulator of rRNA transcription),
ygfA
(5-formyl-tetrahydrofolate cyclo-ligase), and
yigB
(flavin mononucleotide [FMN] phosphatase). The prominent presence of global regulators among these strains pointed to the likely redundancy of persister cell formation mechanisms: the elimination of a regulator controlling several redundant persister genes would be expected to produce a phenotype. This observation is consistent with previous findings for a possible role of redundant genes such as toxin/antitoxin modules in persister cell formation.
ygfA
and
yigB
were of special interest. The mammalian homolog of YgfA (methenyltetrahydrofolate synthetase) catalyzes the conversion of 5-formyl-tetrahydrofolate (THF) into the rapidly degraded 5,10-methenyl-THF, depleting the folate pool. The YigB protein is a phosphatase of FMN which would deplete the pool of this cofactor. Stochastic overexpression of these genes could lead to dormancy and, hence, tolerance by depleting the folate and FMN pools, respectively. Consistent with this scenario, the overexpression of both genes produced increased tolerance to ofloxacin.
Effect of Chemotherapy with Praziquantel on the Production of Cytokines and Morbidity Associated with Schistosomiasis Mansoni
Authors: Martins-Leite P. , Gazzinelli G. , Alves-Oliveira L. F. , Gazzinelli A. , Malaquias L. C. C. , Correa-Oliveira R. , Teixeira-Carvalho A. , Silveira A. M. S. 
Published: June 2008

ABSTRACTThe objective of the present study was to test the hypothesis that treatment of schistosomiasis mansoni with praziquantel can alter significantly the immune response of patients and generate a reversal of the level of fibrosis. Peripheral blood mononuclear cell (PBMC) samples were collected from, and abdominal ultrasound examinations conducted on, volunteers infected withSchistosoma mansoniand living in an area where the disease is endemic, both prior to and one year after treatment with praziquantel. Subjects were classified into groups according to the level of pathology (i.e., absent, incipient, moderate, or severe fibrosis). PBMCs were stimulated with schistosome soluble egg antigens (SEA), and the levels of production of the cytokines gamma interferon (IFN-γ), tumor necrosis factor alpha, transforming growth factor β, and interleukin-4 (IL-4), IL-10, and IL-13 were determined. The chemotherapy was effective in reducing morbidity, particularly for individuals presenting with severe fibrosis. When levels of cytokine production in posttreatment PBMC cultures stimulated by SEA were categorized as low or high, significant differences in the distribution of IL-13 levels between groups presenting with or not presenting with fibrosis were established. Comparison of pre- and posttreatment SEA-induced cytokine levels in individuals who had experienced no change in the grade of fibrosis following chemotherapy revealed that the level of IFN-γ decreased in subjects with fibrosis whereas that of IL-10 decreased in individuals with and without fibrosis. The data suggest that chemotherapy is effective in reducing the morbidity of the disease and that the level of IL-13 may be a useful indicator of the persistence of fibrosis following treatment.
VIM-15 and VIM-16, Two New VIM-2-Like Metallo-β-Lactamases in
Pseudomonas aeruginosa
Isolates from Bulgaria and Germany
Authors: Schneider Ines , Keuleyan Emma , Rasshofer Rudolf , Markovska Rumyana , Queenan Anne Marie , Bauernfeind Adolf 
Published: June 2008

ABSTRACT

Two
Pseudomonas aeruginosa
urine isolates from Bulgaria and Germany produced two new VIM-2 variants. VIM-15 had one amino acid substitution (Tyr218Phe) which caused a significant increase in hydrolytic efficiency. The substitution Ser54Leu, characterizing VIM-16, showed no influence on enzyme activity. Both genes were part of class I integrons located in the chromosome.
Activities of Ceftobiprole, Linezolid, Vancomycin, and Daptomycin against Community-Associated and Hospital-Associated Methicillin-Resistant
Staphylococcus aureus
Authors: Leonard Steven N. , Cheung Chrissy M. , Rybak Michael J. 
Published: June 2008

ABSTRACT

We evaluated the activity of ceftobiprole against 100 community-associated methicillin-resistant
Staphylococcus aureus
(CA-MRSA) and 100 hospital-associated MRSA (HA-MRSA) isolates. Eight isolates were evaluated by time-kill studies for kill rate and potential for synergy with tobramycin. Ceftobiprole MIC
50
and MIC
90
values were 1 and 2 μg/ml, respectively, against CA-MRSA and HA-MRSA. In time-kill analysis, ceftobiprole was bactericidal at all concentrations tested.
IS
Ecp1
-Mediated Transposition of
qnrB
-Like Gene in
Escherichia coli
Authors: Cattoir Vincent , Nordmann Patrice , Silva-Sanchez Jesus , Espinal Paula , Poirel Laurent 
Published: June 2008

ABSTRACT

A novel QnrB-like plasmid-mediated resistance determinant, QnrB19, was identified from an
Escherichia coli
clinical isolate from Colombia. Its gene was associated with an IS
Ecp1
-like insertion element that did not act as a promoter for its expression. Using an in vitro model of transposition, we showed that the IS
Ecp1
-like element was able to mobilize the
qnrB19
gene.
Potent In Vitro Activity of Tomopenem (CS-023) against Methicillin-Resistant
Staphylococcus aureus
and
Pseudomonas aeruginosa
Authors: Koga Tetsufumi , Masuda Nobuhisa , Kakuta Masayo , Namba Eiko , Sugihara Chika , Fukuoka Takashi 
Published: June 2008

ABSTRACT

Tomopenem (formerly CS-023) is a novel 1β-methylcarbapenem with broad-spectrum coverage of gram-positive and gram-negative pathogens. Its antibacterial activity against European clinical isolates of methicillin-resistant
Staphylococcus aureus
(MRSA) and
Pseudomonas aeruginosa
was compared with those of imipenem and meropenem. The MICs of tomopenem against MRSA and
P. aeruginosa
at which 90% of the isolates tested were inhibited were 8 and 4 μg/ml, respectively, and were equal to or more than fourfold lower than those of imipenem and meropenem. The antibacterial activity of tomopenem against MRSA was correlated with a higher affinity for the penicillin-binding protein (PBP) 2a. Its activity against laboratory mutants of
P. aeruginosa
with (i) overproduction of chromosomally coded AmpC β-lactamase; (ii) overproduction of the multidrug efflux pumps MexAB-OprM, MexCD-OprJ, and MexEF-OprN; (iii) deficiency in OprD; and (iv) various combinations of AmpC overproduction, MexAB-OprM overproduction, and OprD deficiency were tested. The increases in the MIC of tomopenem against each single mutant compared with that against its parent strain were within a fourfold range. Tomopenem exhibited antibacterial activity against all mutants, with an observed MIC range of 0.5 to 8 μg/ml. These results suggest that the antibacterial activity of tomopenem against the clinical isolates of MRSA and
P. aeruginosa
should be ascribed to its high affinity for PBP 2a and its activity against the mutants of
P. aeruginosa
, respectively.
Cell-Penetrating Peptide TP10 Shows Broad-Spectrum Activity against both
Plasmodium falciparum
and
Trypanosoma brucei brucei
Authors: Arrighi Romanico B. G. , Ebikeme Charles , Jiang Yang , Ranford-Cartwright Lisa , Barrett Michael P. , Langel Ülo , Faye Ingrid 
Published: June 2008

ABSTRACT

Malaria and trypanosomiasis are diseases which afflict millions and for which novel therapies are urgently required. We have tested two well-characterized cell-penetrating peptides (CPPs) for antiparasitic activity. One CPP, designated TP10, has broad-spectrum antiparasitic activity against
Plasmodium falciparum
, both blood and mosquito stages, and against blood-stage
Trypanosoma brucei brucei
.
In Vitro Activity of Tigecycline against Multidrug-Resistant
Acinetobacter baumannii
and Selection of Tigecycline-Amikacin Synergy
Authors: Moland Ellen S. , Craft David W. , Hong Seong-geun , Kim Soo-young , Hachmeister Lucas , Sayed Shimon D. , Thomson Kenneth S. 
Published: June 2008

ABSTRACT

Polymyxin B, minocycline, and tigecycline were the most potent of 10 antibiotics against 170 isolates of multidrug-resistant
Acinetobacter baumannii
. In time-kill studies, the exposure of a highly tigecycline-resistant isolate to tigecycline resulted in enhanced susceptibility to amikacin and synergistic bactericidal activities of the two drugs.
Spread of OXA-48-Positive Carbapenem-Resistant
Klebsiella pneumoniae
Isolates in Istanbul, Turkey
Authors: Carrër Amélie , Poirel Laurent , Eraksoy Haluk , Cagatay A. Atahan , Badur Selim , Nordmann Patrice 
Published: June 2008

ABSTRACT

The first outbreak of carbapenem-resistant
Klebsiella pneumoniae
isolates producing the plasmid-encoded carbapenem-hydrolyzing oxacillinase OXA-48 is reported. The 39 isolates belonged to two different clones and were collected at the University Hospital of Istanbul, Turkey, from May 2006 to February 2007, and they coproduced various β-lactamases (SHV-12, OXA-9, and TEM-1 for clone A and CTX-M-15, TEM-1, and OXA-1 for clone B).
Implication of an Outer Surface Lipoprotein in Adhesion of
Bifidobacterium bifidum
to Caco-2 Cells
Authors: Guglielmetti Simone , Tamagnini Isabella , Mora Diego , Minuzzo Mario , Scarafoni Alessio , Arioli Stefania , Hellman Jukka , Karp Matti , Parini Carlo 
Published: June 2008

ABSTRACT

We found that the human intestinal isolate
Bifidobacterium bifidum
MIMBb75 strongly adhered to Caco-2 cells. Proteinase K and lithium chloride treatments showed that proteins play a key role in MIMBb75 adhesion to Caco-2 cells. By studying the cell wall-associated proteins, we identified a surface protein, which we labeled BopA. We purified the protein chromatographically and found that it functioned as an adhesion promoter on Caco-2 cells. In silico analysis of the gene coding for this protein and globomycin experiments showed that BopA is a cysteine-anchored lipoprotein expressed as a precursor polypeptide. A database search indicated that BopA appears to function biologically as an oligopeptide/tripeptide-solute-binding protein in the ABC transport system. We discovered a protein corresponding to BopA and its gene in eight other highly adherent
B. bifidum
strains. Finally, we found that
B. bifidum
MIMBb75 and BopA affected the production of interleukin-8 in Caco-2 epithelial cells. BopA is the first protein described to date to be directly involved in the adhesion of bifidobacteria to Caco-2 cells and to show immunomodulatory activity.
SEL, a Selective Enrichment Broth for Simultaneous Growth of
Salmonella enterica
,
Escherichia coli
O157:H7, and
Listeria monocytogenes
Authors: Kim Hyochin , Bhunia Arun K. 
Published: June 2008

ABSTRACT

Multipathogen detection on a single-assay platform not only reduces the cost for testing but also provides data on the presence of pathogens in a single experiment. To achieve this detection, a multipathogen selective enrichment medium is essential to allow the concurrent growth of pathogens. SEL broth was formulated to allow the simultaneous growth of
Salmonella enterica
,
Escherichia coli
O157:H7, and
Listeria monocytogenes
. The results were compared to those obtained with the respective individual selective enrichment broths, Rappaport-Vassiliadis (RV) for
S. enterica
, modified
E. coli
broth with 20 mg of novobiocin/liter for
E. coli
O157:H7, and Fraser broth for
L. monocytogenes
, and a currently used universal preenrichment broth (UPB). The growth of each pathogen in SEL inoculated at 10
1
or 10
3
CFU/ml was superior to that in the respective individual enrichment broth, except in the case of RV, in which
Salmonella
cells inoculated at both concentrations grew equally well. In mixed-culture experiments with cells of the three species present in equal concentrations or at a 1:10:1,000 ratio, the overall growth was proportional to the initial inoculation levels; however, the growth of
L. monocytogenes
was markedly suppressed when cells of this species were present at lower concentrations than those of the other two species. Further, SEL was able to resuscitate acid- and cold-stressed cells, and recovery was comparable to that in nonselective tryptic soy broth containing 6% yeast extract but superior to that in the respective individual selective broths. SEL promoted the growth of all three pathogens in a mixture in ready-to-eat salami and in turkey meat samples. Moreover, each pathogen was readily detected by a pathogen-specific immunochromatographic lateral-flow or multiplex PCR assay. Even though the growth of each pathogen in SEL was comparable to that in UPB, SEL inhibited greater numbers of nontarget organisms than did UPB. In summary, SEL was demonstrated to be a promising new multiplex selective enrichment broth for the detection of the three most prominent food-borne pathogens by antibody- or nucleic acid-based methods.