bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil organic carbon storage in grazing pasture converted from forest on Andosol soil
Authors: Takahashi Shigeo , Nakagami Koji , Sakanoue Seiichi , Itano Shiro , Kirita Hiromitsu
Published: November 2007

In order to clarify the effect of land‐use change from forest to grazing pasture on the organic carbon storage in Andosol soil, the Rothamsted carbon turnover model for volcanic soil was applied to a pasture situated at the National Livestock Breeding Center (37°09′N, 140°03′E). The top 25‐cm soil layer was considered to be an active soil carbon pool. The carbon storage in the soils of native forest surrounding the pastures ranged 111–163 t C ha−1 with an average of 133 t C ha−1, which was adjusted according to an equivalent soil weight of pasture. The pasture soil carbon stocks ranged 88–135 t C ha−1, with variations according to site and/or pasture age. The carbon inputs to the soil through the above‐ and below‐ground dead material from pasture plants and cattle feces were estimated to be 1.1, 1.8 and 0.9 t C ha−1 year−1, respectively. As the model outputs of 14C content of the soil, which is an index of carbon dating corresponding to nuclear weapons testing, showed a relatively close agreement with the observations, the modeling was acceptable for the purpose of predicting the turnover of organic carbon in Andosol soil. The model simulation demonstrated that, in order to maintain the average forest carbon level, 3–4 t ha−1 year−1 of the organic carbon input would be needed. These inputs would be provided in a grazing pasture producing 8–9 t ha−1 year−1 of above‐ground dry matter.
On the radial distribution of white dwarfs in the globular cluster NGC 6397
Authors: Davis D. S. , Richer H. B. , King I. R. , Anderson J. , Coffey J. , Fahlman G. G. , Hurley J. , Kalirai J. S.
Published: November 2007

We have examined the radial distribution of white dwarfs over a single Hubble Space Telescope/Advanced Camera for Surveys field in the nearby globular cluster NGC 6397. In relaxed populations, such as in a globular cluster, stellar velocity dispersion, and hence radial distribution, is directly dependent on stellar masses. The progenitors of very young cluster white dwarfs had a mass of ∼0.8 M⊙, while the white dwarfs themselves have a mass of ∼0.5 M⊙. We thus expect young white dwarfs to have a concentrated radial distribution (like that of their progenitors) that becomes more extended over several relaxation times to mimic that of ∼0.5-M⊙ main-sequence stars. However, we observe young white dwarfs to have a significantly extended radial distribution compared both with the most massive main-sequence stars in the cluster and with old white dwarfs.
Postprandial hypotension in older Australians: Relationship to glycaemia and habitual food intake
Authors: SIVAKUMAR Pushparani , SOARES Mario
Published: November 2007

The aim of the present study is to document the phenomenon of postprandial hypotension (PPH) in older Australians, and examine whether glycaemia and/or habitual nutrient intake could explain its occurrence. Twenty‐three subjects (8 male, 15 female) aged 69 ± 9.7 years and with body mass index of 29.7 ± 5.2 kg/m2 participated in the study. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and capillary blood glucose were measured at fasting and at regular intervals for two hours following a high‐carbohydrate breakfast meal. Postprandial symptoms of dizziness and nausea were recorded. Habitual food intake was assessed by a food frequency questionnaire. Twelve of 23 subjects had clinical PPH. These subjects also had higher resting SBP (P < 0.005), a trend for a greater fall in DBP (P < 0.08), and showed no change in HR following the test meal in comparison with those without PPH. Only three subjects in each group reported symptoms of nausea. Adjusted for age, body mass index and medication use, change (Δ) in glycaemia was inversely related to ΔDBP (r = −0.53, P = 0.017) and ΔHR (r = −0.52, P = 0.019). Differences in the habitual food intake were not statistically significant, and did not predict any postprandial outcomes. In conclusion, PPH appears to be a relatively common and symptomless condition. The lack of a compensatory increase in HR may underscore the phenomenon. Glycaemia inversely influenced the changes in HR and DBP. The role of habitual dietary composition needs to be further explored.
Over‐ and underreporting of energy intake by patients with metabolic syndrome using an automated dietary assessment website
Authors: PROBST Yasmine , TAPSELL Linda
Published: November 2007

Under‐ and overreporting of dietary intake in a face‐to‐face context is related to age, gender and body mass index. The use of computer technology in dietetic practice is restricted to analysis of nutrient data rather than assessment of the diet. DietAdvice, a website developed to allow patients with metabolic syndrome to self‐report their dietary intake, has been developed in the Illawarra region of New South Wales, Australia. Patients are recruited by their general practitioner, and use the website, and the data are electronically fed to a dietitian for an individualised dietary prescription. The aim of the present study is to describe the reporting status of patients using a pilot test of the website from November 2004 to October 2005, and determine relationships to body mass index, gender and age. Reported energy intake (EI) was compared with predicted basal metabolic rate (BMR). Patients were classified as underreporting if EI : BMR <1.35 and overreporting if EI : BMR >2.4. Chi‐square and ordinal regression analyses were used to determine relationships to patient characteristics. Two hundred patients were recruited, of whom 57 had missing data or did not complete the assessment. Of the remaining 143 patients, 32.3% underreported their intakes, 21.7% overreported their intakes, and 46.2% were on target with their reporting. No relationships were found for age, gender or body mass index. Findings suggest that computerised dietary assessment may encourage patients to report with less bias than in a verbal dietary assessment when compared with the literature.
Monitoring, river restoration and the Water Framework Directive
Authors: England Judy , Skinner Kevin S. , Carter Matthew G.
Published: November 2007

Monitoring is an important aspect of any procedure that seeks to determine whether a technique has worked effectively. The river restoration process is no different. Unfortunately, monitoring is often not undertaken due to constraints on time and resources, as well as the commonly held belief that river restoration is inherently a good thing and, as a result, monitoring is unnecessary. There are many reasons to monitor projects and among the most important is the need to learn from experiences and for regulatory compliance. This paper examines the issues associated with the monitoring of river restoration schemes. In particular, it details monitoring selection models focusing on those associated with ecology and geomorphology. The paper also considers the requirements of monitoring schemes that will help deliver the goals of the Water Framework Directive (WFD).
Accuracy of the ISIS bridge methods for prediction of afflux at high flows
Authors: Atabay Serter
Published: November 2007

This paper presents the experimental results and findings from investigation into the accuracy, capability and suitability of the ISIS software package to model flow through bridge structures. Different types of bridge models, in terms of soffit shape, set in a two‐stage channel with various roughness conditions, were used for this study. In order to simulate natural environmental conditions, the original experimental data were scaled up using the undistorted‐scale method. One‐dimensional ISIS bridge methods, the ARCH bridge method, USBPR bridge method and the Bernoulli loss unit, were applied to both original experimental data and the scaled‐up data. The results for the ARCH bridge method and the USBPR method of ISIS are significantly different from the measured data and the Bernoulli loss unit. The Bernoulli loss unit, which uses Bernoulli's equation in ISIS, is the most accurate method to compute the afflux of bridges in waterways.
Decision‐Making: A Neuroeconomic Perspective
Authors: Hardy‐Vallée Benoit
Published: November 2007

This article introduces and discusses from a philosophical point of view the nascent field of neuroeconomics, which is the study of neural mechanisms involved in decision‐making and their economic significance. Following a survey of the ways in which decision‐making is usually construed in philosophy, economics, and psychology, I review many important findings in neuroeconomics to show that they suggest a revised picture of decision‐making and ourselves as choosing agents. Finally, I outline a neuroeconomic account of irrationality.
Emotion
Authors: Goldie Peter
Published: November 2007

After many years of neglect, philosophers are increasingly turning their attention to the emotions, and recently we have seen a number of different accounts of emotion. In this article, we will first consider what facts an account of emotion needs to accommodate if it is going to be acceptable. Having done that, we will then consider some of the leading accounts and see how they fare in accommodating the facts. Two things in particular will emerge. First, an adequate account of emotion cannot be provided without taking into account a wide range of issues in philosophy of mind that extend beyond the emotions in particular. Secondly, the diversity of emotional phenomena makes it especially hard to provide anything like acomprehensiveaccount of emotion; philosophers not only disagree over what are the essential properties of emotion, but also over what are central cases.
Use of a serum‐based glomerular filtration rate prediction equation to assess renal function by age, sex, fasting, and health status in bottlenose dolphins (Tursiops truncatus)
Authors: Venn‐Watson Stephanie , Smith Cynthia R. , Dold Christopher , Ridgway Sam H.
Published: November 2007

Abstract

Glomerular filtration rate (GFR) is a direct measurement of renal function. Although clearance tests using 24‐h urine collection or blood sample series are gold standards for measuring GFR, serum‐based prediction of GFR based upon the Modification of Diet in Renal Disease (MDRD) Study equation is acceptable for routine use in human adults. The purpose of our study was to assess the ability for a modified MDRD Study equation to predict expected changes in GFR in bottlenose dolphins (Tursiops truncatus) using a healthy dolphin population represented by 1,103 routine serum samples collected from 50 dolphins of all age groups, years 1998–2005. Predicted GFR was also calculated from serum collected from a 32‐yr‐old male dolphin with end‐stage renal disease. The dolphin‐adjusted MDRD equation predicted GFR changes in our population that paralleled what has previously been reported in other mammals, including decreasing predicted GFR with age (P < 0.01), higher predicted GFR in dolphins that had recently eaten (P < 0.01), and rapidly decreasing predicted GFR in the animal with end‐stage renal disease. We conclude that a serum‐based GFR prediction equation may be a feasible means of detecting and tracking renal function in bottlenose dolphins.
Estimating the impact of interactions between bottlenose dolphins and artisanal fisheries around the Balearic Islands
Authors: Brotons José María , Grau Antonio María , Rendell Luke
Published: November 2007

Abstract

Interactions between marine mammals and fisheries are a growing problem, and effective management requires assessment of the factors driving the interaction and of the impacts on fisheries. We used data from interactions between artisanal fisheries and bottlenose dolphins around the Balearic Islands to assess these factors and impacts. Observers collected data during 1,040 fishing operations over 3 yr. Location and year were important factors affecting interaction probability, with some areas showing large increases over the study period. We estimated the combined cost of catch loss and net damage as 6.5% of the total catch value (95% CI −12.3%, −1.6%), and the annual loss to be 3.4% (95% CI −6.5%, −0.1%) of the total catch by weight. This weight equates to the dietary needs of ∼12 dolphins (95% CI 0.2, 22), suggesting the fishery is not a vital food source for the dolphin population. Two dolphins died through entanglement during the observed fishing operations. We observed 3% of the total fishing activity, by weight, in 2003; scaling up this mortality directly suggests that as many as sixty dolphins may be dying in nets each year. This interaction likely has serious conservation implications for the dolphin population.
Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans
Authors: Burgomaster Kirsten A. , Howarth Krista R. , Phillips Stuart M. , Rakobowchuk Mark , MacDonald Maureen J. , McGee Sean L. , Gibala Martin J.
Published: November 2007

Low‐volume ‘sprint’ interval training (SIT) stimulates rapid improvements in muscle oxidative capacity that are comparable to levels reached following traditional endurance training (ET) but no study has examined metabolic adaptations during exercise after these different training strategies. We hypothesized that SIT and ET would induce similar adaptations in markers of skeletal muscle carbohydrate (CHO) and lipid metabolism and metabolic control during exercise despite large differences in training volume and time commitment. Active but untrained subjects (23 ± 1 years) performed a constant‐load cycling challenge (1 h at 65% of peak oxygen uptake before and after 6 weeks of either SIT or ET (n= 5 men and 5 women per group). SIT consisted of four to six repeats of a 30 s ‘all out’ Wingate Test (mean power output ∼500 W) with 4.5 min recovery between repeats, 3 days per week. ET consisted of 40–60 min of continuous cycling at a workload that elicited ∼65% (mean power output ∼150 W) per day, 5 days per week. Weekly time commitment (∼1.5 versus∼4.5 h) and total training volume (∼225 versus∼2250 kJ week−1) were substantially lower in SIT versus ET. Despite these differences, both protocols induced similar increases (P < 0.05) in mitochondrial markers for skeletal muscle CHO (pyruvate dehydrogenase E1α protein content) and lipid oxidation (3‐hydroxyacyl CoA dehydrogenase maximal activity) and protein content of peroxisome proliferator‐activated receptor‐γ coactivator‐1α. Glycogen and phosphocreatine utilization during exercise were reduced after training, and calculated rates of whole‐body CHO and lipid oxidation were decreased and increased, respectively, with no differences between groups (all main effects, P < 0.05). Given the markedly lower training volume in the SIT group, these data suggest that high‐intensity interval training is a time‐efficient strategy to increase skeletal muscle oxidative capacity and induce specific metabolic adaptations during exercise that are comparable to traditional ET.
Transition to seizures in the isolated immature mouse hippocampus: a switch from dominant phasic inhibition to dominant phasic excitation
Authors: Derchansky M. , Jahromi S. S. , Mamani M. , Shin D. S. , Sik A. , Carlen P. L.
Published: November 2007

The neural dynamics and mechanisms responsible for the transition from the interictal to the ictal state (seizures) are unresolved questions in epilepsy. It has been suggested that a shift from inhibitory to excitatory GABAergic drive can promote seizure generation. In this study, we utilized an experimental model of temporal lobe epilepsy which produces recurrent seizure‐like events in the isolated immature mouse hippocampus (P8–16), perfused with low magnesium ACSF, to investigate the cellular dynamics of seizure transition. Whole‐cell and perforated patch recordings from CA1 pyramidal cells and from fast‐ and non‐fast‐spiking interneurons in the CA1 stratum oriens hippocampal region showed a change in intracellular signal integration during the transition period, starting with dominant phasic inhibitory synaptic input, followed by dominant phasic excitation prior to a seizure. Efflux of bicarbonate ions through the GABAA receptor did not fully account for this excitation and GABAergic excitation via reversed IPSPs was also excluded as the prime mechanism generating the dominant excitation, since somatic and dendritic GABAA responses to externally applied muscimol remained hyperpolarizing throughout the transition period. In addition, abolishing EPSPs in a single neuron by intracellularly injected QX222, revealed that inhibitory synaptic drive was maintained throughout the entire transition period. We suggest that rather than a major shift from inhibitory to excitatory GABAergic drive prior to seizure onset, there is a change in the interaction between afferent synaptic inhibition, and afferent and intrinsic excitatory processes in pyramidal neurons and interneurons, with maintained inhibition and increasing, entrained ‘overpowering’ excitation during the transition to seizure.
Lipopolysaccharide‐induced down‐regulation of Ca2+release‐activated Ca2+currents (ICRAC) but not Ca2+‐activated TRPM4‐like currents (ICAN) in cultured mouse microglial cells
Authors: Beck Andreas , Penner Reinhold , Fleig Andrea
Published: November 2007

Microglia are the main immunocompetent cells of the mammalian central nervous system (CNS). Activation of cultured microglial cells and subsequent release of nitric oxide and cytokines critically depends on intracellular calcium levels. Since microglia undergo dramatic morphological, biochemical and electrophysiological changes in response to pathological events in the CNS, we investigated temporal changes in expression levels of ion channels involved in cellular calcium homeostasis in mouse cortical microglial cells in culture. Specifically, we assessed the inward and delayed outward rectifier potassium currents (IIRKandIDRK), calcium (Ca2+) release‐activated Ca2+currents (ICRAC) and Ca2+‐activated TRPM4‐like currents (ICAN) in non‐activated microglia and cells that were activated by exposure to lipopolysaccharide (LPS) between 3 and 48 h. Unstimulated microglial cells, subcultured from an astrocyte coculture, typically exhibited a ramified, rod‐shaped morphology. During the first 3 days of culture cell size and shape were maintained, but the percentage of cells showing prominentIIRKwent up and those expressingIDRKwent down. Cells retainingIDRKexhibited smaller amplitudes, whereas those ofIIRKandICRACwere not affected. However, after 24 h of exposure to 1 μg ml−1LPS, most cells showed an amoeboid (‘fried egg’‐shaped) morphology with a 62% increase in cell capacitance. At that point in time, only 14% of the cells revealedIIRKand 3% hadIDRKexclusively, whereas the majority of cells expressed both currents. The amplitudes ofICRACandIIRKprogressively decreased after stimulation, whereasIDRKtransiently reached a maximum after 6 h of LPS exposure and then returned to pre‐stimulation expression levels. Cultured microglia also revealed TRPM4‐like, Ca2+‐activated non‐selective currents (ICAN) with an EC50of 1.2 μm[Ca2+]i. The expression levels of this current did not change significantly during and after 24 h of LPS exposure. We propose that LPS‐induced down‐regulation ofIIRKandICRACwill reduce the cell's capacity to produce significant calcium influx upon receptor activation and result in decreased sensitivity to exogenous stimulation. In this scenario,ICANexpression would remain constant, although its activity would automatically be reduced due to the diminished calcium influx capacity of the cell.
Attenuated hypothalamo‐pituitary‐adrenal axis responses to immune challenge during pregnancy: the neurosteroid–opioid connection
Authors: Brunton Paula J. , Russell John A.
Published: November 2007

In late pregnancy maternal hypothalamo‐pituitary‐adrenal (HPA) axis responses to emotional and physical stressors are attenuated. This is expected to minimize the detrimental programming effects of glucocorticoid exposure on the fetuses. We have utilized a model of immune challenge, systemic administration of interleukin‐1β (IL‐1β), to investigate the underlying mechanisms. Intravenous IL‐1β activates corticotropin‐releasing hormone (CRH) neurones in the parvocellular division of the paraventricular nucleus (pPVN) via noradrenergic (A2 cell group) neurones in the nucleus tractus solitarii (NTS). Despite comparable activation of these brainstem neurones by IL‐1β in virgin and in late pregnant rats, pPVN CRH neurones are activated only in virgin rats. As a consequence IL‐1β fails to evoke ACTH and corticosterone secretion in late pregnant rats, in contrast to virgin rats. Suppressed responsiveness of the CRH neurones, and hence the HPA axis, following IL‐1β in late pregnancy is explained by presynaptic inhibition of noradrenaline release in the pPVN, due to increased endogenous enkephalin and μ‐opioid receptor production in brainstem NTS neurones. The factor that signals to the brain the pregnancy status of the animal and stimulates opioid production in the brainstem is allopregnanolone, a neurosteroid metabolite of progesterone. The supporting evidence for these mechanisms is discussed.
Both Orai1 and Orai3 are essential components of the arachidonate‐regulated Ca2+‐selective (ARC) channels
Authors: Mignen Olivier , Thompson Jill L. , Shuttleworth Trevor J.
Published: November 2007

Agonist‐activated Ca2+ signals in non‐excitable cells are profoundly influenced by calcium entry via both store‐operated and store‐independent conductances. Recent studies have demonstrated that STIM1 plays a key role in the activation of store‐operated conductances including the Ca2+‐release‐activated Ca2+ (CRAC) channels, and that Orai1 comprises the pore‐forming component of these channels. We recently demonstrated that STIM1 also regulates the activity of the store‐independent, arachidonic acid‐regulated Ca2+ (ARC) channels, but does so in a manner entirely distinct from its regulation of the CRAC channels. This shared ability to be regulated by STIM1, together with their similar biophysical properties, suggested that these two distinct conductances may be molecularly related. Here, we report that whilst the levels of Orai1 alone determine the magnitude of the CRAC channel currents, both Orai1 and the closely related Orai3 are critical for the corresponding currents through ARC channels. Thus, in cells stably expressing STIM1, overexpression of Orai1 increases both CRAC and ARC channel currents. Whilst similar overexpression of Orai3 alone has no effect, ARC channel currents are specifically increased by expression of Orai3 in cells stably expressing Orai1. Moreover, expression of a dominant‐negative mutant Orai3, either alone or in cells expressing wild‐type Orai1, profoundly and specifically reduces currents through the ARC channels without affecting those through the CRAC channels, and siRNA‐mediated knockdown of either Orai1 or Orai3 markedly inhibits ARC channel currents. Importantly, our data also show that the precise effects observed critically depend on which of the three proteins necessary for effective ARC channel activity (STIM1, Orai1 and Orai3) are rate limiting under the specific conditions employed.
A General Model of Prion Strains and Their Pathogenicity
Authors: Collinge John , Clarke Anthony R.
Published: November 2007

Prions are lethal mammalian pathogens composed of aggregated conformational isomers of a host-encoded glycoprotein and which appear to lack nucleic acids. Their unique biology, allied with the public-health risks posed by prion zoonoses such as bovine spongiform encephalopathy, has focused much attention on the molecular basis of prion propagation and the “species barrier” that controls cross-species transmission. Both are intimately linked to understanding how multiple prion “strains” are encoded by a protein-only agent. The underlying mechanisms are clearly of much wider importance, and analogous protein-based inheritance mechanisms are recognized in yeast and fungi. Recent advances suggest that prions themselves are not directly neurotoxic, but rather their propagation involves production of toxic species, which may be uncoupled from infectivity.
Arguing for Computational Power
Authors: Diermeier Daniel
Published: November 2007

Generative Social Science
. Studies in Agent-Based Computational Modeling.
By Joshua M. Epstein
. Princeton University Press, Princeton, NJ, 2006. 378 pp. plus CD. $49.50, £29.95. ISBN 9780691125473. Princeton Studies in Complexity.

This collection of papers by Epstein and his collaborators is presented as an argument that the best way to explain social science phenomena is to model them.
A Deubiquitinase That Regulates Type I Interferon Production
Authors: Kayagaki Nobuhiko , Phung Qui , Chan Salina , Chaudhari Ruchir , Quan Casey , O'Rourke Karen M. , Eby Michael , Pietras Eric , Cheng Genhong , Bazan J. Fernando , Zhang Zemin , Arnott David , Dixit Vishva M.
Published: November 2007

Production of type I interferon (IFN-I) is a critical host defense triggered by pattern-recognition receptors (PRRs) of the innate immune system. Deubiquitinating enzyme A (DUBA), an ovarian tumor domain-containing deubiquitinating enzyme, was discovered in a small interfering RNA–based screen as a regulator of IFN-I production. Reduction of DUBA augmented the PRR-induced IFN-I response, whereas ectopic expression of DUBA had the converse effect. DUBA bound tumor necrosis factor receptor–associated factor 3 (TRAF3), an adaptor protein essential for the IFN-I response. TRAF3 is an E3 ubiquitin ligase that preferentially assembled lysine-63–linked polyubiquitin chains. DUBA selectively cleaved the lysine-63–linked polyubiquitin chains on TRAF3, resulting in its dissociation from the downstream signaling complex containing TANK-binding kinase 1. A discrete ubiquitin interaction motif within DUBA was required for efficient deubiquitination of TRAF3 and optimal suppression of IFN-I. Our data identify DUBA as a negative regulator of innate immune responses.
IRE1 Signaling Affects Cell Fate During the Unfolded Protein Response
Authors: Lin Jonathan H. , Li Han , Yasumura Douglas , Cohen Hannah R. , Zhang Chao , Panning Barbara , Shokat Kevan M. , LaVail Matthew M. , Walter Peter
Published: November 2007

Endoplasmic reticulum (ER) stress activates a set of signaling pathways, collectively termed the unfolded protein response (UPR). The three UPR branches (IRE1, PERK, and ATF6) promote cell survival by reducing misfolded protein levels. UPR signaling also promotes apoptotic cell death if ER stress is not alleviated. How the UPR integrates its cytoprotective and proapoptotic outputs to select between life or death cell fates is unknown. We found that IRE1 and ATF6 activities were attenuated by persistent ER stress in human cells. By contrast, PERK signaling, including translational inhibition and proapoptotic transcription regulator
Chop
induction, was maintained. When IRE1 activity was sustained artificially, cell survival was enhanced, suggesting a causal link between the duration of UPR branch signaling and life or death cell fate after ER stress. Key findings from our studies in cell culture were recapitulated in photoreceptors expressing mutant rhodopsin in animal models of retinitis pigmentosa.
Sex-Linked Genetic Influence on Caste Determination in a Termite
Authors: Hayashi Yoshinobu , Lo Nathan , Miyata Hitoshi , Kitade Osamu
Published: November 2007

The most ecologically successful and destructive termite species are those with both a nymph caste and an irreversibly wingless worker caste. The early developmental bifurcation separating these castes is widely accepted to be strictly environmentally determined. We present evidence that genotype also influences this process. Offspring from four different crosses of nymph- and worker-derived secondary reproductive individuals had strongly differentiated caste and sex ratios, despite uniform rearing conditions. These data fit an X-linked, one-locus-two-allele model. Of five possible genotypes, one was lethal, two resulted in workers, and two resulted in either nymphs or environmentally determined workers. Caste is thus controlled both by environment and by a complex genetic inheritance pattern.
Magnetic Resonance Spectroscopy Identifies Neural Progenitor Cells in the Live Human Brain
Authors: Manganas Louis N. , Zhang Xueying , Li Yao , Hazel Raphael D. , Smith S. David , Wagshul Mark E. , Henn Fritz , Benveniste Helene , Djurić Petar M. , Enikolopov Grigori , Maletić-Savatić Mirjana
Published: November 2007

The identification of neural stem and progenitor cells (NPCs) by in vivo brain imaging could have important implications for diagnostic, prognostic, and therapeutic purposes. We describe a metabolic biomarker for the detection and quantification of NPCs in the human brain in vivo. We used proton nuclear magnetic resonance spectroscopy to identify and characterize a biomarker in which NPCs are enriched and demonstrated its use as a reference for monitoring neurogenesis. To detect low concentrations of NPCs in vivo, we developed a signal processing method that enabled the use of magnetic resonance spectroscopy for the analysis of the NPC biomarker in both the rodent brain and the hippocampus of live humans. Our findings thus open the possibility of investigating the role of NPCs and neurogenesis in a wide variety of human brain disorders.
Bypass of DNA Lesions Generated During Anticancer Treatment with Cisplatin by DNA Polymerase η
Authors: Alt Aaron , Lammens Katja , Chiocchini Claudia , Lammens Alfred , Pieck J. Carsten , Kuch David , Hopfner Karl-Peter , Carell Thomas
Published: November 2007

DNA polymerase η (Pol η) is a eukaryotic lesion bypass polymerase that helps organisms to survive exposure to ultraviolet (UV) radiation, and tumor cells to gain resistance against cisplatin-based chemotherapy. It allows cells to replicate across cross-link lesions such as 1,2-d(GpG) cisplatin adducts (Pt-GG) and UV-induced
cis
–
syn
thymine dimers. We present structural and biochemical analysis of how Pol η copies Pt-GG–containing DNA. The damaged DNA is bound in an open DNA binding rim. Nucleotidyl transfer requires the DNA to rotate into an active conformation, driven by hydrogen bonding of the templating base to the dNTP. For the 3′dG of the Pt-GG, this step is accomplished by a Watson-Crick base pair to dCTP and is biochemically efficient and accurate. In contrast, bypass of the 5′dG of the Pt-GG is less efficient and promiscuous for dCTP and dATP as a result of the presence of the rigid Pt cross-link. Our analysis reveals the set of structural features that enable Pol η to replicate across strongly distorting DNA lesions.
One-Dimensional Fast Migration of Vacancy Clusters in Metals
Authors: Matsukawa Yoshitaka , Zinkle Steven J.
Published: November 2007

The migration of point defects, for example, crystal lattice vacancies and self-interstitial atoms (SIAs), typically occurs through three-dimensional random walk in crystalline solids. However, when vacancies and SIAs agglomerate to form planar clusters, the migration mode may change. We observed nanometer-sized clusters of vacancies exhibiting one-dimensional (1D) fast migration. The 1D migration transported a vacancy cluster containing several hundred vacancies with a mobility higher than that of a single vacancy random walk and a mobility comparable to a single SIA random walk. Moreover, we found that the 1D migration may be a key physical mechanism for self-organization of nanometer-sized sessile vacancy cluster (stacking fault tetrahedron) arrays. Harnessing this 1D migration mode may enable new control of defect microstructures such as effective defect removal and introduction of ordered nanostructures in materials, including semiconductors.
GNAT-Like Strategy for Polyketide Chain Initiation
Authors: Gu Liangcai , Geders Todd W. , Wang Bo , Gerwick William H. , Håkansson Kristina , Smith Janet L. , Sherman David H.
Published: November 2007

An unexpected biochemical strategy for chain initiation is described for the loading module of the polyketide synthase of curacin A, an anticancer lead derived from the marine cyanobacterium
Lyngbya majuscula
. A central GCN5-related
N
-acetyltransferase (GNAT) domain bears bifunctional decarboxylase/
S
-acetyltransferase activity, both unprecedented for the GNAT superfamily. A CurA loading tridomain, consisting of an adaptor domain, the GNAT domain, and an acyl carrier protein, was assessed biochemically, revealing that a domain showing homology to GNAT (GNAT
L
) catalyzes (i) decarboxylation of malonyl-coenzyme A (malonyl-CoA) to acetyl-CoA and (ii) direct
S
-acetyl transfer from acetyl-CoA to load an adjacent acyl carrier protein domain (ACP
L
). Moreover, the N-terminal adapter domain was shown to facilitate acetyl-group transfer. Crystal structures of GNAT
L
were solved at 1.95 angstroms (ligand-free form) and 2.75 angstroms (acyl-CoA complex), showing distinct substrate tunnels for acyl-CoA and holo-ACP
L
binding. Modeling and site-directed mutagenesis experiments demonstrated that histidine-389 and threonine-355, at the convergence of the CoA and ACP tunnels, participate in malonyl-CoA decarboxylation but not in acetyl-group transfer. Decarboxylation precedes acetyl-group transfer, leading to acetyl-ACP
L
as the key curacin A starter unit.
A Cretaceous Hoofed Mammal from India
Authors: Prasad G. V. R. , Verma O. , Sahni A. , Parmar V. , Khosla A.
Published: November 2007

The sedimentary record documenting the northward drift of India (Late Cretaceous to late Early Eocene) has recently provided important clues to the evolution, radiation, and dispersal of mammals. Here, we report a definitive Late Cretaceous (Maastrichtian) archaic ungulate (Kharmerungulatum vanvaleni genus et species nova) from the Deccan volcano-sedimentary sequences exposed near Kisalpuri village in Central India. This find has important implications for the origin and diversification of early ungulates and raises three possible paleobiogeographic scenarios: (i) Archaic ungulates may have been cosmopolitan in distribution. (ii) Kharmerungulatum might be an immigrant from Western Asia. (iii) Archaic ungulates may have originated in India.
Stable Magnesium(I) Compounds with Mg-Mg Bonds
Authors: Green Shaun P. , Jones Cameron , Stasch Andreas
Published: November 2007

The chemistry of the group 2 metals (beryllium, magnesium, calcium, strontium, and barium) is dominated by the +2 oxidation state. Here, we report the reductions of two magnesium(II) iodide complexes with potassium metal in toluene, leading to thermally stable magnesium(I) compounds, (L)MgMg(L) (where L is [(Ar)NC(NPr
i
2
)N(Ar)]
–
or {[(Ar)NC(Me)]
2
CH}
–
, Ar is 2,6-diisopropylphenyl, Me is methyl, and Pr
i
is isopropyl) in moderate yields. The results of x-ray crystallographic and theoretical studies are consistent with central Mg
2+
2
units that have single, covalent magnesium-magnesium bonding interactions with 2.8508 ± 0.0012 (standard deviation) and 2.8457 ± 0.0008 angstrom bond lengths, respectively, and predominantly ionic interactions with the anionic ligands (L).
Multicenter Comparison of Different Real-Time PCR Assays for Quantitative Detection of Epstein-Barr Virus
Authors: Hayden R. T. , Hokanson K. M. , Pounds S. B. , Bankowski M. J , Belzer S. W. , Carr J. , Diorio D. , Forman M. S. , Joshi Y. , Hillyard D. , Hodinka R. L. , Nikiforova M. N. , Romain C. A. , Stevenson J. , Valsamakis A. , Balfour H. H.
Published: November 2007

Quantification of Epstein-Barr virus (EBV) in peripheral blood is important for the diagnosis and management of serious EBV diseases, including posttransplant lymphoproliferative disorder. A variety of PCR-based methods are currently in use; however, there is little information on their comparability. This study assessed the relative performance of different quantitative assays. A multicenter comparative study was performed at eight sites using three panels consisting of serial dilutions of quantified EBV DNA and extracts from a total of 19 whole-blood specimens. Samples were distributed and tested blindly. Instrumentation, probe chemistries, amplification targets, and other test-related aspects varied considerably between laboratories. Each laboratory's calibration curve indicated strong evidence of a consistent log-linear relationship between viral load and cycle threshold, suggesting that intralaboratory tracking of a given patient would yield similar relative quantitative trends among the participating test sites. There was strong concordance among laboratories with respect to qualitative test results; however, marked quantitative discordance was seen. For most samples, the across-laboratory interquartile range of the reported viral load (in copies/μl) was roughly 0.6 log-units, and for one sample the overall range was approximately 4.2 log-units. While intralaboratory tracking of patients may yield similar results, these data indicate a need for caution when attempting to compare clinical results obtained at different institutions and suggest the potential value to be gained by more standardized testing methodology.
Comparison of Molecular Typing Methods for Characterization of
Staphylococcus epidermidis
: Proposal for Clone Definition
Authors: Miragaia M. , Carriço J. A. , Thomas J. C. , Couto I. , Enright M. C. , de Lencastre H.
Published: November 2007

In the present study we give some direction on the selection of the most appropriate typing method(s) to be used for the characterization of
Staphylococcus epidermidis
, in view of the most recent findings on the evolution, population structure, and epidemiology of this species. In order to achieve this aim, quantitative assessment of the correlation of the results of three typing methods—pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and staphylococcal chromosomal cassette
mec
(SCC
mec
) typing, which target different regions of the chromosome that evolve at different rates—was performed. In order to evaluate the discriminatory ability and the strength and direction of the correlation of the different typing methods, Simpson's index of diversity (SID), the adjusted Rand coefficient (AR), and the Wallace coefficient (
W
) were calculated. PFGE was the most discriminatory method (SID = 99%), followed by MLST (SID = 90%) and SCC
mec
typing (SID = 75%). The values of AR and
W
(0.10 < AR < 0.30; 0.50 <
W
< 0.75) indicated that the partition of the same isolate collection by PFGE, MLST, and SCC
mec
typing provided results that had only a poor correlation with each other. However, the information provided by the combination of PFGE and SCC
mec
enabled the prediction of the results obtained by MLST at the level of the clonal complex with a high degree of precision (
W
> 0.90). We propose that clones of
S. epidermidis
be defined by the combination of the PFGE type followed by the SCC
mec
type, which provides reliable information on the short-term epidemiology and the ability to predict with consistency long-term clonal evolution.
The Anticancer Drug Ellipticine is an Inducer of Rat NAD(P)H:Quinone Oxidoreductase
Authors: Stiborová Marie , Dračínská Helena , Aimová Dagmar , Hodek Petr , Hudeček Jiří , Ryšlavá Helena , Schmeiser Heinz H. , Frei Eva
Published: November 2007

The antineoplastic agent ellipticine was investigated for its ability to induce the biotransformation enzyme NAD(P)H:quinone oxidoreductase (DT-diaphorase, EC 1.6.99.2) in male Wistar rats. Using the real-time polymerase chain reaction, the levels of NAD(P)H:quinone oxidoreductase mRNA were determined in livers, kidneys and lungs of rats treated intraperitoneally with ellipticine (40 mg/kg body weight) and of control (untreated) rats. Cytosolic fractions were isolated from the same tissues of control and ellipticine-treated rats and tested for NAD(P)H:quinone oxidoreductase protein expression and its enzymatic activity. The results demonstrate that ellipticine is a potent inducer of NAD(P)H:quinone oxidoreductase in rat livers and kidneys, while no induction of this enzyme was detectable in rat lungs. The increase in levels of NAD(P)H:quinone oxidoreductase mRNA correlates with the increase in expression of its protein and enzymatic activity, measured with menadione and 3-nitrobenzanthrone as substrates. The results, the identification of the potential of ellipticine to induce NAD(P)H:quinone oxidoreductase, suggest that this drug is capable of modulating biological efficiencies of the toxicants and/or drugs that are reductively metabolized by this enzyme.
Synthesis and Characterization of Spherical Hollow Assembly Composed of Cu Nanoparticles
Authors: Yang Ming , Yang Xiao
Published: November 2007

Hollow spheres of Cu nanoparticles with an average diameter of 300-500 nm have been prepared by a simple reaction of CuCl and hydrazine in suspension in the presence of gelatin at 60 °C. Gelatin played a decisive role as an inhibitor of the direct attack of hydrazine on CuCl surfaces and in coagulation of the growing Cu producing the hollow spheres. The products were characterized by X-ray powder diffraction, transmission electron microscopy, UV-VIS absorption spectroscopy and X-ray photoelectron spectrometry.
Developing common metrics of mechanical exposures across aetiological studies of low back pain in working populations for use in meta-analysis
Authors: Griffith L E , Wells R P , Shannon H S , Walter S D , Cole D C , Hogg-Johnson S ,   on behalf of the Meta-Analysis of Pain in the Lower Back and Work Exposures (MAPLE) Collaborative Group
Published: November 2007

Objectives:

One of the challenges of conducting meta-analyses on the relationship between workplace mechanical exposures and low back pain is that mechanical exposures are reported in a wide variety of ways. We aimed to develop common metrics to apply in the translation of literature-based workplace mechanical exposures for use in meta-analyses, and to test the metrics’ measurement properties.

Methods:

We developed a set of 7-point scales to capture the intensity of important aspects of mechanical exposures that may be related to the development of low back pain in workers. The scales represented three dimensions of mechanical exposures at work: (1) trunk posture, (2) weight lifted or force exerted and (3) spinal loading, and estimated both peak and cumulative loads. Measurement properties of the scales were tested through a survey of experts in biomechanics and ergonomics who were asked to rate literature-based workplace exposure definitions using the scales and provide estimates of their confidence in their ratings.

Results:

For each dimension the ratings for peak loads tended to be higher than the cumulative load ratings. The inter-rater reliability for the scales ranged from 0.3 to 0.5; we would need to average the ratings of at least four expert raters to have an acceptable level of reliability (>0.7). Inter-expert reliability was positively related to the experts’ level of confidence in their ratings. In most cases the ranking of intensity ratings from the experts matched the ranking of exposure intensity from the original articles.

Conclusions:

This study provides insight into estimating the intensity of literature-based mechanical exposure metrics using a common set of scales which can be applied across epidemiologic studies. These metrics may be useful to quantify the relationship between workplace mechanical exposure and low back pain in a systematic review and meta-analysis.
DARK ENERGY AND THE FUTURE FATE OF THE UNIVERSE
Authors: GONG YUNGUI , ZHANG YUAN-ZHONG
Published: November 2007

We consider the possibility of observing the onset of the late time inflation of our patch of the Universe. The Hubble size criterion and the event horizon criterion are applied to several dark energy models to discuss the problem of future inflation of the Universe. We find that the acceleration has not lasted long enough to confirm the onset of inflation by present observations for the dark energy model with constant equation of state, the holographic dark energy model and the generalized Chaplygin gas (GCG) model. For the flat ΛCDM model with Ωm0 = 0.3, we find that if we use the Hubble size criterion, we need to wait until the av which is the scale factor at the time when the onset of inflation is observed reaches 3.59 times of the scale factor aT when the Universe started acceleration, and we need to wait until av = 2.3aT to see the onset of inflation if we use the event horizon criterion. For the flat holographic dark energy model with d = 1, we find that av = 3.46aT with the Hubble horizon and av = 2.34aT with the event horizon, respectively. For the flat GCG model with the best supernova fitting parameter α = 1.2, we find that av = 5.50aT with the Hubble horizon and av = 2.08aT with the event horizon, respectively.
WKB FORMALISM AND A LOWER LIMIT FOR THE ENERGY EIGENSTATES OF BOUND STATES FOR SOME POTENTIALS
Authors: BARRAGÁN-GIL LUIS F. , CAMACHO ABEL
Published: November 2007

In this work the conditions appearing in the so-called WKB approximation formalism of quantum mechanics are analyzed. It is shown that, in general, a careful definition of an approximation method requires the introduction of two length parameters, one of them always considered in the textbooks on quantum mechanics, whereas the other is usually neglected. Afterwards we define a particular family of potentials and prove, resorting to the aforementioned length parameters, that we may find an energy which is a lower bound to the ground energy of the system. The idea is applied to the case of a harmonic oscillator and also to a particle freely falling in a homogeneous gravitational field, and in both cases the consistency of our method is corroborated. This approach, together with the so-called Rayleigh–Ritz formalism, allows us to define an energy interval in which the ground energy of any potential, belonging to our family, must lie.
NONCOMMUTATIVE NONRELATIVISTIC FERMIONS
Authors: JAHAN A. , NASSERI M. , JAFARI M.
Published: November 2007

Spatial noncommutativity removes the degeneracy of nonrelativistic electron gas. In particular one can interpret the noncommutativity parameter appearing in the second-order correlation term, as a new temperature reference. We investigate the effect of the noncommutativity of space on a many-particle system composed of locally interacting nonrelativistic fermions. We calculate the first-order energy shift of the system up to the second order in noncommutativity parameter and as a result the noncommutativity of space eliminates the degeneracy of the model. Thus, as the case of electron gas, one may interpret the noncommutativity parameter as a new reference temperature.
STOCHASTIC BACKGROUND OF RELIC SCALAR GRAVITATIONAL WAVES FROM SCALAR–TENSOR GRAVITY
Authors: CAPOZZIELLO SALVATORE , CORDA CHRISTIAN , DE LAURENTIS MARIAFELICIA
Published: November 2007

A stochastic background of relic gravitational waves is achieved by the so-called adiabatically-amplified zero-point fluctuations process derived from early inflation. In principle, it provides a distinctive spectrum of relic gravitational waves. In the framework of scalar–tensor gravity, we discuss the scalar modes of gravitational waves and the primordial production of this scalar component which is generated besides tensorial one. We also discuss the upper limit for such a relic scalar component with respect to the WMAP constraints.
ELECTRONIC STRUCTURE, DIELECTRIC AND DYNAMICAL PROPERTIES OF ZINC-BLENDE AlN FROM FIRST PRINCIPLES CALCULATION
Authors: WANG HUAN-YOU , XU HUI , XIAO JIAN-RONG , LI MINGJUN
Published: November 2007

We have performed density-functional perturbation calculation for zinc-blende AlN using the pseudopotential plane-wave method. The results obtained using both the local-density approximate (LDA) and the generalized-gradient approximate (GGA) for exchange-correlation functional are compared. The ground state properties and response function properties for zinc-blende AlN , including the electronic band structure, charge density, Born effective charge, dielectric constant and vibrational properties are reported. Our results are basically in agreement with experimental data and theoretical values available, but the bandgap is underestimated and the first optical mode in the phonon band structure is overestimated. This can be attributed to the underestimation of the lattice parameter and selection of the pseudopotential.