bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of dietary nitrate on oxygen cost during exercise
Authors: Larsen F. J. , Weitzberg E. , Lundberg J. O. , Ekblom B.
Published: July 2007

Aim:  Nitric oxide (NO), synthesized from l‐arginine by NO synthases, plays a role in adaptation to physical exercise by modulating blood flow, muscular contraction and glucose uptake and in the control of cellular respiration. Recent studies show that NO can be formed in vivo also from the reduction of inorganic nitrate (NO3−) and nitrite (NO2−). The diet constitutes a major source of nitrate, and vegetables are particularly rich in this anion. The aim of this study was to investigate if dietary nitrate had any effect on metabolic and circulatory parameters during exercise.

Method:  In a randomized double‐blind placebo‐controlled crossover study, we tested the effect of dietary nitrate on physiological and metabolic parameters during exercise. Nine healthy young well‐trained men performed submaximal and maximal work tests on a cycle ergometer after two separate 3‐day periods of dietary supplementation with sodium nitrate (0.1 mmol kg−1 day−1) or an equal amount of sodium chloride (placebo).

Results:  The oxygen cost at submaximal exercise was reduced after nitrate supplementation compared with placebo. On an average Vo2 decreased from 2.98 ± 0.57 during CON to 2.82 ± 0.58 L min−1 during NIT (P < 0.02) over the four lowest submaximal work rates. Gross efficiency increased from 19.7 ± 1.6 during CON to 21.1 ± 1.3% during NIT (P < 0.01) over the four lowest work rates. There was no difference in heart rate, lactate [Hla], ventilation (VE), VE/Vo2 or respiratory exchange ratio between nitrate and placebo during any of the submaximal work rates.

Conclusion:  We conclude that dietary nitrate supplementation, in an amount achievable through a diet rich in vegetables, results in a lower oxygen demand during submaximal work. This highly surprising effect occurred without an accompanying increase in lactate concentration, indicating that the energy production had become more efficient. The mechanism of action needs to be clarified but a likely first step is the in vivo reduction of dietary nitrate into bioactive nitrogen oxides including nitrite and NO.
Control of the triceps surae during the postural sway of quiet standing
Authors: Tokuno C. D. , Carpenter M. G. , Thorstensson A. , Garland S. J. , Cresswell A. G.
Published: July 2007

Aim:  The present study investigated how the triceps surae are controlled at the spinal level during the naturally occurring postural sway of quiet standing.

Methods:  Subjects stood on a force platform as electrical stimuli were applied to the posterior tibial nerve when the center of pressure (COP) was either 1.6 standard deviations anterior (COPant) or posterior (COPpost) to the mean baseline COP signal. Peak‐to‐peak amplitudes of the H‐reflex and M‐wave from the soleus (SOL) and medial gastrocnemius (MG) muscles were recorded to assess the efficacy of the Ia pathway.

Results:  A significant increase in the Hmax : Mmax ratio for both the SOL (12 ± 6%) and MG (23 ± 6%) was observed during the COPant as compared to the COPpost condition. The source of the modulation between COP conditions cannot be determined from this study. However, the observed changes in the synaptic efficacy of the Ia pathway are unlikely to be simply a result of an altered level of background electromyographic activity in the triceps surae. This was indicated by the lack of differences observed in the Hmax : Mmax ratio when subjects stood without postural sway (via the use of a tilt table) at two levels of background activity.

Conclusions:  It is suggested that the phase‐dependent modulation of the triceps surae H‐reflexes during the postural sway of quiet standing functions to maintain upright stance and may explain the results from previous studies, which, until now, had not taken the influence of postural sway on the H‐reflex into consideration.
Molecular and functional expression of anion exchangers in cultured normal human nasal epithelial cells
Authors: Shin J.‐H. , Son E. J. , Lee H. S. , Kim S. J. , Kim K. , Choi J. Y. , Lee M. G. , Yoon J.‐H.
Published: July 2007

Aims:  Anions have an important role in the regulation of airway surface liquid (ASL) volume, viscosity and pH. However, functional localization and regulation of anion exchangers (AEs) have not been clearly described. The aim of this study was to investigate the regulation of AE mRNA expression level in accordance with mucociliary differentiation and the functional expression of AEs cultured normal human nasal epithelial (NHNE) cells.

Methods:  Nasal mucosal specimens from three patients are obtained and serially cultured cells are subjected to morphological examinations, RT‐PCR, Western blot analysis and immunocytochemistry. AE activity is assessed by pHi measurements.

Results:  Expression of ciliated cells on the apical membrane and expression of MUC5AC, a marker of mucous differentiation, increased with time. AE2 and SLC26A4 mRNA expression decreased as mucociliary differentiation progressed, and AE4, SLC26A7 and SLC26A8 mRNA expression increased on the 14th and 28th day after confluence. Accordingly, AE4 protein expression also progressively increased. AE activity in 100 mm K+ buffer solutions was nearly twofold higher than that in 5 mm K+ buffer solutions. Moreover, only luminal AE activity increased about fourfold over the control in the presence of 5 μm forskolin. In the presence of 100 μm adenosine‐5′‐triphosphate (ATP) which evokes intracellular calcium signalling through activation of purinergic receptors, only luminal AE activity was again significantly increased. On the other hand, 500 μm 4,4′‐diisothiocyanostilbene‐2,2′‐disulfonic acid (DIDS), an inhibitor of most SLC4 and SLC26AE isoforms, nearly abolished AE activity in both luminal and basolateral membranes. We found that AE activity was affected by intracellular cAMP and calcium signalling in the luminal membrane and was DIDS‐sensitive in both membranes of cultured NHNE cells.

Conclusion:  Our findings through molecular and functional studies using cultured NHNE cells suggest that AEs may have an important role in the regulation of ASL.
Reduced sarcoplasmic reticulum content of releasable Ca2+ in rat soleus muscle fibres after eccentric contractions
Authors: Nielsen J. S. , Sahlin K. , Ørtenblad N.
Published: July 2007

Aim:  The purpose was to evaluate the effects of fatiguing eccentric contractions (EC) on calcium (Ca2+) handling properties in mammalian type I muscles. We hypothesized that EC reduces both endogenous sarcoplasmic reticulum (SR) content of releasable Ca2+ (eSRCa2+) and myofibrillar Ca2+ sensitivity.

Methods:  Isolated rat soleus muscles performed 30 EC bouts. Single fibres were isolated from the muscle and after mechanical removal of sarcolemma used to measure eSRCa2+, rate of SR Ca2+ loading and myofibrillar Ca2+ sensitivity.

Results:  Following EC maximal force in whole muscle was reduced by 30% and 16/100 Hz force ratio by 33%. The eSRCa2+ in fibres from non‐stimulated muscles was 45 ± 5% of the maximal loading capacity. After EC, eSRCa2+ per fibre CSA decreased by 38% (P = 0.05), and the maximal capacity of SR Ca2+ loading was depressed by 32%. There were no effects of EC on either myofibrillar Ca2+ sensitivity, maximal Ca2+ activated force per cross‐sectional area and rate of SR Ca2+ loading, or in SR vesicle Ca2+ uptake and release.

Conclusions:  We conclude that EC reduces endogenous SR content of releasable Ca2+ but that myofibrillar Ca2+ sensitivity and SR vesicle Ca2+ kinetics remain unchanged. The present data suggest that the long‐lasting fatigue induced by EC, which was more pronounced at low frequencies (low frequency fatigue), is caused by reduced Ca2+ release occurring secondary to reduced SR content of releasable Ca2+.
Nanotribological characterization of vapor phase deposited fluorosilane self-assembled monolayers deposited on polydimethylsiloxane surfaces for biomedical micro-/nanodevices
Authors: Bhushan Bharat , Cichomski Michal
Published: July 2007

Fluorosilane self-assembled monolayers for polydimethylsiloxane (PDMS) nanochannels are desirable to control the hydrophobicity of the surface to reduce or prevent undesired protein adsorption or cell interactions, critical for the performance of many biomedical micro-/nanodevices. Surface modifications using vapor phase deposition have become increasingly important for some biomedical micro-/nanodevices and have advantages over liquid phase deposition since the vapor phase can permeate more efficiently into nanochannels. In this study, vapor phase deposition was used to deposit four fluorosilanes on PDMS, and deposition conditions for an optimal process were identified. The films were characterized by means of a contact angle analyzer for hydrophobicity and an atomic force microscope for adhesion and friction measurements. The influence of relative humidity, temperature, and sliding velocity on the friction and adhesion behavior is studied. Failure mechanisms of self-assembled monolayers are investigated by wear tests.
Reaction properties of NO and CO over an Ir(211) surface
Authors: Nakamura I. , Suzuki K. , Takahashi A. , Haneda M. , Hamada H. , Fujitani T.
Published: July 2007

The adsorption and thermal reactivity of NO and CO over an Ir(211) surface were studied using x-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and temperature-programed desorption. NO adsorbed on the atop site of the (111) terrace and the bridge site of the (100) step at 273K. In contrast, CO adsorbed only on the atop site at 273K, initially on the (111) terrace and then on the (100) step. Both atop NO and bridge NO decomposed to N2 through the recombination of atomic nitrogen, indicating that the Ir(211) surface provides high NO dissociation activity. When NO and CO were coadsorbed, the preadsorption of atop CO on the terrace sites selectively inhibited the adsorption of atop NO on the terrace sites, while preadsorption of atop CO on the step sites significantly inhibited the adsorption of bridge NO on the step sites. These results indicate that NO may be selectively reduced by CO in the presence of O2 when Ir(211) is used as the catalyst.
Performance and analysis of an electron cyclotron resonance plasma cathode
Authors: Hidaka Y. , Foster J. E. , Getty W. D. , Gilgenbach R. M. , Lau Y. Y.
Published: July 2007

A scalable electron cyclotron resonance (ECR) plasma source was investigated for plasma cathode applications. The rectangular source utilized permanent magnets to establish the ECR condition. The microwave applicator region was windowless, making the source applicable to sputtering environment applications. The source was characterized using primarily two diagnostics: (1) a near-field and far-field Langmuir probe and (2) a downstream electron extraction electrode. Source operation and plasma properties were characterized at low pressures ranging from 0.2to5mTorr and power levels up to 250W. Evidence of grad-B drift in the plane of the source was observed. Extracted currents agreed well with predictions.
Influence of the normalized ion flux on the constitution of alumina films deposited by plasma-assisted chemical vapor deposition
Authors: Kurapov Denis , Reiss Jennifer , Trinh David H. , Hultman Lars , Schneider Jochen M.
Published: July 2007

Alumina thin films were deposited onto tempered hot working steel substrates from an AlCl3–O2–Ar–H2 gas mixture by plasma-assisted chemical vapor deposition. The normalized ion flux was varied during deposition through changes in precursor content while keeping the cathode voltage and the total pressure constant. As the precursor content in the total gas mixture was increased from 0.8% to 5.8%, the deposition rate increased 12-fold, while the normalized ion flux decreased by approximately 90%. The constitution, morphology, impurity incorporation, and the elastic properties of the alumina thin films were found to depend on the normalized ion flux. These changes in structure, composition, and properties induced by normalized ion flux may be understood by considering mechanisms related to surface and bulk diffusion.
Use of a Bioluminescent
Pseudomonas aeruginosa
Strain within an In Vitro Microbiological System, as a Model of Wound Infection, To Assess the Antimicrobial Efficacy of Wound Dressings by Monitoring Light Production
Authors: Thorn R. M. S. , Nelson S. M. , Greenman J.
Published: July 2007

A bioluminescent
Pseudomonas aeruginosa
was incorporated into an in vitro static diffusion method to determine whether light output could be used as a measure of wound dressing efficacy. A significant linear correlation was observed between viable counts and bioluminescence during exponential growth in planktonic culture (
r
2
= 0.969). Exponential-phase cells were used to inoculate cellulose discs for integration into an in vitro wound model that incorporated a reservoir of serum. A significant linear correlation was found between bioluminescence (photon counts monitored by a low-light camera) and viable counts in this growth environment (
r
2
= 0.982). Three antimicrobial wound dressings were applied to the surface of freshly prepared sample discs within the wound model, and the kill kinetics were codetermined by photon and viable counts. Quantifiable kill rates gave the same order of efficacy for the three wound dressings using both types of measurement, and a significant linear correlation was shown between photon and viable counts (
r
2
= 0.873) within this killing environment. Under all defined conditions, a significant linear correlation between bioluminescence and viable counts was shown but the actual slope of the correlation was different, depending on the physicochemical environment of the cells. Hence, significantly more light per cell (
P
< 0.0001) was produced when cells in discs were exposed to a killing environment compared to a growing environment. As long as defined conditions are employed, the resulting linear correlation enables the state of the system to be continually monitored without disturbance, allowing more immediate and accurate calculations of kill rates without the need for viable counting.
Population Pharmacokinetics of Micafungin in Pediatric Patients and Implications for Antifungal Dosing
Authors: Hope William W. , Seibel Nita L. , Schwartz Cindy L. , Arrieta Antonio , Flynn Patricia , Shad Aziza , Albano Edythe , Keirns James J. , Buell Donald N. , Gumbo Tawanda , Drusano George L. , Walsh Thomas J.
Published: July 2007

The echinocandins potentially have an important role in treatment of infections caused by
Candida
spp. and
Aspergillus
spp. in immunocompromised children. However, there are no population pharmacokinetic models of the echinocandins for pediatric patients. The safety and descriptive pharmacokinetics of micafungin in children were recently reported. However, a population pharmacokinetic model in children is needed in order to accurately determine the dosage of micafungin that produces an equivalent magnitude of drug exposure to that observed in adults. In order to explore the effect of weight on micafungin pharmacokinetics, a standard two-compartment pharmacokinetic model, a linear model, and an allometric power model were developed. For all three models, the fit to the data was excellent, with comparable measures of precision and bias. However, the superior log-likelihood value of the allometric power model suggested that it best reflected the data and was therefore chosen for a more detailed analysis of the magnitude and pattern of drug exposure which develop following the administration of micafungin. The allometric power model suggested that clearance in smaller children is higher than that predicted on the basis of weight alone. Consequently, a degree of dosage increase is required in smaller children to ensure comparable levels of drug exposure to those observed in larger children and adults. The allometric power model developed in this study enables identification of pediatric dosage regimens of micafungin which, based upon Monte Carlo simulations, result in equivalent drug exposures to those observed in adults, for which antifungal efficacy has been established.
Doxycycline versus Azithromycin for Treatment of Leptospirosis and Scrub Typhus
Authors: Phimda Kriangsak , Hoontrakul Siriwan , Suttinont Chuanpit , Chareonwat Sompong , Losuwanaluk Kitti , Chueasuwanchai Sunee , Chierakul Wirongrong , Suwancharoen Duangjai , Silpasakorn Saowaluk , Saisongkorh Watcharee , Peacock Sharon J. , Day Nicholas P. J. , Suputtamongkol Yupin
Published: July 2007

Leptospirosis and scrub typhus are important causes of acute fever in Southeast Asia. Options for empirical therapy include doxycycline and azithromycin, but it is unclear whether their efficacies are equivalent. We conducted a multicenter, open, randomized controlled trial with adult patients presenting with acute fever (<15 days), without an obvious focus of infection, at four hospitals in Thailand between July 2003 and January 2005. Patients were randomly allocated to receive either a 7-day course of doxycycline or a 3-day course of azithromycin. The cure rate, fever clearance time, and adverse drug events were compared between the two study groups. A total of 296 patients were enrolled in the study. The cause of acute fever was determined for 151 patients (51%): 69 patients (23.3%) had leptospirosis; 57 patients (19.3%) had scrub typhus; 14 patients (4.7%) had murine typhus; and 11 patients (3.7%) had evidence of both leptospirosis and a rickettsial infection. The efficacy of azithromycin was not inferior to that of doxycycline for the treatment of both leptospirosis and scrub typhus, with comparable fever clearance times in the two treatment arms. Adverse events occurred more frequently in the doxycycline group than in the azithromycin group (27.6% and 10.6%, respectively;
P
= 0.02). In conclusion, doxycycline is an affordable and effective choice for the treatment of both leptospirosis and scrub typhus. Azithromycin was better tolerated than doxycycline but is more expensive and less readily available.
Salmonella
Pathogenicity Island 4-Mediated Adhesion Is Coregulated with Invasion Genes in
Salmonella enterica
Authors: Gerlach Roman G. , Jäckel Daniela , Geymeier Nina , Hensel Michael
Published: July 2007

Salmonella
pathogenicity island 4 (SPI4) encodes a type I secretion system and the cognate substrate protein, SiiE. We have recently demonstrated that SiiE is a giant nonfimbrial adhesin involved in the adhesion of
Salmonella enterica
serovar Typhimurium to polarized epithelial cells. We also observed that under in vitro culture conditions, the synthesis and secretion of SiiE coincided with the activation of
Salmonella
invasion genes. These observations prompted us to investigate the regulation of SPI4 genes in detail. A novel approach for the generation of reporter gene fusions was employed to generate single-copy chromosomal fusions to various genes within SPI4, and the expression of these fusions was investigated. We analyzed the regulation of SPI4 genes and the roles of various regulatory systems for SPI4 expression. Our data show that the expression of SPI4 genes is coregulated with SPI1 invasion genes by the global regulator SirA. Expression of a SPI4 gene was also reduced in the absence of HilA, the central local regulator of SPI1 gene expression. Both SirA and HilA functions were required for the secretion of SiiE and the SPI4-mediated adhesion. Our data demonstrate that SPI4-mediated adhesion, as well as SPI1-mediated invasion, are tightly coregulated by the same regulatory circuits and induced under similar environmental conditions.
Global Effects of the Cell-to-Cell Signaling Molecules Autoinducer-2, Autoinducer-3, and Epinephrine in a
luxS
Mutant of Enterohemorrhagic
Escherichia coli
Authors: Kendall Melissa M. , Rasko David A. , Sperandio Vanessa
Published: July 2007

Intrakingdom cell-to-cell communication and interkingdom cell-to-cell communication play essential roles in the virulence of enterohemorrhagic
Escherichia coli
(EHEC). Four signals, autoinducer 2 (AI-2), AI-3, and the human hormones epinephrine and norepinephrine, are important in this communication. The effect of these signaling compounds on the transcriptome of EHEC was examined in this study. We demonstrated that the
luxS
mutation affects primarily central metabolic genes in both pathogenic and nonpathogenic strains of
E. coli
and that addition of exogenous AI-2 does not fully restore the expression profile in a
luxS
-deficient strain lacking the ability to synthesize AI-2. Addition of AI-3 or epinephrine increased expression of the locus of enterocyte effacement regulon, which is known to play a pivotal role in EHEC virulence. Moreover, when epinephrine was added to the culture medium, the greatest number of gene alterations was observed. These alterations included a greater proportion of alterations in EHEC genes than in MG1655 genes, suggesting that epinephrine may be a global virulence signal. Detailed examination with real-time reverse transcriptase PCR (RT-PCR) confirmed the increases in virulence gene expression with addition of AI-3 and epinephrine. Additional studies with real-time RT-PCR examining the EHEC secreted effectors and putative fimbrial gene expression showed a variable expression profile, indicating that there is differential regulation of the secreted molecules. This study began to examine the global signaling networks in EHEC and revealed expression profiles that are signal and pathogen specific.
Noncapsulated Toxinogenic
Bacillus anthracis
Presents a Specific Growth and Dissemination Pattern in Naive and Protective Antigen-Immune Mice
Authors: Glomski Ian J. , Corre Jean-Philippe , Mock Michèle , Goossens Pierre L.
Published: July 2007

Bacillus anthracis
is a spore-forming bacterium that causes anthrax.
B. anthracis
has three major virulence factors, namely, lethal toxin, edema toxin, and a poly-γ-
d
-glutamic acid capsule. The toxins modulate host immune responses, and the capsule inhibits phagocytosis. With the goal of increasing safety, decreasing security concerns, and taking advantage of mammalian genetic tools and reagents, mouse models of
B. anthracis
infection have been developed using attenuated bacteria that produce toxins but no capsule. While these models have been useful in studying both toxinogenic infections and antitoxin vaccine efficacy, we questioned whether eliminating the capsule changed bacterial growth and dissemination characteristics. Thus, the progression of infection by toxinogenic noncapsulated
B. anthracis
was analyzed and compared to that by previously reported nontoxinogenic capsulated bacteria, using in vivo bioluminescence imaging. The influence of immunization with the toxin component protective antigen (PA) on the development of infection was also examined. The toxinogenic noncapsulated bacteria were initially confined to the cutaneous site of infection. Bacteria then progressed to the draining lymph nodes and, finally, late in the infection, to the lungs, kidneys, and frequently the gastrointestinal tract. There was minimal colonization of the spleen. PA immunization reduced bacterial growth from the outset and limited infection to the site of inoculation. These in vivo observations show that dissemination by toxinogenic noncapsulated strains differs markedly from that by nontoxinogenic capsulated strains. Additionally, PA immunization counters bacterial growth and dissemination in vivo from the onset of infection.
Poly-
N
-Acetylglucosamine Is Not a Major Component of the Extracellular Matrix in Biofilms Formed by
icaADBC
-Positive
Staphylococcus lugdunensis
Isolates
Authors: Frank Kristi L. , Patel Robin
Published: July 2007

Staphylococcus lugdunensis
is a pathogen of heightened virulence that causes infections resembling those caused by
Staphylococcus aureus
rather than those caused by its coagulase-negative staphylococcal counterparts. Many types of
S. lugdunensis
infection, including native valve endocarditis, prosthetic joint infection, and intravascular catheter-related infection, are associated with biofilm etiology. Poly-
N
-acetylglucosamine (PNAG), a polysaccharide synthesized by products of the
icaADBC
locus, is a common mechanism of intercellular adhesion in staphylococcal biofilms. Here we report the characterization of
ica
homologues and the in vitro biofilm formation properties of a collection of
S. lugdunensis
clinical isolates. Isolates formed biofilms in microtiter wells to various degrees. Biofilm formation by most isolates was enhanced with glucose but diminished by sodium chloride or ethanol.
icaADBC
homologues were found in all
S. lugdunensis
isolates tested, although the locus organization differed substantially from that of other staphylococcal
ica
loci.
icaR
was not detected in
S. lugdunensis
, but a novel open reading frame with putative glycosyl hydrolase function is located upstream of the
ica
locus.
icaADBC
sequence heterogeneity did not explain the variability in biofilm formation among isolates. PNAG was not detected in
S. lugdunensis
extracts by immunoblotting with an anti-deacetylated PNAG antibody or wheat germ agglutinin. Confocal microscopy with fluorescently labeled wheat germ agglutinin showed a paucity of PNAG in
S. lugdunensis
biofilms, but abundant extracellular protein was visualized with SYPRO Ruby staining. Biofilms were resistant to detachment by dispersin B and sodium metaperiodate but were susceptible to detachment by proteases. Despite the genetic presence of
icaADBC
homologues in
S. lugdunensis
isolates, PNAG is not a major component of the extracellular matrix of in vitro biofilms formed by this species. Our data suggest that the
S. lugdunensis
biofilm matrix contains proteinaceous factors.
Choosing sowing strategies for containerized seedling operations
Authors: Pepper William D. , Barnett James P.
Published: July 2007

Choosing a container sowing strategy was formulated as a linear programming problem. The independent variables are fractions of containers seeded to one, two, and three seeds. An optimal sowing strategy is achieved by choosing, subject to certain constraints, the three fractions to minimize an economic penalty function, which penalizes a sowing strategy if it does not deal effectively with problems caused by blank cells. Two options were considered for producing a required number of seedlings with a given number of containers. With option 1 strategies, the three fractions of containers must be chosen so that the predicted number of plantable seedlings cannot be less than the required number, but no provision is made for replanting blank cells. Option 2 strategies have the same constraint that the predicted number of blank cells cannot exceed the predicted number of excess seedlings. Numerical analyses were conducted with hypothetical container sowing problems using estimated costs for procuring and sowing seeds, for carrying or replanting blank cells, and for thinning excess seedlings. Linear programming methods were used to choose a sowing strategy that minimized a penalty function. Mixed sowing strategies, as opposed to the standard strategy of sowing two seeds per cell, were generally optimal for a wide range of values for the germination and survival rate of seeds. A user-oriented, interactive computer program was developed for the nursery manager who wishes to use these methods to choose a sowing strategy.
Forest fire history of Desolation Peak, Washington
Authors: Agee James K. , Finney Mark , Gouvenain Roland de
Published: July 2007

not available
The use of a 32P root bioassay to indicate the phosphorus status of forest trees. 1. Seasonal variation
Authors: McDonald M. A. , Malcolm D. C. , Harrison A. F.
Published: July 2007

A phosphorus deficiency bioassay based on the rate of uptake of 32P by forest tree roots was developed for use as a field predictor of the phosphorus status of trees in mature forest stands. Results of a study on the influence of the time of sampling on the results of the bioassay in the field, and on the influence of temperature and moisture under controlled conditions, are reported. Seasonal variations in 32P uptake were recorded in the field study, but the effects of moisture and temperature in the greenhouse experiments were inconclusive. However, it was assumed that the field bioassay response integrated the effects of moisture and temperature simultaneously, and that if the variation could be explained as a consequence of climatic differences over several seasons, then it should be possible to determine optimal sampling times.
Impacts des milieux pédologiques en bosses et creux sur les teneurs en composés phénoliques et en éléments minéraux dans les feuilles d'érables à sucre (Acersaccharum) en dépérissement du Québec
Authors: Sauvesty A. , Pagé F. , Giroux M.
Published: July 2007

We conducted a study on the influence of microrelief on the content of phenolic compounds and mineral elements in leaves of sugar maple (Acersaccharum Marsh.) at various stages of decline. The stand of origin was located in the Appalachian Highlands of Quebec, on acidic material with a microrelief constituted of hollows and bumps, the height of the latter varying between 30 and 60 cm. Well aerated podzols developed on bumps, while gleysols developed in hollows. Trees generally grew on bumps and their roots could extend as far as 5 m away from the tree. Microrelief and soils were described within a 5-m radius around every sugar maple under study. Pedological sites were classified into three categories according to their microrelief (percent surface area covered by bumps): (i) less than 30% of surface (dominance of poorly drained soils), (ii) between 30 and 50% of surface (dominance of imperfectly drained soils), and (iii) more than 50% of surface (dominance of well drained soils). A principal component analysis on site distribution and a chemical analysis of soils showed an increase in total N and in K, Ca, and Mg availability with an increase in soil humidity. The principal component analysis and chemical analysis of leaves indicated that the content of phenolic compounds was highest, and those of N and K lowest, in moistest soils. The decline was also greatest on those sites. There was a strong correlation between synthesis of phenolic compounds and foliar N contents, and between decline intensity and foliar N content. The high humidity of some soils of the study sites reduces the availability of N, causing a stress to sugar maples. This phenomenon would result in an increased synthesis of phenolic compounds and a decline in less resistant trees. Phenolic compounds could then be utilized as a physiological indicator of stress. Those results explain why healthy trees can grow next to declining trees.
Estimating top-kill volumes with large-scale photos on trees defoliated by the jack pine budworm
Authors: Hall R.J. , Titus S.J. , Volney W.J.A.
Published: July 2007

The estimation of tree top-kill volumes is an important component of quantifying defoliation impact of severe budworm (Choristoneurapinus Freeman) defoliation on jack pine (Pinusbanksiana Lamb.) trees. Field survey is the only method by which this assessment is currently undertaken. This study evaluated an alternative methodology based on large-scale aerial photo (1:900) measurements and a taper model fitted for jack pine. This included generating linear models for the prediction of actual top-kill length from photo-measured top-kill length, the prediction of DBH from photo-measured tree height and crown area, and the estimation of top-kill volumes from a jack pine taper model. The set of three linear equations fitted with ordinary least squares resulted in top-kill volume estimates that showed no bias. The volume of damaged trees not visible on photographs was less than 1% of the volume of all damaged trees, and therefore adjustment for missed trees was not considered necessary. The methodology is convenient to implement, and if combined with forest sampling procedures, the projection of tree top-kill volumes to the stand level can provide an estimate of defoliation impact. The methodology is also potentially suitable for assessing other insect defoliation impacts that cause top kill.
A reexamination of moose damage to balsam fir–white birch forests in central Newfoundland: 27 years later
Authors: Thompson Ian D. , Curran William J.
Published: July 2007

A 1960 study from central Newfoundland suggested that moose (Alcesalces L.) would: (i) reduce the commercial value of second-growth forests of central Newfoundland by excessive damage to balsam fir (Abiesbalsamea (L.) Mill.); (ii) eliminate white birch (Betulapapyrifera Marsh.) from the forest canopy; (iii) alter conifer species composition; and (iv) reduce the carrying capacity of the area for moose. We resurveyed the original study areas in 1987. Our data suggest that moose have altered species composition in favour of white spruce (Piceaglauca (Moench) Voss) and black spruce (Piceamariana (Mill.) B.S.P.) on some sites and have reduced the mean height of balsam fir trees. White birch was generally absent from the canopy. However, contrary to the 1960 prediction, moose appear to have had a positive influence on forest growth by thinning most areas to stem densities comparable with those of precommercially thinned stands. Data from this study were compared with a general model of the influence of moose on balsam fir forests developed for Isle Royale, Michigan. Our data supported two predictions from Isle Royale: moose damage was highest at low balsam fir densities and at highest moose densities. Our results contradicted a third prediction, that height growth was greater in high density stands of saplings. Also, unlike at Isle Royale, despite heavy browsing pressure for extended periods, balsam fir will continue to dominate central Newfoundland forests.
A RADIAL BASIS FUNCTION NETWORK APPROACH FOR THE COMPUTATION OF INVERSE CONTINUOUS TIME VARIANT FUNCTIONS
Authors: MAYORGA RENÉ V. , CARRERA JONATHAN
Published: July 2007

This Paper presents an efficient approach for the fast computation of inverse continuous time variant functions with the proper use of Radial Basis Function Networks (RBFNs). The approach is based on implementing RBFNs for computing inverse continuous time variant functions via an overall damped least squares solution that includes a novel null space vector for singularities prevention. The singularities avoidance null space vector is derived from developing a sufficiency condition for singularities prevention that conduces to establish some characterizing matrices and an associated performance index.
AN SOM-BASED ALGORITHM FOR OPTIMIZATION WITH DYNAMIC WEIGHT UPDATING
Authors: CHEN YI-YUAN , YOUNG KUU-YOUNG
Published: July 2007

The self-organizing map (SOM), as a kind of unsupervised neural network, has been used for both static data management and dynamic data analysis. To further exploit its search abilities, in this paper we propose an SOM-based algorithm (SOMS) for optimization problems involving both static and dynamic functions. Furthermore, a new SOM weight updating rule is proposed to enhance the learning efficiency; this may dynamically adjust the neighborhood function for the SOM in learning system parameters. As a demonstration, the proposed SOMS is applied to function optimization and also dynamic trajectory prediction, and its performance compared with that of the genetic algorithm (GA) due to the similar ways both methods conduct searches.
SUPERNOVA EXPLOSIONS: UNDERSTANDING MIXING
Authors: FRYER CHRIS L. , HUNGERFORD AIMEE L. , ROCKEFELLER GABRIEL
Published: July 2007

It has been known since 1987 that many features of supernovae cannot be described by the spherically-symmetric picture assumed in one-dimensional explosion models. However, the study of the propagation of a supernova shock through a star in more than one spatial dimension is still in its infancy. Understanding this propagation, and the mixing associated with it, is critical for determining accurate supernova yields and correctly interpreting observations based on those yields — from gamma-rays and overall light curves produced in supernova explosions to the abundances of isotopes studied in stars. Here we review the current state-of-the-art in this field. By necessity, this problem is computational and therefore provides an ideal setting to discuss how verification and validation techniques can play an important role in taking full advantage of the results from numerical simulations. We discuss this problem using the full arsenal of verification and validation techniques currently available.
DIRAC BRACKETS FROM MAGNETIC BACKGROUNDS
Authors: ISIDRO JOSÉ M.
Published: July 2007

In symplectic mechanics, the magnetic term describing the interaction between a charged particle and an external magnetic field has to be introduced by hand. On the contrary, in generalized complex geometry, such magnetic terms in the symplectic form arise naturally by means of B-transformations. Here we prove that, regarding classical phase space as a generalized complex manifold, the transformation law for the symplectic form under the action of a weak magnetic field gives rise to Dirac's prescription for Poisson brackets in the presence of constraints.
Target Sequence Accessibility Limits Activation-Induced Cytidine Deaminase Activity in Primary Mediastinal B-Cell Lymphoma
Authors: Popov Sergey W. , Moldenhauer Gerhard , Wotschke Beate , Brüderlein Silke , Barth Thomas F. , Dorsch Karola , Ritz Olga , Möller Peter , Leithäuser Frank
Published: July 2007

Activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) in activated B lymphocytes and is potentially implicated in genomic instability of B-cell malignancies. For unknown reasons, B-cell neoplasms often lack SHM and CSR in spite of high AID expression. Here, we show that primary mediastinal B-cell lymphoma (PMBL), an immunoglobulin (Ig)–negative lymphoma that possesses hypermutated, class-switched Ig genes, expresses high levels of AID with an intact primary structure but does not do CSR in 14 of 16 cases analyzed. Absence of CSR coincided with low Ig germ-line transcription, whereas high level germ-line transcription was observed only in those two cases with active CSR. Interleukin-4/CD40L costimulation induced CSR and a marked up-regulation of germ-line transcription in the PMBL-derived cell line MedB-1. In the PMBL cell line Karpas 1106P, CSR was not inducible and germ-line transcription remained low on stimulation. However, Karpas 1106P, but not MedB-1, had ongoing SHM of the Ig gene and BCL6. These genes were transcribed in Karpas 1106P, whereas transcription was undetectable or low in MedB-1 cells. Thus, accessibility of the target sequences seems to be a major limiting factor for AID-dependent somatic gene diversification in PMBL. [Cancer Res 2007;67(14):6555–64]
Lipid Rafts and Nonrafts Mediate Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand–Induced Apoptotic and Nonapoptotic Signals in Non–Small Cell Lung Carcinoma Cells
Authors: Song Jin H. , Tse Margaret C.L. , Bellail Anita , Phuphanich Surasak , Khuri Fadlo , Kneteman Norman M. , Hao Chunhai
Published: July 2007

Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is capable of inducing apoptosis in non–small cell lung carcinoma (NSCLC). However, many of the human NSCLC cell lines are resistant to TRAIL, and TRAIL treatment of the resistant cells leads to the activation of nuclear factor-κB (NF-κB) and extracellular signal–regulated kinase 1/2 (ERK1/2). TRAIL can induce apoptosis in TRAIL-sensitive NSCLC cells through the induction of death-inducing signaling complex (DISC) assembly in lipid rafts of plasma membrane. In the DISC, caspase-8 is cleaved and initiates TRAIL-induced apoptosis. In contrast, TRAIL-DISC assembly in the nonraft phase of the plasma membrane leads to the inhibition of caspase-8 cleavage and NF-κB and ERK1/2 activation in TRAIL-resistant NSCLC cells. Receptor-interacting protein (RIP) and cellular Fas-associated death domain–like interleukin-1β–converting enzyme-inhibitory protein (c-FLIP) mediates the DISC assembly in nonrafts and selective knockdown of either RIP or c-FLIP with interfering RNA redistributes the DISC from nonrafts to lipid rafts, thereby switching the DISC signals from NF-κB and ERK1/2 activation to caspase-8–initiated apoptosis. Chemotherapeutic agents inhibit c-FLIP expression, thereby enhancing the DISC assembly in lipid rafts for caspase-8–initiated apoptosis. These studies indicate that RIP and c-FLIP–mediated assembly of the DISC in nonrafts is a critical upstream event in TRAIL resistance and thus targeting of either RIP or c-FLIP may lead to the development of novel therapeutic strategies that can overcome TRAIL resistance in human NSCLC. [Cancer Res 2007;67(14):6946–55]
BEX2 Is Overexpressed in a Subset of Primary Breast Cancers and Mediates Nerve Growth Factor/Nuclear Factor-κB Inhibition of Apoptosis in Breast Cancer Cell Lines
Authors: Naderi Ali , Teschendorff Andrew E. , Beigel Juergen , Cariati Massimiliano , Ellis Ian O. , Brenton James D. , Caldas Carlos
Published: July 2007

We have identified a novel subtype of estrogen receptor (ER)-positive breast cancers with improved outcome after tamoxifen treatment and characterized by overexpression of the gene BEX2. BEX2 and its homologue BEX1 have highly correlated expression and are part of a cluster enriched for ER response and apoptosis genes. BEX2 expression is induced after estradiol (E2) treatment with a peak at 3 h, suggesting BEX2 is an estrogen-regulated gene. BEX2 belongs to a family of genes, including BEX1, NGFRAP1 (alias BEX3), BEXL1 (alias BEX4), and NGFRAP1L1 (alias BEX5). Both BEX1 and NGFRAP1 interact with p75NTR and modulate nerve growth factor (NGF) signaling through nuclear factor-κB (NF-κB) to regulate cell cycle, apoptosis, and differentiation in neural tissues. In breast cancer cells, NGF inhibits C2-induced apoptosis through binding of p75NTR and NF-κB activation. Here, we show that BEX2 expression is necessary and sufficient for the NGF-mediated inhibition (through NF-κB activation) of C2-induced apoptosis. We also show that BEX2 modulates apoptosis of breast cancer cells in response to E2 (50 nmol/L) and tamoxifen (5 and 10 μmol/L). Furthermore, BEX2 overexpression enhances the antiproliferative effect of tamoxifen at pharmacologic dose (1 μmol/L). These data suggest that a NGF/BEX2/NF-κB pathway is involved in regulating apoptosis in breast ancer cells and in modulating response to tamoxifen in primary tumors. [Cancer es 2007;67(14):6725–36]
Dual Specificity Phosphatase 1/CL100 Is a Direct Transcriptional Target of E2F-1 in the Apoptotic Response to Oxidative Stress
Authors: Wang Jianli , Yin David P. , Liu Yu-Xin , Baer Richard , Yin Yuxin
Published: July 2007

E2F-1 mediates apoptosis through transcriptional regulation of its targets. We report here that E2F-1 acts as a direct transcriptional regulator of dual specificity phosphatase 1 (DUSP1; CL100), a threonine and tyrosine phosphatase that inhibits mitogen-activated protein (MAP) kinases. We found that DUSP1 is transcriptionally induced by ectopic E2F-1 expression and that extracellular signal–regulated kinase 1/2 are dephosphorylated in the presence of E2F-1 and DUSP1. E2F-1 mediates apoptosis in the cellular response to oxidative stress. DUSP1 levels are significantly increased in an E2F-1–dependent manner following oxidative stress but not other stresses examined. DUSP1 mediates the cellular response to oxidative stress. We found that E2F-1 binds to chromatin encompassing the DUSP1 promoter and greatly stimulates the promoter activity of the DUSP1 gene. In particular, E2F-1 physically binds to an E2F-1 consensus sequence and a palindromic motif in the DUSP1 promoter. Interestingly, E2F-1 is acetylated following oxidative stress. Our findings show that E2F-1 is a transcriptional activator of DUSP1 and that DUSP1 is a link between E2F-1 and MAP kinases. [Cancer Res 2007;67(14):6737–44]
Control of Her-2 Tumor Immunity and Thyroid Autoimmunity by MHC and Regulatory T Cells
Authors: Jacob Jennifer B. , Kong Yi-chi M. , Meroueh Chady , Snower Daniel P. , David Chella S. , Ho Ye-Shih , Wei Wei-Zen
Published: July 2007

Immune reactivity to self-antigens in both cancer and autoimmune diseases can be enhanced by systemic immune modulation, posing a challenge in cancer immunotherapy. To distinguish the genetic and immune regulation of tumor immunity versus autoimmunity, immune responses to human ErbB-2 (Her-2) and mouse thyroglobulin (mTg) were tested in transgenic mice expressing Her-2 that is overexpressed in several cancers, and HLA-DRB1*0301 (DR3) that is associated with susceptibility to several human autoimmune diseases, as well as experimental autoimmune thyroiditis (EAT). To induce Her-2 response, mice were electrovaccinated with pE2TM and pGM-CSF encoding the extracellular and transmembrane domains of Her-2 and the murine granulocyte macrophage colony-stimulating factor, respectively. To induce EAT, mice received mTg i.v. with or without lipopolysaccharide. Depletion of regulatory T cells (Treg) with anti-CD25 monoclonal antibody enhanced immune reactivity to Her-2 as well as mTg, showing control of both Her-2 and mTg responses by Treg. When immunized with, Her-2xDR3 and B6xDR3 mice expressing H2bxDR3 haplotype developed more profound mTg response and thyroid pathology than Her-2 or B6 mice that expressed the EAT-resistant H2b haplotype. In Her-2xDR3 mice, the response to mTg was further amplified when mice were also immunized with pE2TM and pGM-CSF. On the contrary, Her-2 reactivity was comparable whether mice expressed DR3 or not. Therefore, induction of Her-2 immunity was independent of DR3 but development of EAT was dictated by this allele, whereas Tregs control the responses to both self-antigens. These results warrant close monitoring of autoimmunity during cancer immunotherapy, particularly in patients with susceptible MHC class II alleles. [Cancer Res 2007;67(14):7020–7]
A Galactolipid Possesses Novel Cancer Chemopreventive Effects by Suppressing Inflammatory Mediators and Mouse B16 Melanoma
Authors: Hou Chia-Chung , Chen Yi-Ping , Wu Jyh-Horng , Huang Chi-Chang , Wang Sheng-Yang , Yang Ning-Sun , Shyur Lie-Fen
Published: July 2007

Crassocephalum rabens (Asteraceae) is a popular anti-inflammatory folk medicine and food supplement. We investigated the cancer chemopreventive bioactivity of C. rabens phytocompounds in vitro and in vivo using cell- and gene-based bioassays and a mouse B16 melanoma model. The bioactive glyceroglycolipid 1,2-di-O-α-linolenoyl-3-O-β-galactopyranosyl-sn-glycerol (dLGG) that was identified from C. rabens was found in vitro and in vivo to be a potent nitric oxide (NO) scavenger. dLGG treatment inhibited both mRNA and protein expression of inducible NO synthase and cyclooxygenase-2 (COX-2) in murine macrophages and inhibited COX-2 gene transcription in 12-O-tetradecanoylphorbol-13-acetate (TPA)–treated B16 cells. In immunohistochemical studies, dLGG inhibited TPA-induced expression of COX-2 and nitration of proteins in mouse skin. dLGG could also significantly inhibit lipopolysaccharide-induced prostaglandin E2 production in murine macrophages. Furthermore, dLGG prevented nuclear translocation of cytoplasmic nuclear factor-κB (NF-κB) by suppressing IκBα phosphorylation and degradation. Structure-activity relationship study by electrophoretic mobility shift assay indicated that the dilinolenoylglycerol moiety in dLGG is the essential structural feature preventing NF-κB·DNA complex formation. A dLGG-enriched extract from C. rabens (10 mg/kg) markedly suppressed B16 melanoma growth in C57BL/6J mice following i.p. administration, an effect comparable with that of cisplatin, a cancer chemotherapeutic drug. This study shows the detailed molecular mechanism(s) underlying the anti-inflammatory and tumor-suppressive effects of a natural galactolipid. [Cancer Res 2007;67(14):6907–15]