bluuebunny/crossref_metadata_2025 huggingface dataset:
Succession of Bacterial Communities during Early Plant Development: Transition from Seed to Root and Effect of Compost Amendment
Authors: Green Stefan J. , Inbar Ehud , Michel Frederick C. , Hadar Yitzhak , Minz Dror
Published: June 2006

Compost amendments to soils and potting mixes are routinely applied to improve soil fertility and plant growth and health. These amendments, which contain high levels of organic matter and microbial cells, can influence microbial communities associated with plants grown in such soils. The purpose of this study was to follow the bacterial community compositions of seed and subsequent root surfaces in the presence and absence of compost in the potting mix. The bacterial community compositions of potting mixes, seed, and root surfaces sampled at three stages of plant growth were analyzed via general and newly developed
Bacteroidetes
-specific, PCR-denaturing gradient gel electrophoresis methodologies. These analyses revealed that seed surfaces were colonized primarily by populations detected in the initial potting mixes, many of which were not detected in subsequent root analyses. The most persistent bacterial populations detected in this study belonged to the genus
Chryseobacterium
(
Bacteroidetes
) and the family
Oxalobacteraceae
(
Betaproteobacteria
). The patterns of colonization by populations within these taxa differed significantly and may reflect differences in the physiology of these organisms. Overall, analyses of bacterial community composition revealed a surprising prevalence and diversity of
Bacteroidetes
in all treatments.
Diversity of Heteropolysaccharide-Producing Lactic Acid Bacterium Strains and Their Biopolymers
Authors: Mozzi Fernanda , Vaningelgem Frederik , Hébert Elvira María , Van der Meulen Roel , Foulquié Moreno María Remedios , Font de Valdez Graciela , De Vuyst Luc
Published: June 2006

Thirty-one lactic acid bacterial strains from different species were evaluated for exopolysaccharide (EPS) production in milk. Thermophilic strains produced more EPS than mesophilic ones, but EPS yields were generally low. Ropiness or capsular polysaccharide formation was strain dependent. Six strains produced high-molecular-mass EPS. Polymers were classified into nine groups on the basis of their monomer composition. EPS from
Enterococcus
strains were isolated and characterized.
Genotypic Diversity of
Haemophilus parasuis
Field Strains
Authors: Olvera A. , Calsamiglia M. , Aragon V.
Published: June 2006

Haemophilus
parasuis
is the cause of Glässer's disease and other
clinical disorders in pigs. It can also be isolated from the upper
respiratory tracts of healthy pigs, and isolates can have significant
differences in virulence. In this work, a partial sequence from the
60-kDa heat shock protein (Hsp60) gene was assessed as an
epidemiological marker. We analyzed partial sequences of
hsp60
and 16S rRNA genes from 103 strains of
H. parasuis
and other
related species to obtain a better classification of the strains and
examine the correlation with virulence. The results were compared with
those obtained by enterobacterial repetitive intergenic consensus PCR.
Our results showed that
hsp60
is a reliable marker for
epidemiological studies of
H. parasuis
and that the analysis
of its sequence is a better approach than fingerprinting methods.
Furthermore, the analysis of the
hsp60
and 16S rRNA gene
sequences revealed the presence of a separate lineage of virulent
strains and indicated the occurrence of lateral gene transfer among
H. parasuis
and
Actinobacillus
strains.
Dynamics and Characterization of Refractory Dissolved Organic Matter Produced by a Pure Bacterial Culture in an Experimental Predator-Prey System
Authors: Gruber David F. , Simjouw Jean-Paul , Seitzinger Sybil P. , Taghon Gary L.
Published: June 2006

We studied the effects of a bacterium (
Pseudomonas chlororaphis
) and a bactivorous protozoan (
Uronema
sp.) on transformations of labile dissolved organic carbon (DOC). In 36-day time series experiments, bacteria were grown on glucose both with and without protozoa. We measured bulk organic carbon pools and used electrospray ionization mass spectrometry to characterize dissolved organic matter on a molecular level. Bacteria rapidly utilized glucose, depleting it to nondetectable levels and producing new DOC compounds of higher molecular weight within 2 days. Some of these new compounds, representing 3 to 5% of the initial glucose-C, were refractory and persisted for over a month. Other new compounds were produced and subsequently used by bacteria during the lag and exponential growth phases, pointing to a dynamic cycling of organic compounds. Grazers caused a temporary spike in the DOC concentration consisting of labile compounds subsequently utilized by the bacteria. Grazing did not increase the complexity of the DOC pool already established by the bacteria but did continually decrease the particulate organic carbon pool and expedited the conversion of glucose-C to CO
2
. After 36 days, 29% of initial glucose-C remained in pure bacteria cultures, while only 6% remained in cultures where a grazer was present. In this study the bacteria were the primary shapers of the complex DOC continuum, suggesting higher trophic levels possibly have less of an impact on the qualitative composition of DOC than previously assumed.
Characterization of Antimicrobial Substances Produced by
Enterococcus faecalis
MRR 10-3, Isolated from the Uropygial Gland of the Hoopoe (
Upupa epops
)
Authors: Martín-Platero Antonio M. , Valdivia Eva , Ruíz-Rodríguez Magdalena , Soler Juan J. , Martín-Vivaldi Manuel , Maqueda Mercedes , Martínez-Bueno Manuel
Published: June 2006

The uropygial gland (preen gland) is a holocrine secretory gland situated at the base of the tail in birds which produces a hydrophobic fatty secretion. In certain birds, such as the hoopoe,
Upupa epops
, the composition of this secretion is influenced by both seasonal and sexual factors, becoming darker and more malodorous in females and in their nestlings during the nesting phase. The secretion is spread throughout the plumage when the bird preens itself, leaving its feathers flexible and waterproof. It is also thought to play a role in defending the bird against predators and parasites. We have isolated from the uropygial secretion of a nestling a bacterium that grows in monospecific culture which we have identified unambiguously by phenotypic and genotypic means as
Enterococcus faecalis
. The strain in question produces antibacterial substances that are active against all gram-positive bacteria assayed and also against some gram-negative strains. Its peptide nature identifies it as a bacteriocin within the group known as enterocins. Two peptides were purified to homogeneity (MR10A and MR10B), and matrix-assisted laser desorption ionization-time of flight (mass spectrometry) analysis showed masses of 5201.58 and 5207.7 Da, respectively. Amino acid sequencing of both peptides revealed high similarity with enterocin L50A and L50B (L. M. Cintas, P. Casaus, H. Holo, P. E. Hernández, I. F. Nes, and L. S. Håvarstein, J. Bacteriol.
180:
1988-1994, 1998). PCR amplification of total DNA from strain MRR10-3 with primers for the L50A/B structural genes and sequencing of the amplified fragment revealed almost identical sequences, except for a single conservative change in residue 38 (Glu→Asp) in MR10A and two changes in residues 9 (Thr→Ala) and 15 (Leu→Phe) in MR10B. This is the first time that the production of bacteriocins by a bacterium isolated from the uropygial gland has been described. The production of these broad-spectrum antibacterial substances by an enterococcal strain living in the uropygial gland may be important to the hygiene of the nest and thus to the health of the eggs and chicks.
Transcriptome of a
Nitrosomonas europaea
Mutant with a Disrupted Nitrite Reductase Gene (
nirK
)
Authors: Cho Catherine Mee-Hie , Yan Tingfen , Liu Xueduan , Wu Liyou , Zhou Jizhong , Stein Lisa Y.
Published: June 2006

Global gene expression was compared between the
Nitrosomonas europaea
wild type and a nitrite reductase-deficient mutant using a genomic microarray. Forty-one genes were differentially regulated between the wild type and the
nirK
mutant, including the
nirK
operon, genes for cytochrome
c
oxidase, and seven iron uptake genes. Relationships of differentially regulated genes to the
nirK
mutant phenotype are discussed.
Protein Engineering of the 4-Methyl-5-Nitrocatechol Monooxygenase from
Burkholderia
sp. Strain DNT for Enhanced Degradation of Nitroaromatics
Authors: Leungsakul Thammajun , Johnson Glenn R. , Wood Thomas K.
Published: June 2006

4-Methyl-5-nitrocatechol (4M5NC) monooxygenase (DntB) from
Burkholderia
sp. strain DNT catalyzes the second step of 2,4-dinitrotoluene degradation by converting 4M5NC to 2-hydroxy-5-methylquinone with the concomitant removal of the nitro group. DntB is a flavoprotein that has a very narrow substrate range. Here, error-prone PCR was used to create variant DntB M22L/L380I, which accepts the two new substrates 4-nitrophenol (4NP) and 3-methyl-4-nitrophenol (3M4NP). At 300 μM of 4NP, the initial rate of the variant expressing M22L/L380I enzyme (39 ± 6 nmol/min/mg protein) was 10-fold higher than that of the wild-type enzyme (4 ± 2 nmol/min/mg protein). The values of
k
cat
/

K
m

of the purified wild-type DntB enzyme and purified variant M22L/L380I were 40 and 450 (s
−1
M
−1
), respectively, which corroborates that the variant M22L/L380I enzyme has 11-fold-higher efficiency than the wild-type enzyme for 4NP degradation. In addition, the variant M22L/L380I enzyme has fourfold-higher activity toward 3M4NP; at 300 μM, the initial nitrite release rate of M22L/L380I enzyme was 17 ± 4 nmol/min/mg protein, while that of the wild-type enzyme was 4.4 ± 0.7 nmol/min/mg protein. Saturation mutagenesis was also used to further investigate the role of the individual amino acid residues at positions M22, L380, and M22/L380 simultaneously. Mutagenesis at the individual positions M22L and L380I did not show appreciable enhancement in 4NP activity, which suggested that these two sites should be mutated together; simultaneous saturation mutagenesis led to the identification of the variant M22S/L380V, with 20% enhanced degradation of 4NP compared to the variant M22L/L380I. This is the first report of protein engineering for nitrite removal by a flavoprotein.
Comparative and Functional Analysis of Sortase-Dependent Proteins in the Predicted Secretome of
Lactobacillus salivarius
UCC118
Authors: van Pijkeren Jan-Peter , Canchaya Carlos , Ryan Kieran A. , Li Yin , Claesson Marcus J. , Sheil Barbara , Steidler Lothar , O'Mahony Liam , Fitzgerald Gerald F. , van Sinderen Douwe , O'Toole Paul W.
Published: June 2006

Surface proteins are important factors in the interaction of probiotic and pathogenic bacteria with their environment or host. We performed a comparative bioinformatic analysis of four publicly available
Lactobacillus
genomes and the genome of
Lactobacillus salivarius
subsp.
salivarius
strain UCC118 to identify secreted proteins and those linked to the cell wall. Proteins were identified which were predicted to be anchored by WXL-binding domains, N- or C-terminal anchors, GW repeats, lipoprotein anchors, or LysM-binding domains. We identified 10 sortase-dependent surface proteins in
L. salivarius
UCC118, including three which are homologous to mucus-binding proteins (LSL_0152, LSL_0311, and LSL_1335), a collagen-binding protein homologue (LSL_2020b), two hypothetical proteins (LSL_1838 and LSL_1902b), an enterococcal surface protein homologue (LSL_1085), a salivary agglutinin-binding homologue (LSL_1832b), an epithelial binding protein homologue (LSL_1319), and a proteinase homologue (LSL_1774b). However, two of the genes are gene fragments and four are pseudogenes, suggesting a lack of selection for their function. Two of the 10 genes were not transcribed in vitro, and 1 gene showed a 10-fold increase in transcript level in stationary phase compared to logarithmic phase. The sortase gene was deleted, and three genes encoding sortase-dependent proteins were disrupted. The sortase mutant and one sortase-dependent protein (mucus-binding homologue) mutant showed a significant reduction in adherence to human epithelial cell lines. The genome-wide investigation of surface proteins can thus help our understanding of their roles in host interaction.
Complete Genome Sequence of
Yersinia pestis
Strains Antiqua and Nepal516: Evidence of Gene Reduction in an Emerging Pathogen
Authors: Chain Patrick S. G. , Hu Ping , Malfatti Stephanie A. , Radnedge Lyndsay , Larimer Frank , Vergez Lisa M. , Worsham Patricia , Chu May C. , Andersen Gary L.
Published: June 2006

Yersinia pestis
, the causative agent of bubonic and pneumonic plagues, has undergone detailed study at the molecular level. To further investigate the genomic diversity among this group and to help characterize lineages of the plague organism that have no sequenced members, we present here the genomes of two isolates of the “classical” antiqua biovar, strains Antiqua and Nepal516. The genomes of Antiqua and Nepal516 are 4.7 Mb and 4.5 Mb and encode 4,138 and 3,956 open reading frames, respectively. Though both strains belong to one of the three classical biovars, they represent separate lineages defined by recent phylogenetic studies. We compare all five currently sequenced
Y. pestis
genomes and the corresponding features in
Yersinia pseudotuberculosis
. There are strain-specific rearrangements, insertions, deletions, single nucleotide polymorphisms, and a unique distribution of insertion sequences. We found 453 single nucleotide polymorphisms in protein-coding regions, which were used to assess the evolutionary relationships of these
Y. pestis
strains. Gene reduction analysis revealed that the gene deletion processes are under selective pressure, and many of the inactivations are probably related to the organism's interaction with its host environment. The results presented here clearly demonstrate the differences between the two biovar antiqua lineages and support the notion that grouping
Y. pestis
strains based strictly on the classical definition of biovars (predicated upon two biochemical assays) does not accurately reflect the phylogenetic relationships within this species. A comparison of four virulent
Y. pestis
strains with the human-avirulent strain 91001 provides further insight into the genetic basis of virulence to humans.
DNA Binding by the
Methanothermobacter thermautotrophicus
Cdc6 Protein Is Inhibited by the Minichromosome Maintenance Helicase
Authors: Kasiviswanathan Rajesh , Shin Jae-Ho , Kelman Zvi
Published: June 2006

The Cdc6 proteins from the archaeon
Methanothermobacter thermautotrophicus
were previously shown to bind double-stranded DNA. It is shown here that the proteins also bind single-stranded DNA. Using minichromosome maintenance (MCM) helicase mutant proteins unable to bind DNA, it was found that the interaction of MCM with Cdc6 inhibits the DNA binding activity of Cdc6.
Cysteine-Scanning Analysis of the Chemoreceptor-Coupling Domain of the
Escherichia coli
Chemotaxis Signaling Kinase CheA
Authors: Zhao Jinshi , Parkinson John S.
Published: June 2006

The C-terminal P5 domain of the histidine kinase CheA is essential for coupling CheA autophosphorylation activity to chemoreceptor control through a binding interaction with the CheW protein. To locate P5 determinants critical for CheW binding and chemoreceptor control, we surveyed cysteine replacements at 39 residues predicted to be at or near the P5 surface in
Escherichia coli
CheA. Two-thirds of the Cys replacement proteins exhibited in vitro defects in CheW binding, either before or after modification with a bulky fluorescein group. The binding-defective sites were widely distributed on the P5 surface and were often interspersed with sites that caused no functional defects, implying that relatively minor structural perturbations, often far from the actual binding site, can influence its conformation or accessibility. The most likely CheW docking area included loop 2 in P5 folding subdomain 1. All but four of the binding-defective P5-Cys proteins were defective in receptor-mediated activation, suggesting that CheW binding, as measured in vitro, is necessary for assembly of ternary signaling complexes and/or subsequent CheA activation. Other Cys sites specifically affected receptor-mediated activation or deactivation of CheA, demonstrating that CheW binding is not sufficient for assembly and/or operation of receptor signaling complexes. Because P5 is quite similar to CheW, whose structure is known to be dynamic, we suggest that conformational flexibility and dynamic motions govern the signaling activities of the P5 domain. In addition, relative movements of the CheA domains may be involved in CheW binding, in ternary complex assembly, and in subsequent stimulus-induced conformational changes in receptor signaling complexes.
Children’s acquisition and retention of safety skills: the Lifeskills program
Authors: Lamb R , Joshi M S , Carter W , Cowburn G , Matthews A
Published: June 2006

Objectives:Assessment of safety skills performance and knowledge, to evaluate the education offered by the Lifeskills “Learning for Living” village, Bristol, UK which emphasizes interactive learning-by-doing.

Design:Two quasi-experimental matched control group studies. Study 1: knowledge and performance three months post-intervention. Study 2: knowledge pre-intervention and post-intervention at three time points, to distinguish between immediate learning and longer term retention.

Setting:The Lifeskills training village, Bristol, UK; primary schools in four education authorities in the area.

Participants:Study 1: 145 children aged 10–11 years; 109 from the Lifeskills program, 36 control. Study 2: 671 children aged 10–11 years; 511 Lifeskills, 160 control.

Outcome measures:Three areas (road, home, and fire safety). Five performance tests: observation of children’s safety skills. Five knowledge tests: pictorial quiz.

Results:Study 1: Lifeskills/intervention children did better than control children on performance and knowledge tests. The knowledge-performance correlation wasr = 0.51. Study 2: intervention children did better than control children immediately after the intervention and three months later on all five knowledge tests. On three tests the intervention group showed retention of knowledge from immediately post-intervention to three months, but on two tests there was some loss. This loss was primarily among children from scholastically lower achieving schools. In all other respects the intervention was equally successful for boys and girls, and for children from higher and lower achieving schools.

Conclusions:The Lifeskills package improved both knowledge and performance but had shortcomings. Complexity of material did not affect knowledge acquisition but did affect its retention.
THE EVOLUTION OF GENERALIZED CHAPLYGIN GAS
Authors: WU YABO , DENG XUEMEI , LU JIANBO , LI SONG , YANG XIUYI
Published: June 2006

We consider the generalized Chaplygin gas (GCG) proposal for the unification of dark matter and dark energy with p = pdeand ρ = ρdm+ρde. The unified equation of state for GCG has been obtained: [Formula: see text]. On the basis of the function χ(z), some cosmological quantities such as the fractional contributions of different components of the universe Ωi(i respectively denotes baryons, dark matter and dark energy) to the critical density, the equation of state for dark energy ωde, the deceleration parameter q are all obtained, which are consistent with observations. In addition, the transition from deceleration to acceleration is described in our model. We find that the behavior of GCG will be like ΛCDM in the future. So, it has been ruled out in our model that our universe will end up with Big Rip in the future.
CAN BRANS–DICKE SCALAR FIELD ACCOUNT FOR DARK ENERGY AND DARK MATTER?
Authors: ARIK M. , ÇALIK M. C.
Published: June 2006

By using a linearized non-vacuum late time solution in Brans–Dicke cosmology, we account for the 75% dark energy contribution but not for approximately 23% dark matter contribution to the present day energy density of the universe.
HOPF SOLITON SOLUTIONS FROM LOW ENERGY EFFECTIVE ACTION OF SU(2) YANG–MILLS THEORY
Authors: SAWADO NOBUYUKI , SHIIKI NORIKO , TANAKA SHINGO
Published: June 2006

The Skyrme–Faddeev–Niemi (SFN) model which is an O(3) σ-model in three-dimensional space up to fourth-order in the first derivative is regarded as a low-energy effective theory of SU(2) Yang–Mills theory. One can show from the Wilsonian renormalization group argument that the effective action of Yang–Mills theory recovers the SFN in the infrared region. However, the theory contains another fourth-order term which destabilizes soliton solutions. We find the stable soliton solutions in this extended action, introducing a second derivative term as a stabilizer. A perturbative technique for the second derivative term is applied to exclude (or reduce) the ill behavior of the action. A new topological energy bound formula is inferred for the action.
QUANTUM MECHANICS IN NONINERTIAL FRAMES WITH A MULTITEMPORAL QUANTIZATION SCHEME I: RELATIVISTIC PARTICLES
Authors: ALBA DAVID , LUSANNA LUCA
Published: June 2006

After a review of the few attempts to define quantum mechanics in noninertial frames, we introduce a family of relativistic nonrigid noninertial frames (equal-time parallel hyper-planes with differentially rotating 3-coordinates) as a gauge fixing of the description of N positive energy particles in the framework of parametrized Minkowski theories. Then we define a multitemporal quantization scheme in which the particles are quantized, but not the gauge variables describing the noninertial frames: they are considered as c-number generalized times. We study the coupled Schrödinger-like equations produced by the first class constraints and we show that there is a physical scalar product independent both from time and generalized times and a unitary evolution. Since a path in the space of the generalized times defines a nonrigid noninertial frame, we can find the associated self-adjoint effective Hamiltonian [Formula: see text] for the noninertial evolution: it differs from the inertial energy operator for the presence of inertial potentials and turns out to be frame-dependent like the energy density in general relativity. After a separation of the relativistic center of mass from the relative variables by means of a recently developed relativistic kinematics, inside [Formula: see text] we can identify the self-adjoint relative energy operator (the invariant mass) [Formula: see text] corresponding to the inertial energy and producing the same levels for the spectra of atoms as in inertial frames. Instead the (in general time-dependent) effective Hamiltonian is responsible for the interferometric effects signaling the noninertiality of the frame. It cannot be interpreted as an energy (there is no relativity principle and no kinematic group in noninertial frames) and generically, like in the case of time-dependent c-number external electromagnetic fields, it has no associated eigenvalue equation defining a noninertial spectrum. This formulation should help to find relativistic Bel inequalities and to define a quantization scheme for canonical gravity after having found a ultraviolet regularization of the Tomonaga–Schwinger formalism in special relativity as required by the Torre–Varadarajan no-go theorem.
COSMOLOGY, EINSTEIN'S "MACH PRINCIPLE" AND THE HIGGS FIELDS
Authors: NE'EMAN YUVAL
Published: June 2006

According to Einstein's "Mach Principle" idea, inertia and mass are the result of a dynamical effect — namely a containment–confinement due to a universal energy to energy interaction, dominated by the contribution of the most distant sources in the universe, e.g. if the force weakens with distance like 1/rn, n < 2. In the present treatment of high energy (particle) physics, quarks and leptons acquire their mass by interacting with "Higgs" fields related to symmetry breakdowns. Assuming that these mass-endowing fields in fact collect and channel the cosmical contributions we find that their basic action is repulsive, so that the universal expansion is the recoil of the mass-making.
Decrease in density of INa is in the common final pathway to heart block in murine hearts overexpressing calcineurin
Authors: Guo J. , Zhan S. , Somers J. , Westenbroek R. E. , Catterall W. A. , Roach D. E. , Sheldon R. S. , Lees-Miller J. P. , Li P. , Shimoni Y. , Duff H. J.
Published: June 2006

Overexpression of calcineurin in transgenic mouse heart results in massive cardiac hypertrophy followed by sudden death. Sudden deaths are caused by abrupt transitions from sinus rhythm to heart block (asystole) in calcineurin-overexpressing (CN) mice. Preliminary studies showed decreased maximum change in potential over time (d V/d tmax) of phase 0 of the action potential. Accordingly, the hypothesis was tested that decreased activity of the sodium channel contributes to heart block. Profound decreases in activity of sodium currents ( INa) paralleled the changes in action potential characteristics. Progressive age-dependent decreases were observed such that at 42–50 days of life little sodium channel function existed. However, this was not paralleled by decreased protein expression as assessed by immunocytochemistry or by Western blot. Since calcineurin can interact with the ryanodine receptor, we assessed whether chronic in vitro treatment with BAPTA-AM, thapsigargin, and ryanodine could rescue the decrease of INa. All of these treatments rescued INa to levels indistinguishable from wild type. The nonspecific PKC inhibitor bisindolylmaleimide I also rescued the decrease of INa. To assess whether decreased sodium channel activity contributes to sudden death in vivo, the response to encainide (20 mg/kg) was assessed: 6 of 10 young CN mice died because of asystole, whereas 0 of 10 wild-type mice died ( P < 0.01). Moreover, encainide produced exaggerated prolongation of the QRS width in sinus beats before the heart block. Catecholamine tone appears necessary to support life in older CN mice because propranolol (1 mg/kg) triggered asystolic death in five of six CN mice. We conclude that decrease in sodium channel activity is in the common final pathway to asystole in CN mice.
Seasonal changes in glycogen content and Na+-K+-ATPase activity in the brain of crucian carp
Authors: Vornanen Matti , Paajanen Vesa
Published: June 2006

Changes in the number of Na+-K+-ATPase α-subunits, Na+-K+-ATPase activity and glycogen content of the crucian carp ( Carassius carassius) brain were examined to elucidate relative roles of energy demand and supply in adaptation to seasonal anoxia. Fish were collected monthly around the year from the wild for immediate laboratory assays. Equilibrium dissociation constant and Hill coefficient of [3H]ouabain binding to brain homogenates were 12.87 ± 2.86 nM and −1.18 ± 0.07 in June and 11.93 ± 2.81 nM and −1.17 ± 0.06 in February ( P > 0.05), respectively, suggesting little changes in Na+-K+-ATPase α-subunit composition of the brain between summer and winter. The number of [3H]ouabain binding sites and Na-K-ATPase activity varied seasonally ( P < 0.001) but did not show clear connection to seasonal changes in oxygen content of the fish habitat. Six weeks’ exposure of fish to anoxia in the laboratory did not affect Na+-K+-ATPase activity ( P > 0.05) confirming the anoxia resistance of the carp brain Na pump. Although anoxia did not suppress the Na pump, direct Q10effect on Na+-K+-ATPase at low temperatures resulted in 10 times lower catalytic activity in winter than in summer. Brain glycogen content showed clear seasonal cycling with the peak value of 203.7 ± 16.1 μM/g in February and a 15 times lower minimum (12.9 ± 1.2) in July. In winter glycogen stores are 15 times larger and ATP requirements of Na+-K+-ATPase at least 10 times less than in summer. Accordingly, brain glycogen stores are sufficient to fuel brain function for about 8 min in summer and 16 h in winter, meaning about 150-fold extension of brain anoxia tolerance by seasonal changes in energy supply-demand ratio.
Effects of cholesterol manipulation on the signaling of the human oxytocin receptor
Authors: Reversi Alessandra , Rimoldi Valeria , Brambillasca Silvia , Chini Bice
Published: June 2006

We have recently shown that oxytocin inhibits cell growth when the vast majority of oxytocin receptors (OTRs) are excluded from detergent-resistant membranes (DRMs; the biochemical counterpart of lipid rafts), but has a strong mitogenic effect when the receptors are targeted to these plasma membrane domains upon fusion with caveolin-2, a resident raft protein. The aim of this study was to investigate whether the manipulation of total cell cholesterol can influence OTR localization and signaling. Our data indicate that cholesterol depletion in HEK-293 cells does not affect the signaling events mediated by the OTRs located outside DRMs. When treated with 2 mM methyl-β-cyclodextrin (MβCD), the receptors remained outside and continued to inhibit cell growth. On the contrary, the MβCD treatment of cells expressing receptors fused to caveolin-2 led to their redistribution outside DRMs, and converted the receptor-mediated proliferative effect into cell growth inhibition. These data indicate that 1) once released from DRMs, the receptors fused to caveolin-2 signal exactly as wild-type OTRs and 2) their DRM location is responsible for the specific OTR signaling leading to cell proliferation. Finally, we evaluated whether cholesterol loading could force the OTRs into lipid rafts and change their signaling, but, after cell treatment with an MβCD/cholesterol complex, receptor stimulation continued to lead to cell growth inhibition, thus indicating that increasing cell cholesterol levels is not sufficient per se to affect OTR signaling.
Exaggerated vasomotor response to ANG II in rats with fetal programming of hypertension associated with exposure to a low-protein diet during gestation
Authors: Yzydorczyk C. , Gobeil F. , Cambonie G. , Lahaie I. , Lê N. L. O. , Samarani S. , Ahmad A. , Lavoie J. C. , Oligny L. L. , Pladys P. , Hardy P. , Nuyt A. M.
Published: June 2006

The renin-angiotensin system plays a key role in the initiation and maintenance of elevated blood pressure associated with altered intrauterine milieu. The current studies were undertaken to verify whether vascular response to ANG II is increased in adult offspring of low-protein fed dams (LP) compared with control (CTRL) and if so, to examine underlying mechanism(s). ANG II-induced contraction of carotid rings was increased in LP (Emax, the maximum asymptote of the curve, relative to maximal response to KCl 80 mM: 230 ± 3% LP vs. 201 ± 2% CTRL, P < 0.05). In both groups, contraction to ANG II was mediated solely by AT1R. Responses to thromboxane A2 analog U-46619 and to KCl 80 mM under step increases in tension were similar between groups. Endothelium depletion enhanced contraction to ANG II in both groups, more so in LP. Blockade of endothelin formation had no effect on response to ANG II, and ANG-(1–7) did not elicit vasomotor response in either group. Superoxide dismutase (SOD) analog Tempol normalized LP without modifying CTRL response to ANG II. Basal levels of superoxide (aortic segments, lucigenin-enhanced chemiluminescence and fluorescent dye hydroethidine) were higher in LP. ANG II further increased superoxide production in LP only, and this was inhibited by coincubation with diphenylene iodonium or apocynin (inhibitor of NADPH oxidase complex). AT1R expression in carotid arteries was increased in LP, whereas SOD expression was unchanged. In conclusion, vasoconstriction to ANG II is exaggerated in this model of developmental programming of hypertension, secondary to enhanced vascular production of superoxide anion by NADPH oxidase with concomitant increase of AT1R expression.
Measuring partial body potassium in the arm versus total body potassium
Authors: Wielopolski L. , Ramirez L. M. , Gallagher D. , Heymsfield S. B. , Wang Z. M.
Published: June 2006

Skeletal muscle (SM), the body's main structural support, has been implicated in metabolic, physiological, and disease processes in humans. Despite being the largest tissue in the human body, its assessment remains difficult and indirect. However, being metabolically active it contains over 50% of the total body potassium (TBK) pool. We present our preliminary results from a new system for measuring partial body K (PBK) that presently are limited to the arm yet provide a direct and specific measure of the SM. This uniquely specific quantification of the SM mass in the arm, which is shielded from the body during measurement, allows us to simplify the assumptions used in deriving the total SM, thereby possibly improving the modeling of the human body compartments. Preliminary results show that PBK measurements are consistent with those from the TBK previously obtained from the same subjects, thus offering a simpler alternative to computed tomography and magnetic resonance imaging used for the same purposes. The PBK system, which can be set up in a physician's office or bedside in a hospital, is completely passive, safe, and inexpensive; it can be used on immobilized patients, children, pregnant women, or other at-risk populations.
The Structure of Dasatinib (BMS-354825) Bound to Activated ABL Kinase Domain Elucidates Its Inhibitory Activity against Imatinib-Resistant ABL Mutants
Authors: Tokarski John S. , Newitt John A. , Chang Chieh Ying J. , Cheng Janet D. , Wittekind Michael , Kiefer Susan E. , Kish Kevin , Lee Francis Y.F. , Borzillerri Robert , Lombardo Louis J. , Xie Dianlin , Zhang Yaqun , Klei Herbert E.
Published: June 2006

Chronic myeloid leukemia (CML) is caused by the constitutively activated tyrosine kinase breakpoint cluster (BCR)-ABL. Current frontline therapy for CML is imatinib, an inhibitor of BCR-ABL. Although imatinib has a high rate of clinical success in early phase CML, treatment resistance is problematic, particularly in later stages of the disease, and is frequently mediated by mutations in BCR-ABL. Dasatinib (BMS-354825) is a multitargeted tyrosine kinase inhibitor that targets oncogenic pathways and is a more potent inhibitor than imatinib against wild-type BCR-ABL. It has also shown preclinical activity against all but one of the imatinib-resistant BCR-ABL mutants tested to date. Analysis of the crystal structure of dasatinib-bound ABL kinase suggests that the increased binding affinity of dasatinib over imatinib is at least partially due to its ability to recognize multiple states of BCR-ABL. The structure also provides an explanation for the activity of dasatinib against imatinib-resistant BCR-ABL mutants. (Cancer Res 2006; 66(11): 5790-7)
Involvement of the Paxillin Pathway in JB6 Cl41 Cell Transformation
Authors: Tatsumi Yasuaki , Cho Yong-Yeon , He Zhiwei , Mizuno Hideya , Seok Choi Hong , Bode Ann M. , Dong Zigang
Published: June 2006

Paxillin is a substrate of the Src tyrosine onco-kinase and is involved in cell transformation, cell spreading, migration, and cancer development mediated through the mitogen-activated protein kinase signaling cascades. Here, we showed that paxillin plays a key role in skin cell transformation induced by epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA). To investigate the mechanism of paxillin's role in cell transformation, we established a paxillin knockdown stably transfected cell line by introducing small interfering RNA-paxillin (si-paxillin). The si-paxillin cells displayed a dramatic suppression of cell proliferation and anchorage-independent cell transformation induced by EGF or TPA compared with si-mock control cells. In si-paxillin cells, decreased activator protein-1 (AP-1)–dependent luciferase activity corresponded with suppressed AP-1 DNA binding activity. Importantly, knockdown of paxillin inhibited EGF- or TPA-induced c-Jun phosphorylation at Ser63 and Ser73. Furthermore, total c-Jun protein level was dramatically decreased in si-paxillin cells and was dependent on serum deprivation time. The down-regulation of c-Jun was restored in si-paxillin cells by treatment with the proteasome inhibitor lactacystin but not by the lysosome inhibitor leupeptin. These results clearly provided evidence that paxillin regulates c-Jun protein level and plays a key role in cell transformation most likely through the regulation of c-Jun stability. (Cancer Res 2006; 66(11): 5968-74)
Sulforaphane Causes Autophagy to Inhibit Release of Cytochrome c and Apoptosis in Human Prostate Cancer Cells
Authors: Herman-Antosiewicz Anna , Johnson Daniel E. , Singh Shivendra V.
Published: June 2006

The present study reports a novel response to sulforaphane, a highly promising anticancer constituent of several edible cruciferous vegetables, in PC-3 and LNCaP human prostate cancer cells involving induction of autophagy. Exposure of PC-3 and LNCaP cells to sulforaphane resulted in several specific features characteristic of autophagy, including appearance of membranous vacuoles in the cytoplasm as revealed by transmission electron microscopy and formation of acidic vesicular organelles as revealed by fluorescence microscopy following staining with the lysosomotropic agent acridine orange. The sulforaphane-induced autophagy was associated with up-regulation, processing, and recruitment to autophagosomes of microtubule-associated protein 1 light chain 3 (LC3), which is a mammalian homologue of the yeast autophagy regulating protein Apg8/Aut7p. Treatment of cells with a specific inhibitor of autophagy (3-methyladenine) attenuated localization of LC3 to autophagosomes but exacerbated cytosolic release of cytochrome c as well as apoptotic cell death as revealed by analysis of subdiploid fraction and cytoplasmic histone–associated DNA fragmentation. In conclusion, the present study indicates that induction of autophagy represents a defense mechanism against sulforaphane-induced apoptosis in human prostate cancer cells. To the best of our knowledge, the present study is the first published report to convincingly document induction of autophagy by an isothiocyanate class of dietary chemopreventive agent. (Cancer Res 2006; 66(11): 5828-35)
A Phase I Trial to Determine the Optimal Biological Dose of Celecoxib when Combined with Erlotinib in Advanced Non–Small Cell Lung Cancer
Authors: Reckamp Karen L. , Krysan Kostyantyn , Morrow Jason D. , Milne Ginger L. , Newman Robert A. , Tucker Christopher , Elashoff Robert M. , Dubinett Steven M. , Figlin Robert A.
Published: June 2006

Purpose: Overexpression of cyclooxygenase-2 (COX-2) activates extracellular signal-regulated kinase/mitogen-activated protein kinase signaling in an epidermal growth factor receptor (EGFR) tyrosine kinase inhibition (TKI)–resistant manner. Because preclinical data indicated that tumor COX-2 expression caused resistance to EGFR TKI, a phase I trial to establish the optimal biological dose (OBD), defined as the maximal decrease in urinary prostaglandin E-M (PGE-M), and toxicity profile of the combination of celecoxib and erlotinib in advanced non–small cell lung cancer was done.

Experimental Design: Twenty-two subjects with stage IIIB and/or IV non–small cell lung cancer received increasing doses of celecoxib from 200 to 800 mg twice daily (bid) and a fixed dose of erlotinib. Primary end points included evaluation of toxicity and determination of the OBD of celecoxib when combined with erlotinib. Secondary end points investigate exploratory biological markers and clinical response.

Results: Twenty-two subjects were enrolled, and 21 were evaluable for the determination of the OBD, toxicity, and response. Rash and skin-related effects were the most commonly reported toxicities and occurred in 86%. There were no dose-limiting toxicities and no cardiovascular toxicities related to study treatment. All subjects were evaluated on intent to treat. Seven patients showed partial responses (33%), and five patients developed stable disease (24%). Responses were seen in patients both with and without EGFR-activating mutations. A significant decline in urinary PGE-M was shown after 8 weeks of treatment, with an OBD of celecoxib of 600 mg bid.

Conclusions: This study defines the OBD of celecoxib when combined with a fixed dose of EGFR TKI. These results show objective responses with an acceptable toxicity profile. Future trials using COX-2 inhibition strategies should use the OBD of celecoxib at 600 mg bid.
DNA on Loan: Issues to Consider when Carrying Out Genetic Research with Aboriginal Families and Communities
Authors: Arbour Laura , Cook Doris
Published: June 2006

In the current research milieu where genetic etiology is considered a critical component in the discovery of pathogenesis, aboriginal families and communities affected with genetic conditions may be considered as research participants. However, because of concerns about the impact of genetic information and historical harmful research practices, some aboriginal communities have considerable unease when faced with this prospect. Therefore, in the circumstance that genetics is considered an important part of research inquiry by aboriginal families and communities, there needs to be assurance that the research will be carried out according to mutual expectations. A research relationship that respects aboriginal individuals and communities within their culture and is in keeping with their values is essential. This respect extends to the use of biological samples, considering the DNA to be ‘on loan’ to the researcher for the purpose of the research for which consent was obtained. This paper will explore practical ways of maintaining a respectful research relationship when genetics research with aboriginal people is undertaken.
Public Knowledge, Public Trust: Understanding the ‘Knowledge Deficit’
Authors: Brunk Conrad G.
Published: June 2006

This article examines the ‘knowledge deficit’ model, which still persists in liberal, technological societies. It is based upon the assumption that expert forms of knowledge, both in the sciences and the humanities, provide a sufficient basis for deciding the most important public policy questions. In this view, public perceptions and beliefs that run counter to this expert knowledge provide unacceptable justifications for public policies. Instead, support of expert knowledge needs to be ‘built’ through education and public relations strategies. This view is challenged on the basis of basic democratic theory, using the debate about genetically modified maize in Mexico as an example. ‘Knowledge deficits’ also exist on the side of experts.
The Influence of Enamel Defects on the Development of Early Childhood Caries in a Population with Low Socioeconomic Status: A Longitudinal Study
Authors: Oliveira A.F.B. , Chaves A.M.B. , Rosenblatt A.
Published: June 2006

The purpose of this study was to evaluate the influence of enamel defects in the development of dental caries and their association with feeding practices and oral health behaviors in a cohort study of low-socioeconomic children from birth to 36 months of age in northeastern Brazil. Subjects were registered at birth and examined from 12 to 36 months of age. At baseline, 246 children were examined and at follow-up 228. The teeth were clinically examined and dried with gauze under natural light. Enamel defects were determined using the Developmental Defects of Enamel (DDE) index. Dental caries was determined using WHO criteria. Data were analyzed using descriptive and analytical techniques. At 36 months 78.9% infants presented at least one tooth with enamel defects and 25% of the children had at least one decayed tooth. A total of 16.9% teeth with enamel defects had become decayed (p = 0.0001). Opacity with enamel hypoplasia was the defect most frequently associated with dental caries (p = 0.001). Only 0.9% of the teeth without enamel defects developed caries. Multivariate analyses revealed that enamel defects, night breast-feeding and poor oral hygiene habits were predictors of dental caries at 18 and 24 months (p < 0.05). Considering the risk factors evaluated at 30 months of age, the presence of enamel defects was the single predictor of caries development at 36 months (p = 0.0001). Enamel defects are strongly associated with early childhood caries and, therefore, this correlation must be considered when focussing on low-socioeconomic communities.
Comparison of Gated Blood Pool SPECT and Multi-Detector Row Computed Tomography for Measurements of Left Ventricular Volumes and Ejection Fraction in Patients with Atypical Chest Pain: Validation with Radionuclide Ventriculography
Authors: Kim In-Ju , Choo Ki Seok , Lee Jung Sub , Kim Seong-Jang , Kim June Hong , Kim Yong-Ki , Kim Dong-Soo , Cho Hyun Jun
Published: June 2006

Gated blood pool SPECT (GBPS) is an alternative to planar radionuclide ventriculography (PRNV) and offers potential advantages. The aim of this study was to compare GBPS, multi-row detector spiral computed tomography (MDCT), and PRNV for the determination of left ventricular ejection fraction (LVEF) and left ventricular volumes (LV) in subjects with atypical chest pain. Method: Twenty-three consecutive patients (14 men, 9 women; mean age 56.2 ± 9.5 years) referred for MDCT for evaluation of atypical chest pain. All patients underwent PRNV, GBPS, and MDCT at the same day. Results: The mean LVEFs calculated with PRNA (57.3 ± 8.6%), GBPS (55.2 ± 6.6%), and MDCT (56 ± 9.1%) were not statistically different (F value 0.3374, p = 0.715). Comparison of LVEFs from GBPS and MDCT yielded correlation coefficients of 0.5238 (p = 0.0178, 95% CI = 0.1057–0.7845). The correlation of LVEFs between GBPS and PRNV showed a correlation coefficient of 0.8073 (p < 0.0001, 95% CI = 0.5676–0.9209) and 0.6190 (p = 0.0036, 95% CI = 0.2431–0.8333) between MDCT and PRNV. The mean LV end-diastolic volume (EDV) calculated with GBPS (82.7 ± 17.5 ml) was significantly lower than MDCT (106.8 ± 18.5 ml) (p = 0.0001). The mean LV end-systolic volume (ESV) calculated with GBPS (37.2 ± 9.6 ml) was also significantly lower than MDCT (48.1 ± 15.8 ml) (p = 0.012). Comparison of EDV from GBPS and MDCT yielded a correlation coefficient of 0.5220 (p = 0.0182, 95% CI = 0.1033–0.7835). The correlation of ESV between GBPS and MDCT showed a correlation coefficient of 0.6642 (p = 0.0014, 95% CI = 0.3140–0.8553). Conclusion: In conclusion, the LVEF, EDV, and ESV calculated by GBPS correlated significantly with those of obtained with 16-MDCT. In addition, there were no statistical differences of LVEF calculated from PRNV, GBPS, and MDCT. However, with regard to LV, EDV and ESV from GBPS revealed statistically significantly lower than those of MDCT. Also, these results should be addressed whether similar results could also be found in patients with cardiac diseases by the consequent larger population-based study.
Prognostic Value of Myocardial Perfusion Imaging in Symptomatic and Asymptomatic Patients after Percutaneous Coronary Intervention
Authors: Solodky Alejandro , Assali Abid R. , Mats Israel , Ben-Gal Tuvia , Kornowski Ran , Battler Alexander , Zafrir Nili
Published: June 2006

The aim of this study was to evaluate the value of myocardial perfusion imaging (MPI) in predicting major adverse cardiovascular events (MACE) in symptomatic and asymptomatic patients after percutaneous coronary intervention (PCI). We revised retrospectively patients after PCI that underwent MPI and were followed for a year for the presence of MACE. We found no differences in the incidence of MACE between symptomatic and asymptomatic patients. On multivariate analysis, the presence of ischemia by MPI was the most important independent predictor of MACE (OR 5.09, CI 95% 2.15–12.05, p < 0.001). The presence of myocardial ischemia by MPI performed after PCI, and no symptom status, predicts a worse outcome during 1 year of follow-up.