bluuebunny/crossref_metadata_2025 huggingface dataset:
Population Pharmacokinetics of Arbekacin in Patients Infected with Methicillin-Resistant
Staphylococcus aureus
Authors: Tanigawara Yusuke , Sato Reiko , Morita Kunihiko , Kaku Mitsuo , Aikawa Naoki , Shimizu Kihachiro
Published: October 2006

Arbekacin, a derivative of dibekacin, is an aminoglycoside developed and widely used in Japan for the treatment of patients infected with methicillin-resistant
Staphylococcus aureus
(MRSA). The population pharmacokinetics of arbekacin was investigated in the Japanese, using 353 patients infected with MRSA and 50 healthy or renally impaired volunteers. The age of the study population ranged from 8 to 95 years, and weight ranged from 10.8 to 107 kg. In total, 1,581 serum arbekacin concentrations were measured (primarily from routine patient care) and used to perform the present pharmacokinetic analysis. Drug concentration-time data were well described by a two-compartment open model. Factors influencing arbekacin pharmacokinetics were investigated using a nonlinear mixed-effect model analysis. The best-developed model showed that drug clearance (CL) was related to creatinine clearance (CL
CR
), age, and body weight (WT), as expressed by CL (liter/h) = 0.0319CL
CR
+ (26.5/age) (CL
CR
< 80 ml/min) and CL (liter/h) = 0.0130 CL
CR
+ 0.0342WT + (26.5/age) (CL
CR
≥ 80 ml/min). The volume of distribution for the central and peripheral compartments was different in healthy subjects and infected patients, and this difference was more pronounced among disease types. The elderly subjects (aged 80 years or over) exhibited, on average, a 19% greater volume for the central compartment. The volumes for the peripheral compartment were 50.6 liters in patients with pneumonia and 24.3 liters in patients with sepsis. The population pharmacokinetic parameters of arbekacin obtained here are useful for optimal use of this aminoglycoside in the treatment of MRSA-infected patients.
Complete Nucleotide Sequence of pK245, a 98-Kilobase Plasmid Conferring Quinolone Resistance and Extended-Spectrum-β-Lactamase Activity in a Clinical
Klebsiella pneumoniae
Isolate
Authors: Chen Ying-Tsong , Shu Hung-Yu , Li Ling-Hui , Liao Tsai-Lien , Wu Keh-Ming , Shiau Yih-Ru , Yan Jing-Jou , Su Ih-Jen , Tsai Shih-Feng , Lauderdale Tsai-Ling
Published: October 2006

A plasmid containing the
qnrS
quinolone resistance determinant and the gene encoding the SHV-2 β-lactamase has been discovered from a clinical
Klebsiella pneumoniae
strain isolated in Taiwan. The complete 98-kb sequence of this plasmid, designated pK245, was determined by using a whole-genome shotgun approach. Transfer of pK245 conferred low-level resistance to fluoroquinolones in electroporant
Escherichia coli
epi300. The sequence of the immediate region surrounding
qnrS
in pK245 is nearly identical (>99% identity) to those of pAH0376 from
Shigella flexneri
and pINF5 from
Salmonella enterica
serovar Infantis, the two other
qnr
S-carrying plasmids reported to date, indicating a potential common origin. Other genes conferring resistance to aminoglycosides (
aacC2
,
strA
, and
strB
), chloramphenicol (
catA2
), sulfonamides (
sul
2), tetracycline (
tetD
), and trimethoprim (
dfrA14
) were also detected in pK245. The
dfrA14
gene is carried on a class I integron. Several features of this plasmid, including three separate regions containing putative replicons, a partitioning-control system, and a type II restriction modification system, suggest that it may be able to replicate and adapt in a variety of hosts. Although no critical conjugative genes were detected, multiple insertion sequence elements were found scattered throughout pK245, and these may facilitate the dissemination of the antimicrobial resistance determinants. We conclude that pK245 is a chimera which acquired its multiple antimicrobial resistance determinants horizontally from different sources. The identification of pK245 plasmid expands the repertoire of the coexistence of quinolone and extended-spectrum-β-lactam resistance determinants in plasmids carried by various species of the family
Enterobacteriaceae
in different countries.
Anidulafungin Pharmacokinetics and Microbial Response in Neutropenic Mice with Disseminated Candidiasis
Authors: Gumbo Tawanda , Drusano George L. , Liu Weiguo , Ma Lei , Deziel Mark R. , Drusano Michael F. , Louie Arnold
Published: October 2006

Candidemia is often fatal, especially in patients with persistent neutropenia. New therapies are needed. We performed 24-h pharmacodynamic studies to compare the efficacies of anidulafungin, fluconazole, and amphotericin B in neutropenic mice with disseminated candidiasis caused by one of three strains of
Candida glabrata
. Anidulafungin produced a maximal fungal kill (
E
max
) of 1.4 to 1.9 log
10
CFU/g in kidneys and was not influenced by resistance to either fluconazole or amphotericin B. Fluconazole produced an
E
max
of 1.3 log
10
CFU/g in mice infected with fluconazole-susceptible
C. glabrata
, but the
E
max
was 0 for mice infected with a
C. glabrata
strain that had a fluconazole MIC of ≥32 mg/liter. Amphotericin B achieved an
E
max
of 4.2 log
10
CFU/g in mice infected with amphotericin B-susceptible
C. glabrata
, but the
E
max
was 0 for mice infected with a
C. glabrata
strain with an amphotericin B MIC of 2 mg/liter. In all instances, anidulafungin's maximal microbial kill was superior to that of fluconazole. Next, we performed a 96-h anidulafungin pharmacokinetic-pharmacodynamic study. Anidulafungin exhibited delayed peak concentrations in kidneys compared to those in serum, after which the concentrations declined, with a serum terminal half-life of 21.6 (±4.6) h. This was accompanied by a persistent 96-h decrease in the kidney fungal burden after treatment with a single anidulafungin dose of ≥8 mg/kg of body weight. This pharmacokinetic-pharmacodynamic picture of anidulafungin persistence in tissues and the resultant persistent fungal decline should be exploited to improve the efficacy of anidulafungin therapy for candidemia.
The Anti-Methicillin-Resistant
Staphylococcus aureus
Quinolone WCK 771 Has Potent Activity against Sequentially Selected Mutants, Has a Narrow Mutant Selection Window against Quinolone-Resistant
Staphylococcus aureus
, and Preferentially Targets DNA Gyrase
Authors: Bhagwat Sachin S. , Mundkur Lakshmi A. , Gupte Shrikant V. , Patel Mahesh V. , Khorakiwala Habil F.
Published: October 2006

WCK 771 is a broad-spectrum fluoroquinolone with enhanced activity against quinolone-resistant staphylococci. To understand the impact of the target-level interactions of WCK 771 on its antistaphylococcal pharmacodynamic properties, we determined the MICs for genetically defined mutants and studied the mutant prevention concentrations (MPCs), the frequency of mutation, and the cidality against the wild type and double mutants. There was a twofold increase in the MICs of WCK 771 for single
gyrA
mutants, indicating that DNA gyrase is its primary target. All first- and second-step mutants selected by WCK 771 revealed
gyrA
and
grlA
mutations, respectively. The MICs of WCK 771 and clinafloxacin were found to be superior to those of other quinolones against strains with double and triple mutations. WCK 771 was also cidal for high-density double mutants at low concentrations. WCK 771 and clinafloxacin showed narrow mutant selection windows compared to those of the other quinolones. Against a panel of 50 high-level quinolone-resistant clinical isolates of staphylococci (ciprofloxacin MIC ≥ 16 μg/ml), the WCK 771 MPCs were ≤2 μg/ml for 68% of the strains and ≤4 μg/ml for 28% of the strains. Our results demonstrate that
gyrA
is the primary target of WCK 771 and that it has pharmacodynamic properties remarkably different from those of quinolones with dual targets (garenoxacin and moxifloxacin) and topoisomerase IV-specific quinolones (trovafloxacin). WCK 771 displayed an activity profile comparable to that of clinafloxacin, a dual-acting quinolone with a high affinity to DNA gyrase. Overall, the findings signify the key role of DNA gyrase in determining the optimal antistaphylococcal features of quinolones.
Molecular Basis for Enhanced Activity of Posaconazole against
Absidia corymbifera
and
Rhizopus oryzae
Authors: Chau Andrew S. , Chen Guodong , McNicholas Paul M. , Mann Paul A.
Published: October 2006

Posaconazole and itraconazole were more potent inhibitors of ergosterol synthesis, in both intact cells and cell extracts from
Absidia corymbifera
and
Rhizopus oryzae
, than voriconazole and fluconazole. Similarly, expression of CYP51 from
R. oryzae
in
Saccharomyces cerevisiae
significantly increased resistance to fluconazole and voriconazole but not to posaconazole and itraconazole.
Combinations of R207910 with Drugs Used To Treat Multidrug-Resistant Tuberculosis Have the Potential To Shorten Treatment Duration
Authors: Lounis Nacer , Veziris Nicolas , Chauffour Aurélie , Truffot-Pernot Chantal , Andries Koen , Jarlier Vincent
Published: October 2006

The objective of the present study was to identify the optimal R207910-containing regimen to administer to patients who cannot receive rifampin (RIF) and isoniazid (INH) because of multidrug-resistant tuberculosis (MDR-TB), concomitant use of antiretroviral drugs, or toxicity. Mice were infected intravenously with 5 × 10
6
CFU of the H37Rv strain and treated five times per week with R207910 alone or various combinations of R207910 with the second-line drugs amikacin (AMK), pyrazinamide (PZA), moxifloxacin (MXF), and ethionamide (ETH). All R207910-containing regimens were significantly more active than the non-R207910-containing regimens after 1 month of therapy. When given for 2 months, R207910 alone was more active than the WHO standard first-line regimen RIF-INH-PZA. When R207910 was combined with second-line drugs, the combinations were more active than the currently recommended regimen of MDR-TB AMK-ETH-MXF-PZA, and culture negativity of both the lungs and spleen was reached after 2 months of treatment in almost every case.
Interaction between Miltefosine and Amphotericin B: Consequences for Their Activities towards Intestinal Epithelial Cells and
Leishmania donovani
Promastigotes In Vitro
Authors: Ménez Cécile , Buyse Marion , Besnard Madeleine , Farinotti Robert , Loiseau Philippe M. , Barratt Gillian
Published: October 2006

The aim of this study was to evaluate the potential of a combination of two antileishmanial drugs, miltefosine (HePC) and amphotericin B (AMB), when administered by the oral route. Caco-2 cell monolayers were used as a validated in vitro model of the intestinal barrier and
Leishmania donovani
promastigotes as a model for evaluating the effect of the drug combination. Spectroscopic measurements demonstrated that HePC and AMB associate, leading to the formation of mixed aggregates in which AMB is solubilized as monomers. The incubation of the association of HePC and AMB with Caco-2 cell monolayers, at a concentration higher than 5 μM, led to (i) a reduction of the HePC-induced paracellular permeability enhancement in Caco-2 cell monolayers, (ii) an inhibition of the uptake of both drugs, and (iii) a decrease in the transepithelial transport of both drugs, suggesting that a pharmacokinetic antagonism between HePC and AMB could occur after their oral administration. However, the combination did not exhibit any antagonism or synergy in its antileishmanial activity. These results demonstrated a strong physicochemical interaction between HePC and AMB, depending on the concentration of each, which could have important consequences for their biological activities, if they are administered together.
Efficacy of Novel Rifamycin Derivatives against Rifamycin-Sensitive and -Resistant
Staphylococcus aureus
Isolates in Murine Models of Infection
Authors: Rothstein David M. , Farquhar Ronald S. , Sirokman Klari , Sondergaard Karen L. , Hazlett Charles , Doye Angelia A. , Gwathmey Judith K. , Mullin Steve , van Duzer John , Murphy Christopher K.
Published: October 2006

Novel rifamycins (new chemical entities [NCEs]) having MICs of 0.002 to 0.03 μg/ml against
Staphylococcus aureus
and retaining some activity against rifampin-resistant mutants were tested for in vivo efficacy against susceptible and rifampin-resistant strains of
S. aureus
. Rifalazil and rifampin had a 50% effective dose (ED
50
) of 0.06 mg/kg of body weight when administered as a single intravenous (i.v.) dose in a murine septicemia model against a susceptible strain of
S. aureus.
The majority of NCEs showed efficacy at a lower i.v. dose (0.003 to 0.06 mg/kg). In addition, half of the NCEs tested for oral efficacy had ED
50
s in the range of 0.015 to 0.13 mg/kg, i.e., lower or equivalent to the oral ED
50
s of rifampin and rifalazil. NCEs were also tested in the septicemia model against a rifampin-resistant strain of
S. aureus
. Twenty-four of 169 NCEs were efficacious when administered as a single oral dose of 80 mg/kg. These NCEs were examined in the murine thigh infection model against a susceptible strain of
S. aureus
. Several NCEs dosed by intraperitoneal injection at 0.06 mg/kg caused a significant difference in bacterial titer compared with placebo-treated animals. No NCEs showed efficacy in the thigh model against a highly rifampin-resistant strain. However, several NCEs showed an effect when tested against a partially rifampin-resistant strain. The NCEs having a 25-hydroxyl moiety were more effective as a group than their 25-
O
-acetyl counterparts. These model systems defined candidate NCEs as components of potential combination therapies to treat systemic infections or as monotherapeutic agents for topical applications.
The effect of breathing an ambient low-density, hyperoxic gas on the perceived effort of breathing and maximal performance of exercise in well-trained athletes
Authors: Ansley L , Petersen D , Thomas A , St Clair Gibson A , Robson-Ansley P , Noakes T D
Published: October 2006

Background:The role of the perception of breathing effort in the regulation of performance of maximal exercise remains unclear.

Aims:To determine whether the perceived effort of ventilation is altered through substituting a less dense gas for normal ambient air and whether this substitution affects performance of maximal incremental exercise in trained athletes.

Methods:Eight highly trained cyclists (mean SD) maximal oxygen consumption (VO2max) = 69.9 (7.9) (mlO2/kg/min) performed two randomised maximal tests in a hyperbaric chamber breathing ambient air composed of either 35% O2/65% N2(nitrox) or 35% O2/65% He (heliox). A ramp protocol was used in which power output was incremented at 0.5 W/s. The trials were separated by at least 48 h. The perceived effort of breathing was obtained via Borg Category Ratio Scales at 3-min intervals and at fatigue. Oxygen consumption (VO2) and minute ventilation (VE) were monitored continuously.

Results:Breathing heliox did not change the sensation of dyspnoea: there were no differences between trials for the Borg scales at any time point. Exercise performance was not different between the nitrox and heliox trials (peak power output = 451 (58) and 453 (56) W), nor was VO2max (4.96 (0.61) and 4.88 (0.65) l/min) or maximal VE(157 (24) and 163 (22) l/min). Between-trial variability in peak power output was less than either VO2max or maximal VE.

Conclusion:Breathing a less dense gas does not improve maximal performance of exercise or reduce the perception of breathing effort in highly trained athletes, although an attenuated submaximal tidal volume and VEwith a concomitant reduction in VO2suggests an improved gas exchange and reduced O2cost of ventilation when breathing heliox.
Comparison of once-weekly and twice-weekly strength training in older adults
Authors: DiFrancisco-Donoghue J , Werner W , Douris P C
Published: October 2006

Background:Strength training has been shown to benefit the health and function of older adults.

Objective:To investigate whether one set of exercises performed once a week was as effective in increasing muscle strength as training twice a week.

Methods:18 subjects (7 women and 11 men) aged 65–79 years were randomly assigned to two groups. Both groups performed one set of exercises to muscular fatigue; group 1 trained 1 day/week and group 2 trained 2 days/week on three lower and three upper body exercises for 9 weeks. The data were analysed using a mixed model 2×2 analysis of variance.

Results:A significant main effect of time (p<0.001), but not group, on one-repetition maximum scores was observed. No significant interaction was observed between time and group and therefore no difference in strength changes between training once a week versus twice a week after 9 weeks.

Conclusions:One set of exercises performed once weekly to muscle fatigue improved strength as well as twice a week in the older adult. Our results provide information that will assist in designing strength-training programmes that are more time and cost efficient in producing health and fitness benefits for older adults.
Chronic tendinopathy: effectiveness of eccentric exercise
Authors: Woodley Brett L , Newsham-West Richard J , Baxter G David
Published: October 2006

Objectives:To determine the effectiveness of eccentric exercise (EE) programmes in the treatment of common tendinopathies.

Data sources:Relevant randomised controlled trials (RCTs) were sourced using the OVID website databases: MEDLINE (1966–Jan 2006), CINAHL (1982–Jan 2006), AMED (1985–Jan 2006), EMBASE (1988–Jan 2006), and all EBM reviews – Cochrane DSR, ACP Journal Club, DARE, and CCTR (Jan 2006). The Physiotherapy Evidence Database (PEDro) was also searched using the keyword: eccentric.

Review methods:The PEDro and van Tulder scales were employed to assess methodological quality. Levels of evidence were then obtained according to predefined thresholds:Strong–consistent findings among multiple high-quality RCTs.Moderate–consistent findings among multiple low-quality RCTs and/or clinically controlled trials (CCTs) and/or one high-quality RCT.Limited–one low-quality RCT and/or CCT.Conflicting–inconsistent findings among multiple trials (RCTs and/or CCTs).No evidence–no RCTs or CCTs.

Results:Twenty relevant studies were sourced, 11 of which met the inclusion criteria. These included studies of Achilles tendinopathy (AT), patella tendinopathy (PT) and tendinopathy of the common wrist extensor tendon of the lateral elbow (LET). Limited levels of evidence exist to suggest that EE has a positive effect on clinical outcomes such as pain, function and patient satisfaction/return to work when compared to various control interventions such as concentric exercise (CE), stretching, splinting, frictions and ultrasound. Levels of evidence were found to be variable across the tendinopathies investigated.

Conclusions:This review demonstrates the dearth of high-quality research in support of the clinical effectiveness of EE over other treatments in the management of tendinopathies. Further adequately powered studies that include appropriate randomisation procedures, standardised outcome measures and long-term follow-up are required.
Uniformitarianism as a guide to rocky-shore ecosystems in the geological record
Authors: Johnson Markes E
Published: October 2006

Literature on Pleistocene and Neogene rocky shores is reviewed from a uniformitarian perspective to assess the fidelity of physical and biological information entrained in the geological record through present-day processes. Coverage by latitude spans tropical to subarctic shores. Variations in paleotopography are illustrated by unconformities between sedimentary accumulations and rocks of igneous or non-igneous origin. Former rocky shores occur across a range of geographic scales that include (i) spot localities, (ii) embayments with continuous transition from exposed outer to protected inner shores, and (iii) entire islands with windward and leeward shores. Differences in rate and magnitude of sea-level change affect rocky-shore physiography. Terrace deposits characterize the Pleistocene, but ramp deposits typify older Neogene shores. On average, species with hard parts account for about 50% of the modern rocky intertidal fauna on a regional basis, regardless of latitude. Biodiversity is highest in mid-latitudes. Fixed organisms with encrusting, wedging, or boring habits (corals, barnacles, oysters, other bivalves, and vermetid gastropods) show high potential for fossilization in growth position. Mobile organisms that cling to rocks (gastropods, crabs, and echinoids) suffer post-mortem transport but may be immured within neptunian dikes or interstices among cobbles and boulders. At best, localized fossil deposits from the Pleistocene reflect <30% of the biodiversity of skeletonized organisms tabulated from modern rocky shores on a regional basis. Uniformitarianism provides little insight into the diversity of soft-bodied organisms (excluding stromatolites) that joined the ecosystem in Precambrian times and the extent to which soft-bodied organisms dominated shore life through later times.
Variable unroofing in the western Superior Province - metamorphic evidence and possible origin
Authors: Hynes Andrew , Song Zixin
Published: October 2006

Western Superior Lithoprobe seismic-reflection line 1 exhibits a broad region of northward-dipping reflectors in the Uchi subprovince, which gives way to southward-dipping reflectors farther north in the Berens River sub province. Mafic metavolcanic rocks across the region of northward-dipping reflectors exhibit a decline in metamorphic pressure, from pressures of 6 kbar (1 kbar = 100 MPa) in the south to only 2 kbar 80 km to the north. This indicates that the southern edge of the Uchi subprovince has undergone significantly more unroofing than regions farther north. The differential unroofing is not consistent with a doubly vergent thrusting origin for the northward- and southward-dipping reflector pattern. It could result from a crustal-scale synform, of which the region of northward-dipping reflectors would make up the southern limb. Metamorphic pressures from samples off the seismic line, however, provide only limited support for a regional synform, and suggest that much of the pressure variation may result from deformation associated with motion on late faults that are widespread in the western Superior Province. These faults occur in a WNW-striking set with dextral offsets and an ENE-striking set with sinistral offsets. They could result from northsouth compression and eastwest extension, provided the faults have rotated towards the eastwest direction during deformation. Regional tilting and (or) jostling of crustal blocks is attributed to deformation associated with the fault rotation. Motion on the faults and the associated deformation of intervening fault blocks may be important contributors to the present crustal architecture of the western Superior Province, including the surface distribution and form of the greenstone belts.
Gradual encroachment of a rocky shoreline by an invasive sea during the Mississippian at the southeastern margin of the Maritimes Basin, Nova Scotia, Canada
Authors: Jutras Pierre , Ryan Robert J , Fitzgerald Roger
Published: October 2006

Onlap of a rocky shoreline by marine beds of the Mississippian Windsor Group occurred at the southeastern margin of the composite upper Paleozoic Maritimes Basin in central Nova Scotia. The sedimentology of thin basal rudaceous deposits suggests that, although the transgression was rapid, there were times of prolonged shoreline stability. Boulder beach deposits indicate a high-energy coastline and a large marine basin. Clastic delta deposits were proximal to thick biohermal banks in shallow areas near the southeast margin of the sea while sulphate deposition was occurring basinward. According to their contained biota and stratigraphic relationships, the marginal banks evolved in a less saline environment than banks forming away from river inputs, on paleotopographic highs located farther offshore. Because diversity of the biota decreases with an increase in both water depth and distance from the paleoshore and because bank development in shallow or marginal areas was apparently synchronous with evaporitic deposition in deeper or less marginal areas, we conclude that both a vertical and a lateral gradient of salinity existed due to the thrusting of fluvial fresh water above salt water and its infiltration along the paleoshoreline. As salinity increased with time, bank building eventually aborted and sulphate deposition gave way to salt deposition in the deepest parts of the basin. Lastly, the onlap of evaporites above marginal clastic deposits indicates that evaporite deposition occurred in a transgressive context, although a gradual thinning of the water column may have simultaneously occurred due to basin infilling.
Robust digestion and passage rate estimates for hard parts of grey seal (Halichoerus grypus) prey
Authors: Grellier Kate , Hammond Philip S
Published: October 2006

Application of digestion correction factors to measurements and counts of fish otoliths and cephalopod beaks recovered from seal scats is required before the size or quantity of prey consumed can be accurately estimated. We carried out 86 feeding trials with seven grey seals (Halichoerus grypus) and 18 prey species to derive estimates of digestion coefficients (to account for partial digestion), recovery rates (to account for complete digestion), and passage rates (to estimate the time between consumption and excretion of an item). Mean digestion coefficients were greatest for sandeel (Ammodytes marinus) and then less for large gadoid, flatfish, and Trisopterus spp. otoliths; and finally squid (Loligo forbesii) beaks. Recovery rates were greatest for squid beaks and then less for large gadoid, Trisopterus spp., flatfish, and sandeel otoliths. Greater than 95% of otoliths and beaks recovered were passed within 4 days (~88 h) of consumption. The large differences in partial and complete digestion rates found among prey species reinforce the importance of obtaining robust estimates of these quantities. Results from this study are the most comprehensive and systematically obtained for any species of pinniped and will allow accurate and precise estimation of the number and size of fish represented by otoliths recovered from grey seal scat samples collected in the wild.
Characterization of elasticity patterns of North American freshwater fishes
Authors: Vélez-Espino Luis A , Fox Michael G , McLaughlin Robert L
Published: October 2006

We applied elasticity analysis to 88 North American freshwater fishes to assess the relative impacts of changes in the vital rates on asymptotic population growth. Variance in vital rates was summarized for four distinct functional groups: (i) species with population growth rates strongly sensitive to perturbations in adult survival; (ii) species with population growth rates sensitive to perturbations in overall survival; (iii) species with population growth rates most sensitive to perturbations in juvenile survival; and (iv) species with population growth rates sensitive to perturbations in juvenile survival and fecundity. The results of the present study also showed that (a) elasticity patterns cannot be inferred in a straightforward manner from trade-offs between life-history traits, (b) the sensitivity of a population's growth rate to changes in adult survival and fecundity can be predicted empirically from life span and age at maturity, respectively, (c) elasticities are highly conserved among genera within the same taxonomic family, and (d) there are key divergences between elasticity patterns of freshwater fish and other vertebrate taxa.
Density-dependent overwinter survival in young-of-year bluefish (Pomatomus saltatrix)? A new approach for assessing stage-structured survival
Authors: Wiedenmann John , Essington Timothy E
Published: October 2006

Identifying the life history stages where density-dependent mortality occurs is essential for understanding fish population dynamics. Here we present an approach to evaluate density-dependent survivorship using catch-at-length data on bluefish (Pomatomus saltatrix) from fishery-independent data in the northwest Atlantic, focusing on the stage transition from age-0 to age-1. Abundance indices for each stage were generated by partitioning annual length frequency distributions into catch estimates for individual stages and by using a generalized additive model to standardize survey effort across years. We tested for the existence of density dependence by fitting the data to alternative stage-transition models and using model selection procedures to identify the best-fitting model. We found that that the transition from fall age-0 to age-1 is density dependent and that that significant dampening occurred throughout much of the time series we examined. Estimates of process error were small, suggesting relatively modest variance around the stage-transition model and little interannual variation in survivorship other than that generated by density-dependent effects. Further, we found our conclusions are robust to any potential bias imposed by observation error. We conclude that an improved understanding of bluefish population dynamics might follow from a fuller exploration of the processes dictating overwinter survivorship.
Estimation of annual mortality rates caused by early mortality syndromes (EMS) and their impact on salmonid stockrecruit relationships
Authors: Michielsens Catherine G.J , Mäntyniemi Samu , Vuorinen Pekka J
Published: October 2006

In this paper, we demonstrate how information from broodstocks can be combined with lab information on alevins to obtain annual stock-specific mortality estimates from early mortality syndromes (EMS) using a probabilistic approach, how a hierarchical model structure can be used to predict these mortality rates for related, partly sampled, or unsampled stocks, and why these estimates should be used to remove the effect of this mortality on stockrecruit estimates. The approach has been illustrated for Atlantic salmon (Salmo salar) stocks in the Baltic Sea affected by the M74 syndrome. Results indicate that data on the proportion of M74-affected females, commonly used to approximate M74 mortality, overestimate actual M74-related mortality because of a declining trend in mortality among offspring of these females. The stock-specific M74 mortality estimates are used to account for nonstationarity in the stockrecruitment relationship caused by this fluctuating mortality. Because hierarchical meta-analyses assume exchangeability, the effect of M74 mortality is removed before including these stocks within hierarchical stockrecruit analyses of Atlantic salmon stocks, which are commonly unaffected by M74 mortality. Failure to remove the effect of M74 mortality on the stockrecruit data results in underestimation of the stock's productivity and resilience to exploitation, especially in the case of stocks with steep stockrecruit curves.
Reporting and shedding rate estimates from tag-recovery experiments on Atlantic cod (Gadus morhua) in coastal Newfoundland
Authors: Cadigan Noel G , Brattey John
Published: October 2006

It is important to have good estimates of tag reporting rates when inferring exploitation rates and other mortality rates from tagging experiments. We estimate the reporting rates of single- and double-tagged Atlantic cod (Gadus morhua) caught in commercial fisheries around coastal Newfoundland, Canada, based on an extensive series of multi-reward tagging experiments conducted during 1997–2004. Reporting rates for single-tagged cod varied from 58% to almost 100%, with significant temporal and spatial variability. The odds of reporting a double-tagged cod was almost double that of a single-tagged cod. Returns from double-tagged cod allow us to estimate tag shedding rates. Tag shedding rates suggested that 22% of fish lost their tag during their first year at liberty; subsequently, tag shedding rates were much lower (<10%). We also found that twice as many fish lost tags when the tags were attached anteriorly at the base of the first dorsal fin compared with a position more towards the posterior end.
Longitudinal gradients in threshold sizes for alternative male life history tactics in a population of Atlantic salmon (Salmo salar)
Authors: Aubin-Horth Nadia , Bourque Jean-Francois , Daigle Gaetan , Hedger Richard , Dodson Julian J
Published: October 2006

Atlantic salmon (Salmo salar) males may mature early in life in freshwater, rather than maturing after a migration to sea, if their size is above a threshold value. We analyzed the spatiotemporal variation in size and incidence of the early maturity tactic among males over an 8-year period in six subpopulations on two branches of a river and collected environmental data on each site and across the river scape. A positive longitudinal trend in the frequency of early maturing males that was stable over the 8-year period occurred from the mouth to the head of the river. Threshold sizes for early maturation varied among subpopulations; size thresholds for male parr to mature were higher in downstream habitats and lowest upstream. This pattern was consistent in both river branches over the 8-year period and was not related to either the density of parr or site-specific abiotic habitat characteristics. However, the cumulative incidence of habitat features that could impede migration of large individuals increased with increasing upstream distance. Migration costs may contribute to the observed variation in threshold sizes.
A spatial model to estimate gear efficiency and animal density from depletion experiments
Authors: Rago Paul J , Weinberg James R , Weidman Christopher
Published: October 2006

Depletion experiments are conducted to estimate efficiency of sampling gear and density of organisms. Traditional models for analyzing these experiments make restrictive assumptions that are often violated. We present a new spatial model, suitable for sessile benthic invertebrates, that does not depend on these restrictive assumptions. The new model (i) allows flexibility during the experiment in choosing the spatial location of successive samples, (ii) does not require organisms or successive samples to be randomized over the entire area of the experiment, and (iii) permits target organisms to be lost or added during the experiment. The model treats total catch per sample as a sum of catches from smaller cells with different, but known, sampling histories. A negative binomial model is used to describe the distribution of catches from tows made during the depletion experiment. Maximum likelihood methods are used to estimate parameters, derive confidence regions for parameters, and evaluate goodness of fit between data and the model. Data from an experiment involving Atlantic surfclams (Spisula solidissima) are used to demonstrate the model.
Crown shyness in lodgepole pine stands of varying stand height, density, and site index in the upper foothills of Alberta
Authors: Fish Heather , Lieffers Victor J , Silins Uldis , Hall Ronald J
Published: October 2006

Crown shyness is the empty space between crowns in fully stocked stands that is not related to tree-fall gaps. The objectives of this study were to determine the stand and site factors that control crown shyness in lodgepole pine (Pinus contorta Dougl. ex Loud.) stands and to evaluate whether stands experiencing crown shyness compensate for leaf area losses by maintaining longer crowns. We measured canopy closure (i.e., the inverse of crown shyness), crown radius and length, and green litterfall in stands of various height, relative density, and site index. Canopy closure decreased with stand height and increased with site index and relative density. Green litterfall increased with height and relative density. Crown radius and crown length reached a plateau by 8-10 m height, despite increased spacing between tree boles with increasing stand height. Crown radius increased with height and site index but declined with relative density and slenderness coefficient. Crown length also increased with height and site index but declined with slenderness coefficient. Despite the fact that, in tall stands, where >50% of the sky was not covered by crowns, there was not an accompanying increase in crown length to take advantage of the apparent increase in light transmission to the lower crown.
Use of amphibians to define riparian zones of headwater streams
Authors: Perkins D W , Hunter, Jr. M L
Published: October 2006

Riparian areas are known for their high species richness and their influence on ecological processes. However, riparian zones are difficult to define because of their ambiguous borders. Defining riparian zones by examining habitat use of species that require both terrestrial and aquatic environments is one method that has not been thoroughly examined. We sampled amphibians in Maine, USA, with pitfall traps located at five distances (1, 8, 18, 28, and 33 m) from 15 headwater streams. We captured 1897 amphibians of 10 species over 73 536 trap-nights. We used a repeated-measures analysis of variance to determine if species' capture rates varied among pitfall-trap locations. The highest numbers of three species, spring salamander (Gyrinophilus porphyriticus), two-lined salamander (Eurycea bislineata), and dusky salamander (Desmognathus fuscus), were captured in trap locations closest to the streams. Total species richness and average species richness were highest in the trap location located closest to the stream. We conclude that the riparian zone along headwater streams, as defined by amphibian species richness and abundance, is relatively narrow (79 m).
Relationships among forest soil C isotopic composition, partitioning, and turnover times
Authors: Garten Jr. Charles T
Published: October 2006

The purpose of this research was to test the hypothesis that vertical enrichment of soil δ13C values is related to rates of soil C turnover in undisturbed, mature forest ecosystems. Soil C and N were measured at nine sites along an altitudinal gradient in the southern Appalachian Mountains (Tennessee and North Carolina, USA). Measurements indicated greater labile and total soil C stocks with increasing altitude. Laboratory incubations (3 days) of rewetted, air-dry soils indicated potential soil C mineralization (µg CO2 produced·g1 soil C) declined with elevation. A principal component analysis indicated N availability increased with altitude. At each site, there was a significant relationship between δ13C and log-transformed C concentrations in the soil profile (30 cm deep). Enrichment factors (ε) from the Rayleigh equation were also equally useful for describing soil δ13C profiles at each site. Soil C partitioning and turnover times along the gradient were correlated with 13C-enrichment factors. Greater rates of change in δ13C through the soil profile were correlated with faster soil C turnover. Environmental factors, soil C partitioning, and the rate of vertical change in soil 13C abundance are interrelated such that δ13C measurements are a potential indicator of C dynamics in undisturbed forest soils.
Influence of nutrition and stress on sugar maple at a regional scale
Authors: Hallett Richard A , Bailey Scott W , Horsley Stephen B , Long Robert P
Published: October 2006

Sugar maple (Acer saccharum Marsh.) decline disease on the Allegheny Plateau (region 1) resulted in high levels of mortality during the 1990s. Sugar maple was predisposed to decline because of an imbalance in Mg, Ca, and Mn nutrition and incited to decline by repeated defoliation. We sampled 33 stands in New York, Vermont, and New Hampshire (region 2) to determine if this model of sugar maple decline applies to a broader region. Low Ca and Mg and higher Mn levels were correlated with poorer tree health in both regions, but region 2 stands had little defoliation and few dead trees, suggesting that both unbalanced nutrition and stress are required for mortality to occur. We predict that stands with low foliar Ca and Mg and high Mn levels would incur increased mortality if stressed. In region 2, relationships between Ca, Mg, and Mn levels and dieback suggested that impacts on sugar maple may be caused by nutritional imbalance alone. Partial correlation analysis suggests that antagonism between Mg and Mn is the most important nutritional factor in region 1, while Mn supply is most important in region 2. We suggest that more research is needed on the interacting roles played by Ca, Mg, Al, and Mn in sugar maple performance.
Nonconstituent species in soil seed banks as indicators of anthropogenic disturbance in forest fragments
Authors: Lin Luxiang , Cao Min , He Yongtao , Baskin Jerry M , Baskin Carol C
Published: October 2006

Forest fragmentation is prevalent in regions with high human population density, but also with high biological diversity, such as southwestern China. Predicting potential changes in species composition in native forest ecosystems resulting from forest fragmentation is an important approach in assessing forest ecosystems and sustainable management of forests. The term nonconstituent species is proposed for plant species that occur in a natural landscape but are not native to it. We hypothesized that fragmentation of continuous forests significantly increases both the richness and the size of soil seed banks of nonconstituent species. To test our hypothesis we compared soil seed banks in three small fragments and one large tract of subtropical evergreen broad-leaved forest in Yunnan Province, southwestern China. In total, 249 species were identified in all soil samples from the four sites. Nonconstituent species represented 36.4%–61.5% of the total taxa and 33.8%–59.6% of total germinants from soil samples in the three forest fragments, but only 3.7%–7.9% of total taxa and 7.5%–9.4% of total germinants from soil samples in the continuous forest tract. Both richness and size of soil seed banks of nonconstituent species were greater under forest fragments than under continuous forest. A majority of nonconstituent species were native weeds and annual herbs with wind-dispersed seeds; most were present in soil seed banks but not in aboveground vegetation. We suggest that nonconstituent species in soil seed banks could be used as an indicator species group for assessing human disturbance. If so, the richness and size of soil seed banks of nonconstituent species could play an important role in quantifying disturbance in forests.
CPT I overexpression protects L6E9 muscle cells from fatty acid-induced insulin resistance
Authors: Sebastián David , Herrero Laura , Serra Dolors , Asins Guillermina , Hegardt Fausto G.
Published: October 2006

Oversupply of lipids to skeletal muscle causes insulin resistance by promoting the accumulation of lipid-derived metabolites that inhibit insulin signaling. In this study, we tested the hypothesis that overexpression of carnitine palmitoyltransferase I (CPT I) could protect myotubes from fatty acid-induced insulin resistance by reducing lipid accumulation in the muscle cell. Incubation of L6E9 myotubes with palmitate caused accumulation of triglycerides, diacylgycerol, and ceramide, produced an activation of PKCθ and PKCζ, and blocked insulin-stimulated glucose metabolism, reducing insulin-stimulated PKB activity by 60%. Transduction of L6E9 myotubes with adenoviruses encoding for liver CPT I (LCPT I) wild-type (WT), or a mutant form of LCPT I (LCPT I M593S), which is insensitive to malonyl-CoA, produced a twofold increase in palmitate oxidation when LCPT I activity was increased threefold. LCPT I WT and LCPT I M593S-overexpressing L6E9 myotubes showed normal insulin-stimulated glucose metabolism and an improvement in PKB activity when pretreated with palmitate. Moreover, LCPT I WT- and LCPT I M593S-transduced L6E9 myotubes were protected against the palmitate-induced accumulation of diacylglycerol and ceramide and PKCθ and -ζ activation. These results suggest that LCPT I overexpression protects L6E9 myotubes from fatty acid-induced insulin resistance by inhibiting both the accumulation of lipid metabolites and the activation of PKCθ and PKCζ.
Primate Area MST-l Is Involved in the Generation of Goal-Directed Eye and Hand Movements
Authors: Ilg Uwe J. , Schumann Stefan
Published: October 2006

The contributions of the middle superior temporal area (MST) in the posterior parietal cortex of rhesus monkeys to the generation of smooth-pursuit eye movements as well as the contributions to motion perception are well established. Here, we present the first experimental evidence that this area also contributes to the generation of goal-directed hand movements toward a moving target. This evidence is based on the outcome of intracortical microstimulation experiments and transient lesions by small injections of muscimol at identified sites within the lateral part of area MST (MST-l). When microstimulation was applied during the execution of smooth-pursuit eye movements, postsaccadic eye velocity in the direction of the preferred direction of the stimulated site increased significantly (in 93 of 136 sites tested). When microstimulation was applied during a hand movement trial, the hand movement was displaced significantly in the same direction (in 28 of 39 sites tested). When we lesioned area MST-l transiently by injections of muscimol, steady-state eye velocity was exclusively reduced for ipsiversive smooth-pursuit eye movements. In contrast, hand movements were displaced toward the contralateral side, irrespective of the direction of the moving target. Our results provide evidence that area MST-l is involved in the processing of moving targets and plays a role in the execution of smooth-pursuit eye movements as well as visually guided hand movements.
Gene expression profiling of monocyte-derived macrophages following infection withMycobacterium aviumsubspeciesaviumandMycobacterium aviumsubspeciesparatuberculosis
Authors: Murphy Judith T. , Sommer Sandra , Kabara Edward A. , Verman Nitin , Kuelbs Michael A. , Saama Peter , Halgren Robert , Coussens Paul M.
Published: October 2006

Mycobacterium avium subspecies paratuberculosis (MAP) and Mycobacterium avium subspecies avium (MAA) represent two closely related intracellular bacteria with vastly different associated pathologies. MAA can cause severe respiratory infections in immune compromised humans but is nonpathogenic in ruminants and is more readily controlled by the bovine immune system than MAP. MAP causes a fatal wasting syndrome in ruminants, typified by granulomatous enteritis localized in the small intestine. MAP has also been cited as a potential cause of human Crohn's disease. We used a bovine immune-specific microarray (BOTL-5) to compare the response of mature bovine monocyte-derived macrophages (MDM cells) to MAP and MAA. Statistical analysis of microarray data revealed 21 genes not appreciably expressed in resting MDM cells that were activated following infection with either MAA or MAP. Further analysis revealed 144 genes differentially expressed in MDM cells following infection with MAA and 99 genes differentially expressed following infection with MAP. Of these genes, 37 were affected by both types of mycobacteria, with three being affected in opposite directions. Over 41% of the differentially expressed genes in MAA and MAP infected MDM cells were members of, regulated by, or regulators of the MAPK pathways. Expression of selected genes was validated by quantitative real-time reverse transcriptase PCR and in several key genes (i.e., IL-2 receptor, tissue inhibitor of matrix metalloproteinases-1, and Fas-ligand) MAA was found to be a stronger activating factor than MAP. These gene expression patterns were correlated with prolonged activation of p38 MAPK and ERK1/2 by MAA, relative to MAP.