bluuebunny/crossref_metadata_2025_split huggingface dataset:
Typing of SHV Extended-Spectrum β-Lactamases by Pyrosequencing in
Klebsiella pneumoniae
Strains with Chromosomal SHV β-Lactamase
Authors: Haanperä Marjo , Forssten Sofia D. , Huovinen Pentti , Jalava Jari 
Published: May 2008

ABSTRACT

In
Klebsiella pneumoniae
, the cooccurrence of chromosomal and plasmid-mediated beta-lactamases can hinder their accurate molecular detection. We developed a fast and reliable method that allows the typing of isolates carrying more than one SHV gene. The method is based on pyrosequencing the DNA sequence corresponding to amino acid positions 35, 238, and 240.
Use of an In Vitro Pharmacodynamic Model To Derive a Linezolid Regimen That Optimizes Bacterial Kill and Prevents Emergence of Resistance in
Bacillus anthracis
Authors: Louie A. , Heine H. S. , Kim K. , Brown D. L. , VanScoy B. , Liu W. , Kinzig-Schippers M. , Sörgel F. , Drusano G. L. 
Published: May 2008

ABSTRACT

Simulating the average non-protein-bound (free) human serum drug concentration-time profiles for linezolid in an in vitro pharmacodynamic model, we characterized the pharmacodynamic parameter(s) of linezolid predictive of kill and for prevention of resistance in
Bacillus anthracis
. In 10-day dose-ranging studies, the average exposure for ≥700 mg of linezolid given once daily (QD) resulted in >3-log CFU/ml declines in
B. anthracis
without resistance selection. Linezolid at ≤600 mg QD amplified for resistance. With twice-daily (q12h) dosing, linezolid at ≥500 mg q12 h was required for resistance prevention. In dose fractionation studies, killing of
B. anthracis
was predicted by the area under the time-concentration curve (AUC)/MIC ratio. However, resistance prevention was linked to the maximum serum drug concentration (
C
max
)/MIC ratio. Monte Carlo simulations predicted that linezolid at 1,100 mg QD would produce in 96.7% of human subjects a free 24-h AUC that would match or exceed the average 24-h AUC of 78.5 mg·h/liter generated by linezolid at 700 mg QD while reproducing the shape of the concentration-time profile for this pharmacodynamically optimized regimen. However, linezolid at 700 mg q12h (cumulative daily dose of 1,400 mg) would produce an exposure that would equal or exceed the average free 24-h AUC of 90 mg·h/liter generated by linezolid at 500 mg q12h in 93.8% of human subjects. In conclusion, in our in vitro studies, the QD-administered, pharmacodynamically optimized regimen for linezolid killed drug-susceptible
B. anthracis
and prevented resistance emergence at lower dosages than q12h regimens. The lower dosage for the pharmacodynamically optimized regimen may decrease drug toxicity. Also, the QD administration schedule may improve patient compliance.
Molecular Characterization ofEnterococcus faecalisN06-0364 with Low-Level Vancomycin Resistance Harboring a Noveld-Ala-d-Ser Gene Cluster,vanL
Authors: Boyd David A. , Willey Barbara M. , Fawcett Darlene , Gillani Nazira , Mulvey Michael R. 
Published: May 2008

ABSTRACTEnterococcus faecalisN06-0364, exhibiting a vancomycin MIC of 8 μg/ml, was found to harbor a noveld-Ala-d-Ser gene cluster, designatedvanL. ThevanLgene cluster was similar in organization to thevanCoperon, but the VanT serine racemase was encoded by two separate genes,vanTmL(membrane binding) andvanTrL(racemase).
Sequence of Conjugative Plasmid pIP1206 Mediating Resistance to Aminoglycosides by 16S rRNA Methylation and to Hydrophilic Fluoroquinolones by Efflux
Authors: Périchon Bruno , Bogaerts Pierre , Lambert Thierry , Frangeul Lionel , Courvalin Patrice , Galimand Marc 
Published: May 2008

ABSTRACT

Self-transferable IncFI plasmid pIP1206, isolated from an
Escherichia coli
clinical isolate, carries two new resistance determinants:
qepA
, which confers resistance to hydrophylic fluoroquinolones by efflux, and
rmtB
, which specifies a 16S rRNA methylase conferring high-level aminoglycoside resistance. Analysis of the 168,113-bp sequence (51% G+C) revealed that pIP1206 was composed of several subregions separated by copies of insertion sequences. Of 151 open reading frames, 56 (37%) were also present in pRSB107, isolated from a bacterium in a sewage treatment plant. pIP1206 contained four replication regions (RepFIA, RepFIB, and two partial RepFII regions) and a transfer region 91% identical with that of pAPEC-O1-ColBM, a plasmid isolated from an avian pathogenic
E. coli
. A putative
oriT
region was found upstream from the transfer region. The antibiotic resistance genes
tet
(A),
catA1, bla
TEM-1
,
rmtB
, and
qepA
were clustered in a 33.5-kb fragment delineated by two IS
26
elements that also carried a class 1 integron, including the
sulI, qacE
Δ
1, aad4
, and
dfrA17
genes and Tn
10
, Tn
21
, and Tn
3
-like transposons. The plasmid also possessed a raffinose operon, an arginine deiminase pathway, a putative iron acquisition gene cluster, an
S
-methylmethionine metabolism operon, two virulence-associated genes, and a type I DNA restriction-modification (R-M) system. Three toxin/antitoxin systems and the R-M system ensured stabilization of the plasmid in the host bacteria. These data suggest that the mosaic structure of pIP1206 could have resulted from recombination between pRSB107 and a pAPEC-O1-ColBM-like plasmid, combined with structural rearrangements associated with acquisition of additional DNA by recombination and of mobile genetic elements by transposition.
Analysis of Type II Secretion of Recombinant Pneumococcal PspA and PspC in a
Salmonella enterica
Serovar Typhimurium Vaccine with Regulated Delayed Antigen Synthesis
Authors: Xin Wei , Wanda Soo-Young , Li Yuhua , Wang Shifeng , Mo Hua , Curtiss Roy 
Published: May 2008

ABSTRACT

Recombinant attenuated
Salmonella
vaccines (RASVs) have been used extensively to express and deliver heterologous antigens to host mucosal tissues. Immune responses can be enhanced greatly when the antigen is secreted to the periplasm or extracellular compartment. The most common method for accomplishing this is by fusion of the antigen to a secretion signal sequence. Finding an optimal signal sequence is typically done empirically. To facilitate this process, we constructed a series of plasmid expression vectors, each containing a different type II signal sequence. We evaluated the utilities of these vectors by fusing two different antigens, the α-helix domains of pneumococcal surface protein A (PspA) and pneumococcal surface protein C (PspC), to the signal sequences of β-lactamase (
bla
SS),
ompA
, and
phoA
and the signal sequence and C-terminal peptide of β-lactamase (
bla
SS+CT) on Asd
+
plasmids under the control of the P
trc
promoter. Strains were characterized for level of expression, subcellular antigen location, and the capacity to elicit antigen-specific immune responses and protection against challenge with
Streptococcus pneumoniae
in mice. The immune responses to each protein differed depending on the signal sequence used. Strains carrying the
bla
SS-
pspA
and
bla
SS+CT-
pspC
fusions yielded the largest amounts of secreted PspA and PspC, respectively, and induced the highest serum IgG titers, although all fusion proteins tested induced some level of antigen-specific IgG response. Consistent with the serum antibody responses, RASVs expressing the
bla
SS-
pspA
and
bla
SS+CT-
pspC
fusions induced the greatest protection against
S. pneumoniae
challenge.
LiaS Regulates Virulence Factor Expression in
Streptococcus mutans
Authors: Chong Patrick , Drake Laura , Biswas Indranil 
Published: May 2008

ABSTRACT

Streptococcus mutans
, a major oral pathogen responsible for dental caries formation, possesses a variety of mechanisms for survival in the human oral cavity, where the conditions of the external environment are diverse and in a constant state of flux. The formation of biofilms, survival under conditions of acidic pH, and production of mutacins are considered to be important virulence determinants displayed by this organism. Biofilm formation is facilitated by the production of GbpC, an important cell surface-associated protein that binds to glucan, an adhesive polysaccharide produced by the organism itself. To better understand the nature of the environmental cues that induce GbpC production, we examined the roles of 14 sensor kinases in the expression of
gbpC
in
S. mutans
strain UA159. We found that only the LiaS sensor kinase regulates
gbpC
expression, while the other sensor kinases had little or no effect on
gbpC
expression. We also found that while LiaS negatively regulates
gbpC
expression, the inactivation of its cognate response regulator, LiaR, does not appear to affect the expression of
gbpC
. Since both
gbpC
expression and mutacin IV production are regulated by a common regulatory network, we also tested the effect of the
liaS
mutation on mutacin production and found that LiaS positively regulates mutacin IV production. Furthermore, reverse transcription-PCR analysis suggests that LiaS does so by regulating the expression of
nlmA
, which encodes a peptide component of mutacin IV, and
nlmT
, which encodes an ABC transporter. As with the expression of
gbpC
, LiaR did not have any apparent effect on mutacin IV production. Based on the results of our study, we speculate that LiaS is engaged in cross talk with one or more response regulators belonging to the same family as LiaR, enabling LiaS to regulate the expression of several genes coding for virulence factors.
Application of Capillary Electrophoresis Mass Spectrometry and Liquid Chromatography Multiple-Step Tandem Electrospray Mass Spectrometry To Profile Glycoform Expression during
Haemophilus influenzae
Pathogenesis in the Chinchilla Model of Experimental Otitis Media
Authors: Lundström Susanna L. , Li Jianjun , Månsson Martin , Figueira Marisol , Leroy Magali , Goldstein Richard , Hood Derek W. , Moxon E. Richard , Richards James C. , Schweda Elke K. H. 
Published: May 2008

ABSTRACT

Otitis media caused by nontypeable
Haemophilus influenzae
(NTHi) is a common and recurrent bacterial infection of childhood. The structural variability and diversity of
H. influenzae
lipopolysaccharide (LPS) glycoforms are known to play a significant role in the commensal and disease-causing behavior of this pathogen. In this study, we determined LPS glycoform populations from NTHi strain 1003 during the course of experimental otitis media in the chinchilla model of infection by mass spectrometric techniques. Building on an established structural model of the major LPS glycoforms expressed by this NTHi strain in vitro (M. Månsson, W. Hood, J. Li, J. C. Richards, E. R. Moxon, and E. K. Schweda, Eur. J. Biochem. 269:808-818, 2002), minor isomeric glycoform populations were determined by liquid chromatography multiple-step tandem electrospray mass spectrometry (LC-ESI-MS

n

). Using capillary electrophoresis ESI-MS (CE-ESI-MS), we determined glycoform profiles for bacteria from direct middle ear fluid (MEF) samples. The LPS glycan profiles were essentially the same when the MEF samples of 7 of 10 animals were passaged on solid medium (chocolate agar). LC-ESI-MS

n

provided a sensitive method for determining the isomeric distribution of LPS glycoforms in MEF and passaged specimens. To investigate changes in LPS glycoform distribution during the course of infection, MEF samples were analyzed at 2, 5, and 9 days postinfection by CE-ESI-MS following minimal passage on chocolate agar. As previously observed, sialic acid-containing glycoforms were detected during the early stages of infection, but a trend toward more-truncated and less-complex LPS glycoforms that lacked sialic acid was found as disease progressed.
Characterization of a
Helicobacter hepaticus putA
Mutant Strain in Host Colonization and Oxidative Stress
Authors: Krishnan Navasona , Doster Alan R. , Duhamel Gerald E. , Becker Donald F. 
Published: May 2008

ABSTRACT

Helicobacter hepaticus
is a gram-negative, spiral-shaped microaerophilic bacterium associated with chronic intestinal infection leading to hepatitis and colonic and hepatic carcinomas in susceptible strains of mice. In the closely related human pathogen
Helicobacter pylori
,
l
-proline is a preferred respiratory substrate and is found at significantly high levels in the gastric juice of infected patients. A previous study of the proline catabolic PutA flavoenzymes from
H. pylori
and
H. hepaticus
revealed that
Helicobacter
PutA generates reactive oxygen species during proline oxidation by transferring electrons from reduced flavin to molecular oxygen. We further explored the preference for proline as a respiratory substrate and the potential impact of proline metabolism on the redox environment in
Helicobacter
species during host infection by disrupting the
putA
gene in
H. hepaticus
. The resulting
putA
knockout mutant strain was characterized by oxidative stress analysis and mouse infection studies. The
putA
mutant strain of
H. hepaticus
exhibited increased proline levels and resistance to oxidative stress relative to that of the wild-type strain, consistent with proline's role as an antioxidant. The significant increase in stress resistance was attributed to higher proline content, as no upregulation of antioxidant genes was observed for the
putA
mutant strain. The wild-type and
putA
mutant
H. hepaticus
strains displayed similar levels of infection in mice, but in mice challenged with the
putA
mutant strain, significantly reduced inflammation was observed, suggesting a role for proline metabolism in
H. hepaticus
pathogenicity in vivo.
A heat acclimation protocol for team sports
Authors: Sunderland C , Morris J G , Nevill M E 
Published: May 2008

Background:It is well documented that heat acclimation of six or more sessions of at least 60 min duration prolongs the time to exhaustion during endurance walking, cycling and running in the heat. However, this type of acclimation is not specific to team sport activity and the effect of acclimation on prolonged high-intensity intermittent running has not yet been investigated.Objective:To assess the impact of an intermittent acclimation protocol on distance run during team sport activity.Methods:The impact of four short heat acclimation sessions (30–45 min of the Loughborough Intermittent Shuttle Test; LIST) on high-intensity intermittent running capacity (LIST) in the heat (30°C, 27% relative humidity (RH)), was examined. Seventeen female well-trained games players were split into three groups: an acclimation group (30°C, 24% RH), a moderate training group (18°C, 41% RH) and a control group who did not complete any training between the main trials (pre-acclimation and post-acclimation). The pre-acclimation (A) and post-acclimation (B) trials were separated by 28 days to control for menstrual phase and verified using hormonal analysis. The four acclimation or moderate training sessions utilising the LIST were completed with one or two rest days interspersed between each session in a 10-day period prior to the post-acclimation trial (B).Results:In the post-acclimation trial distance run was increased by 33% in the acclimation group (A: 7703 (SEM 1401) m vs B: 10215 (SEM 1746) m; interaction group × trial p<0.05), but was unchanged in the moderate and control groups. The acclimation group had a lower rectal temperature (interaction group × trial × time p<0.01) due to a lower rate of rise, and an increase in thermal comfort1 after acclimation (End A: 7 (SEM 2) vs 6 (SEM 2); interaction group × trial p<0.01). There was no difference in serum progesterone, aldosterone or cortisol concentrations following acclimation or between groups.Conclusion:Four 30–45 min sessions of intermittent exercise induced acclimation, and resulted in an improvement in intermittent running exercise capacity in female games players. A lower rectal temperature and a concomitant rise in thermal comfort may be partly responsible for the improvement in exercise capacity.
Hypoxia and exercise: different models for different questions
Authors: Sheel A. William 
Published: May 2008

The focus of this symposium is on the physiological demands of exercise in hypoxia. The study of hypoxia by exercise physiologists has a strong tradition and many questions first asked over 100 years ago continue to be relevant, yet still unsatisfactorily answered. The primary theme of the following papers is how different models of hypoxia allow different questions to be asked. The first paper addresses questions of exercise ventilatory control using intermittent, rather than continuous, hypoxia. The second manuscript attempts to understand the hypoxic exercise responses using a population-level approach (i.e., generations spanning millennia). Lastly, the third paper uses acute hypoxia to better understand cardio-pulmonary interactions during exercise. Collectively, these reviews are intended to stimulate additional study and debate.
Association between HMOX-1 genotype and cardiac function during exercise
Authors: He Zihong , Hu Yang , Feng Lianshi , Lu Yingli , Bao Dapeng , Xi Yi , Wen Li , Lucia Alejandro 
Published: May 2008

The human gene for heme oxygenase-1 (HMOX-1) plays an important role in the regulation of cardiovascular function and its adaptive response to a variety of stressors. The purpose of this study was to examine the possible association between HMOX-1 genotypes (for –1135A/G, –413A/T, and rs5755720 polymorphisms) and cardiac structural and functional parameters at rest and during submaximal cycle-ergometer exercise (50, 100, and 150 W) in a pre-training state (baseline) and after endurance training (18 weeks, 95%~105% individual ventilatory threshold). The study population consisted of 102 Chinese young males (non-athletes) of Han origin. For the –1135A/G polymorphism, we found a significant genotype effect (p < 0.05) in cardiac output (Q) corrected for body surface area (BSA; Q·BSA–1) at 50 W and stroke volume (SV) corrected for BSA (SV·BSA–1) at 100 W. For the –413A/T polymorphism, we found a significant genotype effect (p < 0.05) in ejection fraction (EF) at 100 W. For the rs5755720 polymorphism, we found a significant genotype effect (p < 0.01 or p < 0.05) in most variables (Q·BSA–1 across all workloads, SV·BSA–1 at 100 W, and EF at 50 and 100 W). Briefly, rs5755720 individuals with a CC genotype presented overall higher values in the different cardiac variables than their CT and (or) TT counterparts. In summary, although more research is needed with diseased populations and other ethnic groups, we found preliminary evidence of an association between cardiac response to submaximal exercise and HMOX-1 genotype. The present preliminary findings could provide insights to future studies searching for cardioprotective genotypes.
The effects of ibuprofen on muscle hypertrophy, strength, and soreness during resistance training
Authors: Krentz Joel R. , Quest Braden , Farthing Jonathan P. , Quest Dale W. , Chilibeck Philip D. 
Published: May 2008

High doses of ibuprofen have been shown to inhibit muscle protein synthesis after a bout of resistance exercise. We determined the effect of a moderate dose of ibuprofen (400 mg·d–1) consumed on a daily basis after resistance training on muscle hypertrophy and strength. Twelve males and 6 females (~24 years of age) trained their right and left biceps on alternate days (6 sets of 4–10 repetitions), 5 d·week–1, for 6 weeks. In a counter-balanced, double-blind design, they were randomized to receive 400 mg·d–1 ibuprofen immediately after training their left or right arm, and a placebo after training the opposite arm the following day. Before- and after-training muscle thickness of both biceps was measured using ultrasound and 1 repetition maximum (1 RM) arm curl strength was determined on both arms. Subjects rated their muscle soreness daily. There were time main effects for muscle thickness and strength (p < 0.01). Ibuprofen consumption had no effect on muscle hypertrophy (muscle thickness of biceps for arm receiving ibuprofen: pre 3.63 ± 0.14, post 3.92 ± 0.15 cm; and placebo: pre 3.62 ± 0.15, post 3.90 ± 0.15 cm) and strength (1 RM of arm receiving ibuprofen: pre 18.6 ± 2.8, post 23.4 ± 3.5 kg; and placebo: pre 18.8 ± 2.8, post 22.8 ± 3.4 kg). Muscle soreness was elevated during the first week of training only, but was not different between the ibuprofen and placebo arm. We conclude that a moderate dose of ibuprofen ingested after repeated resistance training sessions does not impair muscle hypertrophy or strength and does not affect ratings of muscle soreness.
Central adiposity and associated lifestyle factors in Cree children
Authors: Downs Shauna M. , Marshall Dru , Ng Carmina , Willows Noreen D. 
Published: May 2008

Aboriginal children are prone to central adiposity (CA), a component of the metabolic syndrome. The objective of this study was to determine if lifestyle factors were associated with CA in Canadian Cree children. Children aged 9–12 years were classified as having CA if their waist circumference met or exceeded the 85th percentile of the NHANES III reference. Weight status was determined using the CDC growth reference, dietary intake using three 24 h dietary recalls, physical activity using pedometers, and fitness by completion of the 20 m shuttle run test. Of the 178 children (79% participation rate), 32.6% were normal weight, 23.6% were overweight, and 43.8% were obese. Half (52.2%) of the children had CA (97.4% of obese children, 35.7% of overweight children, and 2.2% of normal weight children). Waist circumference was negatively correlated with pedometer step counts (r = –0.187, p = 0.012) and shuttle run time (r = –0.508, p < 0.001). In children with CA, waist circumference was positively correlated with sweetened beverage intake (r = 0.250, p = 0.016). The odds ratio (adjusted for age and sex) for CA for children consuming 3 or more fruits and vegetables per day was 0.43 (95% CI 0.18 – 0.98), for meeting step recommendations for a healthy body weight was 0.45 (95% CI 0.24 – 0.84), and for relative fitness was 0.12 (95% CI 0.04 – 0.33). CA was prevalent in children who were overweight and obese. Preventive strategies might include promoting a healthy diet, physical activity, and fitness.
Multidimensional Longwave Forcing of Boundary Layer Cloud Systems
Authors: Mechem David B. , Kogan Yefim L. , Ovtchinnikov Mikhail , Davis Anthony B. , Evans K. Franklin , Ellingson Robert G. 
Published: May 2008

Abstract
The importance of multidimensional (MD) longwave radiative effects on cloud dynamics is evaluated in an eddy-resolving model (ERM)—the two-dimensional analog to large-eddy simulation (LES)—framework employing multidimensional radiative transfer [Spherical Harmonics Discrete Ordinate Method (SHDOM)]. Simulations are performed for a case of unbroken, marine boundary layer stratocumulus and a broken field of trade cumulus. “Snapshot” calculations of MD and independent pixel approximation (IPA; 1D) radiative transfer applied to simulated cloud fields show that the total radiative forcing changes only slightly, although the MD effects significantly modify the spatial structure of the radiative forcing. Simulations of each cloud type employing MD and IPA radiative transfer, however, differ little. For the solid cloud case, relative to using IPA, the MD simulation exhibits a slight reduction in entrainment rate and boundary layer total kinetic energy (TKE) relative to the IPA simulation. This reduction is consistent with both the slight decrease in net radiative forcing and a negative correlation between local vertical velocity and radiative forcing, which implies a damping of boundary layer eddies. Snapshot calculations of the broken cloud case suggest a slight increase in radiative cooling, although few systematic differences are noted in the interactive simulations. This result is attributed to the fact that radiative cooling is a relatively minor contribution to the total energetics. For the cloud systems in this study, the use of IPA longwave radiative transfer is sufficiently accurate to capture the dynamical behavior of boundary layer clouds. Further investigations are required to generalize this conclusion for other cloud types and longer time integrations.