bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Missile Formation Reconfiguration Optimized Trajectory Generation and Control
Authors: Cui Naigang , Wei Changzhu , Guo Jifeng , Zhao Biao
Published: April 2010

The methods of missile formation reconfiguration optimal trajectory generating and control are described. Given a formation of intelligence missiles, an initial configuration, a final configuration, a time for reconfiguration, and a set of inter- and intramissile constraint, reconfiguration trajectory generation and control problems focused on determining and controlling a normal input trajectory for each intelligence missile such that every intelligence missile can fly as the expected optimal trajectory while satisfying all the sets of constraints. In this paper, solving the optimal trajectory generation problem by posing the input as a polynomial form and analyzing the symbolic reachability computation based on the quantifier elimination theory is of interest. A combination of proportion and differential control with the position error is used in the design of the missile formation controller used to track the optimal transfer trajectory. Simulations by the package REGLOG demonstrate that the optimal transfer trajectory generation process is feasible; the controller is capable of tracking the optimal transfer trajectory.
Debugging Metabolic Disease
Authors: Kiberstis Paula A.
Published: April 2010

The innate immune system may promote metabolic health through effects on gut microbes.
Targeted Delivery of a Photosensitizer to
Aggregatibacter actinomycetemcomitans
Biofilm
Authors: Suci Peter , Kang Sebyung , Gmür Rudolf , Douglas Trevor , Young Mark
Published: April 2010

The ability to selectively target specific biofilm species with antimicrobials would enable control over biofilm consortium composition, with medical applications in treatment of infections on mucosal surfaces that are colonized by a mixture of beneficial and pathogenic microorganisms. We functionalized a genetically engineered multimeric protein with both a targeting moiety (biotin) and either a fluorophore or a photosensitizer (SnCe6). Biofilm microcolonies of
Aggregatibacter actinomycetemcomitans
, a periodontal pathogen, were targeted with the multifunctional dodecamer. Streptavidin was used to couple biotinylated dodecamer to a biotinylated anti-
A. actinomycetemcomitans
antibody. This modular targeting approach enabled us to increase the loading of photosensitizer onto the cells by a cycle of amplification. Scanning laser confocal microscopy was used to characterize transport of fluorescently tagged dodecamer into the microcolonies and targeting of the cells with biotin-labeled, fluorescently tagged dodecamer. Light-induced activity of the targeted photosensitizer reduced the viability of
A. actinomycetemcomitans
biofilm, as indicated by membrane permeability to propidium iodide. The functionalized multimeric protein promises to be a useful tool for controlling periodontal biofilm consortia and offers a modular design whereby moieties that target different species can be readily combined with the functionalized protein construct.
Global Spread of the
hyl
Efm
Colonization-Virulence Gene in Megaplasmids of the
Enterococcus faecium
CC17 Polyclonal Subcluster
Authors: Freitas Ana R. , Tedim Ana P. , Novais Carla , Ruiz-Garbajosa Patricia , Werner Guido , Laverde-Gomez Jenny A. , Cantón Rafael , Peixe Luísa , Baquero Fernando , Coque Teresa M.
Published: April 2010

Enterococcus faecium
has increasingly been reported as a nosocomial pathogen since the early 1990s, presumptively associated with the expansion of a human-associated
Enterococcus faecium
polyclonal subcluster known as clonal complex 17 (CC17) that has progressively acquired different antibiotic resistance (ampicillin and vancomycin) and virulence (
esp
Efm
,
hyl
Efm
, and
fms
) traits. We analyzed the presence and the location of a putative glycoside hydrolase
hyl
Efm
gene among
E. faecium
strains obtained from hospitalized patients (255 patients; outbreak, bacteremic, and/or disseminated isolates from 23 countries and five continents; 1986 to 2009) and from nonclinical origins (isolates obtained from healthy humans [25 isolates], poultry [30], swine [90], and the environment [55]; 1999 to 2007). Clonal relatedness was established by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Plasmid analysis included determination of content and size (S1-PFGE), transferability (filter mating), screening of Rep initiator proteins (PCR), and location of
vanA
,
vanB
,
ermB
, and
hyl
Efm
genes (S1/I-CeuI hybridization). Most
E. faecium
isolates contained large plasmids (>150 kb) and showed variable contents of
van
,
hyl
Efm
, or
esp
Efm
. The
hyl
Efm
gene was associated with megaplasmids (170 to 375 kb) of worldwide spread (ST16, ST17, and ST18) or locally predominant (ST192, ST203, ST280, and ST412) ampicillin-resistant CC17 clones collected in the five continents since the early 1990s. All but one
hyl
Efm
-positive isolate belonged to the CC17 polyclonal subcluster. The presence of
hyl
Efm
megaplasmids among CC17 from Europe, Australia, Asia, and Africa since at least the mid-1990s was documented. This study further demonstrates the pandemic expansion of particular CC17 clones before acquisition of vancomycin resistance and putative virulence traits and describes the presence of megaplasmids in most of the contemporary
E. faecium
isolates with different origins.
Intravenous Voriconazole after Toxic Oral Administration
Authors: Alffenaar J. W. C. , van Assen S. , de Monchy J. G. R. , Uges D. R. A. , Kosterink J. G. W. , van der Werf T. S.
Published: April 2010

In a male patient with rhinocerebral invasive aspergillosis, prolonged high-dosage oral administration of voriconazole led to hepatotoxicity combined with a severe cutaneous reaction while intravenous administration in the same patient did not. High concentrations in the portal blood precipitate liver enzyme abnormalities, and therefore, oral administration of voriconazole may have a hepatotoxicity profile different from that of intravenous (i.v.) administration. Intravenously administered voriconazole might still be an option after oral-voriconazole-induced toxicity has resolved.
Population Pharmacokinetics of Vancomycin in Premature Malaysian Neonates: Identification of Predictors for Dosing Determination
Authors: Lo Yoke-Lin , van Hasselt Johan G. C. , Heng Siow-Chin , Lim Chin-Theam , Lee Toong-Chow , Charles Bruce G.
Published: April 2010

The present study determined the pharmacokinetic profile of vancomycin in premature Malaysian infants. A one-compartment infusion model with first-order elimination was fitted to serum vancomycin concentration data (
n
= 835 points) obtained retrospectively from the drug monitoring records of 116 premature newborn infants. Vancomycin concentrations were estimated by a fluorescence polarization immunoassay. Population and individual estimates of clearance and distribution volume and the factors which affected the variability observed for the values of these parameters were obtained using a population pharmacokinetic modeling approach. The predictive performance of the population model was evaluated by visual inspections of diagnostic plots and nonparametric bootstrapping with replacement. Dosing guidelines targeting a value of ≥400 for the area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC
24
/MIC ratio) were explored using Monte Carlo simulation. Body size (weight), postmenstrual age, and small-for-gestational-age status are important factors explaining the between-subject variability of vancomycin pharmacokinetic parameter values for premature neonates. The typical population parameter estimates of clearance and distribution volume for a 1-kg premature appropriate-for-gestational-age neonate with a postmenstrual age of 30 weeks were 0.0426 liters/h and 0.523 liters, respectively. There was a 20% reduction in clearance for small-for-gestational-age infants compared to the level for the appropriate-for-gestational-age control. Dosage regimens based on
a priori
target response values were formulated. In conclusion, the pharmacokinetic parameter values for vancomycin in premature Malaysian neonates were estimated. Improved dosage regimens based on
a priori
target response values were formulated by incorporating body size, postmenstrual age, and small-for-gestational-age status, using Monte Carlo simulations with the model-estimated pharmacokinetic parameter values.
Antimicrobial Resistance of
Listeria monocytogenes
Strains Isolated from Humans in France
Authors: Morvan A. , Moubareck C. , Leclercq A. , Hervé-Bazin M. , Bremont S. , Lecuit M. , Courvalin P. , Le Monnier A.
Published: April 2010

Susceptibility to antibiotics of 4,816 clinical
L. monocytogenes
strains isolated since 1926 was studied, and the temporal evolution of susceptibility to antibiotics was analyzed through several decades. The mechanisms of resistance in each resistant strain were studied. The prevalence of resistant strains was estimated at 1.27% among isolates from humans. Resistance to tetracyclines+ and fluoroquinolones was more common and has recently emerged. Although acquired resistance in clinical
L. monocytogenes
did not implicate clinically relevant antibiotics, the possibility of resistance gene transfers, the description of the first clinical isolate with high-level resistance to trimethoprim, and the recent increase in penicillin MICs up to 2 μg/ml reinforce the need for microbiological surveillance.
In Vivo
Comparison of the Pharmacodynamic Targets for Echinocandin Drugs against
Candida
Species
Authors: Andes D. , Diekema D. J. , Pfaller M. A. , Bohrmuller J. , Marchillo K. , Lepak A.
Published: April 2010

Previous pharmacodynamic studies using
in vivo
candidiasis models have demonstrated that the 24-h area under the concentration-time curve (AUC)/MIC is a good descriptor of the echinocandin exposure-response relationship. Further studies investigating the 24-h AUC/MIC target for a stasis endpoint identified free-drug 24-h AUC/MIC against
Candida albicans
and were similar for two echinocandins, anidulafungin and micafungin. The current studies expand investigation of a third echinocandin (caspofungin) and compare the pharmacodynamic target among
C. albicans
,
Candida glabrata
, and
Candida parapsilosis
. Treatment studies were conducted with six
C. albicans
, nine
C. glabrata
, and 15
C. parapsilosis
strains with various MICs (anidulafungin, 0.015 to 4.0 μg/ml; caspofungin, 0.03 to 4.0 μg/ml; and micafungin, 0.008 to 1.0 μg/ml). Efficacy was closely tied to MIC and the 24-h AUC/MIC. Therapy against
C. parapsilosis
required more of each echinocandin on a mg/kg basis. Caspofungin required less drug on a mg/kg basis for efficacy against all of the organisms than did the other two drugs. However, the 24-h AUC/MIC targets were similar among the echinocandins when free drug concentrations were considered, suggesting the relevance of protein binding. The targets for
C. parapsilosis
(mean, 7) and
C. glabrata
(mean, 7) were significantly lower than those for
C. albicans
(mean, 20) for each echinocandin. The results suggest that current susceptibility breakpoints and the consideration of organism species in these determinations should be reexplored.
Experimental Conditions That Enhance Potency of an Antibacterial Oligo-Acyl-Lysyl
Authors: Goldfeder Yair , Zaknoon Fadia , Mor Amram
Published: April 2010

Oligo-acyl-lysyls (OAKs) are synthetic mimics of host defense peptides known to exert antibacterial activity both in cultures and in animal models of disease. Here, we investigated how environmental conditions (temperature, pH, and ionic strength) affect the antibacterial properties of an octamer derivative, C12K-7α8. Data obtained with representative bacteria, including the Gram-negative bacteriumEscherichia coliand the Gram-positive bacteriaListeria monocytogenesandStaphylococcus aureus, showed that OAK's potency was proportionally affected by pH changes and subsided essentially throughout a wide range of salt concentrations and temperature values, whereas antistaphyloccocal activity was relatively more vulnerable. It was rather the mode of action that was most susceptible to the environmental changes. Thus, OAK's bactericidal effect was limited to a growth-inhibitory effect under acidic pH, low temperatures, or high salt concentrations, whereas basic pH or high temperatures have enhanced the bactericidal kinetics. Properties of binding to model phospholipid membranes provided evidence that correlated the differential modes of action with variable binding affinities. Interestingly, combination of the optimal incubation conditions resulted in a remarkable increase in potency, as expressed by a 16- to 32-fold reduction in the MIC value and by much faster bactericidal rates (>99% death induced within minutes versus hours) compared with the standard incubation conditions. Collectively, the data suggest that OAKs might be useful in developing design strategies for robust antimicrobial peptides that are able to affect a pathogen's viability under a large spectrum of incubation conditions.
Natamycin Inhibits Vacuole Fusion at the Priming Phase via a Specific Interaction with Ergosterol
Authors: te Welscher Yvonne Maria , Jones Lynden , van Leeuwen Martin Richard , Dijksterhuis Jan , de Kruijff Ben , Eitzen Gary , Breukink Eefjan
Published: April 2010

The antifungal antibiotic natamycin belongs to the family of polyene antibiotics. Its antifungal activity arises via a specific interaction with ergosterol in the plasma membrane (te Welscher et al., J. Biol. Chem. 283:6393-6401, 2008). However, this activity does not involve disruption of the membrane barrier function, a well-known property of other members of the polyene antibiotic family, such as filipin and nystatin. Here we tested the effect of natamycin on vacuole membrane fusion, which is known to be ergosterol dependent. Natamycin blocked the fusion of isolated vacuoles without compromising the barrier function of the vacuolar membrane. Sublethal doses of natamycin perturbed the cellular vacuole morphology, causing the formation of many more small vacuolar structures in yeast cells. Using vacuoles isolated from yeast strains deficient in the ergosterol biosynthesis pathway, we showed that the inhibitory activity of natamycin was dependent on the presence of specific chemical features in the structure of ergosterol that allow the binding of natamycin. We found that natamycin inhibited the priming stage of vacuole fusion. Similar results were obtained with nystatin. These results suggest a novel mode of action of natamycin and perhaps all polyene antibiotics, which involves the impairment of membrane fusion via perturbation of ergosterol-dependent priming reactions that precede membrane fusion, and they may point to an effect of natamycin on ergosterol-dependent protein function in general.
Pharmacokinetic-Pharmacodynamic-Model-Guided Doripenem Dosing in Critically Ill Patients
Authors: Samtani Mahesh N. , Flamm Robert , Kaniga Koné , Nandy Partha
Published: April 2010

The growing number of infections caused by multidrug-resistant pathogens has prompted a more rational use of available antibiotics given the paucity of new, effective agents. Monte Carlo simulations were utilized to determine the appropriateness of several doripenem dosing regimens based on the probability of attaining the critical drug exposure metric of time that drug concentrations remain above the drug MIC (
T
>MIC) for 35% (and lower thresholds) of the dosing interval in >80 to 90% of the population (
T
>MIC 35% target). This exposure level generally correlates with
in vivo
efficacy for carbapenems. In patients with creatinine clearance of >50 ml/min, a 500-mg dose of doripenem infused over 1 h every 8 h is expected to be effective against bacilli with doripenem MICs of ≤1 μg/ml based on a
T
>MIC 35% target and MICs of ≤2 μg/ml based on lower targets. A longer, 4-hour infusion time improved target attainment in most cases, such that the
T
>MIC was adequate for pathogens with doripenem MICs as high as 4 μg/ml. Efficacy is expected for infections caused by pathogens with doripenem MICs of ≤2 μg/ml in patients with moderate renal impairment (creatinine clearance, 30 to 50 ml/min) who receive doripenem at 250 mg infused over 1 h every 8 h and in patients with severe impairment (creatinine clearance between 10 and 29 ml/min) who receive doripenem at 250 mg, infused over 1 h or 4 h, every 12 h. Results of pharmacokinetics/pharmacodynamics (PK/PD) modeling can guide dose optimization, thereby potentially increasing the clinical efficacy of doripenem against serious Gram-negative bacterial infections.
Indoleamine 2,3-Dioxygenase 1 Is a Lung-Specific Innate Immune Defense Mechanism That Inhibits Growth ofFrancisella tularensisTryptophan Auxotrophs
Authors: Peng Kaitian , Monack Denise M.
Published: April 2010

Upon microbial challenge, organs at various anatomic sites of the body employ different innate immune mechanisms to defend against potential infections. Accordingly, microbial pathogens evolved to subvert these organ-specific host immune mechanisms to survive and grow in infected organs.Francisella tularensisis a bacterium capable of infecting multiple organs and thus encounters a myriad of organ-specific defense mechanisms. This suggests thatF. tularensismay possess specific factors that aid in evasion of these innate immune defenses. We carried out a microarray-based, negative-selection screen in an intranasal model ofFrancisella novicidainfection to identifyFrancisellagenes that contribute to bacterial growth specifically in the lungs of mice. Genes in the bacterial tryptophan biosynthetic pathway were identified as being important forF. novicidagrowth specifically in the lungs. In addition, a host tryptophan-catabolizing enzyme, indoleamine 2,3-dioxygenase 1 (IDO1), is induced specifically in the lungs of mice infected withF. novicidaorStreptococcus pneumoniae. Furthermore, the attenuation ofF. novicidatryptophan mutant bacteria was rescued in the lungs of IDO1−/−mice. IDO1 is a lung-specific innate immune mechanism that controls pulmonaryFrancisellainfections.
Taming the Elephant:
Salmonella
Biology, Pathogenesis, and Prevention
Authors: Andrews-Polymenis Helene L. , Bäumler Andreas J. , McCormick Beth A. , Fang Ferric C.
Published: April 2010

Salmonella
infections continue to cause substantial morbidity and mortality throughout the world. However, recent discoveries and new paradigms promise to lead to novel strategies to diagnose, treat, and prevent
Salmonella
infections. This review provides an update of the
Salmonella
field based on oral presentations given at the recent 3rd ASM Conference on
Salmonella:
Biology, Pathogenesis and Prevention.
Characterization and Serologic Analysis of theTreponema pallidumProteome
Authors: McGill Melanie A. , Edmondson Diane G. , Carroll James A. , Cook Richard G. , Orkiszewski Ralph S. , Norris Steven J.
Published: April 2010

Treponema pallidumsubsp. pallidumis the causative agent of syphilis, a sexually transmitted disease characterized by widespread tissue dissemination and chronic infection. In this study, we analyzed the proteome ofT. pallidumby the isoelectric focusing (IEF) and nonequilibrating pH gel electrophoresis (NEPHGE) forms of two-dimensional gel electrophoresis (2DGE), coupled with matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analysis. We determined the identity of 148T. pallidumprotein spots, representing 88T. pallidumpolypeptides; 63 of these polypeptides had not been identified previously at the protein level. To examine which of these proteins are important in the antibody response to syphilis, we performed immunoblot analysis using infected rabbit sera or human sera from patients at different stages of syphilis infection. Twenty-nine previously described antigens (predominantly lipoproteins) were detected, as were a number of previously unidentified antigens. The reactivity patterns obtained with sera from infected rabbits and humans were similar; these patterns included a subset of antigens reactive with all serum samples tested, including CfpA, MglB-2, TmpA, TmpB, flagellins, and the 47-kDa, 17-kDa, and 15-kDa lipoproteins. A unique group of antigens specifically reactive with infected human serum was also identified and included the previously described antigen TpF1 and the hypothetical proteins TP0584, TP0608, and TP0965. This combined proteomic and serologic analysis further delineates the antigens potentially useful as vaccine candidates or diagnostic markers and may provide insight into the host-pathogen interactions that occur duringT. palliduminfection.
Milestones in Progression of Primary Pneumonic Plague in Cynomolgus Macaques
Authors: Koster Frederick , Perlin David S. , Park Steven , Brasel Trevor , Gigliotti Andrew , Barr Edward , Myers Leslie , Layton Robert C. , Sherwood Robert , Lyons C. R.
Published: April 2010

Vaccines against primary pneumonic plague, a potential bioweapon, must be tested for efficacy in well-characterized nonhuman primate models. Telemetered cynomolgus macaques (
Macaca fascicularis
) were challenged by the aerosol route with doses equivalent to approximately 100 50% effective doses of
Yersinia pestis
strain CO92 and necropsied at 24-h intervals postexposure (p.e.). Data for telemetered heart rates, respiratory rates, and increases in the temperature greater than the diurnal baseline values identified the onset of the systemic response at 55 to 60 h p.e. in all animals observed for at least 70 h p.e. Bacteremia was detected at 72 h p.e. by a
Yersinia
16S rRNA-specific quantitative reverse transcription-PCR and was detected later by the culture method at the time of moribund necropsy. By 72 h p.e. multilobar pneumonia with diffuse septal inflammation consistent with early bacteremia was established, and all lung tissues had a high bacterial burden. The levels of cytokines or chemokines in serum were not significantly elevated at any time, and only the interleukin-1β, CCL2, and CCL3 levels were elevated in lung tissue. Inhalational plague in the cynomolgus macaque inoculated by the aerosol route produces most clinical features of the human disease, and in addition the disease progression mimics the disease progression from the anti-inflammatory phase to the proinflammatory phase described for the murine model. Defined milestones of disease progression, particularly the onset of fever, tachypnea, and bacteremia, should be useful for evaluating the efficacy of candidate vaccines.
Virulence Gene Regulation by CvfA, a Putative RNase: the CvfA-Enolase Complex inStreptococcus pyogenesLinks Nutritional Stress, Growth-Phase Control, and Virulence Gene Expression
Authors: Kang Song Ok , Caparon Michael G. , Cho Kyu Hong
Published: April 2010

Streptococcus pyogenes, a multiple-auxotrophic human pathogen, regulates virulence gene expression according to nutritional availability during various stages in the infection process or in different infection sites. We discovered that CvfA influenced the expression of virulence genes according to growth phase and nutritional status. The influence of CvfA in C medium, rich in peptides and poor in carbohydrates, was most pronounced at the stationary phase. Under these conditions, up to 30% of the transcriptome exhibited altered expression; the levels of expression of multiple virulence genes were altered, including the genes encoding streptokinase, CAMP factor, streptolysin O, M protein (more abundant in the CvfA−mutant), SpeB, mitogenic factor, and streptolysin S (less abundant). The increase of carbohydrates or peptides in media restored the levels of expression of the virulence genes in the CvfA−mutant to wild-type levels (emm,ska, andcfaby carbohydrates;speBby peptides). Even though the regulation of gene expression dependent on nutritional stress is commonly linked to the stringent response, the levels of ppGpp were not altered by deletion ofcvfA. Instead, CvfA interacted with enolase, implying that CvfA, a putative RNase, controls the transcript decay rates of virulence factors or their regulators according to nutritional status. The virulence of CvfA−mutants was highly attenuated in murine models, indicating that CvfA-mediated gene regulation is necessary for the pathogenesis ofS. pyogenes. Taken together, the CvfA-enolase complex inS. pyogenesis involved in the regulation of virulence gene expression by controlling RNA degradation according to nutritional stress.
Role of Lipid A Acylation in
Yersinia enterocolitica
Virulence
Authors: Pérez-Gutiérrez Camino , Llobet Enrique , Llompart Catalina M. , Reinés Mar , Bengoechea José A.
Published: April 2010

Yersinia enterocolitica
is an important human pathogen.
Y. enterocolitica
must adapt to the host environment, and temperature is an important cue regulating the expression of most
Yersinia
virulence factors. Here, we report that
Y. enterocolitica
8081 serotype O:8 synthesized tetra-acylated lipid A at 37°C but that hexa-acylated lipid A predominated at 21°C. By mass spectrometry and genetic methods, we have shown that the
Y. enterocolitica msbB
,
htrB
, and
lpxP
homologues encode the acyltransferases responsible for the addition of C
12
, C
14
and C
16:1
, respectively, to lipid A. The expression levels of the acyltransferases were temperature regulated. Levels of expression of
msbB
and
lpxP
were higher at 21°C than at 37°C, whereas the level of expression of
htrB
was higher at 37°C. At 21°C, an
lpxP
mutant was the strain most susceptible to polymyxin B, whereas at 37°C, an
htrB
mutant was the most susceptible. We present evidence that the lipid A acylation status affects the expression of
Yersinia
virulence factors. Thus, expression of
flhDC
, the flagellar master regulatory operon, was downregulated in
msbB
and
lpxP
mutants, with a concomitant decrease in motility. Expression of the phospholipase
yplA
was also downregulated in both mutants.
inv
expression was downregulated in
msbB
and
htrB
mutants, and consistent with this finding, invasion of HeLa cells was diminished. However, the expression of
rovA
, the positive regulator of
inv
, was not affected in the mutants. The levels of pYV-encoded virulence factors Yops and YadA in the acyltransferase mutants were not affected. Finally, we show that only the
htrB
mutant was attenuated
in vivo
.
Abilities of organic horizons under some eastern Canadian forest stands to alter the acidity of rainwater
Authors: Mahendrappa M. K.
Published: April 2010

Various precipitation data, collected over a 13-year period, from different softwood and hardwood stands located at the Acadia Forest Experiment Station in central New Brunswick are evaluated to demonstrate differences between stands in their ability to alter the acidity of rainwater. In the soil organic horizons, retention and exchange processes are shown to be effective in altering the acidity of rainwater. Significant species effects in the quantities of water retained by the organic horizons are recognizable owing to differences in the quantities of organic materials accumulated under each stand and their moisture-retention characteristics. In turn, differences in the quantities of liquid retained in the organic horizons affect the residence time of the acid components of rain reaching the mineral soil. Major differences in chemical characteristics such as cation-exchange capacity, percent base saturation, and pH of the organic horizons suggest that the interactions of acid components of wet and dry deposition of air pollutants can be significantly different depending upon the species composition of stands.
A competition index for predicting the vigour of planted Douglas-fir in southwestern British Columbia
Authors: Brand David G.
Published: April 2010

To provide a method of quantifying brush competition in coastal Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations, data from 124 planted trees, 1–5 years old, were used to derive a competition index for predicting changes in tree vigour measured as a relative production rate. The index, including measures of brush proximity, relative height, and percent ground cover, appears to act as a measure of light interception around the tree crown. Tree vigour was found to be largely a function of the age of the tree from planting and the competition index (r2 = 0.71). Foliage-based measures of growth vigour were more strongly related to the index than basal area or height measures. The index has potential for assessing interspecific competition problems in young Douglas-fir plantations.
Nutritional aspects of distorted growth in immature forest stands of southwestern coastal British Columbia
Authors: Carter R. E. , Scagel A. M. , Klinka K.
Published: April 2010

Nutritional problems, deficiencies of B and Zn in particular, have been tentatively identified as the cause of specific distorted growth symptoms in several young stands of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Pacific silver fir (Abiesamabilis (Dougl.) Forbes) in southwestern coastal British Columbia. The most common symptoms associated with these apparent micronutrient deficiencies include leader dieback and discolouration, multileadered and bushy crowns, and, in severely deficient trees, swollen and distorted stems. Visual symptoms of apparent B deficiency become obvious when foliar concentrations are <5.0 ppm; visual symptoms of apparent Zn deficiency are less easily recognized, usually occurring when foliar Zn levels are less than approximately 9.0 ppm. Low foliar concentrations of B were often associated with low levels of Ca and Mg. Foliar B concentration was also correlated with total foliar S. Temporal variation in foliar nutrient levels, examined over 3 years, was quite high with an apparent strong relationship to growing season precipitation. This suggests that deficiencies of B and (or) Zn may be acute rather than chronic, with the appearance of periodic acute deficiencies being influenced by growing season soil moisture supply.
Response of root systems of northern conifer transplants to flooding
Authors: Levan Mary Ann , Riha Susan J.
Published: April 2010

The response of root systems of four conifer species (Pinusstrobus, Pinusresinosa, Piceaglauca, and Piceamariana) to saturated soil conditions was examined in growth chamber experiments using 2- to 4-year-old nursery transplants potted into Plexiglas cylinders using a soil-containing mix. None of the conifers appeared adapted to grow roots into flooded soil, with the deepest roots of any species reaching only 10 cm below a water table after allowing time for maximum growth (30 days, 23 °C). Accordingly, anatomical observations of root cross sections indicated that none of the species had a significant internal air-filled pore space. There was a major difference between the pine and spruce genera in the response of aerobically grown roots to flooding. In both spruce species, no root tips survived flooding treatments longer than 1 day, whereas in both pine species, 35% or more tips survived even the longest (7-day) treatment. This difference could not be readily related to differences between these species in drainage preference in the field. Despite the much greater loss of root tips in the spruces, the postdrainage recovery of transpiration, after a depression during flooding, was as rapid in the spruces as in the pines.
Second-year shoot development in black spruce Piceamariana (Mill.) B.S.P. container seedlings
Authors: Colombo S.J.
Published: April 2010

The relative contributions to 2nd-year shoot elongation by predetermined versus free growth were analyzed for black spruce (Piceamariana (Mill.) B.S.P.) seedlings. Seedlings from three hardening regimes, production run, short day, and extended greenhouse, were given various shoot-pruning treatments, from the terminal bud removed to the entire shoot removed except for a lateral shoot at the base. Pruned seedlings were compared with winter-damaged seedlings. Bud flushing was most rapid in short-day seedlings and in pruned seedlings regardless of hardening regime. The capacity for free growth in nonpruned seedlings varied little among seedlings of different hardening regimes, despite large initial differences in bud development between production-run, short-day, and extended greenhouse seedlings. Stem unit length and number of lateral buds per unit of stem length was greater in free growth compared with predetermined growth. Shoot pruning and winter damage had similar effects on shoot growth; the greater the degree of shoot removal, the greater the amount of free growth.
Seasonal trends of several water relation parameters in Cryptomeriajaponica seedlings
Authors: Doi Kyoji , Morikawa Yasushi , Hinckley Thomas M.
Published: April 2010

The role of osmotic adjustment in turgor maintenance during periods of either cold soil or plant temperatures or of high evaporative demand was described for 2-year-old Cryptomeriajaponica D. Don seedlings. Water relations parameters were measured by the pressure–volume technique for a 1-year period. The osmotic potential at full turgidity and at the point of zero turgor ranged from −1.32 to −2.70 MPa and from −1.70 to −3.52 MPa, respectively. Highest values of osmotic potential were associated with the period of foliage expansion, while lowest values were noted in mid-February during the period of lowest air temperatures. The role of solute changes or changes in symplastic water relative to tissue dry weight in osmotic adjustment is described.
Planting site storage: effects on survival and growth of overwinter-stored Scots pine (Pinussylvestris) containerized seedlings
Authors: Mattsson Anders
Published: April 2010

Survival and growth of outdoor- and cold-stored (−5 °C) Pinussylvestris (L.) containerized seedlings were studied following field storage in wax-lined cardboard boxes at the planting site during three growing seasons. Planting dates varied from early May until late June. The negative effects on subsequent growth were more pronounced for outdoor-stored seedlings. Planting site storage during the period of shoot elongation especially limited subsequent growth of those seedlings. Shoot and needle growth, stem diameter, and dry weight of the shoot and foliage mass were successively depressed by later planting dates for both outdoor-and cold-stored seedlings. No significant differences could be found in survival or growth of outdoor- and cold-stored seedlings that had not been stored at the site before planting. For planting dates in June, dry weight of the shoot and needle growth were depressed compared with seedlings planted in May.
Influence of hydraulic conductance of xylem on water status in cuttings
Authors: Ikeda Takefumi , Suzaki Tamio
Published: April 2010

The reduction in water potential of cuttings after planting in water closely was related to an increase in resistance to water flow in the xylem. From observations of water-conducting tissues using a scanning electron microscope, the increase in resistance to water flow of cuttings was caused by blockage of vessel lumens with tyloses for Populuscarolinensis and aspiration of bordered pits for Cryptomeriajaponica. Water status of cuttings decreased with time after planting and was maintained at a low level by water absorption through bark. After rooting, the total resistance to water flow decreased and the water status of cuttings increased.
Location of hydraulic resistance in the soil–plant pathway in seedlings of Pinussylvestris L. grown in peat
Authors: Örlander Göran , Due Karin
Published: April 2010

Seedlings of Pinussylvestris L. were grown in three different soil media: 100% peat, 40% silt–60% peat, and 60% silt–40% peat. The percentages refer to total dry weight. Needle conductance, needle water potential, and plant water conductance were measured at different levels of soil water potentials controlled with a semipermeable membrane system. Seedlings grown in the 60:40 silt–peat mixture had a plant water conductance at a soil water potential of −0.1 MPa 3 times that of seedlings grown in pure peat. In an experiment where the roots were dipped in a silt slurry before planting, it was found that the plant water conductance at low soil water potential (−0.1 MPa) increased more than 2 times compared with undipped controls. We concluded that an important resistance to water flow in the soil–plant pathway was located in the soil outside the roots and probably was the most important resistance in the root–soil interface. The use of low humified peat as a growth medium is open to discussion from a silvicultural point of view because of its hydraulic properties under dry conditions.
Seedling growth and nutrient relationships in a New Jersey Pine Barrens soil treated with "acid rain"
Authors: Schier George A.
Published: April 2010

The effects of simulated acid rain solutions on growth of pitch pine (Pinusrigida Mill.) seedlings in undisturbed soil cores from the New Jersey Pine Barrens were examined. Solutions of pH 5.6, 4.0, and 3.0 (SO42−–Cl−–NO3−, 4:2:1), totaling 1.4 times annual ambient precipitation, were applied directly to soil cores from the A horizon during a 1-year period. By varying photoperiod and diurnal temperature, two growing "seasons" with an intervening dormant period were simulated. Soil chemistry, soil leachate chemistry, seedling nutrition, and seedling growth were monitored. Seedling dry weight was significantly greater at pH 3.0 than at the less acid treatments. Foliar nutrient contents indicated that growth stimulation at pH 3.0 probably resulted because of increased availability of nitrogen and input of nutrient cations from acid-induced weathering of soil minerals. There were sharp increases in Ca and Mg leaching when the pH of the irrigating solution was lowered, but solution acidity had little effect on depletion of K. Declines in nutrient leaching during the experiment indicated that weatherable cations were becoming depleted. Although Al mobility was greatly accelerated by an increase in acid inputs, Al toxicity symptoms were not observed.
The trouble with benefit–cost ratios: benefit–cost ratio maximization versus wealth maximization
Authors: Rideout Doug
Published: April 2010

The paper analyzes benefit–cost ratios, as a maximization objective, by using the criterion of net present value. A basic Faustmann formulation with rotation age and stocking density as decision variables is expressed as a benefit–cost ratio to demonstrate that maximization of benefit–cost ratios is generally inconsistent with wealth maximization. The paper shows that maximization of the benefit–cost ratio results in the Fisherian solution to rotation age when stocking density is held constant. The paper also shows and that formulating the benefit–cost ratio as an infinite series of rotations is equivalent to formulating the benefit–cost ratio as a single rotation. Maximizing the benefit–cost ratio generally results in suboptimal use of stocking density when rotation age is held constant. In addition, fixed costs can influence the choice of stocking level. The simultaneous solution to stocking density and rotation age indicates the only instance benefit–cost ratio maximization results in correct Faustmann solutions is when the benefit–cost ratio equals one.
Extraction of alcohol dehydrogenase from fresh root tips of loblolly pine
Authors: Denslow Stewart , Hook Donal D.
Published: April 2010

Significant alterations of published methods for extracting alcohol dehydrogenase from plant components were required to obtain measurable enzyme activity from actively growing root tips of loblolly pine (Pinustaeda L.). Necessary steps were quick freezing of roots in liquid nitrogen within 5 min of excising, use of soluble polyvinylpyrrolidone during freezing and fracturing in liquid nitrogen, and use of mercaptoethanol, glycerol, and NAD as protective measures during complete homogenization. No chromatographic purification steps were necessary. Up to 16 samples could be collected and analyzed in a single day by this method with sufficient sensitivity to detect intraspecific variation among loblolly pine families.
Foliar heat content variations in four coniferous tree species of central Alberta
Authors: Chrosciewicz Z.
Published: April 2010

Foliar high heat contents were determined by standard oxygen bomb calorimetry in jack pine (Pinusbanksiana Lamb.), black spruce (Piceamariana (Mill.) B.S.P.), white spruce (Piceaglauca (Moench) Voss), and balsam fir (Abiesbalsamea (L.)Mill.) from samples collected in central Alberta. New foliage, sampled in mid-July and early September, and foliage 1, 2, and 3+ years old, sampled in late May, mid-July, and early September, were included in these determinations. The heat contents of the new foliage in all four species as well as the heat contents of the old foliage in jack pine, black spruce, and balsam fir consistently increased with each sampling time, while the heat contents of the old foliage in white spruce at first increased and then decreased between the times. The variations of the heat contents attributed to foliar ages lacked consistency in all four species, although the contents of the new foliage were predominantly lower than the contents of the old foliage. The overall heat contents for the combined sampling times and foliar ages in both the new foliage and the old foliage were the lowest in white spruce and the highest in balsam fir, with black spruce having the second highest content in the new foliage and jack pine having the second highest content in the old foliage.
Foliar moisture content variations in four coniferous tree species of central Alberta
Authors: Chrosciewicz Z.
Published: April 2010

Trends of foliar moisture content variations were determined for jack pine (Pinusbanksiana Lamb.), black spruce (Piceamariana (Mill.) B.S.P.), white spruce (Piceaglauca (Moench) Voss), and balsam fir (Abiesbalsamea (L.) Mill.) in central Alberta. New and old tree foliage was periodically sampled between early March and mid-September during 2 consecutive years. The seasonally recurring variations in foliar moisture contents were characterized by (i) early spring declines of moisture in the old foliage, (ii) flushing of new foliage at high bud moisture contents when the contents in the old foliage were low, and (iii) summer recoveries of moisture in the old foliage and simultaneous decreases of moisture in the new foliage until both eventually converged toward comparable moisture contents. The cumulative effects of temperature, in terms of degree days above 6 °C, were reflected in timing of the declines and the recoveries of moisture in the old foliage. These results may be applied in rating the crowning potential of local forest fires.
Estimating ovendry mass of trembling aspen and white birch using measurements from aerial photographs
Authors: Alemdag I. S.
Published: April 2010

A pilot study tested the estimation of stem, crown, and whole-tree biomass of single trees from measurements of total tree height and crown area taken from large-scale aerial photographs. The results indicated the feasibility of this method, provided that time of photography is optimal. More extensive testing is required to confirm these encouraging preliminary results.
Using Lead Concentrations and Stable Lead Isotope Ratios to Identify Contamination Events in Alluvial Soils
Authors: Saint-Laurent Diane , St-Laurent Julien , Hähni Marlies , Ghaleb Bassam , Chapados Camille
Published: April 2010

Soils contaminated with hydrocarbons(C10–C50), polycyclic aromatic hydrocarbons (PAHs), and other contaminants (e.g., As, Cd, Cu, Pb) were recently discovered on the banks of the Saint-François and Massawippi rivers. Alluvial soils are contaminated over a distance of 100 kilometers, and the level of the contaminated-hydrocarbon layer in the soil profiles is among the highest at the Windsor and Richmond sites. Concentrations of lead and stable lead isotope ratios(204Pb/206Pb,207Pb/206Pb,208Pb/206Pb)are also used to identify contamination events. The maximum and minimum values detected in soil profiles for arsenic, cadmium, and lead vary from 3.01 to 37.88 mgkg-1(As), 0.11 to 0.81 mgkg-1(Cd) 12.32 to 149.13 mgkg-1(Pb), respectively, while the207Pb/206Pb isotopic ratio values are between 0.8545 and 0.8724 for all the profiles. The highest values of trace elements (As, Pb and Zn) were detected in the hydrocarbon layer(C10–C50), most often located at the bottom of the profiles (160, 200, and 220 cm in depth). The various peaks recorded in the soils and the position of the profiles suggest that various contaminants were transported by the river on several occasions and infiltrated the soil matrix or deposited on floodplains during successive floods. Atmospheric particles which entered the river or deposited on riverbanks must also be considered as another source of pollution recorded in soils.
Extraction Techniques for Polycyclic Aromatic Hydrocarbons in Soils
Authors: Lau E. V. , Gan S. , Ng H. K.
Published: April 2010

This paper aims to provide a review of the analytical extraction techniques for polycyclic aromatic hydrocarbons (PAHs) in soils. The extraction technologies described here include Soxhlet extraction, ultrasonic and mechanical agitation, accelerated solvent extraction, supercritical and subcritical fluid extraction, microwave-assisted extraction, solid phase extraction and microextraction, thermal desorption and flash pyrolysis, as well as fluidised-bed extraction. The influencing factors in the extraction of PAHs from soil such as temperature, type of solvent, soil moisture, and other soil characteristics are also discussed. The paper concludes with a review of the models used to describe the kinetics of PAH desorption from soils during solvent extraction.
Testosterone Depletion by Castration May Protect Mice from Heat-Induced Multiple Organ Damage and Lethality
Authors: Lin Chian-Yuh , Lin Mao-Tsun , Cheng Ruei-Tang , Chen Sheng-Hsien
Published: April 2010

When the vehicle-treated, sham-operated mice underwent heat stress, the fraction survival and core temperature at +4 h of body heating were found to be 5 of 15 and34.4∘C±0.3∘C, respectively. Castration 2 weeks before the start of heat stress decreased the plasma levels of testosterone almost to zero, protected the mice from heat-induced death (fraction survival, 13/15) and reduced the hypothermia (core temperature,37.3∘C). The beneficial effects of castration in ameliorating lethality and hypothermia can be significantly reduced by testosterone replacement. Heat-induced apoptosis, as indicated by terminal deoxynucleotidyl- transferase- mediatedαUDP-biotin nick end-labeling staining, were significantly prevented by castration. In addition, heat-induced neuronal damage, as indicated by cell shrinkage and pyknosis of nucleus, to the hypothalamus was also castration-prevented. Again, the beneficial effects of castration in reducing neuronal damage to the hypothalamus as well as apoptosis in multiple organs during heatstroke, were significantly reversed by testosterone replacement. The data indicate that testosterone depletion by castration may protect mice from heatstroke-induced multiple organ damage and lethality.