bluuebunny/crossref_metadata_2025 huggingface dataset:
Caring connections with older persons with dementia in an acute hospital setting – a hermeneutic interpretation of the staff nurse's experience
Authors: Nolan Louise
Published: November 2006

Background:  The literature highlights the challenges inherent in caring for older persons with dementia in the acute care context. However despite concerns relating to the quality of care available to persons with dementia in this setting, there is a paucity of research with which to guide practice. Specifically the existing literature lacks in‐depth knowledge on nurses’ experiences.

Aim:  The aim of this paper is to report the findings of a study exploring nurses’ experiences of caring for older persons with dementia in an acute hospital setting.

Methods:  Using a hermeneutic approach, a purposive sample of seven nurses was interviewed regarding the research phenomenon. Interview texts were subjected to thematic content analysis. Multiple data sources were employed to expand the horizon of understanding including: the textual data, personal and professional understandings, reflective journal data and conceptual frameworks derived from theoretical and research literature. The data were collected in 2002.

Results:  The findings reported here relate to the theme ‘Meeting the patient as a person’. Meaningful care for the older person with dementia in the acute context required a respectful connection with the patient as person, which required establishing a bond with the person. The meaning of the caring experience was found to relate to the personhood of both the nurse and the patient, experienced within the context of relationship. To make this connection it was necessary to work with those who knew the patient best i.e. relatives/carers.

Conclusions:  Despite the contextual limitations of the acute setting, the importance of knowing and respecting the person with dementia and the centrality of relationship as the medium within which caring is experienced is demonstrated. However, nurses lack specific knowledge on which to base care. Further research is therefore recommended to identify how care which promotes the integrity of the person with dementia may be effectively operationalized across the acute care setting.
Effect of Surface Orientation on Nucleate Boiling of FC-72 on Porous Graphite
Authors: Parker Jack L. , El-Genk Mohamed S.
Published: November 2006

Effects of orientations of porous graphite and smooth copper surfaces, measuring 10mm×10mm, on saturation nucleate boiling and critical heat flux (CHF) of FC-72 dielectric liquid and of liquid subcooling (0, 10, 20, and 30K) on nucleate boiling in the upward facing orientation are investigated. Inclination angles (θ) considered are 0deg (upward-facing), 60, 90, 120, 150, and 180deg (downward facing). The values of nucleate boiling heat flux, nucleate boiling heat transfer coefficient (NBHTC), and CHF are compared with those measured on the smooth copper surface of the same dimensions and CHF values on both copper and porous graphite are compared with those reported by other investigators on the smooth surfaces and microporous coatings. Results demonstrated higher NBHTC and CHF on porous graphite, particularly in the downward-facing orientation (θ=180deg). In the upward-facing orientation, NBHTCs on both surfaces decrease with increased subcooling, but increase with increased surface superheat reaching maxima then decrease with further increase in surface superheat. In saturation boiling on copper and both saturation and subcooled boiling on porous graphite these maxima occur at or near the end of the discrete bubble region, and near CHF in subcooled boiling on copper. Maximum saturation NBHTC on porous graphite increases with decreased surface superheat and inclination angle, while that on copper increases with increased surface superheat and decreased surface inclination. At low surface superheats, saturation nucleate boiling heat flux increases with increased inclination, but decreases with increased inclination at high surface superheats, consistent with previously reported data for dielectric and nondielectric liquids. The fractional decreases in saturation CHF with increased θ on smooth copper and microporous coatings are almost identical, but markedly larger than on porous graphite, particularly in the downward-facing orientation. In this orientation, saturation CHF on porous graphite of 16W∕cm2 is much higher than on copper (4.9W∕cm2) and as much as 53% of that in the upward-facing orientation, compared to only ∼18% on copper.
Influence of substrate properties and annealing temperature on the stress state of magnetron sputtered tungsten thin films
Authors: Oliveira J. C. , Cavaleiro A.
Published: November 2006

The influence of substrate properties and annealing temperature on the stress state of tungsten thin films deposited by dc reactive magnetron sputtering was studied using 310 steel (AISI), Fecralloy® and Invar® substrates. Besides elemental tungsten, only residual amounts of contamination elements (O, C, Ar, etc.) were detected by electron probe microanalysis. Only the α-W crystalline structure, with a preferential ⟨110⟩ orientation, was detected in all the films by x-ray diffraction. The highest lattice parameters were measured for the films deposited on 310 steel substrates, while the smallest values were obtained for the films deposited on Invar® substrates. These results are closely related to the thermal expansion coefficients of the substrates. All the as-deposited films were in a compressive stress state independent of the substrate type (−3GPa for 310 steel and Fecralloy® substrates and −2GPa for Invar® substrates). The residual compressive stresses of the films deposited on Fecralloy® substrates strongly decrease with annealing temperatures up to ≈−8GPa at 1175K. This result shows that the measured compressive stresses are not real, and they are a direct consequence of plastic deformation of the substrate. On the contrary, the compressive stresses measured in the films deposited on Invar® and 310 steel substrates are real as plastic deformation of the substrates is not observed.
Thermal stability of sputter deposited nanocrystalline W2N/amorphous Si3N4 coatings
Authors: Fu T. , Shen Y. G. , Zhou Z. F. , Li K. Y.
Published: November 2006

The thermal stability of nanocomposite W–Si–N coatings, which had been sputter deposited at increased silicon target currents, was studied by annealing at 800 or 900°C in vacuum by using x-ray diffraction, x-ray photoelectron spectroscopy, electron probe microanalysis, scanning electron microscopy, atomic force microscopy, and microhardness testing. The crystalline W2N coatings were decomposed to W with the loss of interstitial N atoms and the presence of microcracks at their surfaces after annealing at 900°C. The coating consisting of nanocrystalline (nc-) W2N imbedded in amorphous (a-) Si3N4 matrices and the amorphous coatings underwent partial recrystallization, the loss of interstitial N atoms, and morphological changes upon annealing. The nc-W2N∕a-Si3N4 coating had the least N in grain boundaries and the lowest atomic O∕N ratio, and it had no failure after annealing at 900°C, showing high thermal stability. The hardness of the coatings was decreased, but the nc-W2N∕a-Si3N4 coating maintained the highest hardness (46.6±3.7GPa) after annealing at 900°C.
The acoustic center of laboratory standard microphones
Authors: Barrera-Figueroa Salvador , Rasmussen Knud , Jacobsen Finn
Published: November 2006

An experimental procedure is described for obtaining the effective acoustic distance between pairs of microphones coupled by a free field, leading to the determination of the position of the acoustic center of the microphones. The procedure, which is based on measuring the modulus of the electrical transfer impedance, has been applied to a large number of microphones. In all cases effects due to reflections from the walls of the anechoic chamber and the interference between the microphones have been removed using a time-selective technique. The procedure of determining the position of the acoustic center from the inverse distance law is analyzed. Experimental values of the acoustic center of laboratory standard microphones are presented, and numerical results obtained using the boundary element method supplement the experimental data. Estimated uncertainties are also presented. The results reported confirm values previously defined in an international standard and extend the frequency range.
Detection of acoustic cavitation in the heart with microbubble contrast agents in vivo: A mechanism for ultrasound-induced arrhythmias
Authors: Rota Claudio , Raeman Carol H. , Child Sally Z. , Dalecki Diane
Published: November 2006

Ultrasound fields can produce premature cardiac contractions under appropriate exposure conditions. The pressure threshold for ultrasound-induced premature contractions is significantly lowered when microbubble contrast agents are present in the vasculature. The objective of this study was to measure directly ultrasound-induced cavitation in the murine heart in vivo and correlate the occurrence of cavitation with the production of premature cardiac contractions. A passive cavitation detection technique was used to quantify cavitation activity in the heart. Experiments were performed with anesthetized, adult mice given intravenous injections of either a contrast agent (Optison®) or saline. Murine hearts were exposed to ultrasound pulses (200kHz, 1ms, 0.1–0.25MPa). Premature beats were produced in mice injected with Optison®and the likelihood of producing a premature beat increased with increasing pressure amplitude. Similarly, cavitation was detected in mice injected with Optison® and the amplitude of the passive cavitation detector signal increased with increasing exposure amplitude. Furthermore, there was a direct correlation between the extent of cavitation and the likelihood of ultrasound producing a premature beat. Neither premature beats nor cavitation activity were observed in animals injected with saline and exposed to ultrasound. These results are consistent with acoustic cavitation as a mechanism for this bioeffect.
Initial Transcription by RNA Polymerase Proceeds Through a DNA-Scrunching Mechanism
Authors: Kapanidis Achillefs N. , Margeat Emmanuel , Ho Sam On , Kortkhonjia Ekaterine , Weiss Shimon , Ebright Richard H.
Published: November 2006

Using fluorescence resonance energy transfer to monitor distances within single molecules of abortively initiating transcription initiation complexes, we show that initial transcription proceeds through a “scrunching” mechanism, in which RNA polymerase (RNAP) remains fixed on promoter DNA and pulls downstream DNA into itself and past its active center. We show further that putative alternative mechanisms for RNAP active-center translocation in initial transcription, involving “transient excursions” of RNAP relative to DNA or “inchworming” of RNAP relative to DNA, do not occur. The results support a model in which a stressed intermediate, with DNA-unwinding stress and DNA-compaction stress, is formed during initial transcription, and in which accumulated stress is used to drive breakage of interactions between RNAP and promoter DNA and between RNAP and initiation factors during promoter escape.
Detecting Immunoglobulin M Antibodies against Microsporidian
Encephalitozoon cuniculi
Polar Tubes in Sera from Healthy and Human Immunodeficiency Virus-Infected Persons in Japan
Authors: Omura Mako , Furuya Koji , Kudo Shinichi , Sugiura Wataru , Azuma Hiroshi
Published: November 2006

Encephalitozoon cuniculi
, a spore-forming obligate intracellular parasitic pathogen belonging to the phylum Microsporidia, has a unique and highly specialized organelle called the polar tube. Using an enzyme immunostaining assay in which germinated
E. cuniculi
spores were coated onto plastic surfaces, we tested healthy and human immunodeficiency virus (HIV)-infected individuals in Japan for anti-polar tube antibodies of each immunoglobulin (Ig) class. Anti-polar tube IgG was detected in just 4 of 380 healthy individuals; no anti-polar tube IgA was detected in any individuals; however, unexpectedly, anti-polar tube IgM antibodies were detected in 138 individuals (36%). When the healthy individuals were grouped by age, the highest rate of positivity to anti-polar tube IgM antibodies was seen in individuals aged 20 years old or younger. Fifty-nine percent (24/41) of the individuals aged 20 years or younger were anti-polar tube IgM antibody positive. This rate tended to decrease among individuals in older age groups. However, no anti-polar tube IgM antibodies were detected in 21 HIV-infected persons who were younger than 30 years of age and who had CD4 cell levels below 250/μl. These seroepidemiological results clearly indicate that circulating anti-polar tube IgM antibodies that are capable of strongly reacting with filaments extruded from geminated spores exist and suggest that such antibodies may play a part in protective immunity.
CbgA, a Protein Involved in Cortex Formation and Stress Resistance inMyxococcus xanthusSpores
Authors: Tengra Farah K. , Dahl John L. , Dutton David , Caberoy Nora B. , Coyne Lia , Garza Anthony G.
Published: November 2006

CbgA plays a role in cortex formation and the acquisition of a subset of stress resistance properties inMyxococcus xanthusspores. ThecbgAmutant produces spores with thin or no cortex layers, and these spores are more sensitive to heat and sodium dodecyl sulfate than their wild-type counterparts.
Agrobacterium rhizogenes
GALLS Protein Contains Domains for ATP Binding, Nuclear Localization, and Type IV Secretion
Authors: Hodges Larry D. , Vergunst Annette C. , Neal-McKinney Jason , den Dulk-Ras Amke , Moyer Deborah M. , Hooykaas Paul J. J. , Ream Walt
Published: November 2006

Agrobacterium tumefaciens
and
Agrobacterium rhizogenes
are closely related plant pathogens that cause different diseases, crown gall and hairy root. Both diseases result from transfer, integration, and expression of plasmid-encoded bacterial genes located on the transferred DNA (T-DNA) in the plant genome. Bacterial virulence (Vir) proteins necessary for infection are also translocated into plant cells. Transfer of single-stranded DNA (ssDNA) and Vir proteins requires a type IV secretion system, a protein complex spanning the bacterial envelope.
A. tumefaciens
translocates the ssDNA-binding protein VirE2 into plant cells, where it binds single-stranded T-DNA and helps target it to the nucleus. Although some strains of
A. rhizogenes
lack VirE2, they are pathogenic and transfer T-DNA efficiently. Instead, these bacteria express the GALLS protein, which is essential for their virulence. The GALLS protein can complement an
A. tumefaciens virE2
mutant for tumor formation, indicating that GALLS can substitute for VirE2. Unlike VirE2, GALLS contains ATP-binding and helicase motifs similar to those in TraA, a strand transferase involved in conjugation. Both GALLS and VirE2 contain nuclear localization sequences and a C-terminal type IV secretion signal. Here we show that mutations in any of these domains abolished the ability of GALLS to substitute for VirE2.
Global Map of Growth-Regulated Gene Expression in
Burkholderia pseudomallei
, the Causative Agent of Melioidosis
Authors: Rodrigues Fiona , Sarkar-Tyson Mitali , Harding Sarah V. , Sim Siew Hoon , Chua Hui Hoon , Lin Chi Ho , Han Xu , Karuturi R. Krishna M. , Sung Ken , Yu Kun , Chen Wei , Atkins Timothy P. , Titball Richard W. , Tan Patrick
Published: November 2006

Many microbial pathogens express specific virulence traits at distinct growth phases. To understand the molecular pathways linking bacterial growth to pathogenicity, we have characterized the growth transcriptome of
Burkholderia pseudomallei
, the causative agent of melioidosis. Using a fine-scale sampling approach, we found approximately 17% of all
B. pseudomallei
genes displaying regulated expression during growth in rich medium, occurring as broad waves of functionally coherent gene expression tightly associated with distinct growth phases and transition points. We observed regulation of virulence genes across all growth phases and identified
serC
as a potentially new virulence factor by virtue of its coexpression with other early-phase virulence genes.
serC
-disrupted
B. pseudomallei
strains were serine auxotrophs and in mouse infection assays exhibited a dramatic attenuation of virulence compared to wild-type
B. pseudomallei
. Immunization of mice with
serC
-disrupted
B. pseudomallei
also conferred protection against subsequent challenges with different wild-type
B. pseudomallei
strains. At a genomic level, early-phase genes were preferentially localized on chromosome 1, while stationary-phase genes were significantly biased towards chromosome 2. We detected a significant level of chromosomally clustered gene expression, allowing us to predict ∼100 potential operons in the
B. pseudomallei
genome. We computationally and experimentally validated these operons by showing that genes in these regions are preferentially transcribed in the same 5′→3′ direction, possess significantly shorter intergenic lengths than the overall genome, and are expressed as a common mRNA transcript. The availability of this transcriptome map provides an important resource for understanding the transcriptional architecture of
B. pseudomallei
.
Critical Residues and Novel Effects of Overexpression of the
Streptomyces coelicolor
Developmental Protein BldB: Evidence for a Critical Interacting Partner
Authors: Eccleston Marcus , Willems Andrew , Beveridge Adam , Nodwell Justin R.
Published: November 2006

The
bldB
gene of
Streptomyces coelicolor
encodes the best-characterized member of a family of small proteins that have low isoelectric points but that lack any previously characterized sequence motifs. BldB is dimeric and is required for the efficient production of antibiotics and spore-forming cells, called aerial hyphae, by growing colonies. The mechanism of action of BldB and its relatives is unknown. Here, we have explored amino acids in BldB that either are highly conserved or have been implicated in function genetically. We show that five amino acids are important for its function at physiological expression levels. Mutations in three of these amino acids gave rise to proteins that were either monomeric or unstable in vivo, while two others are not. We find that overexpression of
bldB
in
S. coelicolor
blocks sporulation prior to sporulation-specific septation but permits the formation of aerial hyphae. Vegetative septation was apparently normal in both the
bldB
null mutant and the
bldB
overexpression strain. To our surprise, overexpression of the dimerization-competent but functionally defective alleles caused a dramatic acceleration of sporulation. Our results suggest that BldB makes at least one important contact with another subcellular constituent and that a loss or alteration of this interaction impairs the phenotypic properties of the organism.
YtxR, a Conserved LysR-Like Regulator That Induces Expression of Genes Encoding a Putative ADP-Ribosyltransferase Toxin Homologue inYersinia enterocolitica
Authors: Axler-DiPerte Grace L. , Miller Virginia L. , Darwin Andrew J.
Published: November 2006

Yersinia enterocoliticacauses human gastroenteritis, and many isolates have been classified as either “American” or “non-American” strains based on their geographic prevalence and virulence properties. In this study we describe identification of a transcriptional regulator that controls expression of theY. enterocolitica ytxABgenes. TheytxABgenes have the potential to encode an ADP-ribosylating toxin with similarity to pertussis toxin. However, aytxABnull mutation did not affect virulence in mice. Nevertheless, theytxABgenes are conserved in manyY. enterocoliticastrains. Interestingly, American and non-American strains have differentytxABalleles encoding proteins that are only 50 to 60% identical. To obtain further insight into theytxABlocus, we investigated whether it is regulated as part of a known or novel regulon. Transposon mutagenesis identified a LysR-like regulator, which we designated YtxR. Expression ofytxRfrom a nonnative promoter increased Φ(ytxA-lacZ) operon fusion expression up to 35-fold. YtxR also activated expression of its own promoter. DNase I footprinting showed that a His6-YtxR fusion protein directly interacted with theytxAandytxRcontrol regions at similar distances upstream of their probable transcription initiation sites, identified by primer extension. Deletion analysis demonstrated that removal of the regions protected by His6-YtxR in vitro eliminated YtxR-dependent induction in vivo. TheytxABlocus is not present in mostYersiniaspecies. In contrast,ytxRis conserved in multipleYersiniaspecies, as well as in the closely related organismsPhotorhabdus luminescensandPhotorhabdus asymbiotica. These observations suggest that YtxR may play a conserved role involving regulation of other genes besidesytxAB.
The ColRS Two-Component System Regulates Membrane Functions and Protects
Pseudomonas putida
against Phenol
Authors: Kivistik Paula Ann , Putrinš Marta , Püvi Külliki , Ilves Heili , Kivisaar Maia , Hõrak Rita
Published: November 2006

As reported, the two-component system ColRS is involved in two completely different processes. It facilitates the root colonization ability of
Pseudomonas fluorescens
and is necessary for the Tn
4652
transposition-dependent accumulation of phenol-utilizing mutants in
Pseudomonas putida
. To determine the role of the ColRS system in
P. putida
, we searched for target genes of response regulator ColR by use of a promoter library. Promoter screening was performed on phenol plates to mimic the conditions under which the effect of ColR on transposition was detected. The library screen revealed the porin-encoding gene
oprQ
and the alginate biosynthesis gene
algD
occurring under negative control of ColR. Binding of ColR to the promoter regions of
oprQ
and
algD
in vitro confirmed its direct involvement in regulation of these genes. Additionally, the porin-encoding gene
ompA
PP0773
and the type I pilus gene
csuB
were also identified in the promoter screen. However, it turned out that
ompA
PP0773
and
csuB
were actually affected by phenol and that the influence of ColR on these promoters was indirect. Namely, our results show that ColR is involved in phenol tolerance of
P. putida
. Phenol MIC measurement demonstrated that a
colR
mutant strain did not tolerate elevated phenol concentrations. Our data suggest that increased phenol susceptibility is also the reason for inhibition of transposition of Tn
4652
in phenol-starving
colR
mutant bacteria. Thus, the current study revealed the role of the ColRS two-component system in regulation of membrane functionality, particularly in phenol tolerance of
P. putida
.
Use of Partial 16S rRNA Gene Sequencing for Identification of
Legionella pneumophila
and Non-
pneumophila Legionella
spp
Authors: Wilson D. A. , Reischl U. , Hall G. S. , Procop G. W.
Published: November 2006

We examined 49
Legionella
species, 26
L. pneumophila
and 23 non-
pneumophila Legionella
spp., using partial 16S rRNA gene sequencing. This approach accurately identified all the
L. pneumophila
isolates, characterized all non-
pneumophila Legionella
isolates as such within this genus, and classified most (20/23; 87%) of the non-
pneumophila Legionella
isolates to the species level.
Analysis of Changes in Recent Tuberculosis Transmission Patterns after a Sharp Increase in Immigration
Authors: Iñigo Jesús , García de Viedma Darío , Arce Araceli , Palenque Elia , Alonso Rodríguez Noelia , Rodríguez Elena , Ruiz Serrano María Jesús , Andrés Sandra , Bouza Emilio , Chaves Fernando
Published: November 2006

We conducted a population-based molecular epidemiological study of tuberculosis (TB) in Madrid, Spain (2002 to 2004), to define transmission patterns and factors associated with clustering. We particularly focused on examining how the increase in TB cases among immigrants in recent years (2.8% in 1997 to 1999 to 36.2% during the current study) was modifying transmission patterns.
Mycobacterium tuberculosis
isolates obtained from patients living in nine districts of Madrid (1,459,232 inhabitants) were genotyped. The TB case rate among foreign-born people was three to four times that of Spanish-born people, and the median time from arrival to the onset of treatment was 22.4 months. During the study period, 227 (36.3%) patients were grouped in 64 clusters, and 115 (50.7%) of them were in 21 clusters with mixed Spanish-born and foreign-born patients. Three of the 21 mixed clusters accounted for 21.1% of clustered patients. Twenty-two of 38 (57.9%) immigrants in mixed clusters were infected with TB strains that had already been identified in the native population in 1997 to 1999, including the three most prevalent strains. Factors identified as independent predictors of clustering were homelessness (odds ratio [OR], 2.3; 95% confidence interval [95% CI], 1.2 to 4.5;
P
= 0.011) and to be born in Spain (OR, 1.8; 95% CI, 1.2 to 2.6;
P
= 0.002). The results indicated that (i) TB transmission was higher in Spanish-born people, associated mainly with homelessness, (ii) that foreign-born people were much less likely to be clustered, suggesting a higher percentage of infection before arriving in Spain, and (iii) that an extensive transmission between Spanish- and foreign-born populations, caused mainly by autochthonous strains, was taking place in Madrid.
Inhibition of Heavy Chain and β2-Microglobulin Synthesis as a Mechanism of Major Histocompatibility Complex Class I Downregulation during Epstein-Barr Virus Replication
Authors: Guerreiro-Cacais Andre Ortlieb , Uzunel Mehmet , Levitskaya Jelena , Levitsky Victor
Published: November 2006

The mechanisms of major histocompatibility complex (MHC) class I downregulation during Epstein-Barr virus (EBV) replication are not well characterized. Here we show that in several cell lines infected with a recombinant EBV strain encoding green fluorescent protein (GFP), the virus lytic cycle coincides with GFP expression, which thus can be used as a marker of virus replication. EBV replication resulted in downregulation of MHC class II and all classical MHC class I alleles independently of viral DNA synthesis or late gene expression. Although assembled MHC class I complexes, the total pool of heavy chains, and β2-microglobulin (β2m) were significantly downregulated, free class I heavy chains were stabilized at the surface of cells replicating EBV. Calnexin expression was increased in GFP+cells, and calnexin and calreticulin accumulated at the cell surface that could contribute to the stabilization of class I heavy chains. Decreased expression levels of another chaperone, ERp57, and TAP2, a transporter associated with antigen processing and presentation, correlated with delayed kinetics of MHC class I maturation. Levels of both class I heavy chain and β2m mRNA were reduced, and metabolic labeling experiments demonstrated a very low rate of class I heavy chain synthesis in lytically infected cells. MHC class I and MHC class II downregulation was mimicked by pharmacological inhibition of protein synthesis in latently infected cells. Our data suggest that although several mechanisms may contribute to MHC class I downregulation in the course of EBV replication, inhibition of MHC class I synthesis plays the primary role in the process.
Creatine intake attenuates corticosteroid-induced impairment of voluntary running in hamsters
Authors: Campos Andrea R. , Serafini Luciano N. , Sobreira Claudia , Menezes Luciana G. , Martinez José A.B.
Published: November 2006

Myopathy is a well-known side effect of corticosteroid therapy. Creatine monohydrate (Cr) supplementation has been shown to increase fat-free mass and muscular function. This study aimed to investigate if Cr administration could offset the deleterious functional effects of high doses of steroids. Fifty-six male Syrian golden hamsters were randomized among 4 groups: GI (n = 10), subcutaneous (s.c.) and intraperitoneal (i.p.) saline; GII (n = 10), s.c. saline and i.p. Cr (600 mg·kg–1·d–1); GIII (n = 18), s.c. dexamethasone (7.5 mg·kg–1·d–1) and i.p. saline; and GIV (n = 18), s.c. dexamethasone and i.p. Cr. Daily voluntary running was measured using activity wheels for 18 d. At the end of the study, statistically significant differences in running were observed between all groups, except for GI versus GII (GI, 8878 ± 2737 m; GII, 9145 ± 2000 m; GIII, 4289 ± 2623 m; GIV, 6339 ± 2345 m). Dexamethasone led to a significant decrease in cross-sectional area of type II fibers of the medial gastrocnemius. The cross-sectional area of type I fibers was significantly larger in GIV than in GIII. In conclusion, Cr administration attenuated the impairment of daily spontaneous running of hamsters receiving a high dose of corticosteroids. Additional research is needed to clarify the clinical implications of this finding.
Acute effects of exercise timing and breakfast meal glycemic index on exercise-induced fat oxidation
Authors: Bennard Patrick , Doucet Éric
Published: November 2006

Fat balance is an important determinant of energy balance. Exercise after an overnight fast can significantly increase fat oxidation; however, little information pertaining to the effects of exercise and meal glycemic index on fat oxidation under these conditions is available. The objective of this investigation was to study the acute effects of exercise timing and meal glycemic index (GI) on whole-body fat oxidation. Eight apparently healthy young men completed 4 randomly ordered trials during which measurements were made at rest, during exercise, and for 2 h post-exercise and (or) post-prandial. After an overnight fast, subjects were required to perform 400 kcal (1 kcal = 4.184 kJ) of treadmill exercise (at FATmax) either before consuming a 400 kcal low-GI (Ex-LG) or high-GI (Ex-HG) oatmeal breakfast, or after consuming the low-GI (LG-Ex) or high-GI (HG-Ex) meal. The amount of fat oxidized during exercise was significantly greater during Ex-LG and Ex-HG (17.2 ± 4.0 and 17.5 ± 4.7 g, respectively) than during LG-Ex and HG-Ex (10.9 ± 3.7 and 11.7 ± 3.5 g, respectively) (p < 0.001), as was the amount of fat oxidized during the entire trial (Ex-LG: 23.4 ± 4.7 g; Ex-HG: 23.4 ± 6.5 g; LG-Ex: 18.4 ± 4.7 g; HG-Ex: 19.6 ± 4.9 g) (p < 0.05), even though energy expenditure was not different across experimental conditions. No significant effect of meal GI on the amount of fat oxidized was noted. Total fat oxidized during exercise, and for 2 h after exercise, was greatest when morning exercise was performed in the fasted state, independently of meal GI.
Addition of glutamine to essential amino acids and carbohydrate does not enhance anabolism in young human males following exercise
Authors: Wilkinson Sarah B. , Kim Paul L. , Armstrong David , Phillips Stuart M.
Published: November 2006

We examined the effect of a post-exercise oral carbohydrate (CHO, 1 g·kg–1·h–1) and essential amino acid (EAA, 9.25 g) solution containing glutamine (0.3 g/kg BW; GLN trial) versus an isoenergetic CHO–EAA solution without glutamine (control, CON trial) on muscle glycogen resynthesis and whole-body protein turnover following 90 min of cycling at 65% VO2 peak. Over the course of 3 h of recovery, muscle biopsies were taken to measure glycogen resynthesis and mixed muscle protein synthesis (MPS), by incorporation of [ring-2H5] phenylalanine. Infusion of [1-13C] leucine was used to measure whole-body protein turnover. Exercise resulted in a significant decrease in muscle glycogen (p < 0.05) with similar declines in each trial. Glycogen resynthesis following 3 h of recovery indicated no difference in total accumulation or rate of repletion. Leucine oxidation increased 2.5 fold (p < 0.05) during exercise, returned to resting levels immediately post-exercise,and was again elevated at 3 h post-exercise (p < 0.05). Leucine flux, an index of whole-body protein breakdown rate, was reduced during exercise, but increased to resting levels immediately post-exercise, and was further increased at 3 h post-exercise (p < 0.05), but only during the CON trial. Exercise resulted in a marked suppression of whole-body protein synthesis (50% of rest; p < 0.05), which was restored post-exercise; however, the addition of glutamine did not affect whole-body protein synthesis post-exercise. The rate of MPS was not different between trials. The addition of glutamine to a CHO + EAA beverage had no effect on post-exercise muscle glycogen resynthesis or muscle protein synthesis, but may suppress a rise in whole-body proteolysis during the later stages of recovery.
Fatigue and muscle–tendon stiffness after stretch–shortening cycle and isometric exercise
Authors: Toumi Hechmi , Poumarat Georges , Best Thomas M. , Martin Alain , Fairclough John , Benjamin Mike
Published: November 2006

The purpose of the present study was to compare vertical jump performance after 2 different fatigue protocols. In the first protocol, subjects performed consecutive sets of 10 repetitions of stretch–shortening cycle (SSC) contractions. In the second protocol, successive sets of 10 repetitions of isometric contractions were performed for 10 s with the knee at 90° of flexion. The exercises were stopped when the subjects failed to reach 50% of their maximum voluntary isometric contractions. Maximal isometric force and maximal concentric power were assessed by performing supine leg presses, squat jumps, and drop jumps. Surface EMG was used to determine changes in muscle activation before and after fatigue. In both groups, the fatigue exercises reduced voluntary isometric force, maximal concentric power, and drop jump performance. Kinematic data showed a decrease in knee muscle–tendon stiffness accompanied by a lengthened ground contact time. EMG analysis showed that the squat and drop jumps were performed similarly before and after the fatigue exercise for both groups. Although it was expected that the stiffness would decrease more after SSC than after isometric fatigue (as a result of a greater alteration of the reflex sensitivity SSC), our results showed that both protocols had a similar effect on knee muscle stiffness during jumping exercises. Both fatigue protocols induced muscle fatigue, and the decrease in jump performance was linked to a decrease in the strength and stiffness of the knee extensor muscles.
Energy expenditure while performing gymnastic-like motion in spacelab during spaceflight: case study
Authors: Kaneko Masahiro , Miyatsuji Kazuki , Tanabe Satoru
Published: November 2006

To estimate energy cost of a gymnastic-like exercise performed by an astronaut during spaceflight (cosmic exercise), energy expenditure was determined by measuring mechanical work done around the center of mass (COM) of the body. The cosmic exercise, which consisted of whole-body flexion and extension, was performed during a spaceflight and recorded with a video camera. By analyzing the videotape, the internal mechanical work (Wint) against inertia load of the body segments was calculated. To compare how human muscles work on Earth, a motion similar to the cosmic exercise was performed by a control subject who had a physique similar to that of the astronaut. The total mechanical power of the astronaut was determined to be about 119 W; although the control subject showed a similar total power value, half of the power was external work (Wext) against gravitational load. By assuming a mechanical efficiency of 0.25, the energy expenditure was estimated to be 476 W or 7.7 W/kg, which is equivalent to that expended during fast walking and half of that used during moderate-speed running. Our results suggest that this form of cosmic exercise is appropriate for astronauts in space and can be performed safely, as there are no COM shifts while floating in a spacecraft and no vibratory disturbance.
Regioselectivity of glycoluril-directed Claisen condensations — A kinetic and mechanistic study of substituent effects in the nucleophilic acyl group
Authors: Chen Mei , Won Katie , McDonald Robert S , Harrison Paul H.M
Published: November 2006

The Claisen-like condensation of a series of 1-arylacetyl-6-acetyl-3,4,7,8-tetramethylglycolurils (Ar = Ph, p-OMeC6H4, and p-ClC6H4) was studied in preparative experiments and by analysis of kinetic data. The reactions proceeded in virtually quantitative yield and were highly regioselective: the corresponding N-(2′-aryl-3′-ketobutanoyl)-3,4,7,8-tetramethylglycolurils were obtained in all cases, with none of the 4′-aryl regioisomers being detected. Clean bimolecular kinetics were observed for each conversion using UV spectroscopy. Reaction rates followed the order Ar = p-OMeC6H4 < Ph < p-ClC6H4. The results are explained by a mechanism in which the deprotonation of the substrates is rate-limiting; thus, deprotonation of the arylacetyl groups is favoured. The ensuing enolate reacts rapidly in the C–C bond-forming step.Key words: glycoluril, biomimetic, Claisen condensation, regioselectivity, kinetics, mechanism, substituent effects.
Characterization of the arginine deiminase ofStreptococcus equisubsp.zooepidemicus
Authors: Hong Kyongsu
Published: November 2006

Streptococcus equi subsp. zooepidemicus is an important cause of infectious diseases in horses and rarely humans. Little is known about the virulence factors or protective antigens of S. equi subsp. zooepidemicus. In the present study, I designed original primers based on an alignment of the gene sagp(arcA) from Streptococcus pyogenes encoding streptococcal acid glycoprotein – arginine deiminase (SAGP/AD) to amplify the S. equi subsp. zooepidemicus counterpart sequence by polymerase chain reaction, and I analyzed the sagp(arcA) gene of the organism. Using chromosomal walking steps, I identified a contiguous eight-gene locus involved in SAGP/AD production. Their open reading frames were found to share significant homologies and to correspond closely in molecular mass to previously sequenced arc genes of S. pyogenes, thus they were designated ahrC.2 (arginine repressor), arcR (CRP/FNR transcription regulator), sagp(arcA) (streptococcal acid glycoprotein – arginine deiminase), putative acetyltransferase gene, arcB (ornithine carbamyl transferase), arcD (arginine–ornithine antiporter), arcT (Xaa-His peptidase), and arcC (carbamate kinase). The SAGP homologue of S. equi subsp. zooepidemicus (SzSAGP), encoded by arcA gene of the bacteria (arcA(SZ)), was successfully expressed in Escherichia coli and purified to homogeneity. When in vitro growth inhibitory activity of the recombinant SzSAGP was tested against MOLT-3 cells, it inhibited the growth of the cells during the 3 days of culture in a dose-dependent manner, accompanied by the induction of apoptotic cell death. The recombinant protein also possessed AD activity. By immunoblot analysis using both anti-SzSAGP-SfbI(H8) and anti-SfbI(H8) sera, I was able to demonstrate that the SzSAGP protein is expressed on the streptococcal surface.Key words: SAGP, arginine deiminase, Streptococcus equi subsp. zooepidemicus.
The constant gene orf14.9, which belongs to the variable eps (exopolysaccharide) cluster, is involved in the cell growth of Streptococcus thermophilus
Authors: Tyvaert Guillaume , Morel Catherine , Joly Jean-Pierre , Decaris Bernard , Charron-Bourgoin Florence
Published: November 2006

In Streptococcus thermophilus, the eps clusters involved in exopolysaccharide (EPS) biosynthesis are very polymorphic, nevertheless they all contain a highly conserved sequence corresponding to that of orf14.9. This open reading frame (ORF) is transcribed in a reverse direction with respect to eps genes. Amino acid sequence analysis showed a possible transmembrane location of the putative Orf14.9 protein but did not permit a proposed function. Insertional mutants of orf14.9 were obtained in strains NST2280 and A054 of S. thermophilus. EPS yields of these mutants are similar to those of their respective wild strains, suggesting that orf14.9 does not modify the quantity of produced EPS. Growth parameter determination for wild strains and their respective mutants showed that orf14.9 is involved in the cell growth of S. thermophilus.Key words: Streptococcus thermophilus, eps cluster, orf14.9, sequence analysis, exopolysaccharide biosynthesis, cell growth.
Dietary fructooligosaccharides alter the cultivable faecal population of rats but do not stimulate the growth of intestinal bifidobacteria
Authors: Gourgue-Jeannot C , Kalmokoff M L , Kheradpir E , Kwan J , Lampi B J , McAllister M , Brooks S P.J
Published: November 2006

The effect of fructans on the cultivable faecal community of Bio Breeding rats fed diets containing 5% (m/v) food-grade fructooligosaccharide (FOS) was investigated. Culturing of faecal material using chicory inulin as the sole carbohydrate source revealed the presence of a greater diversity of inulin-utilizing bacterial species in FOS-fed rats as compared with the control rats, although both contained species which effectively utilized inulin. The majority of cultivable inulin-utilizing species fell within the Clostridium coccoides group and Clostridium leptum subgroup, some of which were related to previously cultured butyrate-producing bacteria from the intestines of various animals. The impact of FOS on the growth of the indigenous bifidobacteria community and three inulin-utilizing isolates was assessed using real-time polymerase chain reaction. While dietary FOS was found to stimulate the growth of all three inulin-utilizing isolates, no growth stimulation of the indigenous bifidobacteria community occurred over the duration of the feeding trial.Key words: fructooligosaccharide, rat, faecal bacteria, bifidobacteria.
Hepatitis C virus infection among First Nation and non-First Nation people in Manitoba, Canada — a public health laboratory study
Authors: Dawood Magdy , Smart Gerry , Wood Michelyn , Wu Hong-Xing , Paton Shirley , Wu Jun
Published: November 2006

Demographic information and laboratory test results on 136 169 clinical serum specimens submitted to the public health laboratory in Manitoba, Canada, for hepatitis C virus (HCV) testing between January 1995 and December 2003 were analyzed. The difference in the clearance rates of HCV infection, without therapeutic intervention, and the HCV genotypes infecting First Nation and non-First Nation people were studied. The rates of co-infection of HCV-positive individuals with other hepatitis viruses were also compared between the two study groups. The results of the analyses of the data indicated that there was a 4.4-fold increase in the number of specimens tested and a 4.9-fold decrease in HCV antibody (anti-HCV) positive cases during the study period. The proportion of specimens submitted for testing from First Nation individuals was lower than their proportion in the Manitoba population. Our study also indicated that there was a significantly higher proportion of First Nation patients who had self-limiting infection (patients cleared the infection and became HCV RNA negative without anti-HCV treatment) in comparison to non-First Nation patients. The proportion of First Nation females who had self-limiting infection was significantly higher than non-First Nation females. HCV genotype 1 infection represented more than 60% of HCV infection in Manitoba. The rate of individuals positive for the hepatitis A virus antibody in the HCV-positive population was higher among First Nation than non-First Nation individuals. On the other hand, there were more HCV-infected First Nation patients than non-First Nation patients who were not immune to the hepatitis B virus. The data indicate that fewer First Nation patients seek anti-HCV therapy in comparison to non-First Nation. In conclusion, the differences in the rates of HCV self-limiting infection between First Nation and non-First Nation individuals in Manitoba may reflect the genetic differences between the two cohorts, which may consequently affect the immune response to the HCV infection.Key words: hepatitis A virus, hepatitis B virus, genotyping, mixed infection, self-limiting infection.
Enriched feather hydrogen isotope values for Wood Thrushes sampled in Georgia, USA, during the breeding season: implications for quantifying dispersal
Authors: Powell L.A. , Hobson K.A.
Published: November 2006

We used an analysis of deuterium values (δD) of 151 Wood Thrush ( Hylocichla mustelina (J.F. Gmelin, 1789)) feathers collected during the breeding season at the Piedmont National Wildlife Refuge in Georgia, USA, to determine fidelity to the study site. We compared δD values in feathers of birds with known molt locations and birds with unknown molt locations. Mean feather value of δD was –24.8‰ (SD = 10.5‰, range = –48.0‰ to –5.5‰), and we were unable to determine a site-specific signature to assess fidelity of breeders within our sample. We used an information criterion approach to evaluate multiple hypotheses to explain the high variation in δD, and the geographic location of sample sites within the study area was selected as the best model. Feather δD values were higher than expected from mean growing-season rainfall δD values predicted for our study site. We discuss possible explanations for the enriched δD values and postulate that heat stress during molt may have contributed to our results. We suggest that future stable isotope data collection consider the potential for small-scale variation in feather δD values; information on diet gathered simultaneously with feather samples may be valuable for future studies.
Bumblebees avoid flowers containing evidence of past predation events
Authors: Abbott K.R.
Published: November 2006

Bees are at risk of predation from flower-dwelling ambush predators. Since these predators tend to be cryptic, bees trying to mitigate predation risk may need to make use of indirect cues of the predator’s presence. For example, they may use cues of past predation events as indirect cues of current predation risk. I conducted a series of experiments that examined how bumblebees (genus Bombus Latreille, 1802) respond to cues of past predation events. In two field experiments, I found that wild rose (genus Rosa L.) flowers containing a freshly killed bumblebee, or the scent of a freshly killed bumblebee, received fewer bumblebee visits than control flowers. To test the possibility that bumblebees in the first two experiments were avoiding cues of competition risk rather than cues of predation risk, captive-reared bumblebees were given a choice between two artificial flowers — one containing a freeze-killed bumblebee (relatively more similar to a live foraging bee) and the other containing a crush-killed bumblebee (relatively more similar to a bee killed by a predator). Most bumblebees chose the flower containing the freeze-killed bee, supporting the hypothesis that the bumblebees in the first two experiments were attempting to avoid predation.
Impact of eutrophication on wood frog, Rana sylvatica, tadpoles infected with Echinostoma trivolvis cercariae
Authors: Belden L.K.
Published: November 2006

In freshwater systems, environmental changes, such as eutrophication, are occurring that could impact the outcome of host–parasite interactions. Using tadpole infection with trematode cercariae as a host–parasite system, this study examined (i) growth, development, and maintenance of trematode ( Echinostoma trivolvis (Cort, 1914)) infection levels in second intermediate host larval wood frogs ( Rana sylvatica LeConte, 1825) and (ii) post-infection impacts of eutrophication on R. sylvatica tadpoles infected to varying degrees with E. trivolvis cercariae. Results from the first experiment suggest no impact of infection with 50 cercariae on R. sylvatica growth and development compared with uninfected controls. Results from the second experiment, investigating the impact of eutrophication on infected tadpoles, showed that survival to metamorphosis of the individuals in the highest infection treatment (80 cercariae) was reduced regardless of eutrophication treatment. However, for individuals surviving infection with 80 cercariae and for individuals infected with only 20 cercariae, no impact of infection on mass at metamorphosis was documented, although individuals were larger at metamorphosis in the eutrophic tanks. These data demonstrate that infection with E. trivolvis can impact R. sylvatica survivorship, at least above some threshold infection level, and that eutrophication may have minimal impacts on tadpole hosts once infection has occurred.