bluuebunny/crossref_metadata_2025 huggingface dataset:
Antimicrobial Resistance in Bacteria from Swiss Veal Calves at Slaughter
Authors: Di Labio E. , Regula G. , Steiner A. , Miserez R. , Thomann A. , Ledergerber U.
Published: October 2007

Bacteria with antimicrobial resistance can be transferred from animals to humans and may compromise antimicrobial treatment in case of infection. To determine the antimicrobial resistance situation in bacteria from Swiss veal calves, faecal samples from 500 randomly selected calves originating from 129 farms were collected at four big slaughterhouses. Samples were cultured for Escherichia coli, Enterococcus sp. and Campylobacter sp. and isolated strains were tested for antimicrobial susceptibility to selected antimicrobial agents by the minimal inhibitory concentration technique using the broth microdilution method. From 100 farms, data on farm management, animal husbandry and antimicrobial treatments of the calves were collected by questionnaire. Risk factors associated with antimicrobial resistance were identified by logistic regression. In total, 467 E. coli, 413 Enterococcus sp. and 202 Campylobacter sp. were isolated. Of those, 68.7%, 98.7% and 67.8%, respectively, were resistant to at least one of the tested antimicrobial agents. Resistance was mainly observed to antimicrobials frequently used in farm animals. Prevalence of resistance to antimicrobials important for human treatment was generally low. However, a rather high number of quinupristin/dalfopristin‐resistant Enterococcus faecium and ciprofloxacin‐resistant Campylobacter sp. were detected. External calf purchase, large finishing groups, feeding of milk by‐products and administration of antimicrobials through feed upon arrival of the animals on the farm significantly increased the risk of antimicrobial resistance at farm level. Participation in a quality assurance programme and injection of a macrolide upon arrival of the animals on the farm had a protective effect. The present study showed that veal calves may serve as a reservoir for resistant bacteria. To ensure food safety, veal calves should be included in the national monitoring programme for antimicrobial resistance in farm animals. By improving farm management and calf husbandry the prevalence of resistance may be reduced.
Mosaic Tetracycline Resistance Genes and Their Flanking Regions in
Bifidobacterium thermophilum
and
Lactobacillus johnsonii
Authors: van Hoek Angela H. A. M. , Mayrhofer Sigrid , Domig Konrad J. , Flórez Ana B. , Ammor Mohammed S. , Mayo Baltasar , Aarts Henk J. M.
Published: October 2007

For the first time, mosaic tetracycline resistance genes were identified in
Lactobacillus johnsonii
and in
Bifidobacterium thermophilum
strains. The
L. johnsonii
strain investigated contains a complex hybrid gene,
tet
(O/W/32/O/W/O), whereas the five bifidobacterial strains possess two different mosaic
tet
genes: i.e.,
tet
(W/32/O) and
tet
(O/W). As reported by others, the crossover points of the mosaic
tet
gene segments were found at similar positions within the genes, suggesting a hot spot for recombination. Analysis of the sequences flanking these genes revealed that the upstream part corresponds to the 5′ end of the mosaic open reading frame. In contrast, the downstream region was shown to be more variable. Surprisingly, in one of the
B. thermophilum
strains a third
tet
determinant was identified, coding for the efflux pump Tet(L).
Interactions of Methylene Blue with Human Disulfide Reductases and Their Orthologues fromPlasmodium falciparum
Authors: Buchholz Kathrin , Schirmer R. Heiner , Eubel Jana K. , Akoachere Monique B. , Dandekar Thomas , Becker Katja , Gromer Stephan
Published: October 2007

Methylene blue (MB) has experienced a renaissance mainly as a component of drug combinations againstPlasmodium falciparummalaria. Here, we report biochemically relevant pharmacological data on MB such as rate constants for the uncatalyzed reaction of MB at pH 7.4 with cellular reductants like NAD(P)H (k= 4 M−1s−1), thioredoxins (k= 8.5 to 26 M−1s−1), dihydrolipoamide (k= 53 M−1s−1), and slowly reacting glutathione. As the disulfide reductases are prominent targets of MB, optical tests for enzymes reducing MB at the expense of NAD(P)H under aerobic conditions were developed. The product leucomethylene blue (leucoMB) is auto-oxidized back to MB at pH 7 but can be stabilized by enzymes at pH 5.0, which makes this colorless compound an interesting drug candidate. MB was found to be an inhibitor and/or a redox-cycling substrate of mammalian andP. falciparumdisulfide reductases, with thekcatvalues ranging from 0.03 s−1to 10 s−1at 25°C. Kinetic spectroscopy of mutagenized glutathione reductase indicates that MB reduction is conducted by enzyme-bound reduced flavin rather than by the active-site dithiol Cys58/Cys63. The enzyme-catalyzed reduction of MB and subsequent auto-oxidation of the product leucoMB mean that MB is a redox-cycling agent which produces H2O2at the expense of O2and of NAD(P)H in each cycle, turning the antioxidant disulfide reductases into pro-oxidant enzymes. This explains the termssubversive substrateorturncoat inhibitorfor MB. The results are discussed in cell-pathological and clinical contexts.
Comparison of the Physicochemical, Antifungal, and Toxic Properties of Two Liposomal Amphotericin B Products
Authors: Olson Jon A. , Adler-Moore Jill P. , Jensen Gerard M. , Schwartz Julie , Dignani M. Cecilia , Proffitt Richard T.
Published: October 2007

Small unilamellar amphotericin B liposomes can reduce the toxicity of amphotericin B. In this study, we compared the physical, antifungal, pharmocokinetic, and toxic properties of two liposomal amphotericin B products, AmBisome and Anfogen, that have the same chemical composition but are manufactured differently. In vitro tests included determinations of the MICs and the concentrations causing the release of 50% of the intracellular potassium from red blood cells (K50values) to assess toxicity. The 50% lethal dose (LD50) was evaluated by using uninfected C57BL/6 mice and single intravenous (i.v.) doses of 1 to 100 mg/kg of body weight. Multiple i.v. dosing over 18 days was performed with 0.5, 1.0, or 5.0 mg of Anfogen/kg or 1.0, 5.0, or 25 mg of AmBisome/kg to evaluate chronic toxicity. DBA/2 mice were infected intranasally with 2.5 × 106Aspergillus fumigatusconidia, treated for 3 or 4 days with 3.0, 5.0, or 7.5 mg of Anfogen/kg or 3, 5, 7.5, or 15 mg of AmBisome/kg, and evaluated to assess the toxicity of the drugs to the kidneys (by measurement of blood urea nitrogen and creatinine levels and histopathology) and the drug efficacy. The median particle size was 77.8 nm for AmBisome and 111.5 nm for Anfogen. In vitro K50values were significantly lower for Anfogen (0.9 μg/ml) than for AmBisome (20 μg/ml), and the LD50of AmBisome was >100 mg/kg, versus 10 mg of Anfogen/kg. There was significant renal tubular necrosis in uninfected and infected mice given Anfogen but no tubular necrosis in AmBisome-treated mice. AmBisome at 7.5 or 15 mg/kg was also more efficacious than 7.5 mg of Anfogen/kg for the treatment of pulmonary aspergillosis, based on survival and weight loss data and numbers of CFU per gram of lung. In conclusion, the efficacy and toxicity of these two liposomal amphotericin B products were significantly different, and thus, the products were not comparable.
Madurahydroxylactone Derivatives as Dual Inhibitors of Human Immunodeficiency Virus Type 1 Integrase and RNase H
Authors: Marchand Christophe , Beutler John A. , Wamiru Antony , Budihas Scott , Möllmann Ute , Heinisch Lothar , Mellors John W. , Le Grice Stuart F. , Pommier Yves
Published: October 2007

A series of 29 madurahydroxylactone derivatives was evaluated for dual inhibition of human immunodeficiency virus type 1 (HIV-1) integrase and RNase H. While most of the compounds exhibited similar potencies for both enzymes, two of the derivatives showed 10- to 100-fold-higher selectivity for each enzyme, suggesting that distinct pharmacophore models could be generated. This study exemplifies the common and divergent structural requirements for the inhibition of two structurally related HIV-1 enzymes and demonstrates the importance of systematically screening for both integrase and RNase H when developing novel inhibitors.
Toluidine Blue-Mediated Photodynamic Effects on Staphylococcal Biofilms
Authors: Sharma Mrinalini , Visai Livia , Bragheri Francesca , Cristiani Ilaria , Gupta Pradeep Kumar , Speziale Pietro
Published: October 2007

Staphylococci are important causes of nosocomial and medical-device-related infections. Their virulence is attributed to the elaboration of biofilms that protect the organisms from immune system clearance and to increased resistance to phagocytosis and antibiotics. Photodynamic treatment (PDT) has been proposed as an alternative approach for the inactivation of bacteria in biofilms. In this study, we have investigated the effect of the photodynamic action of toluidine blue O (TBO) on the viability and structure of biofilms of
Staphylococcus epidermidis
and of a methicillin-resistant
Staphylococcus aureus
strain. Significant inactivation of cells was observed when staphylococcal biofilms were exposed to TBO and laser simultaneously. The effect was found to be light dose dependent. Confocal laser scanning microscopic study suggested damage to bacterial cell membranes in photodynamically treated biofilms. In addition, scanning electron microscopy provided direct evidence for the disruption of biofilm structure and a decrease in cell numbers in photodynamically treated biofilms. Furthermore, the treatment of biofilms with tetrasodium EDTA followed by PDT enhanced the photodynamic efficacy of TBO in
S. epidermidis
, but not in
S. aureus
, biofilms. The results suggest that photodynamic treatment may be a useful approach for the inactivation of staphylococcal biofilms adhering to solid surfaces of medical implants.
Recombinant Holotoxoid Vaccine against Botulism
Authors: Pier Christina L. , Tepp William H. , Bradshaw Marite , Johnson Eric A. , Barbieri Joseph T. , Baldwin Michael R.
Published: October 2007

The botulinum neurotoxins (BoNT) are the most toxic proteins for humans and designated “Category A Select Agents.” The current vaccine against botulism is in limited supply, and there is a need to develop new vaccine strategies. A recombinant BoNT/A toxoid was produced inClostridium botulinumthat contained a double amino acid substitution, R363A Y365F (termed BoNT/ARYM). BoNT/ARYMwas noncatalytic for SNAP25 and nontoxic for mice. Immunization with BoNT/ARYMprotected mice from challenge at levels that were similar to chemically inactivated BoNT/A toxoid. BoNT/ARYMelicited an immune response against the light-chain and heavy-chain components of the toxin. Neutralizing anti-BoNT/ARYMsera blocked BoNT toxicity in primary cortical neurons and blocked ganglioside binding by the heavy chain. BoNT/ARYMrepresents a viable vaccine candidate for a holotoxoid against botulism.
Host Transmission of
Salmonella enterica
Serovar Typhimurium Is Controlled by Virulence Factors and Indigenous Intestinal Microbiota
Authors: Lawley Trevor D. , Bouley Donna M. , Hoy Yana E. , Gerke Christine , Relman David A. , Monack Denise M.
Published: October 2007

Transmission is an essential stage of a pathogen's life cycle and remains poorly understood. We describe here a model in which persistently infected 129X1/SvJ mice provide a natural model of
Salmonella enterica
serovar Typhimurium transmission. In this model only a subset of the infected mice, termed supershedders, shed high levels (>10
8
CFU/g) of
Salmonella
serovar Typhimurium in their feces and, as a result, rapidly transmit infection. While most
Salmonella
serovar Typhimurium-infected mice show signs of intestinal inflammation, only supershedder mice develop colitis. Development of the supershedder phenotype depends on the virulence determinants
Salmonella
pathogenicity islands 1 and 2, and it is characterized by mucosal invasion and, importantly, high luminal abundance of
Salmonella
serovar Typhimurium within the colon. Immunosuppression of infected mice does not induce the supershedder phenotype, demonstrating that the immune response is not the main determinant of
Salmonella
serovar Typhimurium levels within the colon. In contrast, treatment of mice with antibiotics that alter the health-associated indigenous intestinal microbiota rapidly induces the supershedder phenotype in infected mice and predisposes uninfected mice to the supershedder phenotype for several days. These results demonstrate that the intestinal microbiota plays a critical role in controlling
Salmonella
serovar Typhimurium infection, disease, and transmissibility. This novel model should facilitate the study of host, pathogen, and intestinal microbiota factors that contribute to infectious disease transmission.
Outer Membrane Protein Sequence Variation in Lambs Experimentally Infected with
Anaplasma phagocytophilum
Authors: Granquist Erik G. , Stuen Snorre , Lundgren Anna M. , Bråten Margrethe , Barbet Anthony F.
Published: October 2007

Anaplasma phagocytophilum
has long been known to cause tick-borne fever in ruminants and has been identified more recently as the causative agent of the emerging disease human granulocytic anaplasmosis. The related organism
Anaplasma marginale
uses gene conversion of the expression site for two major outer membrane proteins (OMPs) to generate extensive sequence and antigenic variation in these OMPs. This is thought to present a continuously varying repertoire of epitopes to the mammalian host and allow disease persistence. Recent genomic and structural data on human strains of
A
.
phagocytophilum
, together with animal studies in model systems, have implicated an orthologous OMP of
A
.
phagocytophilum
in a similar mechanism of variation. However, to date there has been little investigation of the mechanisms of antigenic variation or disease persistence in hosts naturally infected with field strains of
A
.
phagocytophilum
. Approximately 300,000 lambs in Norway suffer severe disease caused by
A
.
phagocytophilum
annually. We show here the persistent and cyclic nature of infection in these animals that is accompanied by loosely programmed sequence variation of the major OMP expression site in each rickettsemic peak. These data will allow analysis of interactions between
A
.
phagocytophilum
and the host immune system in naturally occurring persistent infections and provide an important comparison with enduring infections of cattle caused by
A
.
marginale
.
DNA sequence components of the Pinusstrobus nuclear genome
Authors: Kriebel Howard B.
Published: October 2007

The nuclear DNA of Pinusstrobus L. was characterized by whole-genome hydroxyapatite reassociation kinetics. The genome, which is very large, is not well described by partition into three, four, or five major kinetic components. Instead, it consists of a large array of sequence components with kinetics suggesting a more or less continuous range of frequencies from very large to a single copy. The single-copy fraction, which is estimated to be about 24% of the total, appears to fit the general hypothesis for large genomes, i.e., most of it probably consists of ancient diverged repeated sequences. Under standard conditions of DNA reassociation kinetics, these sequences are not completely diverged but react with kinetics indicating that there is an average of about three repeats for the fraction. It is estimated that only about 0.1% of white pine nuclear DNA is expressed as mRNAs.
Inoculation of container-grown Douglas-fir seedlings with basidiospores of Rhizopogonvinicolor and R. colossus: effects of fertility and spore application rate
Authors: Castellano Michael A. , Trappe James M. , Molina Randy
Published: October 2007

Basidiospores of Rhizopogonvinicolor Smith and R. colossus Smith were inoculated onto container-grown Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings and grown under two levels of soluble fertilizer and one level of slow-release fertilizer. Both fungi formed abundant ectomycorrhizae on more than 54% of feeder roots under the soluble fertilizer regimes. Slow-release fertilizer suppressed mycorrhizal formation by both fungi. Height growth was significantly increased under low fertility with all basidiospore application rates of R. colossus and the three lowest application rates of R. vinicolor. The high fertility regime produced plantable Douglas-fir seedlings with abundant ectomycorrhizae of R. colossus and R. vinicolor.
Use of pretreatment increment data in evaluating tree growth response to fertilization
Authors: Ballard T. M. , Majid N.
Published: October 2007

The use of pretreatment increment can lead to improved estimates of individual and average tree growth response to fertilization, by helping to adjust for site as well as stand structure differences between fertilized and control areas. It has applications in research using either single-tree or plot fertilization, and also in estimating responses to operational fertilization. Particularly useful equations are R = Af − (Bf)av(Au/Bu) and I = av(Af/Bf) − av(Au/Bu), where R is an estimate of the absolute magnitude of individual tree growth response to fertilization; A and B are increment after and before fertilization, and f and u denote fertilized and unfertilized trees, respectively; av signifies the average of several replicates; and I is an index of whether response has occurred. Equations were evaluated by examining branch length increment data from foliar spray application of iron and copper to Pinuscontorta Dougl. (lodgepole pine) and of nitrogen and iron to Pseudotsugamenziesii (Mirb.) Franco (Douglas-fir).
Forcing additivity of biomass tables: use of the generalized least squares method
Authors: Cunia T. , Briggs R. D.
Published: October 2007

The generalized least squares procedure is applied to sample tree data for which additive biomass tables are required. This procedure is proposed as an alternative to the ordinary weighted least squares in order to account for the fact that several biomass components are measured on the same sample trees. The biomass tables generated by the generalized and the ordinary least squares are very similar, the confidence intervals are sometimes wider, sometimes narrower, but the prediction intervals are always narrower for the generalized least squares method.
Response of red spruce and balsam fir seedlings to aluminum toxicity in nutrient solutions
Authors: Schier George A.
Published: October 2007

Red spruce (Picearubens Sarg.) and balsam fir (Abiesbalsamea (L.) Mill.) were grown in nutrient solutions containing 0, 25, 50, 100, and 200 mg/L aluminum (Al) at pH 3.8. Seedlings died only when placed directly in solutions containing Al without first being conditioned to growth in a hydroponic system. In preconditioned seedlings, no evidence of Al injury was noted in the tops of seedlings at any level of Al, except for small reductions in shoot growth. Aluminum toxicity symptoms in roots, however, were well developed, though spruce showed less tolerance than fir. Inhibition of root growth in both species was first evident at 50 mg/L Al, root lengths decreasing with increasing concentrations of Al. Spruce seedlings at Al concentrations of 100 mg/L and higher were characterized by thickened, stunted, dark brown roots. Root deterioration was caused by Al-induced destruction of epidermal and cortical cells. Although root elongation was severely restricted in spruce and fir, root dry weight was not significantly reduced. Aluminum decreased seedling uptake of most mineral elements; manganese, magnesium, and zinc were affected most and boron and phosphorus least.
Streamflow nitrogen loss following forest fertilization in a southern Vancouver Island watershed
Authors: Hetherington Eugene D.
Published: October 2007

Water quality was monitored in the Lens Creek watershed on southern Vancouver Island to determine nitrogen loss following fall application of 224 kg N/ha urea fertilizer on a second-growth Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forest. Peak nitrogen concentrations measured in two small tributary streams were 14 mg/L as urea, 1.9 mg/L as ammonia, and 9.3 mg/L as nitrate. For the first 14 months, estimated nitrogen outputs in excess of background amounts were 5.9 and 14.5% of the total applied nitrogen for the two subsidiary watersheds with 46 and 80% of their drainage areas fertilized, respectively. These losses were considerably higher than amounts of less than 1% previously reported for western North America. Increased levels of urea N and ammonia N were short-lived, while nitrate N remained above background levels for the study duration. Reasons for the high nitrogen loss include nitrification of the urea during 7 weeks of mild, dry weather following fertilization, presence of alder and swampy areas adjacent to the streams, high soil permeability, steep slopes, and abundant, above average early winter rainfall. The watersheds had been previously fertilized, but any influence of this first fertilization on nitrogen loss during the present study is unknown. Lens Creek water quality was not adversely affected by the fertilization in terms of drinking water standards or toxicity to fish.
Hybridization among several North American firs. II. Hybrid verification
Authors: Hawley Gary J. , DeHayes Donald H.
Published: October 2007

Seedlings resulting from 1980 controlled pollinations involving Vermont and Minnesota balsam fir (Abiesbalsamea (L.) Mill.), bracted balsam fir (A. balsamea var. phanerolepis Fern.), Fraser fir (A. fraseri (Pursh) Poir.), and white fir (A. concolor (Gord. and Glend.) Lindl.) were evaluated to verify hybridity and to describe the expression of parental characteristics in the hybrids. Putative hybrid and parental seedlings were grown indoors in replicated tests for 7 months and subsequently transplanted into an outdoor nursery. Hybrids from all combinations were verified using growth, morphological, and phenological characteristics. Hybrid seedlings were not characteristically intermediate between parents. Most hybrid combinations resembled their paternal parent in a majority of the characteristics that distinguished them from parental seedlings. The tendency for paternal or maternal resemblance in certain characteristics was responsible for considerable differences among reciprocal crosses. After 2 years in the nursery, Fraser × white fir and Fraser × balsam (Vermont) fir were fastest growing and exhibited a desirable combination of morphological and phenological characteristics.
Formation of ectomycorrhizae on Pinustaeda seedlings exposed to simulated acidic rain
Authors: Shafer S. R. , Grand L. F. , Bruck R. I. , Heagle A. S.
Published: October 2007

Effects of simulated acidic rain on formation of ectomycorrhizae were studied with Pinustaeda seedlings grown in plastic trays in a greenhouse. Trays of ectomycorrhizal seedlings were exposed 37 times over 16 weeks to simulated rains adjusted to pH 5.6, 4.0, 3.2, or 2.4. After exposures, mean percentages of short roots that were mycorrhizal (%M) were greatest (62.2%) for seedlings exposed to rains of pH 2.4. Values of %M exhibited a quadratic relationship with rain acidity (%M = 146.49 − 48.96 (rain pH) + 5.68 (rain pH)2). Values of R/S (root/shoot ratio) were negatively correlated (P < 0.01) with %M. Responses of ecetomycorrhiza formation and associated shoot growth to acidity of simulated rains suggest that rains of intermediate acidity (pH 4.0 and 3.2) inhibited ectomycorrhiza formation, or that increased soil acidity or other factors induced by rains at pH 2.4 enhanced ectomycorrhiza formation.
Composition, structure, and aboveground biomass of two old-growth northern hardwood stands in Upper Michigan
Authors: Mroz G. D. , Gale M. R. , Jurgensen M. F. , Frederick D. J. , Clark III A.
Published: October 2007

Two climax northern hardwood stands in Upper Michigan growing on sites of differing quality were characterized on the basis of stand composition and aboveground biomass as estimated by regression techniques. Both stands were dominated by sugar maple (Acersaccharum Marsh.). Total aboveground biomass was estimated at 284 and 325 t•ha−1 on the sites. These values are much lower than previous estimates for climax stands in this region because of the lack of shade tolerant conifers on the sites. Site differences are likely due to elevational differences and differences in soil rooting volume.
Determination of growing season soil water deficits on a forested slope using water balance analysis
Authors: Giles D. G. , Black T. A. , Spittlehouse D. L.
Published: October 2007

Coefficients for the calculation of soil water balance components at seven sites on a forested slope were determined using only measurements of daily solar irradiance, maximum and minimum air temperature and rainfall, and weekly root zone soil water content during a 2-year period. Site parameters required were root zone depth, soil water retention characteristics, and rainfall interception coefficients. Based on daytime net radiation, the Priestley–Taylor evapotranspiration coefficient (α) was found to be 0.73 ± 0.07, which is similar to values reported in other conifer forest studies. Growing season water deficit increased with decreasing root zone water storage capacity, which was mainly a function of root zone depth. A comparison between high and low elevations on the slope showed 100-year site indices ranging from 17 to 53 m corresponding to growing season soil water deficits during the driest year of the study, ranging from 79 to 4 mm. Basal area annual increments were found to be correlated with soil water deficits and growing season transpiration, both for the study period and when both variables were averaged over the last 18 years.
Mechanisms of element transfer to the atmosphere during vegetation fires
Authors: Raison R. J. , Khanna P. K. , Woods P. V.
Published: October 2007

Published data and newly presented evidence demonstrate that the proportion of N or P lost from plant material during combustion under a wide range of conditions increases linearly with percentage loss of fuel weight during combustion. For N the correlation is strong, and the slope (β) of the regression line approaches unity for combustions under field or simulated-field conditions, but reduces to 0.78 for materials combusted in a muffle furnace. Almost all of the losses of N are due to volatilization. The relationship for P is less well defined, and β is lower (0.56 for field studies; about 0.2 for simulated-field or laboratory combustions). Calcium is not volatilized at the temperatures generated in most vegetation fires, thus increases in the ratio of Ca to other elements during combustion (i.e., higher ratios in burnt residue) indicate nonparticulate transfer of elements to the atmosphere. Increased ratios for Ca to N, P, K, Mg, Mn, and B were demonstrated for several components of eucalypt litter fuels, especially where the degree of combustion was high. The positive relationship between increase in Ca:element ratio and percentage element loss in nonparticulate form during combustion, is of Mitscherlich form so that initial increases in the ratio represent proportionally most element loss. Partitioning of the transfer of elements from the litter and understory to the atmosphere measured during low-intensity fires in three eucalypt forest communities demonstrated a low particulate contribution (and thus a high nonparticulate transfer) for N, K, P, and B. Particulate contributions to elemental transfers are less where combustion is more complete, resulting in formation and transport of fine grey ash which has a high Ca:element ratio. Of particular ecological importance is the significant transfer of P by nonparticulate mechanisms, because such P is likely to be permanently lost from burnt sites and natural rates of P replacement are usually very slow. Fine grey or white ash is highly nutrient enriched (e.g., up to 50-fold for P compared with concentrations in unburnt fuel), and hence its transport from the site in the smoke column, or subsequently by either wind or water, can result in substantial export of nutrients.
The jackknife: an introduction with applications in forestry data analysis
Authors: Gregoire Timothy G.
Published: October 2007

not available
Disturbance patterns and forest development in a recently deglaciated valley in the northwestern Cascade Range of Washington, U.S.A.
Authors: Oliver Chadwick Dearing , Adams A. B. , Zasoski Robert J.
Published: October 2007

Advances and retreats of the cast Nooksack glacier and snow avalanches and rock falls have created a mosaic of midelevation forests in the Nooksack valley, ranging in age from 7 to over 800 years since a major disturbance. Trees, shrubs, and herbaceous species invaded disturbed areas simultaneously. Forest development followed a general pattern: (i) species invasion for about 60 years; (ii) tree and shrub exclusion by a dense forest canopy; (iii) understory rcgrowth as the canopy later opened; and (iv) an old-growth, uneven-aged condition in very old stands. Species composition in each stand was strongly related to the type of disturbance which initiated the stand.
White spruce expansion at the tree line and recent climatic change
Authors: Payette Serge , Filion Louise
Published: October 2007

White spruce (Piceaglauca (Moench) Voss) populations at their northern limit of distribution, the tree line along the east coast of Hudson Bay, expanded significantly during the last 100 years in response to recent climatic warming. Expansion began around 1880 but was more important during the 20th century, especially between 1920 and 1965. Although no major change in the position of the forest limit and the latitudinal tree line occurred, local altitudinal tree lines rose a few tens of meters. The seed regeneration line increased to about 100 meters above the present altitudinal tree line during the same period. Tree density increased below the local tree lines at many sites. There, spruce expansion was stepwise, as indicated by widely distributed clustered cohorts belonging to the 10–29, 50–59, and 70–89 age-class groups. Although the expansion process was stimulated by nearby old seed bearers, long-distance seed dispersal did occur. The development of contagious dispersion during the formation of white spruce groves or forests caused important local ecological changes, particularly in snow patterns and tree growth. Fire selectively influenced tree regeneration during the past centuries. Black spruce krummholz were progressively decimated during the last 400 years before present, although the species was characterized by low postfire regeneration. Vigorous postfire white spruce regeneration was stimulated by favorable climatic conditions 100 years ago in the northernmost forest site. Conclusions from this study support the hypothesis that Holocene tree line displacements were of low magnitude in northern Québec, and that the primary influence of climatic change was on tree density.
Phenology of an induced response in loblolly pine following inoculation of fungi associated with the southern pine beetle
Authors: Paine T. D. , Stephen F. M. , Cates R. G.
Published: October 2007

Loblolly pines (Pinustaeda L.) growing in two plantations were inoculated with fungi that are associated with the southern pine beetle, Dendroctonusfrontalis Zimm. Trees were sampled at 12-h intervals to determine the rate of formation of induced lesions. After an initial lag of 60 h, trees responded to infection by the blue-staining Ceratocystisminor (Hedgcock) Hunt with rapid lesion growth during the next 24 h. Trees inoculated with either of two mycangial fungi, C. minor var. barrasii Barras & Taylor or the basidiomycete, showed only limited lesion growth. Inoculations of combinations of fungi produced similar temporal patterns of lesion growth, but only combinations that included C. minor induced lesions that were significantly longer after 3 weeks than after 12 h. The data from this study suggest that the highly specialized mycangial fungi do not trigger the hypersensitive response in host trees when compared with sterile wounding, whereas the less adapted or less specialized nonmycangial C. minor does induce lesion formation. The delay in lesion formation also suggests that there is an initial period of increased vulnerability, when the tree may be killed before the induced response is manifested.
Micropropagation of eastern white pine (Pinusstrobus L.)
Authors: Webb David T. , Flinn Barry S. , Georgis Wanda
Published: October 2007

Cotyledons, epicotyls, and hypocotyls from embryos and "seedlings" of Pinusstrobus formed shoots following exposure to cytokinin on a Schenk and Hildebrandt medium. Benzyladenine and 2-isopentenyladenine were both effective at inducing shoot formation but benzyladenine was 5–10 times more potent. There was no synergistic interaction between these two cytokinins. Benzyladenine concentrations of 0.5–1.0 mg L−1 gave consistently good results with cotyledons. A 2-week cytokinin exposure produced uniformly good results and longer exposures caused callusing and vitrification. Pretreating seeds with hydrogen peroxide for 3 days stimulated caulogenesis. Addition of phenolics to medium containing benzyladenine also stimulated shoot formation and di-substituted phenolics were more effective than p-hydroxybenzoic acid. A short liquid pulse with high concentrations of benzyladenine induced caulogenesis but was not as effective as the application of cytokinin through agar-solidified culture medium. Cotyledons excised from embryos in cultured megagametophytes or from cultured embryos were more caulogenic than cotyledons from imbibed seeds. Best caulogenesis occurred after 1 week of direct embryo culture or culture of the embryo inside the megagametophyte. The caulogenic capacity of cotyledons from cultured embryos declined after 1 week but they retained competence to form shoots for 1 month. Epicotyls and hypocotyl sections from 1-week-old cultured embryos were also caulogenic but roots were not. Epicotyls responded best at benzyladenine levels less than 1 mg L−1, but hypocotyls required higher concentrations. Caulogenesis from hypocotyls was polar in that most shoots formed at the upper end of the apical hypocotyl half. The basal hypocotyl half was less caulogenic and produced callus. Roots only produced callus. Charcoal inhibited shoot induction when it was included with benzyladenine. Charcoal also inhibited rhizogenesis when included in the final rooting medium. Shoot elongation was promoted by charcoal when it was given during the second subculture on basal medium for 1 month. Shoot elongation occurred on full-strength basal medium. Reduced concentrations of minerals and organics failed to enhance shoot elongation. Approximately 80% of microshoots rooted invitro on quarter-strength basal medium without any hormone application. An auxin pulse treatment had little effect on rooting. Application of rooting powders containing indolebutyric acid increased the number of roots formed but had little effect on rooting frequency.
Effect of bud status and seedling biomass on root growth potential of loblolly pine
Authors: Williams Hans M. , South David B. , Glover Glenn R.
Published: October 2007

Container-grown seedlings of Pinustaeda L. with well-formed terminal buds, feather-tops (a succulent shoot tip crowned with a tuft of primary needles), and terminal buds removed (debudded) were sampled in November, December, and January. Root growth potential for unstored and stored seedlings was measured to determine if it is affected by shoot tip morphology. Seedlings with buds or debudded seedlings had higher root growth potential than feather-top seedlings. Root growth potential was correlated with several morphological variables, including total ovendry weight (r = 0.81). As feather-top seedlings were smaller in diameter and biomass, a covariate analysis (using seedling dry weight as a covariate) was conducted. The covariate analysis indicated that differences in root growth potential between shoot types could be accounted for by differences in seedling size. The percentage of seedlings resuming growth and the total amount of new shoot growth during the test of root growth potential showed that feather-top seedlings and seedlings with terminal buds respond similarly to chilling temperatures. These results indicate that seedling size is more important than the presence of a well-formed terminal bud when seedlings are graded before outplanting.
On the economic value of weather forecasts in wildfire suppression mobilization decisions
Authors: Brown Barbara G. , Murphy Allan H.
Published: October 2007

Decision analysis is used to model the rational use and estimate the economic value of weather forecasts in a specific decision-making situation relating to wildfire suppression mobilization. In this situation two fires in a national forest that differ only in timber type and location may require fire-suppression assistance from an adjacent national forest, depending on the weather conditions. The assistance available in the adjacent national forest consists of one 20-man hand crew and one bulldozer. Decisions regarding whether to request assistance and whether and where to deploy these suppression resources are assumed to be made on the basis of weather forecasts. Weather forecasts are found to be useful in this context because they enable the fire manager to select in an optimal manner the fire at which the suppression resources are likely to be most beneficial on each occasion. Specifically, state of the art forecasts have an expected economic value of almost $61 00 in this situation, and perfect information would have a value of approximately $16 600. Sensitivity analysis reveals that these results are quite sensitive to variations in fire outcome (i.e., numbers of acres burned). Improvements in forecast quality would lead to substantial increases in the economic value of weather forecasts in this two-fire situation.
An occurrence of boron deficiency in the deciduous forest of the Quebec Appalachians and the St. Lawrence Lowlands
Authors: Bernier B. , Brazeau M.
Published: October 2007

In mid-June 1985, visual symptoms of boron deficiency were observed on the seedlings of several tree species in the understory of the deciduous forest of the Quebec Appalachians and the St. Lawrence Lowlands. Symptoms observed on sugar maple (Acersaccharum Marsh.) and red maple (Acerrubrum L.) are described and illustrated. Although symptoms were most abundant in stands on sandy soils, they were present throughout a vast area. Symptoms were most developed on fast-growing regeneration, while on overstory trees they were seen in only one of the nine sites visited. This temporary boron deficiency is thought to be related to the low temperatures that prevailed during the 2nd week of June 1985, together with the heavy rainfall in the first 2 weeks of that month.
SOLITON LANGUAGES ARE NEARLY AN ANTI-AFL
Authors: BOLDT OLIVER , JÜRGENSEN HELMUT
Published: October 2007

Soliton automata are a mathematical model for certain proposed molecular switching devices. We investigate the closure properties of the class of languages accepted by soliton automata.
INTRICACIES OF SIMPLE WORD EQUATIONS: AN EXAMPLE
Authors: CZEIZLER ELENA , HOLUB ŠTĚPÁN , KARHUMÄKI JUHANI , LAINE MARKKU
Published: October 2007

As is well known, simple word equations can be very tedious to solve, often requiring specific ad hoc methods. We illustrate this by giving an example of an equation over four unknowns, having only periodic solutions, but for which showing this is not at all obvious.
CHARACTERIZING REGULAR LANGUAGES BY SPIKING NEURAL P SYSTEMS
Authors: IBARRA OSCAR H. , WOODWORTH SARA
Published: October 2007

We look at spiking neural P systems (SN P systems, for short) all of whose neurons are bounded. We show that a language L ⊆ (0 + 1)* is regular if and only if 1L (i. e., with a supplementary prefix of 1) is generated by a bounded SN P system. This result does not hold when the prefix is replaced by a suffix. For example, 0*1 cannot be generated by a bounded SN P system.
NOTES ON DUAL CONCATENATION
Authors: OKHOTIN ALEXANDER
Published: October 2007

It was recently found that concatenation of formal languages has a logical dual (A. Okhotin, The dual of concatenation, Theoret. Comput. Sci., 345 (2005), 425–447). In this paper, the closure or nonclosure of common language families under dual concatenation with finite, co-finite and regular languages is determined. In addition, language equations with union, linear concatenation and dual concatenation with co-finite constants are shown to be almost equal in power to linear conjunctive grammars.
Advances in Antifungal Therapy
Authors: Sable Carole A. , Strohmaier Kim M. , Chodakewitz Jeffrey A.
Published: October 2007

The prevalence of invasive fungal infections (IFIs) has increased over the past three decades owing to the increasing numbers of immunocompromised hosts. These infections are associated with significant morbidity and mortality. Recent significant advances in antifungal therapy include the broad-spectrum triazoles (voriconazole and posaconazole) and a new class of antifungals, the echinocandins (caspofungin, micafungin, and anidulafungin). New treatment strategies, such as combination therapy and pre-emptive therapy, are being investigated. There have also been significant improvements in diagnostics; the galactomannan enzyme immunoassay and the β-glucan test are now part of the EORTC/MSG criteria for diagnosis of IFI. Despite these advances, there remain a number of unanswered questions regarding optimal management of serious fungal infections, and research continues to discover and develop new therapies and evaluate new management strategies.
A Comparison of DNA Copy Number Profiling Platforms
Authors: Greshock Joel , Feng Bin , Nogueira Cristina , Ivanova Elena , Perna Ilana , Nathanson Katherine , Protopopov Alexei , Weber Barbara L. , Chin Lynda
Published: October 2007

The accurate mapping of recurring DNA copy number aberrations (CNAs), a hallmark feature of the cancer genome, has facilitated the discovery of tumor suppressor genes and oncogenes. Microarray-based assays designed to detect these chromosomal copy number alterations on a genome-wide and high-resolution scale have emerged as a cornerstone technology in the genomic era. The diversity of commercially available platforms prompted a systematic comparison of five copy number profiling assays for their ability to detect 2-fold copy number gain and loss (4n or 1n, respectively) as well as focal high-amplitude CNAs. Here, using a collection of established human melanoma cell lines, we defined the reproducibility, absolute signals, signal to noise, and false-positive and false-negative rates for each of the five assays against ground truth defined by spectral karyotyping, in addition to comparing the concordance of CNA detection by two high-resolution Agilent and Affymetrix microarray platforms. Our analyses concluded that the Agilent's 60-mer oligonucleotide microarray with probe design optimized for genomic hybridization offers the highest sensitivity and specificity (area under receiver operator characteristic curve >0.99), whereas Affymetrix's single nucleotide polymorphism microarray seems to offer better detection of CNAs in gene-poor regions. Availability of these comparison results should guide study design decisions and facilitate further computational development. [Cancer Res 2007;67(21):10173–80]
Hormonal Markers in Breast Cancer: Coexpression, Relationship with Pathologic Characteristics, and Risk Factor Associations in a Population-Based Study
Authors: Yang Xiaohong R. , Pfeiffer Ruth M. , Garcia-Closas Montserrat , Rimm David L. , Lissowska Jolanta , Brinton Louise A. , Peplonska Beata , Hewitt Stephen M. , Cartun Richard W. , Mandich Daniza , Sasano Hironobu , Evans Dean B. , Sutter Thomas R. , Sherman Mark E.
Published: October 2007

The objective of this study was to evaluate the coexpression patterns of hormonal markers in breast cancer tissue and their relationship with pathologic characteristics and epidemiologic risk factors. We evaluated the expression of 17 markers by immunohistochemistry in 842 invasive breast carcinomas collected in a population-based case-control study conducted in Poland. Based on marker correlations, factor analysis identified four major coexpression patterns (factors): “nuclear receptor factor” [estrogen receptor (ER)-α, progesterone receptor, androgen receptor, cyclin D1, and aromatase], “estrogen metabolism/ER-β factor” (ER-β, peroxisome proliferator-activated receptor-γ, steroid sulfatase, estrogen sulfonotransferase, and cytochrome P450 1B1), “HER2 factor” (human epidermal growth factor receptor 2, E-cadherin, cyclooxygenase-2, aromatase, steroid sulfatase), and “proliferation factor” (cytokeratin 5, cytokeratin 5/6, epidermal growth factor receptor, P53). Three of these factors corresponded to molecular subtypes previously defined by expression profiling; however, the estrogen metabolism/ER-β factor seemed to be distinctive. High scores for this factor were associated with high tumor grade (P heterogeneity = 0.02), younger age at menarche (P heterogeneity = 0.04), lower current body mass index among premenopausal women (P heterogeneity = 0.01), and older age at menopause (P heterogeneity = 0.04). High scores for the proliferation factor were also associated with early menarche (P heterogeneity < 0.0001), and in contrast to the estrogen metabolism/ER-β factor, higher current body mass index among premenopausal women (P heterogeneity = 0.03). Our analysis of hormonal pathway markers independently confirmed several previously defined molecular subtypes identified by gene expression profiling and augmented these findings by suggesting the existence of additional relationships related to ER-β and enzymes involved in hormone metabolism. [Cancer Res 2007;67(21):10608–17]
The Metabolic Syndrome and Cerebrovascular Disease: Suspicion and Evidence
Authors: Gil-Núñez Antonio
Published: October 2007

The metabolic syndrome (MS) is the combination of factors which, when occurring in an individual, can result in an increased risk of diabetes mellitus (DM) and of episodes of vascular disease. We present a systematic review of the diagnostic criteria, pathology, prevalence and risk of vascular disease (including stroke) associated with the MS and, if the patients have already suffered cerebral ischemia and have the MS and/or DM, the appropriate therapies from which they could benefit.
Systemic Reperfusion Therapy in Acute Ischemic Stroke
Authors: Martínez-Sánchez P. , Díez-Tejedor E. , Fuentes B. , Ortega-Casarrubios M.A. , Hacke W.
Published: October 2007

Introduction: Experimental and clinical studies indicate that early reperfusion of occluded brain-supplying arteries reduces the size of injury and improves outcome. Recombinant tissue plasminogen activator (t-PA) is the only drug approved for systemic reperfusion in acute ischemic stroke. However, the use of intravenous t-PA is currently limited by its narrow therapeutic window. Methods: We reviewed the approaches to extending systemic reperfusion in cerebral ischemia currently under investigation in human clinical studies. Results: Strategies to expand the systemic reperfusion include: a better use of conventional t-PA; to extend the intravenous rt-PA window to 270 min; new fibrinolytic agents (tenecteplase, microplasmin, desmoteplase, V10153); combination of lytics and antithrombotics (t-PA + tirofibran, t-PA + abciximab, reteplase + abciximab, t-PA + eptifibatide and t-PA + eptifibatide + aspirin + tinzaparin); combination of lytics and neuroprotectans; externally applied ultrasound to enhance enzymatic fibrinolysis, and improving patient selection with multimodal imaging. Conclusion: There is considerable opportunity to explore safe strategies to expand systemic reperfusion therapy which could further benefit stroke outcome.