bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cooling and response to hydrogen peroxide in human saphenous vein: role of the endothelium
Authors: Şahin Ayşe Saide , Atalık Kısmet Esra , Şahin Tahir Kemal , Doğan Necdet 
Published: June 2005

AbstractIn the present work we studied the responses of human saphenous vein to H2O2 and effects of moderate cooling on these responses with analysis of the role of endothelium. H2O2 (10−7–10−2 m) induced concentration‐dependent contraction in the intact human saphenous vein strips at both temperatures. At 28 °C, the maximal contraction induced by H2O2 was significantly lower than that at 37 °C. Compared with intact strips, the sensitivity and the maximal contraction to H2O2 were significantly enhanced in endothelium‐denuded strips at 37 and 28 °C. However, pD2 values and maximal contractions were not significantly different in endothelium‐denuded strips at different temperatures. Pretreatment with NG‐nitro‐l‐arginine methyl ester (l‐NAME) increased significantly the maximal contraction and sensitivity to H2O2 at 37 and 28 °C. The contractions increased by l‐NAME were restored by the pre‐incubation of l‐arginine (10−3 m) at every temperature studied. The contractile responses of intact human saphenous veins to H2O2 were reduced significantly by 10−5 m indomethacin at both temperatures. Our results suggest that H2O2‐induced contraction of human saphenous vein are mediated by its direct effect on the smooth muscle and by the generation of products of the cyclooxygenase pathway from the endothelium. Signalling pathways of these contractile effects are the same at 37 and 28 °C. Under normal temperature conditions, the contraction to H2O2 is possibly modulated by endothelial nitric oxide. Cooling reduces the contraction to H2O2 by increasing release of nitric oxide.
Performance Limitation and Autotuning of Inverse Optimal PID Controller for Lagrangian Systems
Authors: Choi Youngjin , Chung Wan Kyun 
Published: June 2005

Abstract
The PID trajectory tracking controller for Lagrangian systems shows performance limitation imposed by inverse dynamics according to desired trajectory. Since the equilibrium point cannot be defined for the control system involving performance limitation, we define newly the quasiequilibrium region as an alternative for equilibrium point. This analysis result of performance limitation can guide us the autotuning method for PID controller. The quasiequilibrium region is used as the target performance of autotuning PID trajectory tracking controller. The autotuning law is derived from the direct adaptive control scheme, based on the extended disturbance input-to-state stability and the characteristics of performance limitation. Finally, experimental results show that the target performance can be achieved by the proposed automatic tuning method.
Acceleration-Driven-Damper (ADD): An Optimal Control Algorithm For Comfort-Oriented Semiactive Suspensions
Authors: Savaresi Sergio M. , Silani Enrico , Bittanti Sergio 
Published: June 2005

Abstract
The problem considered in this paper is the design and analysis of control strategies for semiactive suspensions in road vehicles. The most commonly used control framework is the well-known Sky–Hook (SH) damping. Two-state or linear approximation of the SH concept are typically implemented. The goal of this paper is to analyze the optimality of SH-based control algorithms, and to propose an innovative control strategy, named Acceleration-Driven-Damper (ADD) control. It is shown that ADD is optimal in the sense that it minimizes the vertical body acceleration (comfort objective) when no road-preview is available. This control strategy is extremely simple; it requires the same sensors of the SH algorithms, and a simple two-state controllable damper. In order to assess and to compare the closed-loop performance of the SH and ADD control strategies, both a theoretical and a numerical analysis of performance are proposed.
Snap-Curing Electrically Conductive Formulation for Solder
Replacement Applications
Authors: Mościcki Andrzej , Felba Jan , Sobierajski Tadeusz , Kudzia Józef 
Published: June 2005

Abstract
Pb-free soldering and the use of electrically conducive adhesives in the electronics industry are a segment of the global trend towards a lead-free environment. In comparison to lead-free solders, current commercial isotropic conductive adhesives are characterized by lower conductivity and need much more time for curing. Usually, a few minutes at 150°C are enough only for precuring. In this paper we describe the developed family of formulations with a curing time of several seconds at 150°C. There are single-component formulations, solvent-free type, prepared in a special way on the base of the common, accessible resins. They have very convenient handling properties; e.g., no drying on open screen during printing process. Viscosity depends on the resin and may be intentionally changed. Shelf life for all these formulations is about 12months at room temperature in closed containers. Refrigeration is not necessary. Unfortunately, the material needs the highest quality and purity of electronic grade silver fillers. The total permitted level of impurities is estimated as less than 10ppm. However, this is, rather, an advantage of the silver-filled adhesives.
Genetic Diversity and Antibiotic Resistance Patterns in aCampylobacterPopulation Isolated from Poultry Farms in Switzerland
Authors: Wittwer M. , Keller J. , Wassenaar T. M. , Stephan R. , Howald D. , Regula G. , Bissig-Choisat B. 
Published: June 2005

ABSTRACTThe diversity and genetic interrelation ofCampylobacter jejuniandC. coliisolated from Swiss poultry were assessed by three independent typing methods. Samples were derived prior to slaughter from 100 randomly selected flocks (five birds per flock) raised on three different farm types. The observed flock prevalence was 54% in total, with 50% for conventional and 69% for free-range farms. Birds held on farms with a confined roaming area had the lowest prevalence of 37%.Campylobacterisolates were characterized by amplified fragment length polymorphism (AFLP), restriction fragment length polymorphism offlaAPCR fragments (flaA-RFLP), and disk diffusion testing for eight antimicrobial agents that are commonly used in veterinary or human medicine in Switzerland. Analysis of the genotypic results indicates that theCampylobacterpopulation in Swiss poultry is genetically highly diverse. Nevertheless, occasionally, isolates with identical or nearly identical characteristics were isolated from different farms or farm types in different locations. Genetic typing by AFLP andflaA-RFLP was found to be complementary. The majority of isolates (67%) were susceptible to all tested antibiotics; however, single, double, and triple resistances were observed in 7%, 23%, and 2% of the strains, respectively. There was no correlation between genotype and antibiotic resistance. Surprisingly, sulfonamide resistance was frequently found together with streptomycin resistance. Our findings illustrate the results of common genetic exchange in the studied bacterial population.
Erosion and Subsequent Transport State of
Escherichia coli
from Cowpats
Authors: Muirhead Richard William , Collins Robert Peter , Bremer Philip James 
Published: June 2005

ABSTRACT

Processes by which fecal bacteria enter overland flow and their transportation state to surface waters are poorly understood, making the effectiveness of measures designed to intercept this pathway, such as vegetated buffer strips, difficult to predict. Freshly made and aged (up to 30 days) cowpats were exposed to simulated rainfall, and samples of the cowpat material and runoff were collected.
Escherichia coli
in the runoff samples were separated into attached (to particles) and unattached fractions, and the unattached fraction was analyzed to determine if the cells were clumped. Within cowpats,
E. coli
grew for 6 to 14 days, rather than following a typical logarithmic die-off curve.
E. coli
numbers in the runoff correlated with numbers inside the cowpat. Most of the
E. coli
organisms eroded from the cowpats were transported as single cells, and only a small percentage (about 8%) attached to particles. The erosion of
E. coli
from cowpats and the state in which the cells were transported did not vary with time within a single rainfall event or over time as the cowpats aged and dried out. These findings indicate that cowpats can remain a significant source of
E. coli
in overland flow for more than 30 days. As well, most of the
E. coli
organisms eroded from cowpats will occur as readily transportable single cells.
Identification of a Gene Cluster for the Formation of Extracellular Polysaccharide Precursors in the Chemolithoautotroph
Acidithiobacillus ferrooxidans
Authors: Barreto Marlen , Jedlicki Eugenia , Holmes David S. 
Published: June 2005

ABSTRACT

A cluster of five genes, proposed to be involved in the formation of extracellular polysaccharide (EPS) precursors via the Leloir pathway, have been identified in the acidophilic autotroph
Acidithiobacillus ferrooxidans
. The order of the genes is
luxA-galE-galK-pgm-galM
, encoding a LuxA-like protein, UDP-glucose 4-epimerase, galactokinase, phosphoglucomutase, and galactose mutarotase, respectively. The
gal
cluster forms a single transcriptional unit and is therefore an operon. Two other putative genes of the Leloir pathway,
galU
, potentially encoding UDP-glucose pyrophosphorylase, and a gene designated
galT-like
, which may encode a galactose-1-phosphate uridylyltransferase-like activity, were found unlinked in the genome. Using semiquantitative reverse transcription-PCR, the genes of the
gal
operon were shown to be expressed more during growth in iron medium than in growth in sulfur medium. The functions of
galE
,
pgm
,
galU
, and the
galT-like
gene were validated by complementation of
Escherichia coli
mutants and by in vitro enzyme assays. The data suggest that
A. ferrooxidans
is capable of synthesizing the EPS precursors UDP-glucose and UDP-galactose. In addition, genes
rfbA
, -
B
, -
C
, and -
D
were identified in the genome of
A. ferrooxidans
, suggesting that it can also synthesize the EPS precursor dTDP-rhamnose. Since EPSs constitute the major bulk of biofilms, this study may provide an initial model for the metabolic pathways involved in biofilm formation in
A. ferrooxidans
and aid in understanding the role of biofilms in mineral leaching and the formation of acid mine drainage.
High-Frequency Conjugation System Facilitates Biofilm Formation and pAMβ1 Transmission by
Lactococcus lactis
Authors: Luo Hongliang , Wan Kai , Wang Hua H. 
Published: June 2005

ABSTRACT

The importance of conjugation as a mechanism to spread biofilm determinants among microbial populations was illustrated with the gram-positive bacterium
Lactococcus lactis
. Conjugation triggered the enhanced expression of the clumping protein CluA, which is a main biofilm attribute in lactococci. Clumping transconjugants further transmitted the biofilm-forming elements among the lactococcal population at a much higher frequency than the parental nonclumping donor. This cell-clumping-associated high-frequency conjugation system also appeared to serve as an internal enhancer facilitating the dissemination of the broad-host-range drug resistance gene-encoding plasmid pAMβ1 within
L. lactis
, at frequencies more than 10,000 times higher than those for the nonclumping parental donor strain. The implications of this finding for antibiotic resistance gene dissemination are discussed.
Starvation Response ofSaccharomyces cerevisiaeGrown in Anaerobic Nitrogen- or Carbon-Limited Chemostat Cultures
Authors: Thomsson Elisabeth , Gustafsson Lena , Larsson Christer 
Published: June 2005

ABSTRACTAnaerobic starvation conditions are frequent in industrial fermentation and can affect the performance of the cells. In this study, the anaerobic carbon or nitrogen starvation response ofSaccharomyces cerevisiaewas investigated for cells grown in anaerobic carbon or nitrogen-limited chemostat cultures at a dilution rate of 0.1 h−1at pH 3.25 or 5. Lactic or benzoic acid was present in the growth medium at different concentrations, resulting in 16 different growth conditions. At steady state, cells were harvested and then starved for either carbon or nitrogen for 24 h under anaerobic conditions. We measured fermentative capacity, glucose uptake capacity, intracellular ATP content, and reserve carbohydrates and found that the carbon, but not the nitrogen, starvation response was dependent upon the previous growth conditions. All cells subjected to nitrogen starvation retained a large portion of their initial fermentative capacity, independently of previous growth conditions. However, nitrogen-limited cells that were starved for carbon lost almost all their fermentative capacity, while carbon-limited cells managed to preserve a larger portion of their fermentative capacity during carbon starvation. There was a positive correlation between the amount of glycogen before carbon starvation and the fermentative capacity and ATP content of the cells after carbon starvation. Fermentative capacity and glucose uptake capacity were not correlated under any of the conditions tested. Thus, the successful adaptation to sudden carbon starvation requires energy and, under anaerobic conditions, fermentable endogenous resources. In an industrial setting, carbon starvation in anaerobic fermentations should be avoided to maintain a productive yeast population.
sacB
–5-Fluoroorotic Acid–
pyrE
-Based Bidirectional Selection for Integration of Unmarked Alleles into the Chromosome of
Rhodobacter capsulatus
Authors: Yano Takahiro , Sanders Carsten , Catalano John , Daldal Fevzi 
Published: June 2005

ABSTRACT

The gram-negative, purple nonsulfur, facultative photosynthetic bacterium
Rhodobacter capsulatus
is a widely used model organism and has well-developed molecular genetics. In particular, interposon mutagenesis using selectable gene cartridges is frequently employed for construction of a variety of chromosomal knockout mutants. However, as the gene cartridges are often derived from antibiotic resistance-conferring genes, their numbers are limited, which restricts the construction of multiple knockout mutants. In this report,
sacB
—5-fluoroorotic acid (5FOA)—
pyrE
-based bidirectional selection that facilitates construction of unmarked chromosomal knockout mutations is described. The
R. capsulatus pyrE
gene encoding orotate phosphoribosyl transferase, a key enzyme of the de novo pyrimidine nucleotide biosynthesis pathway, was used as an interposon in a genetic background that is auxotrophic for uracil (Ura
−
) and hence resistant to 5FOA (5FOA
r
). Although Ura
+
selection readily yielded chromosomal allele replacements via homologous recombination, selection for 5FOA
r
to replace
pyrE
with unmarked alleles was inefficient. To improve the latter step, 5FOA
r
selection was combined with sucrose tolerance selection using a suicide plasmid carrying the
Bacillus subtilis sacB
gene encoding levansucrase that induces lethality upon exposure to 5% (wt/vol) sucrose in the growth medium. Sucrose-tolerant, 5FOA
r
colonies that were obtained carried chromosomal unmarked mutant alleles of the target gene via double crossovers between the resident
pyrE-
marked and incoming unmarked alleles. The effectiveness of this double selection was proven by seeking insertion and deletion alleles of
helC
involved in
R. capsulatus
cytochrome
c
biogenesis, which illustrated the usefulness of this system as a genetic means for facile construction of
R. capsulatus
unmarked chromosomal mutants.
Persistence and Differential Survival of Fecal Indicator Bacteria in Subtropical Waters and Sediments
Authors: Anderson Kimberly L. , Whitlock John E. , Harwood Valerie J. 
Published: June 2005

ABSTRACT

Fecal coliforms and enterococci are indicator organisms used worldwide to monitor water quality. These bacteria are used in microbial source tracking (MST) studies, which attempt to assess the contribution of various host species to fecal pollution in water. Ideally, all strains of a given indicator organism (IO) would experience equal persistence (maintenance of culturable populations) in water; however, some strains may have comparatively extended persistence outside the host, while others may persist very poorly in environmental waters. Assessment of the relative contribution of host species to fecal pollution would be confounded by differential persistence of strains. Here, freshwater and saltwater mesocosms, including sediments, were inoculated with dog feces, sewage, or contaminated soil and were incubated under conditions that included natural stressors such as microbial predators, radiation, and temperature fluctuations. Persistence of IOs was measured by decay rates (change in culturable counts over time). Decay rates were influenced by IO, inoculum, water type, sediment versus water column location, and
Escherichia coli
strain. Fecal coliform decay rates were significantly lower than those of enterococci in freshwater but were not significantly different in saltwater. IO persistence according to mesocosm treatment followed the trend: contaminated soil > wastewater > dog feces.
E. coli
ribotyping demonstrated that certain strains were more persistent than others in freshwater mesocosms, and the distribution of ribotypes sampled from mesocosm waters was dissimilar from the distribution in fecal material. These results have implications for the accuracy of MST methods, modeling of microbial populations in water, and efficacy of regulatory standards for protection of water quality.
Rapid Differentiation and In Situ Detection of 16 Sourdough
Lactobacillus
Species by Multiplex PCR
Authors: Settanni Luca , van Sinderen Douwe , Rossi Jone , Corsetti Aldo 
Published: June 2005

ABSTRACT

A two-step multiplex PCR-based method was designed for the rapid detection of 16 species of lactobacilli known to be commonly present in sourdough. The first step of multiplex PCR was developed with a mixture of group-specific primers, while the second step included three multiplex PCR assays with a mixture of species-specific primers. Primers were derived from sequences that specify the 16S rRNA, the 16S-23S rRNA intergenic spacer region, and part of the 23S rRNA gene. The primer pairs designed were shown to exclusively amplify the targeted
rrn
operon fragment of the corresponding species. Due to the reliability of simultaneously identifying
Lactobacillus plantarum
,
Lactobacillus pentosus
, and
Lactobacillus paraplantarum
, a previously described multiplex PCR method employing
recA
gene-derived primers was included in the multiplex PCR system. The combination of a newly developed, quick bacterial DNA extraction method from sourdough and this multiplex PCR assay allows the rapid in situ detection of several sourdough-associated lactobacilli, including the recently described species
Lactobacillus rossii
, and thus represents a very useful alternative to culture-based methodologies.
An Ergot Alkaloid Biosynthesis Gene and Clustered Hypothetical Genes from
Aspergillus fumigatus
Authors: Coyle Christine M. , Panaccione Daniel G. 
Published: June 2005

ABSTRACT

The ergot alkaloids are a family of indole-derived mycotoxins with a variety of significant biological activities.
Aspergillus fumigatus
, a common airborne fungus and opportunistic human pathogen, and several fungi in the relatively distant taxon
Clavicipitaceae
(clavicipitaceous fungi) produce different sets of ergot alkaloids. The ergot alkaloids of these divergent fungi share a four-member ergoline ring but differ in the number, type, and position of the side chains. Several genes required for ergot alkaloid production are known in the clavicipitaceous fungi, and these genes are clustered in the genome of the ergot fungus
Claviceps purpurea
. We investigated whether the ergot alkaloids of
A. fumigatus
have a common biosynthetic and genetic origin with those of the clavicipitaceous fungi. A homolog of
dmaW
, the gene controlling the determinant step in the ergot alkaloid pathway of clavicipitaceous fungi, was identified in the
A. fumigatus
genome. Knockout of
dmaW
eliminated all known ergot alkaloids from
A. fumigatus
, and complementation of the mutation restored ergot alkaloid production. Clustered with
dmaW
in the
A. fumigatus
genome are sequences corresponding to five genes previously proposed to encode steps in the ergot alkaloid pathway of
C. purpurea
, as well as additional sequences whose deduced protein products are consistent with their involvement in the ergot alkaloid pathway. The corresponding genes have similarities in their nucleotide sequences, but the orientations and positions within the cluster of several of these genes differ. The data indicate that the ergot alkaloid biosynthetic capabilities in
A. fumigatus
and the clavicipitaceous fungi had a common origin.
Host Distributions of Uncultivated Fecal
Bacteroidales
Bacteria Reveal Genetic Markers for Fecal Source Identification
Authors: Dick Linda K. , Bernhard Anne E. , Brodeur Timothy J. , Santo Domingo Jorge W. , Simpson Joyce M. , Walters Sarah P. , Field Katharine G. 
Published: June 2005

ABSTRACT

The purpose of this study was to examine host distribution patterns among fecal bacteria in the order
Bacteroidales
, with the goal of using endemic sequences as markers for fecal source identification in aquatic environments. We analyzed
Bacteroidales
16S rRNA gene sequences from the feces of eight hosts: human, bovine, pig, horse, dog, cat, gull, and elk. Recovered sequences did not match database sequences, indicating high levels of uncultivated diversity. The analysis revealed both endemic and cosmopolitan distributions among the eight hosts. Ruminant, pig, and horse sequences tended to form host- or host group-specific clusters in a phylogenetic tree, while human, dog, cat, and gull sequences clustered together almost exclusively. Many of the human, dog, cat, and gull sequences fell within a large branch containing cultivated species from the genus
Bacteroides
. Most of the cultivated
Bacteroides
species had very close matches with multiple hosts and thus may not be useful targets for fecal source identification. A large branch containing cultivated members of the genus
Prevotella
included cloned sequences that were not closely related to cultivated
Prevotella
species. Most ruminant sequences formed clusters separate from the branches containing
Bacteroides
and
Prevotella
species. Host-specific sequences were identified for pigs and horses and were used to design PCR primers to identify pig and horse sources of fecal pollution in water. The primers successfully amplified fecal DNAs from their target hosts and did not amplify fecal DNAs from other species. Fecal bacteria endemic to the host species may result from evolution in different types of digestive systems.