bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human erythrocyte δ‐aminolevulinate dehydratase inhibition by monosaccharides is not mediated by oxidation of enzyme sulfhydryl groups
Authors: Gabriel D. , Pivetta L. , Folmer V. , Soares J.C.M. , Augusti G.R. , Nogueira C.W. , Zeni G. , Rocha J.B.T. 
Published: June 2005

AbstractThe heme pathway enzyme δ‐aminolevulinate dehydratase is a good marker for oxidative stress and metal intoxication. This sulfhydryl enzyme is inhibited in such oxidative pathologies as lead, mercury and aluminum intoxication, exposure to selenium organic species and diabetes. Oxidative stress is a complicating factor in diabetes, inducing non‐enzymatic glucose‐mediated reactions that change protein structures and impair enzyme functions. We have studied the effects of high glucose, fructose and ribose concentrations on δ‐ALA‐D activity in vitro. These reducing sugars inhibited δ‐ALA‐D with efficacies in the order fructose = ribose > glucose. The possible mechanism of glucose inhibition was investigated using lysine, DTT, and t‐butylamine. Oxidation of the enzyme's critical sulfhydryl groups was not involved because DTT had no effect. We concluded that high concentrations of reducing sugars or their autoxidation products inhibit δ‐ALA‐D by a mechanism not related to thiol oxidation. Also, we are not able to demonstrate that the formation of a Schiff base with the critical lysine residue of the enzyme is involved in the inhibition of δ‐ALA‐D by hexoses.
Treatment of peripheral neuropathic pain: A simulation model
Authors: Vera‐Llonch Montserrat , Dukes Ellen , Delea Thomas E. , Wang Si‐Tien , Oster Gerry ,   The Neuropathic Pain Outcomes Modeling Working Group
Published: June 2005

AbstractObjective To describe the use of a generalizable stochastic‐simulation model of the treatment of neuropathic pain associated with peripheral neuropathies.Methods We developed a model to simulate treatment outcomes in a hypothetical cohort of patients with peripheral neuropathies. Each patient was randomly assigned an average pretreatment daily pain score (on a 0–10 scale), based on an assumed distribution of mean pretreatment pain scores in the cohort. Patients were randomly assigned daily pain scores, based on their pretreatment average and an assumed distribution of daily pain scores around this mean. Treatment outcomes were then simulated using the expected mean change (vs. baseline) in pain scores. Model outcomes include the expected increase in days with no or mild pain (score ≤3), days with ≥30% and ≥50% reductions in pain intensity, and days with 2‐ and 3‐point absolute reductions in pain intensity. To illustrate its use, the model was estimated over a 12‐week period using data from a recent clinical trial of a new antiepileptic (pregabalin).Results Treatment over 12 weeks (84 days) was projected to result in 26 (−0.4) (mean [−SE]) additional (vs. no treatment) days with no or mild pain, 33 (−0.5) days with a ≥30% reduction in pain intensity, 28 (−0.4) days with ≥50% reduction in pain intensity, and 34 (−0.5) and 30 (−0.5) days with ≥2‐point and ≥3‐point absolute reductions in pain intensity.Conclusions When combined with data on health‐state utilities and treatment costs, this new analytical tool can provide a foundation for formal cost‐effectiveness evaluations of interventions for painful peripheral neuropathies.
Immediate impacts and recovery trajectories of macrofaunal communities following hydraulic clam dredging on Banquereau, eastern Canada
Authors: Gilkinson Kent D. , Gordon Donald C. , MacIsaac Kevin G. , McKeown David L. , Kenchington Ellen L.R. , Bourbonnais Cynthia , Vass W. Peter 
Published: June 2005

Abstract
A hydraulic clam dredging experiment, designed to mimic offshore commercial dredging practices, was carried out at a depth of approximately 70 m on a sandy seabed on Banquereau, on the Scotian Shelf, eastern Canada. The experiment was designed to study the separate and combined effects of dredging through three treatment boxes (Dredging Only, Dredging and Discarding, Discarding Only) and two spatially separated reference boxes. In all, 270 taxa were identified from grab samples. Of these, four bivalves are targeted in the commercial fishery (Arctica islandica, Cyrtodaria siliqua, Mactromeris polynyma, and Serripes groenlandicus) while 266 taxa were non-target species. Sample biomass was dominated by the propellerclam, C. siliqua, and the echinoderm, Echinarachnius parma, while the polychaete, Spiophanes bombyx, was the numerical dominant. The dredges captured 33 invertebrate and two fish taxa, although >80% of the catch biomass comprised propellerclams and echinoderms. Immediately after dredging, most macrofaunal species decreased in abundance, with the greatest declines inside dredge furrows (which covered 53–68% of the area inside the dredged boxes). Large numbers of propellerclams were excavated to the seabed surface, with a large proportion showing massive damage. There were few signs of discards on the sediment surface. Recovery trajectories of target and non-target species were followed for 2 years. Following initial declines in abundance and biomass of most taxa immediately after dredging, there were marked increases in abundance of polychaetes and amphipods after 1 year. Two years after dredging, abundances of opportunistic species were generally elevated by ≫100% relative to pre-dredging levels. Two years after dredging, average taxonomic distinctness had decreased (i.e. taxonomic relatedness between species had increased) due, in part, to increased numbers of species of certain polychaetes and amphipods, while communities had become numerically dominated (50–70%) by S. bombyx. It is concluded that the disturbed community was still in the colonizing phase 2 years after dredging. The mobile brittlestar, Ophiura sarsi, displayed increases in abundance ranging from 200% to 300% in the dredged and reference boxes over the 2-year post-dredging. A similar response of non-target macrofauna in the reference boxes suggests, possibly, a coincident natural recruitment pulse. Dredging resulted in pronounced, sustained reductions in biomass (up to 67%) of the target bivalves with no signs of recovery after 2 years. Recruitment of target bivalves (>1-mm shell length) was very low throughout the experimental area during this interval.
Acoustic backscattering by Atlantic mackerel as being representative of fish that lack a swimbladder. Backscattering by individual fish
Authors: Gorska Natalia , Ona Egil , Korneliussen Rolf 
Published: June 2005

Abstract
Developing acoustic methods for the identification of fish remains a long-term objective of fisheries acoustics. The accuracy of abundance estimation may be increased when the acoustic-scattering characteristics of the fish are known, including their expected variability and uncertainty. The modelling approach is valuable during the process of interpreting multi-frequency echograms. This paper attempts to improve the understanding of sound backscattering of fish without a swimbladder, here represented by Atlantic mackerel (Scomber scombrus). Our approach includes results from modelling as well as comparisons with field data. There will be two papers. The first is a study of the non-averaged backscattering characteristics. This initial analysis is important for the understanding of the averaged backscattering cross-section, which will be considered in the second paper. In that paper the relative importance of bones in acoustic backscattering at higher frequencies will be verified.
Postnatal cerebellar defects in mice deficient in methylenetetrahydrofolate reductase
Authors: Chen Zhoutao , Schwahn Bernd C. , Wu Qing , He Xinying , Rozen Rima 
Published: June 2005

AbstractPatients with severe deficiency of methylenetetrahydrofolate reductase (MTHFR) suffer from a wide variety of neurological problems, which can begin in the neonatal period. MTHFR is a critical enzyme in folate metabolism; the product of the MTHFR reaction, 5‐methyltetrahydrofolate, is required for homocysteine remethylation to methionine and synthesis of S‐adenosylmethionine (SAM). To understand the mechanisms by which MTHFR deficiency leads to significant neuropathology, we examined early postnatal brain development in mice with a homozygous knockout of the Mthfr gene. These mice displayed a dramatically reduced size of the cerebellum and cerebral cortex, with enlarged lateral ventricles. Mthfr deficiency affected granule cell maturation, but not neurogenesis. Depletion of external granule cells and disorganization of Purkinje cells were mainly confined to the anterior lobules of mutant cerebella. Decreased cellular proliferation and increased cell death contributed to the granule cell loss. Reduced expression of Engrailed‐2 (En2), Reelin (Reln) and inositol 1,4,5‐triphosphate receptor type 1 (Itpr1) genes was observed in the cerebellum. Supplementation of Mthfr+/− dams with an alternate methyl donor, betaine, reduced cerebellar abnormalities in the Mthfr−/− pups. Our findings suggest that MTHFR plays a role in cerebellar patterning, possibly through effects on proliferation or apoptosis.
Rivalry under price and quantity uncertainty
Authors: Paxson Dean , Pinto Helena 
Published: June 2005

AbstractWe present a real option model for a duopoly setting where there are two stochastic factors and where the roles of the players are defined both exogenously and endogenously. The two stochastic factors are the number of units (market volume) and the profit per unit, which may have significantly different drifts and volatilities, and different correlations, depending on market structure and (dis)economies of scale.The paper shows that the degree of correlation between unit profits and market volume might result in different value functions and triggers, especially for followers and simultaneous investors in non‐pre‐emptive games. Monopoly‐like volume is a critical determinant of the leader's trigger in both pre‐emptive and non‐pre‐emptive games. First‐mover advantages are significant in the definition of the leader's optimal entry moment, if the players are fighting for the leader's position (pre‐emptive game).
Abnormal maturation of the retinal vasculature in type XVIII collagen/endostatin deficient mice and changes in retinal glial cells due to lack of collagen types XV and XVIII
Authors: Hurskainen Merja , Eklund Lauri , Hägg Pasi O. , Fruttiger Marcus , Sormunen Raija , Ilves Mika , Pihlajaniemi Taina 
Published: June 2005

ABSTRACTType XVIII collagen is important in the early phase of retinal vascular development and for the regression of the primary vasculature in the vitreous body after birth. We show here that the retina in Col18a1−/− mice becomes densely vascularized by anomalous anastomoses from the persistent hyaloid vasculature by day 10 after birth. In situ hybridizations revealed normal VEGF mRNA expression, but the phenotype of collagen XVIII deficient mice closely resembled that of mice expressing VEGF120 and VEGF188 isoforms only, suggesting that type XVIII collagen may be involved in VEGF function. Type XVIII collagen was found to be indispensable for angiogenesis in the eye, as also oxygen‐induced neovascularization was less intense than normal in the Col18a1−/− mice. We observed a marked increase in the amount of retinal astrocytes in the Col18a1−/− mice. Whereas the retinal vessels of wild‐type mice are covered by astrocytes and the regressing, thin hyaloid vessels are devoid of astrocytes, the retinal vessels in the Col18a1−/− mice were similarly covered by astrocytes but not the persistent hyaloid vessels in the vitreous body. Interestingly, double null mice lacking type XVIII collagen and its homologue type XV collagen had the persistent hyaloid vessels covered by astrocytes, including the parts located in the vitreous body. We thus hypothesize that type XV collagen is a regulator of glial cell recruitment around vessels and that type XVIII collagen regulates their proliferation.
Acoustic and petrophysical relationships in low‐shale sandstone reservoir rocks
Authors: Khazanehdari Jalal , McCann Clive 
Published: June 2005

ABSTRACTThis paper describes the measurements of the acoustic and petrophysical properties of two suites of low‐shale sandstone samples from North Sea hydrocarbon reservoirs, under simulated reservoir conditions. The acoustic velocities and quality factors of the samples, saturated with different pore fluids (brine, dead oil and kerosene), were measured at a frequency of about 0.8 MHz and over a range of pressures from 5 MPa to 40 MPa.The compressional‐wave velocity is strongly correlated with the shear‐wave velocity in this suite of rocks. The ratio VP/VS varies significantly with change of both pore‐fluid type and differential pressure, confirming the usefulness of this parameter for seismic monitoring of producing reservoirs.The results of quality factor measurements were compared with predictions from Biot‐flow and squirt‐flow loss mechanisms. The results suggested that the dominating loss in these samples is due to squirt‐flow of fluid between the pores of various geometries. The contribution of the Biot‐flow loss mechanism to the total loss is negligible. The compressional‐wave quality factor was shown to be inversely correlated with rock permeability, suggesting the possibility of using attenuation as a permeability indicator tool in low‐shale, high‐porosity sandstone reservoirs.
The estimation of shear‐wave statics using in situ measurements in marine near‐surface sediments
Authors: Winsborrow Gavin , Huws Dei G. , Muyzert Everhard 
Published: June 2005

ABSTRACTShear‐wave statics in marine seismic exploration data are routinely too large to be estimated using conventional techniques. Near‐surface unconsolidated sediments are often characterized by low values of Vs and steep velocity gradients. Minor variations in sediment properties at these depths correspond to variations in the shear‐wave velocity and will produce significant static shifts. It is suggested that a significant proportion of the shear‐wave statics solution can be estimated by performing a separate high‐resolution survey to target near‐surface unconsolidated sediments. Love‐wave, shear‐wave refraction and geotechnical measurements were individually used to form high‐resolution near‐surface shear‐wave velocity models to estimate the shear‐wave statics for a designated survey line. Comparisons with predicted statics revealed that shear‐wave statics could not be estimated using a velocity model predicted by substituting geotechnical measurements into empirical relationships. Empirical relationships represent a vast simplification of the factors that control Vs and are therefore not sufficiently sensitive to estimate shear‐wave statics. Refraction measurements are potentially sensitive to short‐wavelength variations in sediment properties when combined with accurate navigational data. Statics estimated from Love‐wave data are less sensitive, and sometimes smoothed in appearance, since interpreted velocity values represent an average both laterally and vertically over the receiver array and the frequency–depth sensitivity range, respectively.For the survey site, statics estimated from near‐surface irregularities using shear‐wave refraction measurements represent almost half the total statics solution. More often, this proportion will be greater when bedrock relief is less.
Simple relative space–time scaling of electrical and electromagnetic depth sounding arrays: implications for electrical static shift removal and joint DC‐TEM data inversion with the most‐squares criterion
Authors: Meju Max A. 
Published: June 2005

ABSTRACTA simple scaling relationship is shown to facilitate comparison, correlation and integration of data recorded using the common experimental configurations in electrical and electromagnetic depth sounding. Applications of the scheme to field data from typical geological and landfill environments show that it is robust and, where transient electromagnetic (TEM) data are available, enables easy identification and quantification of electrical static shift (galvanic distortion) in magnetotelluric and direct current (DC) sounding curves. TEM‐based procedures are suggested for both the direct removal of static shift in DC sounding curves and effective joint data inversion with the most‐squares criterion in the presence of static shift. A case study of aquifer characterization using sounding data from borehole sites in the Vale of York in England shows that static shift is a common problem in this glacial‐covered terrain and demonstrates the effectiveness of the proposed joint DC‐TEM inversion strategy in handling distorted soundings.
3D modelling and sensitivity in DC resistivity using charge density
Authors: Boulanger Olivier , Chouteau Michel 
Published: June 2005

ABSTRACTA three‐dimensional (3D) electrical resistivity modelling code is developed to interpret surface and subsurface data. Based on the integral equation, it calculates the charge density caused by conductivity gradients at each interface of the mesh, allowing the estimation of the potential everywhere without the need to interpolate between nodes. Modelling generates a huge matrix, made up of Green's functions, which is stored by using the method of pyramidal compression. The potential is compared with the analytical and the numerical solutions obtained by finite‐difference codes for two models: the two‐layer case and the vertical contact case. The integral method is more accurate around the source point and at the limits of the domain for the potential calculation using a pole‐pole array. A technique is proposed to calculate the sensitivity (Jacobian) and Hessian matrices in 3D. The sensitivity is based on the derivative with respect to the block conductivity of the potential computed using the integral equation; it is only necessary to compute the electrical field at the source location. A direct extension of this technique allows the determination of the second derivatives. The technique is compared with the analytical solutions and with the calculation of the sensitivity according to the method using the inner product of the current densities calculated at the source and receiver points. Results are very accurate when the Green's function that includes the source image is used. The calculation of the three components of the electric field on the interfaces of the mesh is carried out simultaneously and quickly, using matrix compression.
Ultrasonic velocities of North Sea chalk samples: influence of porosity, fluid content and texture
Authors: Røgen Birte , Fabricius Ida L. , Japsen Peter , Høier Christian , Mavko Gary , Pedersen Jacob M. 
Published: June 2005

ABSTRACTWe have studied 56 unfractured chalk samples of the Upper Cretaceous Tor Formation of the Dan, South Arne and Gorm Fields, Danish North Sea. The samples have porosities of between 14% and 45% and calcite content of over 95%. The ultrasonic compressional‐ and shear‐wave velocities (VP and VS) for dry and water‐saturated samples were measured at up to 75 bar confining hydrostatic pressure corresponding to effective stress in the reservoir. The porosity is the main control of the ultrasonic velocities and therefore of the elastic moduli. The elastic moduli are slightly higher for samples from the South Arne Field than from the Dan Field for identical porosities. This difference may be due to textural differences between the chalk at the two locations because we observe that large grains (i.e. filled microfossils and fossil fragments) that occur more frequently in samples from the Dan Field have a porosity‐reducing effect and that samples rich in large grains have a relatively low porosity for a given P‐wave modulus. The clay content in the samples is low and is mainly represented by either kaolinite or smectite; samples with smectite have a lower P‐wave modulus than samples with kaolinite at equal porosity. We find that ultrasonic VP and VS of dry chalk samples can be satisfactorily estimated with Gassmann's relationships from data for water‐saturated samples. A pronounced difference between the VP/VS ratios for dry and water‐saturated chalk samples indicates promising results for seismic amplitude‐versus‐offset analyses.
Piecewise 1D laterally constrained inversion of resistivity data
Authors: Auken Esben , Christiansen Anders V. , Jacobsen Bo H. , Foged Nikolaj , Sørensen Kurt I. 
Published: June 2005

ABSTRACTIn a sedimentary environment, layered models are often capable of representing the actual geology more accurately than smooth minimum structure models. Furthermore, interval thicknesses and resistivities are often the parameters to which non‐geophysicist experts can relate and base decisions on when using them in waste site remediation, groundwater modelling and physical planning.We present a laterally constrained inversion scheme for continuous resistivity data based on a layered earth model (1D). All 1D data sets and models are inverted as one system, producing layered sections with lateral smooth transitions. The models are regularized through laterally equal constraints that tie interface depths and resistivities of adjacent layers. Prior information, e.g. originating from electric logs, migrates through the lateral constraints to the adjacent models, making resolution of equivalences possible to some extent. Information from areas with well‐resolved parameters will migrate through the constraints in a similar way to help resolve the poorly constrained parameters. The estimated model is complemented by a full sensitivity analysis of the model parameters, supporting quantitative evaluation of the inversion result.Examples from synthetic 2D models show that the model recognition of a sublayered 2D wedge model is improved using the laterally constrained inversion approach when compared with a section of combined 1D models and when compared with a 2D minimum structure inversion. Case histories with data from two different continuous DC systems support the conclusions drawn from the synthetic example.
Parsimonious 3D post‐stack Kirchhoff depth migration
Authors: Hua Biaolong , McMechan George A. 
Published: June 2005

ABSTRACTParsimonious post‐stack migration is extended to three dimensions. By tracing single rays back along each incident wave direction (as determined by a local slant stack at the receivers), the ray tracing can be embedded in the migration. This approach significantly reduces the computer time and disk space needed because it is not necessary to build and save image time maps; 3D migration can be performed on a workstation or personal computer rather than using a supercomputer or cluster.The location of a reflector in the output image is defined by tracing a zero‐offset ray to the one‐way traveltime (the image condition); the orientation of the reflector is defined as a surface perpendicular to the raypath. The migration impulse response operator is confined to the first Fresnel zone around the estimated reflection point, which is much smaller than the large isochronic surface in traditional Kirchhoff depth migration. Additional efficiency is obtained by applying an amplitude threshold to reduce the amount of data to be migrated. Tests on synthetic data show that the proposed implementation of parsimonious 3D post‐stack Kirchhoff depth migration is at least two orders of magnitude faster than traditional Kirchhoff migration, at the expense of slightly degraded migration image coherence. The proposed migration is expected to be a useful complement to conventional time migrations for fast initial imaging of subsurface structures and for real‐time imaging of near‐offset sections during data acquisition for quality control.