bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diapause and overwintering of the hoverflyEpisyrphus balteatus
Authors: Hondelmann Peter , Poehling Hans‐Michael 
Published: May 2007

AbstractThe overwintering biology of the hoverflyEpisyrphus balteatus(DeGeer) (Diptera: Syrphidae) was studied and analysed. In Europe, females of this species can overwinter as adults in a facultative, reproductive diapause. The diapause phase is characterized by the ovaries ceasing to develop and by hypertrophy of the fat body. Diapause was induced during the second and third larval instars. The critical photoperiod for inducing diapause was between 11.8 and 11.9 h, corresponding to the day lengths that occur during mid‐ to late September in Hannover, Germany. When temperatures were lower, insects could be induced into diapause at longer day lengths, similar to those that occur in early September in Hannover. A semifield study was done during the winter of 1999/2000 to confirm the results obtained under laboratory conditions and to obtain additional information on the over‐wintering development and mortality ofE. balteatus. The results suggested that mortality was correlated with the duration of the experiment and with humidity, rainfall, and temperature. The importance of these results for the regulation of cereal aphid populations by this hoverfly is discussed.
Neurotoxicity upon infusion of dimethylsulfoxide‐cryopreserved peripheral blood stem cells in patients with and without pre‐existing cerebral disease
Authors: Mueller Lutz P. , Theurich Sebastian , Christopeit Maximilian , Grothe Wilfried , Muetherig Anke , Weber Thomas , Guenther Susanne , Behre Gerhard 
Published: May 2007

AbstractObjective:  Toxicity related to the infusion of dimethylsulfoxide (DMSO)‐cryopreserved peripheral blood stem cells (DMSO‐PBSC) mainly comprises cardiovascular events. Fatal neurotoxicity has been reported in a few cases. DMSO represents the putative causative agent of such rare toxicities and elaborate strategies to replace DMSO would benefit from the identification of predisposing factors for DMSO‐related toxicities.Methods:  Here, we report on DMSO‐related neurotoxicity in a series of patients (n = 51) receiving DMSO‐PBSC. The analyzed patient‐series included eight patients with pre‐existing cerebral disease, partially with a history of epileptic seizures.Results:  Neurotoxicity was observed in only one patient who suffered from a generalized tonic seizure upon infusion of DMSO‐PBSC and for which the clinical course is reported herein. No neurotoxicity was observed in the group of patients with pre‐existing neurological disease. Furthermore, no neurotoxicity was observed in patients who received particularly large volumes of DMSO. In all patients, mild non‐neurological side effects occurred but besides the reported seizure no other severe adverse events were observed upon PBSC‐infusion.Conclusions:  To our knowledge, this is the first report addressing the identification of predisposing factors for DMSO‐related neurotoxicty. We conclude that infusion of DMSO‐PBSC can be performed safely in patients with pre‐existing cerebral disease despite the rare occurrence of severe neurotoxicity. Retrospective multicenter studies are warranted to identify patients who would benefit from elaborate methods of DMSO‐replacement.
The Energetic Determination, Spatial Dispersion and Density Dependence of Myrmeleon Ant Lion Pits in Las Cruces, Costa Rica
Authors: Swenson Nathan G. , Luke Mahler D. , Ferro Michael , Ritchie Andrew 
Published: May 2007

ABSTRACTThe amount of space used by an organism is energetically determined. We utilized a population of ant lion larvae in Costa Rica to test allometric theories concerning the use of space by organisms and how different densities of individuals affect the use of space. The area of ant lion trapping pits scaled with mass to the three‐quarters power, supporting allometric theory for sessile organisms. Our analyses also show that larger ant lion larvae show spatial repulsion and facultative density dependent pit‐building strategies.
Cost recovery of community‐managed piped water systems in Ashanti region, Ghana
Authors: Nyarko K. B. , Oduro‐Kwarteng S. , Adama I. 
Published: May 2007

AbstractRecovering the cost of water services is a major obstacle in achieving a sustainable drinking water supply in developing countries. This paper assesses the levels of cost recovery, household willingness and ability to pay for the full supply cost of water services, and financial management. The study was conducted in five out of 30 community‐managed piped systems in Ashanti region, Ghana. The study shows that the existing tariffs are not sufficient to recover the full supply cost of the service based on the guidelines of the Government Community Water Supply and Sanitation Agency (CWSA). Using 5% of household income as the ability‐to‐pay criteria, 67–87% of the households in the five communities could pay the full supply cost of the service. The poor recovery of the supply cost threatens the long‐term financial sustainability of the small towns' water supply sector.
Modelling the Manchester Ship Canal
Authors: Heatlie Fiona , Drake John , Debski Damian 
Published: May 2007

AbstractOne of the great engineering projects of the Victorian era, the Manchester Ship Canal extends for 55 km from central Manchester to the Mersey estuary on England's northwest coast. In addition to providing navigation to Manchester for ocean‐going ships, the canal drains a total catchment of over 3000 km2. As such, the canal plays a vital role in the prevention of flooding in central Manchester and Warrington. Despite its importance in terms of flood relief, the unique character and ownership of the canal have left it excluded from legislation regarding flood management. Unlike the majority of rivers, no model of the canal had ever been constructed, leaving a missing piece in the puzzle of flood management in the northwest. This paper describes the creation of a one‐dimensional ISIS hydrodynamic model of the canal and the testing of a range of flood scenarios with that model.
Comparison of model approaches for predicting coliform removal in waste stabilization ponds
Authors: Buchauer Konrad 
Published: May 2007

AbstractThis paper compares the two most frequently used approaches for the prediction of faecal coliforms in the effluent (FCe) of waste stabilization ponds (WSPs): the continuous stirred reactor (CSTR) model and the dispersed flow (DF) model. On the basis of theoretical and practical analysis, it is concluded that, under most conditions usually found in practice, the DF model can be expected to predict unrealistically low FCe. This trend is more pronounced the more the flow conditions in the pond(s) approach plug flow, and the higher the average retention time per pond. Model differences in FCe prediction typically deviate from one another by up to 1–2 log units. This can lead to the design of substantially different pond sizes, with footprint differences between the two models of 30–50% not being exceptional. Consequently, on the basis of usually applied model parameters, for the time being it appears safer to use the CSTR model for FCe prediction in WSP systems.
Mapping Three‐Dimensional Water‐Quality Data in the Chesapeake Bay Using Geostatistics1
Authors: Chehata Mondher , Jasinski David , Monteith Michael C. , Samuels William B. 
Published: May 2007

Abstract: Data interpretation and visualization software tools with geostatistical capabilities were adapted, customized, and tested to assist the Chesapeake Bay Program in improving its water‐quality modeling protocols. Tools were required to interpolate, map, and visualize three‐dimensional (3D) water‐quality data, with the capability to determine estimation errors. Components of the software, originally developed for ground‐water modeling, were customized for application in estuaries. Additional software components were developed for retrieval, and for pre‐ and post‐ processing of data. The Chesapeake Bay Program uses the 3D mapped data for input to the Bay water‐quality model that projects the future health of the Bay and its tidal tributary system. In determining water‐quality attainment criteria, 3D kriging estimation errors are needed as a statistical measure of uncertainty. Furthermore, given the high cost of installing and operating new monitoring stations, geostatistical techniques can assist the Chesapeake Bay Program in the identification of suitable data collection locations. Following the evaluation, selection, and development of the software components phase, 3D ordinary kriging techniques with directional semi‐variograms to account for anisotropy were successfully demonstrated for mapping 3D fixed station water‐quality data, such as dissolved oxygen and salinity. Additionally, an improved delineation tool was implemented to simulate the upper and lower pycnocline boundary surfaces allowing the segregation of the interpolated 3D data into three separate zones for a better characterization of the pycnocline layer.
Cytoplasmic-Membrane Anchoring of a Class A β-Lactamase and Its Capacity in Manifesting Antibiotic Resistance
Authors: Suvorov Maxim , Vakulenko Sergei B. , Mobashery Shahriar 
Published: May 2007

ABSTRACT

Bacterial β-lactamases are the major causes of resistance to β-lactam antibiotics. Three classes of these enzymes are believed to have evolved from ancestral penicillin-binding proteins (PBPs), enzymes responsible for bacterial cell wall biosynthesis. Both β-lactamases and PBPs are able to efficiently form acyl-enzyme species with β-lactam antibiotics. In contrast to β-lactamases, PBPs are unable to efficiently turn over antibiotics and therefore are susceptible to inhibition by β-lactam compounds. Although both PBPs and gram-negative β-lactamases operate in the periplasm, PBPs are anchored to the cytoplasmic membrane, but β-lactamases are not. It is believed that β-lactamases shed the membrane anchor in the course of evolution. The significance of this event remains unclear. In an attempt to demonstrate any potential influence of the membrane anchor on the overall biological consequences of β-lactamases, we fused the TEM-1 β-lactamase to the C-terminal membrane-anchor of penicillin-binding protein 5 (PBP5) of
Escherichia coli
. The enzyme was shown to express well in
E. coli
and was anchored to the cytoplasmic membrane. Expression of the anchored enzyme did not result in any changes in antibiotic resistance pattern of bacteria or growth rates. However, in the process of longer coincubation, the organism that harbored the plasmid for the anchored TEM-1 β-lactamase lost out to the organism transformed by the plasmid for the nonanchored enzyme over a period of 8 days of continuous growth. The effect would appear to be selection of a variant that eliminates the problematic protein through elimination of the plasmid that encodes it and not structural or catalytic effects at the protein level. It is conceivable that an evolutionary outcome could be the shedding of the sequence for the membrane anchor or alternatively evolution of these enzymes from nonanchored progenitors.
Efficacy of a Novel Rifamycin Derivative, ABI-0043, against
Staphylococcus aureus
in an Experimental Model of Foreign-Body Infection
Authors: Trampuz Andrej , Murphy Christopher K. , Rothstein David M. , Widmer Andreas F. , Landmann Regine , Zimmerli Werner 
Published: May 2007

ABSTRACT

We compared the efficacy of a novel rifamycin derivative, ABI-0043, with that of rifampin, alone and in combination with levofloxacin, against methicillin-susceptible
Staphylococcus aureus
ATCC 29213 in a guinea pig tissue-cage infection model. The MIC, logarithmic-growth-phase minimal bactericidal concentration, and stationary-growth-phase minimal bactericidal concentration of ABI-0043 were 0.001, 0.008, and 0.25 μg/ml, respectively; the corresponding concentrations of rifampin were 0.016, 0.8, and 3.6 μg/ml, respectively. After a single intraperitoneal dose of 12.5 mg/kg of body weight, the peak concentration in cage fluid was 1.13 μg/ml of ABI-0043 and 0.98 μg/ml of rifampin. Five days after completion of treatment, levofloxacin administered alone (5 mg/kg/12 h) resulted in bacterial counts in cage fluid that were similar to those for untreated controls (>8.0 log
10
CFU/ml), whereas rifampin and ABI-0043 administered alone (12.5 mg/kg/12 h) decreased the mean titers of bacteria ± standard deviations to 1.43 ± 0.28 log
10
and 1.57 ± 0.53 log
10
CFU/ml, respectively, in cage fluid. In combination with levofloxacin, both rifamycins cleared bacteria from the cage fluid. The cure rates of cage-associated infections with rifampin and ABI-0043 administered alone were 46% and 58%, respectively, and increased to 88% and 92% in combination with levofloxacin. Emergence of rifamycin resistance was observed in 42% of cages after ABI-0043 therapy and in 38% of cages after rifampin therapy; no emergence of resistance occurred with combination treatment with levofloxacin. In conclusion, ABI-0043 had cure rates comparable to that of rifampin. ABI-0043 in combination with a quinolone has the potential for treatment of implant-associated infections caused by susceptible strains of
S. aureus
, potentially without drug-drug interactions.
Dual Targeting of DNA Gyrase and Topoisomerase IV: Target Interactions of Heteroaryl Isothiazolones in
Staphylococcus aureus
Authors: Cheng Jijun , Thanassi Jane A. , Thoma Christy L. , Bradbury Barton J. , Deshpande Milind , Pucci Michael J. 
Published: May 2007

ABSTRACT

Heteroaryl isothiazolones (HITZs) are antibacterial agents that display excellent in vitro activity against
Staphylococcus aureus
. We recently identified a series of these compounds that show potent bactericidal activities against methicillin-resistant
Staphylococcus aureus
(MRSA). We report here the results of in vitro resistance studies that reveal potential underlying mechanisms of action. HITZs selected
gyrA
mutations exclusively in first-step mutants of wild-type
S. aureus
, indicating that in contrast to the case with most quinolones, DNA gyrase is the primary target. The compounds displayed low mutation frequencies (10
−9
to 10
−10
) at concentrations close to the MICs and maintained low MICs (≤0.016 μg/ml) against mutants with single mutations in either
gyrA
or
grlA
(
parC
). These data suggested that HITZs possess significant inhibitory activities against target enzymes, DNA gyrase and topoisomerase IV. This dual-target inhibition was supported by low 50% inhibitory concentrations against topoisomerase IV as measured in a decatenation activity assay and against DNA gyrase as measured in a supercoiling activity assay. Good antibacterial activities (≤1 μg/ml) against staphylococcal
gyrA grlA
double mutants, as well as low frequencies (10
−9
to 10
−10
) of selection of still higher-level mutants, also suggested that HITZs remained active against mutant enzymes. We further demonstrated that HITZs exhibit good inhibition of both
S. aureus
mutant enzymes and thus continue to possess a novel dual-targeting mode of action against these mutant strains. In stepwise acquisition of mutations, HITZs selected quinolone resistance determining region mutations
gyrA
(
Ser84Leu
),
grlA
(
Ser80Phe
),
grlA
(
Ala116Val
), and
gyrA
(
Glu88Lys
) sequentially, suggesting that the corresponding amino acids are key amino acids involved in the binding of HITZs to topoisomerases. The overall profile of these compounds suggests the potential utility of HITZs in combating infections caused by
S. aureus
, including multidrug-resistant MRSA.
Pyrophosphorolytic Excision of Nonobligate Chain Terminators by Hepatitis C Virus NS5B Polymerase
Authors: Deval Jérôme , Powdrill Megan H. , D'Abramo Claudia M. , Cellai Luciano , Götte Matthias 
Published: May 2007

ABSTRACT

Nonobligate chain terminators, such as 2′-C-methylated nucleotides, block RNA synthesis by the RNA-dependent RNA polymerase (RdRp) of hepatitis C virus (HCV). Previous studies with related viral polymerases have shown that classical chain terminators lacking the 3′-hydroxyl group can be excised in the presence of pyrophosphate (PP
i
), which is detrimental to the inhibitory activity of these compounds. Here we demonstrate that the HCV RdRp enzyme is capable of removing both obligate and clinically relevant nonobligate chain terminators. Pyrimidines are more efficiently excised than are purines. The presence of the next complementary templated nucleotide literally blocks the excision of obligate chain terminators through the formation of a dead-end complex (DEC). However, 2′-C-methylated CMP is still cleaved efficiently under these conditions. These findings show that a 2′-methylated primer terminus impedes nucleotide binding. The S282T mutation, associated with resistance to 2′-C-methylated nucleotides, does not affect the excision patterns. Thus, the decreased susceptibility to 2′-C-methylated nucleotides appears to be based solely on improved discrimination between the inhibitor and its natural counterpart. In conclusion, our data suggest that the phosphorolytic excision of nonobligate, pyrimidine-based chain terminators can diminish their potency. The templated nucleotide does not appear to provide protection from excision through DEC formation.
Interaction of the GraRS Two-Component System with the VraFG ABC Transporter To Support Vancomycin-Intermediate Resistance in
Staphylococcus aureus
Authors: Meehl Michael , Herbert Silvia , Götz Friedrich , Cheung Ambrose 
Published: May 2007

ABSTRACT

Current treatment for serious infections caused by methicillin-resistant
Staphylococcus aureus
relies heavily upon the glycopeptide antibiotic vancomycin. Unfortunately, this practice has led to an intermediate resistance phenotype that is particularly difficult to treat in invasive staphylococcal diseases, such as septicemia and its metastatic complications, including endocarditis. Although the vancomycin-intermediate resistance phenotype has been linked to abnormal cell wall structures and autolytic rates, the corresponding genetic changes have not been fully elucidated. Previously, whole-genome array studies listed numerous genes that are overexpressed in vancomycin-intermediate sensitive strains, including
graRS
(SACOL0716 to -0717), encoding a two-component regulatory system (TCRS), as well as the adjacent
vraFG
(SACOL0718 to -0720), encoding an ATP-binding cassette (ABC) transporter; but the exact contribution of these genes to increased vancomycin resistance has not been defined. In this study, we showed that isogenic strains with mutations in genes encoding the GraRS TCRS and the VraFG ABC transporter are hypersensitive to vancomycin as well as polymyxin B. Moreover, GraRS regulates the expression of the adjacent VraFG pump, reminiscent of gram-positive bacteriocin-immunity regulons. Mutations of
graRS
and
vraFG
also led to increased autolytic rates and a more negative net surface charge, which may explain, in part, to their increased sensitivity to cationic antimicrobial peptides. Taken together, these data reveal an important genetic mediator to the vancomycin-intermediate
S. aureus
phenotype and may hold clues to the selective pressures on staphylococci upon exposure to selective cationic peptide antibiotics used in clinical practice.
Lack of an Effect of Antibiotic Treatment on Prolonged Detection of Chlamydial DNA in Murine Genital Tract Infection
Authors: Reeves Dawn M. , Nagarajan Uma , O'Connell Catherine , Andrews Charles W. , Darville Toni 
Published: May 2007

ABSTRACT
Mice treated with antibiotics early or late after active infection had resolved were examined for chlamydial DNA in endocervical swabs. The early eradication of infection limited oviduct pathology, despite the continued detection of chlamydial DNA by nested PCR. Late antibiotic treatment had no effect on the ability to detect DNA or oviduct pathology.
gyrA
and
parC
Mutations and Associated Quinolone Resistance in
Vibrio anguillarum
Serotype O2b Strains Isolated from Farmed Atlantic Cod (
Gadus morhua
) in Norway
Authors: Colquhoun D. J. , Aarflot L. , Melvold C. F. 
Published: May 2007

ABSTRACT

MIC testing of
Vibrio anguillarum
isolates recovered from diseased farmed Atlantic cod revealed oxolinic acid MICs of ≤0.001, 0.06, and 16 μg ml
−1
. Single
gyrA
Ser-Ile substitutions were identified at position 83 of the intermediate and resistant strains, while a
parC
Ser-Leu substitution at position 85 was found only in the resistant strain.
Promoter and Transcription Analysis of Penicillin-Binding Protein Genes in
Streptococcus gordonii
Authors: Haenni Marisa , Moreillon Philippe , Lazarevic Vladimir 
Published: May 2007

ABSTRACT

An optimally cross-linked peptidoglycan requires both transglycosylation and transpeptidation, provided by class A and class B penicillin-binding proteins (PBPs).
Streptococcus gordonii
possesses three class A PBPs (PBPs 1A, 1B, and 2A) and two class B PBPs (PBPs 2B and 2X) that are important for penicillin resistance. High-level resistance (MIC, ≥2 μg/ml) requires mutations in class B PBPs. However, although unmutated, class A PBPs are critical to facilitate resistance development (M. Haenni and P. Moreillon, Antimicrob. Agents Chemother. 50:4053-4061, 2006). Thus, their overexpression might be important to sustain the drug. Here, we determined the promoter regions of the
S. gordonii
PBPs and compared them to those of other streptococci. The extended −10 box was highly conserved and complied with a σ
A
-type promoter consensus sequence. In contrast, the −35 box was poorly conserved, leaving the possibility of differential PBP regulation. Gene expression in a penicillin-susceptible parent (MIC, 0.008 μg/ml) and a high-level-resistant mutant (MIC, 2 μg/ml) was monitored using luciferase fusions. In the absence of penicillin, all PBPs were constitutively expressed, but their expression was globally increased (1.5 to 2 times) in the resistant mutant. In the presence of penicillin, class A PBPs were specifically overexpressed both in the parent (PBP 2A) and in the resistant mutant (PBPs 1A and 2A). By increasing transglycosylation, class A PBPs could promote peptidoglycan stability when transpeptidase is inhibited by penicillin. Since penicillin-related induction of class A PBPs occurred in both susceptible and resistant cells, such a mutation-independent facilitating mechanism could be operative at each step of resistance development.