bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of the Electroanatomical Substrate in Human Atrial Fibrillation: The Relationship between Changes in Atrial Volume, Refractoriness, Wavefront Propagation Velocities, and AF Burden
Authors: KOJODJOJO PIPIN , PETERS NICHOLAS S , DAVIES D. WYN , KANAGARATNAM PRAPA
Published: January 2007

Introduction: Progressive remodeling occurs in experimental models of AF whereby slowing of conduction, shortening of refractoriness, and atrial dilatation are associated with an increased vulnerability to atrial fibrillation (AF). This study investigates the relative changes in atrial geometry and electrophysiology with increasing AF burden in humans.

Methods and Results: Patients undergoing ablation of AF or left‐sided accessory pathways were recruited. Atrial volumes were determined by echocardiography. Wavefront propagation velocities (WPV), specifically in the direction of activation, were calculated from pre‐ablation activation (Carto™) maps of both atria. Dispersion, adaptation of, and effective refractoriness (ERP) were measured at 3 sites. A composite arrhythmogenic index (Atrial Volume/WPV × ERP) was derived to compare the degree of electroanatomical remodeling with AF burden. Fifty‐nine patients (22 paroxysmal AF, 19 recurrent persistent AF, and 18 controls) were recruited. AF subjects had slower right atrial WPV (P = 0.01), but no difference in left atrial WPV compared with controls. ERP was reduced globally (P < 0.05), with increased dispersion (P < 0.05). WPV and ERP did not distinguish between patients with paroxysmal or persistent AF. Biatrial volumes were greater only in patients with persistent AF (P < 0.01). There was a stepwise increase in the AI with increasing AF burden (P < 0.0001).

Conclusion: An arrhythmogenic substrate exists in human AF, characterized by globally decreased refractoriness with greater dispersion, slower right atrial conduction, and atrial dilatation. Persistence of AF is not accompanied by any further electrical remodeling, but only atrial dilatation. The degree of electroanatomical remodeling is associated with the clinical pattern of AF.
Evidence of Cu Deficiency: A Key Point for the Understanding of the Mystery of the Giant Dielectric Constant in CaCu3Ti4O12
Authors: Fang Tsang‐Tse , Mei Li‐Then
Published: January 2007

The compositions of the grains and the grain boundaries in CaCu3Ti4O12 (CCTO) have been characterized by a high‐resolution field emission transmission electron microscope equipped with a high‐angle annular‐dark‐field detector and energy‐dispersive X‐ray spectroscopy (EDS). The excess ions and their clusters at grain boundaries led to the observed strain contrast. These ions are further clarified as Cu ions by Z‐contrast (Z: atomic number) image and EDS. The quantitative EDS analyses further indicate that the grain boundaries of CCTO are Cu rich and the grains are Cu deficient. The Ca‐ or Ti‐rich amorphous phases were observed at corners or edges of the grains of CCTO.
Formation of Al2O3–TiC Composite Nano‐Particles Synthesized from Carbon‐Coated Precursors
Authors: Kaga Hisashi , Koc Rasit
Published: January 2007

The formation of nano‐sized alumina–titanium carbide (Al2O3–TiC) composite powders from a carbon‐coated titanium dioxide–aluminum (TiO2–Al) mixture was investigated. The carbon‐coated TiO2–Al mixture altered the mechanism of the reaction, compared with standard mixtures, to produce high‐quality nano‐sized Al2O3–TiC powders. Data synthesized from intermediate temperatures indicate that these products form via Ti2O3 and Al3Ti. TEM images of the Al2O3–TiC powders showed fine size (50–100 nm), narrow size distribution, and lack of agglomeration. DSC data for the carbon‐coated TiO2–Al mixture showed a single endothermic and four successive weak exothermic reactions as the carbon coating moderated the heat release during the reaction.
Formation of a Metastable Celsian‐Cordierite Eutectic Structure During the Crystallization of a Ba‐Osumilite Glass–Ceramic
Authors: Lambrinou Konstantina , Vleugels Jef , Boccaccini Aldo R.
Published: January 2007

This work addresses the formation conditions and stability of a celsian‐cordierite eutectic structure produced during the crystallization of a barium magnesium aluminosilicate (BMAS) glass–ceramic with the Ba‐osumilite stoichiometry. The melt‐derived BMAS glass–ceramic was pulverized and subsequently hot pressed to produce sintered powder compacts, some of which were subjected to post‐sintering heat treatments in air. The study of the devitrified BMAS glass revealed that a metastable celsian‐cordierite eutectic structure resulted from the prolonged annealing of the BMAS glass–ceramic between 860° and 1000°C. The celsian‐cordierite eutectic structure transformed to the thermodynamically stable Ba‐osumilite phase when annealed at temperatures >1000°C.
Controlling the Morphology of Polymeric Precursor‐Derived ZnO Flower‐Like Structures
Authors: Choppali Uma , Gorman Brian P.
Published: January 2007

The study of the mechanisms of formation and growth of ZnO nanostructures is crucial as they have the potential to find applications in opto‐electronic devices. ZnO nanostructures of different morphologies have been synthesized using a low‐temperature polymeric precursor process. Controlling the Zn cation and nitric acid concentrations, flower‐like morphology of the ZnO nanostructures could be synthesized with excellent reproducibility. Besides chemistry, the effects of spin‐coating variables on morphology were also investigated. The results show that the morphology of the flowers is controlled by Zn2+ ion concentration, whereas spin speed and film thickness are responsible for the size variations. All obtained ZnO structures reveal a polycrystalline hexagonal wurtzite structure and strong UV photoluminescence along with lattice defects. Polar surfaces of ZnO promoting multilayer Volmer–Weber growth play a crucial role in the development of these flower‐like structures. Possible mechanisms for variations of morphology with synthesis parameters are discussed.
Influences of Particle Size of Alumina Filler in an LTCC System
Authors: Seo Yong Jun , Jung Jin Hyun , Cho Yong Soo , Kim Jun Chul , Kang Nam Kee
Published: January 2007

A low temperature co‐fired ceramics system consisting of a typical calcium aluminoborosilicate glass and alumina filler was used to investigate the effects of four different sizes, 13 nm, 0.5, 3, and 39 μm, of a commercially available alumina filler on the resultant densification, crystallization, and dielectric properties. There was definitely a proper range of alumina particle size, which leads to desirable densification and enhanced dielectric properties. The onset temperatures of densification and crystallization depended strongly on the filler particle size. The 3 μm sample as an optimum filler size exhibited a promising performance ofk∼8.1 andQ∼160 at a resonant frequency of 14.8 GHz, which results from early densification and intensive crystallization of the anorthite CaAl2Si2O8phase. Particularly, the use of nano‐sized alumina (13 nm) retarded both densification by ∼200°C and crystallization by ∼80°C compared with the results of the 3 μm alumina case. The dependence of the filler particle size was postulated as being related to the wetting and connectivity behavior of glass through consequent inter‐reactions between glass and ceramic.
Synthesis of Kelp‐Like Crystalline β‐SiC Nanobelts and their Apical Growth Mechanism
Authors: Dong Chao , Zou Guifu , Liu Erkai , Xi Baojuan , Huang Tao , Qian Yitai
Published: January 2007

Novel kelp‐like crystalline β‐SiC nanobelts have been synthesized through direct pyrolysis of methyltrichlorosilane at 600°C in an autoclave. The products are characterized by X‐ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, high‐resolution transmission electron microscopy, electron diffraction, and Raman spectroscopy. On the basis of morphology and structural characterization, an apical growth mechanism is proposed to clarify the formation of as‐prepared nanobelts. Also, at 420 nm, a broad peak is observed in the visible photoluminescence emission.
Sintering Kinetics at Isothermal Shrinkage: II, Effect of Y2O3 Concentration on the Initial Sintering Stage of Fine Zirconia Powder
Authors: Matsui Koji , Tanaka Kenji , Yamakawa Takanori , Uehara Masato , Enomoto Naoya , Hojo Junichi
Published: January 2007

The shrinkage behavior of fine zirconia powders containing 2.9 and 7.8 mol% Y2O3 was investigated to clarify the effect of Y2O3 concentration on the initial sintering stage. The shrinkage of powder compact was measured under both conditions of constant rates of heating (CRH) and constant temperatures. CRH measurements revealed that when the Y2O3 concentration of fine zirconia powder increased, the starting temperature of shrinkage shifted to a high temperature. Isothermal shrinkage measurements revealed that the increase in Y2O3 concentration causes the shrinkage rate to decrease. The values of activation energy (Q) and frequency‐factor term (β0) of diffusion at initial sintering were estimated by applying the sintering‐rate equation to the isothermal shrinkage data. When the Y2O3 concentration increases, both Q and β0 of diffusion increase. It is, therefore, concluded that the increase in Y2O3 concentration of fine zirconia powder decreases the shrinkage rate because of increasing Q of diffusion at the initial stage of sintering.
Patterns of breastfeeding in a UK longitudinal cohort study
Authors: Pontin David , Emmett Pauline , Steer Colin , Emond Alan ,   the ALSPAC Study Team
Published: January 2007

Although exclusive breastfeeding for the first 6 months of infant life is recommended in the UK, there is little information on the extent of exclusive breastfeeding. This study has taken the 1996 and 2003 World Health Organization (WHO) definitions of breastfeeding and investigated breastfeeding rates in the first 6 months of life in infants born to mothers enrolled in a longitudinal, representative, population‐based cohort study – the Avon Longitudinal Study of Parents and Children (ALSPAC). Information about breastfeeding and introduction of solids was available for 11 490 infants at 6 months of age (81% of live births). Exclusive breastfeeding declined steadily from 54.8% in the first month to 31% in the third, and fell to 9.6% in the fourth month mainly due to the introduction of solids to the infants. In the first 2 months, complementary feeding (breastmilk and solid/semi‐solid foods with any liquid including non‐human milk) was used in combination, and declined from 22% in the first month to 16.8% in the second due to a switch to exclusive commercial infant formula feeding. Replacement feeding (exclusive commercial infant formula or combined with any liquid or solid/semi‐solid food but excluding breastmilk) increased steadily from 21.9% in the first month to 67.1% by the seventh. This obscured the change from exclusive commercial infant formula feeding only to commercial infant formula feeding plus solids/semi‐solids, a change which started in the third month and was complete by the fifth. Using categories in the 1996 and 2003 WHO definitions, such as complementary feeding and replacement feeding, presented difficulties for an analysis of the extent of breastfeeding in this population.
Alcohol and tobacco consumption among 6–24‐months post‐partum New Zealand women
Authors: Parackal Sherly , Ferguson Elaine , Harraway John
Published: January 2007

Maternal alcohol or tobacco consumption may negatively impact the fetus and breastfeeding infants. Maternal tobacco consumption is also known to negatively affect exposed young children. The current study therefore aimed to assess the prevalence of these lifestyle behaviours in a sample of 6–24‐months post‐partum women and to elucidate socio‐demographic and maternal factors associated with these behaviours. A community‐based cross‐sectional survey was conducted on 6–24‐months post‐partum women (n = 318) in three cities in the South Island of New Zealand. Self‐reported data on current alcohol and tobacco consumption were collected from these women using a self‐administered questionnaire. The results showed that nearly 72% and 23% of these women consumed alcohol and tobacco, respectively. Being Caucasian, having a higher level of education and higher household income were significant factors for alcohol consumption, while being of younger age and of lower educational status were significant factors for tobacco consumption. Pregnancy was associated with lower odds for alcohol consumption (0.07; P < 0.001), but not with lower odds for tobacco consumption. In contrast, breastfeeding was not associated with lower odds of alcohol consumption (0.08; P = 0.075). In conclusion, younger women with lower levels of education and household income must be targeted for public health education on the negative effects of tobacco consumption on their own health and on the health of their children.
Height and weight of urban preschool children in relation to their mothers’ educational levels and employment status in Rasht City, northern Iran
Authors: Maddah Mohsen , Mohtasham‐Amiri Zahra , Rashidi Arash , Karandish Majid
Published: January 2007

This study determined the relationship between anthropometric status of 3–5‐year‐old urban children and theirs mothers’ educational levels and employment status in Rasht City, northern Iran. A total of 1319 children (638 girls and 681 boys) at the ages of 3 and 6 years in all day‐care centres in Rasht City were studied, using a cross‐sectional design. Height and weight of the children were measured, and data on mothers’ educational levels, employment status and duration of any breastfeeding were collected. Height for age, weight for age and weight for height of the children were compared with the National Center for Health Statistics (NCHS) reference population of the United States, and z‐values ≤−2 were considered as stunted, underweight and wasted, respectively. The data showed that the prevalence of stunting, wasting and underweight were 8.6%, 8.0% and 7.1%, respectively. Our findings indicated that children of both less educated mothers (<5 years of schooling, OR = 2.54; 95% CI: 1.54–4.87) and college‐educated mothers (>12 years of schooling, OR = 1.87; 95% CI: 1.08–2.4) had higher relative risk for underweight than children of mothers with an intermediate level of education (5–12 years of schooling). Children of mothers with college education were also more at risk for development of stunting (OR = 1.41; 95% CI: 1.14–4.22). In addition, children of employed mothers were more likely to be underweight (OR = 1.52; 95% CI: 1.05–2.31), stunted (OR = 2.42; 95% CI: 1.21–6.35) and wasted (OR = 3.35; 95% CI: 1.21–5.58) than children of non‐employed mothers. The relative risk for undernutrition was higher in the children of both less and highly educated mothers compared with children of mothers with an intermediate level of education. Mothers’ employment was also negatively related to nutritional status of these children in day‐care centres in Rasht City.
Training needs survey of midwives, health visitors and voluntary‐sector breastfeeding support staff in England
Authors: Wallace Louise M. , Kosmala‐Anderson Joanna
Published: January 2007

This study, which was part of a learning needs assessment of health professionals in England, reports a survey of the training needs of healthcare practitioners in breastfeeding support skills. Respondents rated their competence on 26 breastfeeding support skills, importance of update, actual and potential helpfulness of training, and accessibility in the next 2 years. Perception of organizational barriers to breastfeeding support and practitioners’ knowledge of policies and guidance on breastfeeding were measured. Data are reported on 549 healthcare practitioners, mostly midwives and health visitors working for public health services, and some voluntary‐sector practitioners, 58% had worked with women and their infants for more than 10 years, and 56% were currently spending at least 25% of their working time providing direct care to breastfeeding women. Those already competent were most likely to want more updating. Those with longer experience of breastfeeding support were more competent on three of the four competence subscales. Relationships between self‐assessed competence and current intensity of breastfeeding experience were inconsistent. Respondents preferred training with a practical component. Respondents had poor knowledge of evidence‐based policy, and only 51% had access to a breastfeeding policy. Organizational barriers to breastfeeding support were experienced by all, and especially by those with fewer years of experience (t = −2.32, d.f. = 547; P = 0.02) and those currently spending less time supporting breastfeeding women (t = −10.35, d.f. = 547; P < 0.0001). Core training is relevant to all practitioners, and practice‐based training with access to evidence‐based policies is required.
Activity of the plant peptide aglycin in mammalian systems
Authors: Dun Xin‐Peng , Wang Jian‐He , Chen Lei , Lu Jie , Li Fa‐Fang , Zhao Yan‐Ying , Cederlund Ella , Bryzgalova Galina , Efendic Suad , Jörnvall Hans , Chen Zheng‐Wang , Bergman Tomas
Published: January 2007

A 37 residue peptide, aglycin, has been purified from porcine intestine. The sequence is identical to that of residues 27–63 of plant albumin 1 B precursor (PA1B, chain b) from pea seeds. Aglycin resists in vitro proteolysis by pepsin, trypsin and Glu‐C protease, compatible with its intestinal occurrence and an exogenous origin from plant food. When subcutaneously injected into mice (at 10 µg·g−1 body weight), aglycin has a hyperglycemic effect resulting in a doubling of the blood glucose level within 60 min. Using surface plasmon resonance biosensor technology, an aglycin binding protein with an apparent molecular mass of 34 kDa was detected in membrane protein extracts from porcine and mice pancreas. The polypeptide was purified by affinity chromatography and identified through peptide mass fingerprinting as the voltage‐dependent anion‐selective channel protein 1. The results indicate that aglycin has the potential to interfere with mammalian physiology.
Fast set‐up of doxycycline‐inducible protein expression in human cell lines with a single plasmid based on Epstein–Barr virus replication and the simple tetracycline repressor
Authors: Bach Markus , Grigat Silke , Pawlik Barbara , Fork Christian , Utermöhlen Olaf , Pal Sonia , Banczyk David , Lazar Andreas , Schömig Edgar , Gründemann Dirk
Published: January 2007

We have developed a novel plasmid vector, pEBTetD, for full establishment of doxycycline‐inducible protein expression by just a single transfection. pEBTetD contains an Epstein–Barr virus origin of replication for stable and efficient episomal propagation in human cell lines, a cassette for continuous expression of the simple tetracycline repressor, and a cytomegalovirus‐type 2 tetracycline operator (tetO2)‐tetO2 promoter. As there is no integration of vector into the genome, clonal isolation of transfected cells is not necessary. Cells are thus ready for use 1 week after transfection; this contrasts with 3–12 weeks for other systems. Adequate regulation of protein expression was accomplished by abrogation of mRNA polyadenylation. In northern analysis of seven cDNAs coding for transport proteins, pools of transfected human embryonic kidney 293 cells showed on/off mRNA ratios in the order of 100 : 1. Cell pools were also analyzed for regulation of protein function. With two transport proteins of the plasma membrane, the on/off activity ratios were 24 : 1 and 34 : 1, respectively. With enhanced green fluorescent protein, a 23 : 1 ratio was observed based on fluorescence intensity data from flow cytometry. The unique advantage of our system rests on the unmodified tetracycline repressor, which is less likely, by relocation upon binding of doxycycline, to cause cellular disturbances than chimera of tetracycline repressor and eukaryotic transactivation domains. Thus, in a comprehensive comparison of on‐ and off‐states, a steady cellular background is provided. Finally, in contrast to a system based on Flp recombinase, the set‐up of our system is inherently reliable.
It is all about resolution
Authors: Soreq Hermona , Honigman Alik
Published: January 2007

The 2006 Global BioMillennium Conference took place in Tbilisi, Georgia, on 13–17 July 2006. The Conference was focused on key aspects of gene expression processes. Characteristic of state‐of‐the‐art research in the life sciences, the invited lectures spanned approaches in cell biology, gene expression, and protein function. A particular aspect that is special to the BioMillenium series of conferences (this has been the 10th in this series) is the emphasis on new and emerging technologies; the various experts in the subfields that were covered presented what, in their view, should be critical to enabling future progress.
Evaluation of Various Infused Cryoprotective Ingredients for Their Freeze–Thaw Stabilizing and Texture Improving Properties in Frozen Red Hake Muscle
Authors: Bigelow W. , Lee C.M.
Published: January 2007

ABSTRACT:  Various cryoprotective ingredients were evaluated for their freeze–thaw stabilizing and texture improving properties during 6‐mo frozen storage when red hake (Urophycis chuss) fillets were injected with sorbitol–sodium tripolyphosphate (STPP) (40% to 60% : 3%), 1.5% alginate, or 0.75% alginate with soy protein isolate (SPI)–sorbitol–STPP (5% to 10% : 40% : 3%). Injection of 10% SPI, 1.5% alginate, or 0.75% alginate–5% SPI effectively improved water binding and retarded the freeze‐induced texture changes when drip and cooking loss, centrifugal expressible moisture, protein extractability, SDS‐PAGE profile, and Instron and sensory texture were assessed. The sorbitol and STPP combination was not as effective as alginate and SPI. Freeze‐susceptible whitefish can be injected with proper cryoprotective ingredients for improved frozen storability.
Occurrence of Virulence and Antimicrobial Resistance Genes in
Escherichia coli
Isolates from Different Aquatic Ecosystems within the St. Clair River and Detroit River Areas
Authors: Hamelin Katia , Bruant Guillaume , El-Shaarawi Abdel , Hill Stephen , Edge Thomas A. , Fairbrother John , Harel Josée , Maynard Christine , Masson Luke , Brousseau Roland
Published: January 2007

Although the number of
Escherichia coli
bacteria in surface waters can differ greatly between locations, relatively little is known about the distribution of
E. coli
pathotypes in surface waters used as sources for drinking or recreation. DNA microarray technology is a suitable tool for this type of study due to its ability to detect high numbers of virulence and antimicrobial resistance genes simultaneously. Pathotype, phylogenetic group, and antimicrobial resistance gene profiles were determined for 308
E. coli
isolates from surface water samples collected from diverse aquatic ecosystems at six different sites in the St. Clair River and Detroit River areas. A higher frequency (48%) of
E. coli
isolates possessing virulence and antimicrobial resistance genes was observed in an urban site located downstream of wastewater effluent outfalls than in the other examined sites (average of 24%). Most
E. coli
pathotypes were extraintestinal pathogenic
E. coli
(ExPEC) pathotypes and belonged to phylogenetic groups B2 and D. The ExPEC pathotypes were found to occur across all aquatic ecosystems investigated, including riverine, estuarine, and offshore lake locations. The results of this environmental study using DNA microarrays highlight the widespread distribution of
E. coli
pathotypes in aquatic ecosystems and the potential public health threat of
E. coli
pathotypes originating from municipal wastewater sources.
Synthesis of
N
-Acyl Homoserine Lactone Analogues Reveals Strong Activators of SdiA, the
Salmonella enterica
Serovar Typhimurium LuxR Homologue
Authors: Janssens Joost C. A. , Metzger Kristine , Daniels Ruth , Ptacek Dave , Verhoeven Tine , Habel Lothar W. , Vanderleyden Jos , De Vos Dirk E. , De Keersmaecker Sigrid C. J.
Published: January 2007

N
-Acyl homoserine lactones (AHLs) are molecules that are synthesized and detected by many gram-negative bacteria to monitor the population density, a phenomenon known as quorum sensing.
Salmonella enterica
serovar Typhimurium is an exceptional species since it does not synthesize its own AHLs, while it does encode a LuxR homologue, SdiA, which enables this bacterium to detect AHLs that are produced by other species. To obtain more information about the specificity of the ligand binding by SdiA, we synthesized and screened a limited library of AHL analogues. We identified two classes of analogues that are strong activators of SdiA: the
N
-(3-oxo-acyl)-homocysteine thiolactones (3O-AHTLs) and the
N
-(3-oxo-acyl)-
trans
-2-aminocyclohexanols. To our knowledge, this is the first report of compounds (the 3O-AHTLs) that are able to activate a LuxR homologue at concentrations that are lower than the concentrations of the most active AHLs. SdiA responds with greatest sensitivity to AHTLs that have a keto modification at the third carbon atom and an acyl chain that is seven or eight carbon atoms long. The
N
-(3-oxo-acyl)-
trans
-2-aminocyclohexanols were found to be less sensitive to deactivation by lactonase and alkaline pH than the 3O-AHTLs and the AHLs are. We also examined the activity of our library with LuxR of
Vibrio fischeri
and identified three new inhibitors of LuxR. Finally, we performed preliminary binding experiments which suggested that SdiA binds its activators reversibly. These results increase our understanding of the specificity of the SdiA-ligand interaction, which could have uses in the development of anti-quorum-sensing-based antimicrobials.
Autoinducer-2-Producing Protein LuxS, a Novel Salt- and Chloride-Induced Protein in the Moderately Halophilic Bacterium
Halobacillus halophilus
Authors: Sewald Xaver , Saum Stephan H. , Palm Peter , Pfeiffer Friedhelm , Oesterhelt Dieter , Müller Volker
Published: January 2007

The moderately halophilic bacterium
Halobacillus halophilus
carries a homologue of LuxS, a protein involved in the activated methyl cycle and the production of autoinducer-2, which mediates quorum sensing between certain species.
luxS
of
H. halophilus
is part of an operon that encodes an
S
-adenosylmethionine-dependent methyltransferase, a cysteine synthase, and a β-cystathionine lyase. Expression of
luxS
was growth phase dependent, with maximal expression in the mid-exponential growth phase. In addition, transcription of
luxS
was strictly salt dependent; maximal mRNA concentrations were observed with 2.0 M NaCl in the growth medium. Chloride ions stimulated
luxS
transcription by a factor of three. Western blot analyses demonstrated a growth phase- and salinity-dependent production of LuxS. Moreover, cellular LuxS levels were strictly chloride dependent. Maximal accumulation of LuxS was observed at 0.5 to 1.0 M Cl
−
and depended on the salinity.
Titration and Conditional Knockdown of the
prfB
Gene in
Escherichia coli
: Effects on Growth and Overproduction of the Recombinant Mammalian Selenoprotein Thioredoxin Reductase
Authors: Rengby Olle , Arnér Elias S. J.
Published: January 2007

Release factor 2 (RF2), encoded by the
prfB
gene in
Escherichia coli
, catalyzes translational termination at UGA and UAA codons. Termination at UGA competes with selenocysteine (Sec) incorporation at Sec-dedicated UGA codons, and RF2 thereby counteracts expression of selenoproteins.
prfB
is an essential gene in
E. coli
and can therefore not be removed in order to increase yield of recombinant selenoproteins. We therefore constructed an
E. coli
strain with the endogenous chromosomal promoter of
prfB
replaced with the titratable P
BAD
promoter. Knockdown of
prfB
expression gave a bacteriostatic effect, while two- to sevenfold overexpression of RF2 resulted in a slightly lowered growth rate in late exponential phase. In a turbidostatic fermentor system the simultaneous impact of
prfB
knockdown on growth and recombinant selenoprotein expression was subsequently studied, using production of mammalian thioredoxin reductase as model system. This showed that lowering the levels of RF2 correlated directly with increasing Sec incorporation specificity, while also affecting total selenoprotein yield concomitant with a lower growth rate. This study thus demonstrates that expression of
prfB
can be titrated through targeted exchange of the native promoter with a P
BAD
-promoter and that knockdown of RF2 can result in almost full efficiency of Sec incorporation at the cost of lower total selenoprotein yield.
Contrasting Geographic Distribution Profiles of the Herpes Simplex Virus Type 1 BgO
L
and BgK
L
Variants in Japan Suggest Dispersion and Replacement
Authors: Eda Hiroyuki , Ozawa Shigeru , Yoshino Kamesaburo , Yanagi Kazuo ,   the Cooperation Group for HSV-1 RFLP Variant Study
Published: January 2007

Thelifelong latent infection-reactivation mode of infection of herpes simplex virus type 1 (HSV-1) transmitted by close contact has allowed a diversity of restriction fragment length polymorphism (RFLP) variations to accumulate in human populations. Whether and how the variants of the HSV-1 that is ubiquitous worldwide spread to different human populations is not clear. In our previous study the geographically
gradient distribution of the HSV-1 BgK
L
variant, which is a good marker for the BgK
L
:SaCFJ
M
:SaGH
M
:SaD/E
L
:KpM
S
variant, suggested that BgK
L
dispersed geographically. Southern hybridization analyses showed that in BgK
L
the
BglII cleavage site between the BglII K and small “Q/#13” fragments is lost, the SalI cleavage sites between the SalI J and C and between SalI F and J fragments are lost, and the SalI E fragment is abnormally large (SaE
L
variation). The RFLP and geographic distribution of one more HSV-1 RFLP variant, BgO
L
, were comparatively analyzed. The BglII cleavage site between the BglII O and Q/#13 fragments is lost in BgOL. BgO
L
clinical isolates were not associated with any of the SaCFJ
M
, SaE
L
, SaGH
M
, or KpM
S
variations, whereas one-fourth of the non-BgO
L
:non-BgK
L
isolates was associated with SaCFJ
M
and SaGH
M
, indicating that BgK
L
and BgO
L
are distant in terms of diversification. BgO
L
is distributed highly in the northeastern region and the southwestern island of Kyushu but is rare between the two regions in Japan, in a remarkable contrast to BgK
L
. These are the first epidemiologic data to show contrasting geographic distribution profiles of two HSV-1 variants and suggest the gradual dispersion and replacement of HSV-1
variants.
Chilling and cultivar type affect the diversity of bacterial endophytes colonizing sweet pepper (Capsicum anuumL.)
Authors: Rasche Frank , Trondl Robert , Naglreiter Christina , Reichenauer Thomas G , Sessitsch Angela
Published: January 2007

A climate chamber experiment was conducted to assay the effect of low temperatures (chilling) on the diversity of bacteria colonizing the endospheres of two thermophilic sweet pepper (Capsicum anuum L.) cultivars, Milder Spiral and Ziegenhorn Bello. Structural diversity was analyzed by 16S rRNA-based terminal restriction fragment length polymorphism (T-RFLP) analysis and by the generation of 16S rRNA gene libraries to determine dominant community members in T-RFLP profiles. Cultivable community members colonizing lines Milder Spiral and Ziegenhorn Bello were identified by 16S rRNA gene analysis. T-RFLP profiles and 16S rRNA gene libraries revealed a high heterogeneity of community composition due to chilling and suggested further the existence of cultivar-specific communities. The majority of isolates obtained from the cultivar Milder Spiral were assigned as high-G+C Gram-positive bacteria (Microbacterium sp., Micrococcus sp., Rhodococcus sp.) and Firmicutes (Staphylococcus sp.). Of the isolated endophytes obtained from cultivar Zeigenhorn Bello, 93% were affiliated with Staphylococcus aureus and Bacillus sp. (Firmicutes). The experimental set-up was suited to demonstrate that chilling and cultivar type can influence the diversity of bacterial endophytes colonizing sweet pepper. We propose additional chilling experiments to investigate the effect of chilling on functional, plant-beneficial abilities of bacterial endophytes associated with low-temperature-sensitive crops, such as sweet pepper.Key words: chilling, thermophilic sweet pepper, bacterial endophyte diversity, 16S rRNA gene analysis.
Intranasal immunization with a recombinant truncated FimH adhesin adjuvanted with CpG oligodeoxynucleotides protects mice against uropathogenicEscherichia colichallenge
Authors: Poggio Thelma Verónica , La Torre José Leonardo , Scodeller Eduardo Alberto
Published: January 2007

In this work, we assessed the efficacy of an experimental intranasal vaccine against urinary-tract infections. The vaccine contained a recombinant truncated FimH (rFimHt) adhesin plus CpG oligodeoxynucleotides. The efficacy of the vaccine was compared with that of an intramuscular vaccine that was formulated with the same immunogen plus Freund's adjuvant. Our results show that serum immunoglobulin G titers of vaccinated animals were similarly enhanced in both cases. However, the intranasal vaccine elicited higher vaginal-wash-specific immunoglobulin A titers against rFimHt than the intramuscular route. Both vaccines reduced the in vivo colonization of the bladder by uropathogenic Escherichia coli more than 100-fold in a murine cystitis model. Our results indicate that a recombinant truncated FimH adhesin plus CpG oligodeoxynucleotides is a suitable immunogenic combination that can contribute to the development of a highly efficacious urinary tract infection vaccine.Key words: FimH adhesin, CpG oligodeoxynucleotides, intranasal vaccine.
Molecular characterization and expression profile of pectin-lyase-encoding genes fromPenicillium griseoroseum
Authors: Bazzolli Denise S , Ribon Andréa O.B , de Queiroz Marisa V , de Araújo Elza F
Published: January 2007

Penicillium griseoroseum has been studied by our group because of its good pectinase production. Attempts have been done to clone pectinolytic genes, aiming to obtain pectinase-overproducing strains for industrial purposes. Here, two genes coding for pectin lyase were isolated from the P. griseoroseum genome. The plg1 gene has an open reading frame of 1341 bp coding for a putative protein of 374 amino acids with a calculated molecular mass of 40.1 kDa. The plg2 gene is characterized by an open reading frame of 1400 nucleotides and codes for a polypeptide of 383 amino acids. The plg1 gene 5′-flanking region contains putative binding sites for the transcription factors involved in regulation by ambient pH and catabolite repression. The primary structure of Plg1 and Plg2 proteins showed a relatively high homology (varying between 32.4% and 74.8%) to fungal pectin lyases characterized to date. Southern blotting analysis revealed that both genes are present as single copies in the fungus genome. Expression studies revealed a differing pattern of gene expression of plg1 and plg2 when mycelium was cultivated on medium containing different pectic components. Citric pectin followed by apple pectin were the carbon sources that best induced plg1 expression, and transcripts were detected from 24 to 76 h. The expression of the plg2 gene was monitored by reverse transcriptase – polymerase chain reaction, since Northern analysis failed to detect hybridization signals. The differential expression of these genes may provide means for the fungus to adapt to various growth conditions.Key words: pectin lyase, gene cloning, Penicillium griseoroseum, gene expression.
Role of the Sulfolobus shibatae viral T6 initiator in conferring promoter strength and in influencing transcription start site selection
Authors: Qureshi Sohail A
Published: January 2007

Archaeal promoters contain a TATA-box, an adjacent upstream TFB-recognition element (BRE), and a downstream initiator (INR) region from which transcription originates. While the contribution of A-box and BRE to promoter strength is well established, the role of DNA sequences within the INR region and its vicinity on transcription efficiency and start site selection remains unclear. Here, I demonstrate using the strong Sulfolobus shibatae viral T6 promoter that either substitution of its natural sequence from –17 and beyond with plasmid DNA or introduction of point transversion mutations at +3, –2, –4, and –5 positions reduce promoter strength dramatically, whereas +1, –1, and –2 mutations influence the transcription start site. These data therefore reveal that the INR region plays a role as important as the BRE and the A-box in T6 gene transcription. Key words: Archaea, transcription, initiator (INR), Sulfolobus shibatae, core promoter.
Differential effects of somatostatin on circulating tissue factor procoagulant activity and protein
Authors: Boden Guenther , Vaidyula Vijender , Homko Carol , Mozzoli Maria , Rao A. Koneti
Published: January 2007

The tissue factor (TF) pathway is the primary mechanism for initiation of blood coagulation. Circulating blood contains TF, which originates mainly from monocytes and is thrombogenic. The presence of somatostatin (SMS) receptors on monocytes suggests the possibility that SMS may regulate TF synthesis and/or release. Circulating TF procoagulant activity (TF-PCA), factor VIIa activity (FVIIa; clotting assays), TF antigen (TF-Ag; ELISA), prothrombin fragment 1.2 (F1.2), thrombin-antithrombin complexes (ELISAs), CD40 ligand expression on platelets, and monocyte-platelet aggregates (flow cytometry) were determined in blood from normal volunteers undergoing 24 h of basal glucose/basal insulin (BG/BI) clamps and high-glucose/high-insulin (HG/HI) clamps with and without SMS. Infusions of SMS under basal conditions (BG/BI) raised TF-PCA 1.8-fold ( P < 0.03), TF-Ag 2.3-fold ( P < 0.001), and TF expression on monocytes by 36% ( P < 0.001) and decreased plasma levels of FVIIa by 30% ( P < 0.001). Infusion of SMS reduced the 8.6-fold HG/HI–induced increase in TF-Ag by 26% and the 8.6-fold increase in TF-PCA by 100%. SMS also prevented the 60% increase in TF expression on monocytes, the 2.2-fold increase in F1.2, the 40% increase in CD40L expression on platelets, and the 17% increase in monocyte-platelet aggregates seen during HG/HI. We conclude that SMS completely prevented HG/HI-induced TF activation in normal volunteers and may be of use to reduce the procoagulant state and acute vascular events in hyperinsulinemic insulin-resistant patients with type 2 diabetes.
Rhythm of the β-cell oscillator is not governed by a single regulator: multiple systems contribute to oscillatory behavior
Authors: Heart Emma , Smith Peter J. S.
Published: January 2007

Pulsatile insulin output, paralleled by oscillations in intracellular Ca2+, reflect oscillating metabolism within β-cells in response to secretory fuels. Here we question whether oscillatory periodicity is conserved or varied from stimulation to stimulation, whether glycolysis is essential for the manifestation of an oscillatory response, and if an environment of nutrient oversupply affects oscillatory regularity. We have determined that a β-cell oscillatory Ca2+ pattern is independent of the type of applied secretory fuel (glucose, methyl-pyruvate, or α-ketoisocaproate). In addition, single cells respond with the same pattern when repeatedly stimulated, regardless of the type of stimulatory fuel. Presence of substimulatory glucose is not necessary to obtain an oscillatory responses to methyl-pyruvate or α-ketoisocaproate. Glucose-6-phosphate, as a measure of glycolytic flux, is not detectable under these conditions. These data suggest that multiple systems, rather than a single enzyme component, can contribute to the β-cell oscillatory behavior. Prolonged exposure to high levels of palmitate impaired oscillatory regularity in the individual β-cells. This supports the hypothesis that a high-fat environment might contribute to loss of regular oscillatory pattern in diabetic subjects, acting, at least in part, at the level of the single β-cell.
IL-4 gene transfer to the small bowel serosa leads to intestinal inflammation and smooth muscle hyperresponsiveness
Authors: Vallance Bruce A. , Radojevic Nicola , Hogaboam Cory M. , Deng Yikang , Gauldie Jack , Collins Stephen M.
Published: January 2007

Intestinal mucosal inflammation can lead to altered function of the underlying smooth muscle, which becomes hyperreactive to most contractile stimuli. Through nematode parasite infection models, T helper type 2 (Th2) cytokines have been implicated in intestinal muscle dysfunction; however, the mechanisms involved and the relevance of these findings to other forms of intestinal inflammation are unclear. Through gene transfer, we explored whether the Th2 cytokine IL-4 can mediate changes in longitudinal muscle function in the context of an adenoviral infection. Following abdominal surgery on mice, control β-galactosidase-encoding recombinant adenoviruses and IL-4-encoding adenoviruses were applied to the serosal surface of the jejunum, leading to infection of cells in the serosa and in the mesentery. Marker transgene expression lasted for 3 wk and was accompanied by the recruitment of macrophages, lymphocytes, and neutrophils into the peritoneal cavity and mild inflammation at the site of infection. IL-4 transgene expression led to a stronger inflammatory response characterized by tissue eosinophilia and increased numbers of peritoneal mast cells and plasma cells. Whereas control virus infection had no effect on intestinal muscle function, infection with the IL-4 virus led to significant jejunal muscle hypercontractility, evident by day 7 postinfection. This modulation of smooth muscle function was shown to be IL-4 specific, since the application of an IL-5-encoding adenovirus induced tissue eosinophilia but did not alter muscle function. These results highlight an important causal role for IL-4 in the pathological regulation of enteric smooth muscle function and identify a novel strategy for gene transfer to the intestine.
Proteomic analysis of the airway surface liquid: modulation by proinflammatory cytokines
Authors: Candiano Giovanni , Bruschi Maurizio , Pedemonte Nicoletta , Musante Luca , Ravazzolo Roberto , Liberatori Sabrina , Bini Luca , Galietta Luis J. V. , Zegarra-Moran Olga
Published: January 2007

The airway surface is covered by a fluid, the airway surface liquid, interposed between the mucous layer and the epithelium. The airway surface liquid contains proteins, secreted by different cell types, that may have pro-/anti-inflammatory or bactericidal functions or have a role in the mucociliary clearance. We have used a proteomics approach to identify the proteins secreted by an isolated in vitro model of human airway epithelium, at resting and under proinflammatory conditions, as a strategy to define the factors involved in epithelial barrier function. To this aim, we have analyzed the airway surface liquid from human bronchial epithelial cells grown as polarized monolayers in the presence and absence of inflammatory stimuli such as IL-4, IL-1β, TNF-α, and IFN-γ. Two-dimensional electrophoresis followed by mass spectrometry analysis has allowed the identification of ∼175 secreted protein spots, among which are immune-related proteins, structural proteins, an actin severer, some protease inhibitors, and a metalloproteinase. Comparisons between treated and untreated conditions have shown that the expression of several proteins was significantly modified by the different cytokines. Our results indicate that the surface epithelium is an active player in the epithelial barrier function and that inflammatory conditions may modulate protein secretion.
Vasculotropic, paracrine actions of infused mesenchymal stem cells are important to the recovery from acute kidney injury
Authors: Tögel Florian , Weiss Kathleen , Yang Ying , Hu Zhuma , Zhang Ping , Westenfelder Christof
Published: January 2007

Acute kidney injury (AKI) is a major clinical problem in which a critical vascular, pathophysiological component is recognized. We demonstrated previously that mesenchymal stem cells (MSC), unlike fibroblasts, are significantly renoprotective after ischemia-reperfusion injury and concluded that this renoprotection is mediated primarily by paracrine mechanisms. In this study, we investigated whether MSC possess vasculoprotective activity that may contribute, at least in part, to an improved outcome after ischemia-reperfusion AKI. MSC-conditioned medium contains VEGF, HGF, and IGF-1 and augments aortic endothelial cell (EC) growth and survival, a response not observed with fibroblast-conditioned medium. MSC and EC share vasculotropic gene expression profiles, as both form capillary tubes in vitro on Matrigel alone or in cooperation without fusion. MSC undergo differentiation into an endothelial-like cell phenotype in culture and develop into vascular structures in vivo. Infused MSC were readily detected in the kidney early after reflow but were only rarely engrafted at 1 wk post-AKI. MSC attached in the renal microvascular circulation significantly decreased apoptosis of adjacent cells. Infusion of MSC immediately after reflow in severe ischemia-reperfusion AKI did not improve renal blood flow, renovascular resistance, or outer cortical blood flow. These data demonstrate that the unique vasculotropic, paracrine actions elicited by MSC play a significant renoprotective role after AKI, further demonstrating that cell therapy has promise as a novel intervention in AKI.
Downregulation of vasopressin V2receptor promoter activity via V1areceptor pathway
Authors: Izumi Yuichiro , Nakayama Yushi , Mori Tomohiko , Miyazaki Hiroki , Inoue Hideki , Kohda Yukimasa , Inoue Takeaki , Nonoguchi Hiroshi , Tomita Kimio
Published: January 2007

Vasopressin V1aand V2receptors (V1aR and V2R, respectively) distribute in the collecting duct of the kidney. Although the function of V2R mediating the antidiuretic effect of AVP has been investigated in detail, the role of V1aR in the collecting ducts has not been elucidated. In the present study, we have investigated the role of the V1aR pathway in V2R promoter activity. We cloned the 5′-flanking region of rat V2R (rV2R) and investigated rV2R promoter activity in the LLC-PK1cell line transfected to express rat V1aR (rV1aR) dominantly (LLC-PK1/rV1aR). AVP induced a transient increase, followed by a sustained decrease, of rV2R promoter activity in these cells. This AVP-induced decrease of rV2R promoter activity was inhibited by V1aR, but not V2R, antagonist. PMA mimicked this decrease of rV2R promoter activity. On the contrary, 8-(4-chlorophenylthio)-cAMP increased rV2R promoter activity. These PMA- and 8-(4-chlorophenylthio)-cAMP-induced effects were not observed on the deletion segment of the 5′-flanking region lacking CAAT and SP1 sites. In conclusion, 1) expression of the V2R is downregulated via the V1aR pathway in LLC-PK1/rV1aR cells, and 2) expression of the V2R is downregulated by the PMA-induced PKC pathway and upregulated by the cAMP-PKA pathway. These opposite effects of PKC and PKA appear to be regulated by the same promoter region of CAAT and SP1.