bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organic phosphorus speciation and pedogenesis: analysis by solution 31P nuclear magnetic resonance spectroscopy
Authors: McDowell R. W. , Cade‐Menun B. , Stewart I. 
Published: July 2007

SummaryChanges in phosphorus (P) during soil development are central to the understanding of labile P for plant productivity and soil P management. We used NaOH‐EDTA extraction with 31P nuclear magnetic resonance spectroscopy (31P NMR), sequential P fractionation, and general soil chemical characterization to better our understanding of P dynamics within two chronosequences (Manawatu and Reefton) and one Basalt maturity sequence under original native vegetation. With time, orthophosphate and orthophosphate monoesters tended to increase with organic C to a maximum of about two‐thirds of NaOH‐EDTA‐extractable P in young soils (16 000 years in the Reefton chronosequence), but gradually declined thereafter to about one‐third of NaOH‐EDTA‐extractable P in the oldest soils (130 000 years old). This coincided with a depletion of P from primary minerals (e.g. apatite) and readily available P for plant production. This depletion of inorganic P resulted in a greater reliance on organic P cycling via mineralization, hence the depletion of the normally recalcitrant monoester‐P pool. Concomitantly, the build‐up of labile P species (diesters and pyrophosphate) and scyllo‐ over myo‐inositol hexakisphosphate occurred as soils developed, and might be attributed to microbial activity, including scavenging for P. This work highlights the importance of organic P cycling during pedogenesis.
Community‐wide character displacement in New Zealand skinks
Authors: Montoya Isabel , Burns K.C. 
Published: July 2007

AbstractAim To test for community‐wide character displacement in New Zealand skinks.Location Four small islands in the New Zealand archipelago.Methods (1) We conducted a field experiment on a single island to evaluate whether prey size selection is correlated with lizard body size. We pitfall trapped 69 skinks from three species, measured several aspects of their morphology and presented each animal with a variety of different‐sized prey in a food choice experiment. (2) We tested whether the morphological characteristics associated with prey size selection were evenly partitioned in four island skink communities using null models.Results Prey size selection was associated with skink morphology; larger skinks consumed larger prey. Null model analyses showed support for evenly displaced body sizes on one island, weak support on one island and no support on two islands.Main conclusions Results showed mixed support for community‐wide character displacement in New Zealand skinks. Differences in body sizes appear to reflect the use of different‐sized prey. Even differentiation in body sizes on one island suggests that species coexistence is facilitated by interspecific differences in prey size selection. However, little support was found on other islands, suggesting that other factors, such as interspecific differences in habitat selection and/or diurnal activity patterns, may interact with differences in prey size selection to promote coexistence among New Zealand skinks.
Chloroplast‐generated reactive oxygen species are involved in hypersensitive response‐like cell death mediated by a mitogen‐activated protein kinase cascade
Authors: Liu Yidong , Ren Dongtao , Pike Sharon , Pallardy Stephen , Gassmann Walter , Zhang Shuqun 
Published: July 2007

SummaryPlant defense against pathogens often includes rapid programmed cell death known as the hypersensitive response (HR). Recent genetic studies have demonstrated the involvement of a specific mitogen‐activated protein kinase (MAPK) cascade consisting of three tobacco MAPKs, SIPK, Ntf4 and WIPK, and their common upstream MAPK kinase (MAPKK or MEK), NtMEK2. Potential upstream MAPKK kinases (MAPKKKs or MEKKs) in this cascade include the orthologs of Arabidopsis MEKK1 and tomato MAPKKKα. Activation of the SIPK/Ntf4/WIPK pathway induces cell death with phenotypes identical to pathogen‐induced HR at macroscopic, microscopic and physiological levels, including loss of membrane potential, electrolyte leakage and rapid dehydration. Loss of membrane potential in NtMEK2DD plants is associated with the generation of reactive oxygen species (ROS), which is preceded by disruption of metabolic activities in chloroplasts and mitochondria. We observed rapid shutdown of carbon fixation in chloroplasts after SIPK/Ntf4/WIPK activation, which can lead to the generation of ROS in chloroplasts under illumination. Consistent with a role of chloroplast‐generated ROS in MAPK‐mediated cell death, plants kept in the dark do not accumulate H2O2 in chloroplasts after MAPK activation, and cell death is significantly delayed. Similar light dependency was observed in HR cell death induced by tobacco mosaic virus, which is known to activate the same MAPK pathway in an N‐gene‐dependent manner. These results suggest that activation of the SIPK/Ntf4/WIPK cascade by pathogens actively promotes the generation of ROS in chloroplasts, which plays an important role in the signaling for and/or execution of HR cell death in plants.
Quantitative phosphoproteomic analysis of plasma membrane proteins reveals regulatory mechanisms of plant innate immune responses
Authors: Nühse Thomas S. , Bottrill Andrew R. , Jones Alexandra M.E. , Peck Scott C. 
Published: July 2007

SummaryAdvances in proteomic techniques have allowed the large‐scale identification of phosphorylation sites in complex protein samples, but new biological insight requires an understanding of their in vivo dynamics. Here, we demonstrate the use of a stable isotope‐based quantitative approach for pathway discovery and structure–function studies in Arabidopsis cells treated with the bacterial elicitor flagellin. The quantitative comparison identifies individual sites on plasma membrane (PM) proteins that undergo rapid phosphorylation or dephosphorylation. The data reveal both divergent dynamics of different sites within one protein and coordinated regulation of homologous sites in related proteins, as found for the PM H+‐ATPases AHA1, 2 and 3. Strongly elicitor‐responsive phosphorylation sites may reflect direct regulation of protein activity. We confirm this prediction for RbohD, an NADPH oxidase that mediates the rapid production of reactive oxygen species (ROS) in response to elicitors and pathogens. Plant NADPH oxidases are structurally distinct from their mammalian homologues, and regulation of the plant enzymes is poorly understood. On RbohD, we found both unchanging and strongly induced phosphorylation sites. By complementing an RbohD mutant plant with non‐phosphorylatable forms of RbohD, we show that only those sites that undergo differential regulation are required for activation of the protein. These experiments demonstrate the potential for use of quantitative phosphoproteomics to determine regulatory mechanisms at the molecular level and provide new insights into innate immune responses.
Place‐selective firing contributes to the reverse‐order reactivation of CA1 pyramidal cells during sharp waves in open‐field exploration
Authors: Csicsvari Jozsef , O'Neill Joseph , Allen Kevin , Senior Timothy 
Published: July 2007

AbstractOn the linear track, the recent firing sequences of CA1 place cells recur during sharp wave/ripple patterns (SWRs) in a reverse temporal order [Foster & Wilson (2006) Nature, 440, 680–683]. We have found similar reverse‐order reactivation during SWRs in open‐field exploration where the firing sequence of cells varied before each SWR. Both the onset times and the firing patterns of cells showed a tendency for reversed sequences during SWRs. These effects were observed for SWRs that occurred during exploration, but not for those during longer immobility periods. Additionally, reverse reactivation was stronger when it was preceded by higher speed (> 5 cm/s) run periods. The trend for reverse‐order SWR reactivation was not significantly different in familiar and novel environments, even though SWR‐associated firing rates of both pyramidal cells and interneurons were reduced in novel environments as compared with familiar. During exploration‐associated SWRs (eSWR) place cells retain place‐selective firing [O'Neill et al. (2006) Neuron, 49, 143–155]. Here, we have shown that each cell's firing onset was more delayed and firing probability more reduced during eSWRs the further the rat was from the middle of the cell's place field; that is, cells receiving less momentary place‐related excitatory drive fired later during SWR events. However, even controlling for place field distance, the recent firing of cells was still significantly correlated with SWR reactivation sequences. We therefore propose that both place‐related drive and the firing history of cells contribute to reverse reactivation during eSWRs.
Aerosolization of mycobacteria and legionellae during dental treatment: low exposure despite dental unit contamination
Authors: Dutil Steve , Veillette Marc , Mériaux Anne , Lazure Louis , Barbeau Jean , Duchaine Caroline 
Published: July 2007

SummaryDental unit waterlines (DUWL) support growth of a dense microbial population that includes pathogens and hypersensitivity‐inducing bacteria, such as Legionella spp. and non‐tuberculous mycobacteria (NTM). Dynamic dental instruments connected to DUWL generate aerosols in the work environment, which could allow waterborne pathogens to be aerosolized. The use of the real‐time quantitative polymerase chain reaction (qPCR) provides a more accurate estimation of exposure levels compared with the traditional culture approach. Bioaerosol sampling was performed 13 times in an isolated dental treatment room according to a standardized protocol that included four dental prophylaxis treatments. Inhalable dust samples were taken at the breathing zone of both the hygienist and patient and outside the treatment room (control). Total bacteria as well as Legionella spp. and NTM were quantified by qPCR in bioaerosol and DUWL water samples. Dental staff and patients are exposed to bacteria generated during dental treatments (up to 4.3 E + 05 bacteria per m3 of air). Because DUWL water studied was weakly contaminated by Legionella spp. and NTM, their aerosolization during dental treatment was not significant. As a result, infectious and sensitization risks associated with legionellae and NTM should be minimal.
Occupying the Margins: Labour Integration and Social Exclusion in Artisanal Mining in Tanzania
Authors: Fisher Eleanor 
Published: July 2007

ABSTRACTThis article examines the marginal position of artisanal miners in sub‐Saharan Africa, and considers how they are incorporated into mineral sector change in the context of institutional and legal integration. Taking the case of diamond and gold mining in Tanzania, the concept of social exclusion is used to explore the consequences of marginalization on people's access to mineral resources and ability to make a living from artisanal mining. Because existing inequalities and forms of discrimination are ignored by the Tanzanian state, the institutionalization of mineral titles conceals social and power relations that perpetuate highly unequal access to resources. The article highlights the complexity of these processes, and shows that while legal integration can benefit certain wealthier categories of people, who fit into the model of an ‘entrepreneurial small‐scale miner’, for others adverse incorporation contributes to socio‐economic dependence, exploitation and insecurity. For the issue of marginality to be addressed within integration processes, the existence of local forms of organization, institutions and relationships, which underpin inequalities and discrimination, need to be recognized.
K+M‐Current Regulates the Transition to Seizures in Immature and Adult Hippocampus
Authors: Qiu Cuie , Johnson Brian N. , Tallent Melanie K. 
Published: July 2007

SummaryPurpose:Loss‐of‐function mutations in Kv7.2 or Kv7.3 K+channel subunits underlies the neonatal epilepsy benign familial neonatal convulsions (BFNC). These two subunits interact to form a functional K+channel that underlies the M‐current (IM), a voltage‐dependent noninactivating K+current. In BFNC, seizures begin shortly after birth, and spontaneously remit in the first few months of life. The nature of this window of vulnerability is unclear. We address this issue using a hippocampal slice model, to study the effects of IMblockade or augmentation on epileptiform activity.Methods:We used the Mg++‐free seizure model in adult and immature (P8‐P15) acute rat hippocampal slices. We recorded from both CA1 and CA3 regions using extracellular and intracellular methods.Results:When M‐channels are blocked pharmacologically, the transition from interictal to ictal bursting becomes much more likely, especially in immature brain. We also show augmentation of IMis effective in stopping ictal events in immature brain, at the developmental age that approximates a human newborn in cortical development. IMappears to counter the sustained N‐methyl‐D‐aspartate (NMDA) receptor‐mediated depolarizations needed to trigger an ictal event. The increased likelihood of ictal bursting by IMblockade is not shared by other selective K+channel blockers that increase hippocampal excitability.Conclusions:Voltage‐dependent M‐channels are activated duringinterictal bursts and contribute to burst termination. When these channels are compromised, interictal burstduration becomes sufficient to trigger the sustained depolarizations that underlie ictal bursts. This transition to ictal bursts upon IMblockade is especially likely to occur in immature hippocampus. This selective function of M‐channels likely contributes to the transient window of vulnerability to seizures that occurs with BFNC.
Effects of Noninvasive Transcutaneous Electrical Stimulation via Concentric Ring Electrodes on Pilocarpine‐induced Status Epilepticus in Rats
Authors: Besio Walter G. , Koka Kanthaiah , Cole Andrew J. 
Published: July 2007

Summary
Purpose: The aim of this pilot study was to investigate the antiepileptic effects of a novel noninvasive stimulation technique, transcutaneous electrical stimulation (TcES) via scalp concentric ring electrodes, on pilocarpine‐induced status epilepticus (SE) in rats.
Methods: Five minutes after the onset of SE, TcES was administered to the experimental rat via bipolar concentric ring electrode at the CZ location. Symmetrical, biphasic, charge‐balanced, constant current, isolated pulses were applied via a custom‐made stimulator. TcES parameters ranged from 200–750 Hz, 200 or 300 μs pulse duration, and 50 or 60 mA, applied for 1 min, started with the least intense parameter set and progressively increased.
Results: TcES attenuated electrographic seizure activity and halted the progression of behavioral seizures. Interruption of seizure activity outlasted the period of stimulation and appeared to be long‐lasting. TcES treatment significantly extended the life and enhanced the survival of rats after SE.
Conclusions: Noninvasive TcES, applied 5 min after SE onset via novel concentric ring electrodes on the scalp, reduced, or abolished electrographic and behavioral seizure activity in pilocarpine‐induced SE in rats. These findings suggest that TcES may have a role in the treatment of SE.
The comparative study of two recently developed A‐scan devices: determination of central corneal thickness, anterior chamber depth and axial length
Authors: Sohajda Zoltán , Papp Júlia , Berta András , Módis László 
Published: July 2007

Abstract.Purpose:  The clinical use and comparison of two recently developed A‐scan ultrasound devices.Methods:  The same investigator determined central corneal thickness (CCT), anterior chamber depth (ACD) and axial length (AL) with an OcuScan RxP (Alcon, Forth Worth, Texas, USA) and an AL‐2000 (Tomey, Erlangen, Germany) ultrasound device in 80 eyes of 40 patients. The mean patient age was 63.72 years [standard deviation (SD) 18.92]. The patients did not suffer from any systemic or eye disease affecting the anterior and posterior segments of the eye, and their refractive error (spherical and astigmatic) did not exceed ± 3.0 dioptres.Results:  The value of the CCT was 541.55 (SD 34.97) µm with the OcuScan RxP, and 547.46 (SD 35.70) µm with the AL‐2000 device (P < 0.001). With respect to the ACD and AL, significantly lower values were obtained with the AL‐2000 instrument (P < 0.001). The ACD was 2.92 (SD 0.48) mm with the AL‐2000 and 3.07 (SD 0.47) mm with the OcuScan RxP device. The AL was 22.67 (SD 0.84) mm with the AL‐2000 and 22.81 (SD 0.87) mm with the OcuScan RxP instrument. However, a positive and significant correlation could be demonstrated between the devices (r = 0.88 CCT, r = 0.86 ACD and r = 0.91 AL; P < 0.001).Conclusion:  The instruments are reliable in clinical use; however, statistically significant differences were found between the devices. During patient follow‐up, the devices cannot simply be used interchangeably.
Insight into Siderophore-Carrying Peptide Biosynthesis: Enterobactin Is a Precursor for Microcin E492 Posttranslational Modification
Authors: Vassiliadis Gaëlle , Peduzzi Jean , Zirah Séverine , Thomas Xavier , Rebuffat Sylvie , Destoumieux-Garzón Delphine 
Published: July 2007

ABSTRACT

Microcin E492-producing bacteria secrete both unmodified and posttranslationally modified microcins. The modification consists of a C-glucosylated linear trimer of
N
-(2,3-dihydroxybenzoyl)-
l
-serine, a catecholate siderophore related to salmochelins and enterobactin. We show here that repression of enterobactin biosynthesis inhibits the acquisition of microcin E492 posttranslational modification, as monitored by high-performance liquid chromatography and mass spectrometry. Furthermore, exogenous enterobactin restored the production of posttranslationally modified microcin in a bacterial strain deficient in enterobactin synthesis. We thus concluded that enterobactin serves as a precursor for the synthesis of the posttranslationally modified microcin and that the unmodified microcin is an incompletely processed form of mature microcin E492. Gene disruption experiments showed that MceC and MceD, two enzymes encoded by the
mceABCDEFGHIJ
gene cluster, are involved in the synthesis of the microcin E492 posttranslational modification, as followed by mass spectrometry. Genes homologous to
iroB
and
iroD
, required for the conversion (linearization and C-glycosylation) of enterobactin into salmochelins, efficiently complemented
mceC
and
mceD
, respectively. Based on our results, a model is proposed for the biosynthesis of the mature siderophore-carrying peptide.
Predictors of 30-Day Mortality among Patients with
Pseudomonas aeruginosa
Bloodstream Infections: Impact of Delayed Appropriate Antibiotic Selection
Authors: Lodise Thomas P. , Patel Nimish , Kwa Andrea , Graves Jeffrey , Furuno Jon P. , Graffunder Eileen , Lomaestro Ben , McGregor Jessina C. 
Published: July 2007

ABSTRACT

Although a growing number of studies have found a relationship between delayed appropriate antibiotic therapy and mortality, few have attempted to quantify the temporal association between delayed appropriate antibiotic therapy and mortality. This study was designed to measure the elapsed time associated with an increased risk of 30-day mortality among patients with
Pseudomonas aeruginosa
bacteremia. The retrospective cohort study was conducted among immunocompetent, adult patients with
P. aeruginosa
bacteremia onset at least 2 days after hospital admission between 1 January 2001 and 30 September 2006. Classification and regression tree analysis (CART) was used to identify the delay in appropriate antibiotic therapy that was associated with an increased risk of 30-day mortality. During the study period, 100 patients met the inclusion criteria. The CART-derived breakpoint between early and delayed treatment was 52 h. The delayed treatment group experienced a >2-fold significant increase in 30-day mortality compared to the early treatment group (44 and 19%, respectively,
P
= 0.008). Delayed appropriate therapy of >52 h (odds ratio [OR] = 4.1; 95% confidence interval [CI] 1.2 to 13.9,
P
= 0.03) was independently associated with 30-day mortality in the multivariate analysis. Antibiotic resistance ≥3 classes (adjusted OR [AOR] = 4.6; 95% CI = 1.9 to 11.2,
P
= 0.001) and chronic obstructive pulmonary disease (AOR = 5.4; 95% CI = 1.5 to 19.7,
P
= 0.01) were independently associated with delayed appropriate therapy of >52 h. The data strongly suggest that delaying appropriate therapy for approximately 2 days significantly increases the risk of 30-day mortality in patients with
P. aeruginosa
bloodstream infections.
Fluorescence Ratio Imaging Microscopy Shows Decreased Access of Vancomycin to Cell Wall Synthetic Sites in Vancomycin-ResistantStaphylococcus aureus
Authors: Pereira Pedro M. , Filipe Sérgio R. , Tomasz Alexander , Pinho Mariana G. 
Published: July 2007

ABSTRACTA new method of fluorescence ratio imaging microscopy was used to compare the in vivo binding capacity and the access of a fluorescent derivative of vancomycin to the cell wall synthetic sites in isogenic pairs of vancomycin-susceptible and -resistant laboratory mutants and vancomycin-intermediate and -susceptible clinical isolates ofStaphylococcus aureus. Live cells of resistant strains were found to bind approximately 1.5 times more antibiotic, but there was no correlation between the increased binding capacity and the MICs of the strains. In both susceptible and resistant bacteria, the subcellular sites of wall synthesis were localized to the division septa, but the rate of diffusion of drug molecules to these sites was reduced in resistant cells. The findings allow a reinterpretation of the mechanism of vancomycin resistance in which the path of vancomycin to its lethal target (lipid II) is considered to be through the division septum and therefore is dependent on the stage of the staphylococcal cell cycle.
Evaluation of Hexadecyloxypropyl-9-
R
-[2-(Phosphonomethoxy)Propyl]- Adenine, CMX157, as a Potential Treatment for Human Immunodeficiency Virus Type 1 and Hepatitis B Virus Infections
Authors: Painter George R. , Almond Merrick R. , Trost Lawrence C. , Lampert Bernhard M. , Neyts Johan , De Clercq Erik , Korba Brent E. , Aldern Kathy A. , Beadle James R. , Hostetler Karl Y. 
Published: July 2007

ABSTRACT

9-
R
-[2-(Phosphonomethoxy)propyl]-adenine (tenofovir) is an acyclic nucleoside phosphonate with antiviral activity against human immunodeficiency virus type 1 (HIV-1) and hepatitis B virus (HBV). Tenofovir is not orally bioavailable but becomes orally active against HIV-1 infection as the disoproxil ester (tenofovir disoproxil fumarate [Viread]). We have developed an alternative strategy for promoting the oral availability of nucleoside phosphonate analogs which involves esterification with a lipid to form a lysolecithin mimic. This mimic can utilize natural lysolecithin uptake pathways in the gut, resulting in high oral availability. Since the mimic is not subject to cleavage in the plasma by nonspecific esterases, it remains intact in the circulation and facilitates uptake by target cells. Significant drops in apparent antiviral 50% effective concentrations (EC
50
s) of up to 3 logs have been observed in comparison with non-lipid-conjugated parent compounds in target cells. We have applied this technology to tenofovir with the goal of increasing oral availability, decreasing the apparent EC
50
, and decreasing the potential for nephrotoxicity by reducing the exposure of the kidney to the free dianionic tenofovir. Here we report that, in vitro, the hexadecyloxypropyl ester of tenofovir, CMX157, is 267-fold more active than tenofovir against HIV-1 and 4.5-fold more active against HBV. CMX157 is orally available and has no apparent toxicity when given orally to rats for 7 days at doses of 10, 30, or 100 mg/kg/day. Consequently, CMX157 represents a second-generation tenofovir analog which may have an improved clinical profile.