bluuebunny/crossref_metadata_2025_split huggingface dataset:
Point-of-care testing, medical error, and patient safety: a 2007 assessment
Authors: Ehrmeyer Sharon S. , Laessig Ronald H. 
Published: June 2007

AbstractPoint-of-care testing (POCT) is the fastest growing segment of a US$30 billion worldwide market. “Errors” in the testing process, as well as medical data interpretation and treatment associated with POCT, are recognized as leading to major compromises of patient safety. In today's environment, most testing errors (pre-analytical, analytical and post-analytical) can be virtually eliminated by proper design of testing systems. We cite examples of two systems that have made exceptional progress in this respect. It has been recently suggested that the basic errors associated with the testing process are amplified in the POC setting. Two of the amplifiers – incoherent regulations and failure of clinician/caregivers to respond appropriately to POCT results – lead us to recognize additional changes in today's POCT environment. The first is a willingness of manufacturers, not laboratories, to take responsibility for the quality of test results – an outgrowth of an industrial philosophy called autonomation. The second is a need to substantially modify the clinician/caregiver test utilization paradigm to take full advantage of POCT results, available on site in real time. Both have already begun to take place.Clin Chem Lab Med 2007;45:766–73.
Risk management in the preanalytical phase of laboratory testing
Authors: Lippi Giuseppe , Guidi Gian Cesare 
Published: June 2007

AbstractThe clinical laboratory is no longer its own limited ecosystem, as it is increasingly integrated with patient care, assisting diagnosis, monitoring therapies and predicting clinical outcomes. Although efforts and resources are continuously focused to achieve a satisfactory degree of analytical quality, there is clear evidence that the preanalytical phase is much more vulnerable to uncertainties and accidents, which can substantially influence patient care. Most errors within the preanalytical phase result from system flaws and insufficient audit of the operators involved in specimen collection and handling responsibilities, leading to an unacceptable number of unsuitable specimens due to in vitro hemolysis, clotting, insufficient volume, wrong container, contamination and misidentification. A reliable approach to overcome this problem entails prediction of accidental events (exhaustive process analysis, reassessment and rearrangement of quality requirements, dissemination of operating guidelines and best-practice recommendations, reduction of complexity and error-prone activities, introduction of error-tracking systems and continuous monitoring of performances), an increase in and diversification of defenses (application of multiple and heterogeneous systems to identify non-conformities), and a decrease in vulnerability (implementation of reliable and objective detection systems and causal relation charts, education and training). This policy, which requires integration between requirements and design, full commitment and interdepartmental cooperation, should make laboratory activity more compliant to the inalienable paradigm of total quality in the testing process.Clin Chem Lab Med 2007;45:720–7.
Asymmetrisches Dimethylarginin (ADMA): ein neuer Marker zur Abschätzung des kardiovaskulären Risikos / Asymmetric dimethyl arginine (ADMA): a new marker for evaluating cardiovascular risk
Authors: Meinitzer Andreas , März Winfried 
Published: June 2007

Zusammenfassung
Asymmetrisches Dimethylarginin (ADMA) ist eine endogen produzierte Aminosäure, die alle drei Isoformen der Stickoxid-Synthase inhibiert. Eine Erhöhung von ADMA in den Endothelzellen schränkt die Freisetzung des relaxierenden Signalmoleküls Stickstoffmonoxid ein und könnte damit die Entstehung arteriosklerotischer Läsionen begünstigen. Als gut abgesichert gilt, dass ADMA in verschiedenen Krankheitsstadien von chronischer Niereninsuffizienz, Diabetes mellitus, arterieller Hypertonie und koronarer Herzkrankheit (KHK) im Plasma kumuliert. ADMA liegt im Plasma in niedriger Konzentration und neben sehr viel höher konzentrierten, strukturell ähnlichen Substanzen vor. Die Bestimmung ist deshalb eine analytische Herausforderung. Die Beurteilung einer pathologischen Konzentration sollte immer im Vergleich mit einer adäquaten Kontrollgruppe erfolgen, die mit identischer Methodik analysiert wurde. Der vorliegende Artikel fasst den aktuellen Wissensstand über die biologische Wirkung, die Entstehung, den Metabolismus und die Elimination von ADMA zusammen. Anhand eigener Befunde wird weiterhin auf die Bedeutung von ADMA als Prognosefaktor für kardiovaskuläre Mortalität und Gesamtmortalität eingegangen.
Lipoprotein(a) – Struktur, Epidemiologie und Funktion / Lipoprotein(a) – structure, epidemiology and function
Authors: Siekmeier Rüdiger , Scharnagl Hubert , Kostner Gert M. , Grammer Tanja , Stojakovic Tatjana , März Winfried 
Published: June 2007

Zusammenfassung
Jahrzehnte nach der Erstbeschreibung durch Berg 1963 ist Lipoprotein(a) (Lp(a)) als von den übrigen kardiovaskulären Risikofaktoren unabhängiger Risikofaktor anerkannt. Lp(a) unterscheidet sich vom LDL durch das kovalent gebundene Apo(a), ein Glykoprotein, das einem ausgeprägten genetischen Polymorphismus unterliegt. Ursache hierfür ist die unterschiedliche Anzahl von Kringle-4-Typ-II-Repeats des eine ausgeprägte Strukturhomologie zum Plasminogen aufweisenden Moleküls. Die in der Bevölkerung sehr schief verteilten Lp(a)-Plasmakonzentrationen sind zu mehr als 90% genetisch determiniert und korrelieren bei Gesunden mit der Synthese des Lp(a), nicht jedoch mit dessen Katabolismus. Darüber hinaus findet sich eine Beeinflussung der Lp(a)-Plasmakonzentration durch verschiedene Erkrankungen (z. B. Nieren- und Lebererkrankungen), hormonelle Faktoren (z. B. Sexualsteroide, Glucocorticoide, Schilddrüsenhormone), individuelle Faktoren und Umweltfaktoren (z. B. Alter, Zigarettenrauchen) sowie Medikamente (z. B. Nikotinsäurederivate) und therapeutische Verfahren (Lipidapherese). Trotz der Vielzahl der zu Lp(a) durchgeführten Studien sind die Kenntnisse über dessen physiologische Funktion und Regulation weiterhin lückenhaft. Darüber hinaus sind die Ergebnisse der hierzu durchgeführten Untersuchungen aufgrund der unterschiedlichen eingeschlossenen Patientenkollektive, der Verwendung nicht hinreichend validierter Testverfahren und der Analytik von eingefrorenen Archivproben teilweise widersprüchlich. Ziel der vorliegenden Übersichtsarbeit ist die Darstellung der Funktion des Lp(a) und dessen physiologischer Regulation sowie wesentlicher, die Plasmakonzentration beeinflussender therapeutischer Faktoren.
Fast and Accurate Estimation of the Population-Scaled Mutation Rate, θ, From Microsatellite Genotype Data
Authors: RoyChoudhury Arindam , Stephens Matthew 
Published: June 2007

Abstract
We present a new approach for estimation of the population-scaled mutation rate, θ, from microsatellite genotype data, using the recently introduced “product of approximate conditionals” framework. Comparisons with other methods on simulated data demonstrate that this new approach is attractive in terms of both accuracy and speed of computation. Our simulation experiments also demonstrate that, despite the theoretical advantages of full-likelihood-based methods, methods based on certain summary statistics (specifically, the sample homozygosity) can perform very competitively in practice.
Combined Nitrogen and Phosphorus Fertilization for Controlling the Toxigenic Alga Prymnesium parvum
Authors: Kurten Gerald L , Barkoh Aaron , Fries Loraine T , Begley Drew C 
Published: June 2007

Abstract
The toxigenic alga Prymnesium parvum has caused significant fish kills in Texas reservoirs and fish hatchery ponds since 2001. Copper sulfate and ammonium sulfate can control P. parvum, but they provide short-term improvement and have undesirable side effects. Copper sulfate also kills desirable algae and invertebrates, and ammonium sulfate can be harmful to fish. Because dominance of the phytoplankton community and toxin production by P. parvum appear to be nutrient related, we evaluated two nitrogen (N) and phosphorus (P) fertilization regimes for their efficacy in controlling P. parvum populations and toxicity. The experiment included two N:P fertilization treatments (300:30 or 300:60 μg/L three times weekly) and an unfertilized control group conducted in limnocorrals suspended in a fish hatchery pond. Ammonium chloride (NH4Cl) and phosphoric acid (H3PO4) were used as the sources of N and P, respectively. In the unfertilized control, P. parvum cells and toxicity persisted throughout the 40-d experiment. In both fertilization treatments, P. parvum cell densities and toxicity declined below detectable levels within 2 weeks and remained undetectable for the duration of the study. The fertilization regimes promoted pH and un-ionized ammonia N levels that may be detrimental to the survival of crustacean zooplankton and sensitive fish species, such as fry and fingerlings of temperate basses Morone spp. However, this approach may be suitable for production of less-sensitive species, such as advanced fingerlings of channel catfish Ictalurus punctatus. The next steps in refining this strategy are reducing the fertilization rates while still achieving P. parvum control, investigating alternative sources of N fertilizer to eliminate the potential confounding effect of un-ionized ammonia, and integrating pH reduction measures for sensitive fish species.
The Acute Toxicity of Praziquantel to Grass Carp and Golden Shiners
Authors: Mitchell Andrew J , Hobbs Melissa S 
Published: June 2007

Abstract
The acute toxicity and highest nonlethal concentration of praziquantel (LC0) were determined in the laboratory for grass carp Ctenopharyngodon idella and golden shiner Notemigonus crysoleucas, two cyprinids known to harbor the Asian tapeworm Bothriocephalus acheilognathi. Praziquantel is an anthelmintic used to treat fish with tapeworms. The 24-h and 96-h LC50 values were 55.1 and 49.7 mg/L for golden shiners (1.3 g) and 63.4 and 60.6 mg/L for grass carp (9.1 g). The 24-h and 96-h LC0 values were 50.0 and 45.0 mg/L for golden shiners and 60.0 and 60.0 mg/L for grass carp.
Acute Hypoxia–Reperfusion Triggers Immunocompromise in Nile Tilapia
Authors: Choi K. , Lehmann D. W. , Harms C. A. , Law J. M. 
Published: June 2007

Abstract
Inadequate dissolved oxygen in the aquatic environment is a well-established cause of fish morbidity and mortality. The specific effects of hypoxia on immune function in fish, however, are not well characterized. In this study, the effects of acute hypoxia followed by reoxygenation (rapid tissue reperfusion) as a source of immunocompromise in Nile tilapia Oreochromis niloticus were investigated. Using a precision apparatus developed in our laboratory for hypoxia exposures, a series of assays of increasing specificity for immune function were performed on acutely hypoxia-stressed Nile tilapia: tier I consisted of histopathology, tier II of hematology, plasma chemistry, and determining cortisol concentration, and tier III of determining the phagocytic index and analyzing the expression of the cytokines transforming growth factor-β (TGF-β) and interleukin-1β (IL-1β). Nile tilapia were exposed to 7% oxygen saturation for 96 h, then tank water was rapidly reoxygenated. Sampling intervals were 48 and 96 h during hypoxia and 12 and 84 h during reperfusion. Histopathology showed no remarkable microscopic abnormalities in lymphoid or other tissues. Lymphopenia and neutrophilia were observed in peripheral blood. Plasma total protein, partial pressure of oxygen, and oxygen saturation were decreased in response to hypoxia. Plasma lipase decreased in response to hypoxia but returned to normal during reperfusion. Phagocytic capability and the phagocytic index decreased during hypoxia and 12 h reperfusion, whereas these values were recovered by 84 h reperfusion. The TGF-β transcription continued to increase during the exposures, the greatest production being at 12 h reperfusion, whereas IL-1β transcription decreased in response to hypoxia and reperfusion. We conclude that acute hypoxia triggered an overall downregulation of the immune system in the test fish. This suggests a possible factor in the pathogenesis of disease outbreaks in fish in which repeated, sublethal bouts of environmentally induced hypoxia lead to increased disease susceptibility and individual mortalities rather than massive fish kills.
Parametric Investigation of WAG Floods Above the MME
Authors: Bermudez Leonardo , Johns Russell T. , Parakh Harshad 
Published: June 2007

SummaryWater-alternating-gas floods (WAG) are commonly used to improve sweep efficiency in heterogeneous reservoirs. There has been little reported in the literature, however, on the effectiveness of WAG processes where the gas is enriched above the minimum miscibility enrichment composition (MME). This paper examines how to optimize WAG processes for enriched gasfloods above the MME, particularly as a primary recovery method. Compositional simulations of x-z cross-sections are used to quantify the effects of WAG parameters, numerical dispersion, level of enrichment, and heterogeneity on local displacement efficiency and sweep efficiency.The main conclusions of this research show that the richer the gas above the MME, the fewer the number of WAG cycles required for maximum oil recovery at a given WAG ratio. Another significant observation is that overenrichment above the MME improves recovery the most when the largest permeability layers are at the bottom of the reservoir. Continuous slug injection performs better than WAG when the largest permeability layers are at the bottom of the aquifer, richer gases are used, and the vertical to horizontal permeability ratio is small.
A Stochastic Optimization Algorithm for Automatic History Matching
Authors: Gao Guohua , Li Gaoming , Reynolds Albert C. 
Published: June 2007

Summary
For large-scale history-matching problems, optimization algorithms which require only the gradient of the objective function and avoid explicit computation of the Hessian appear to be the best approach. Unfortunately, such algorithms have not been extensively used in practice because computation of the gradient of the objective function by the adjoint method requires explicit knowledge of the simulator numerics and expertise in simulation development. Here we apply the simultaneous perturbation stochastic approximation (SPSA) method to history match multiphase flow production data. SPSA, which has recently attracted considerable international attention in a variety of disciplines, can be easily combined with any reservoir simulator to do automatic history matching. The SPSA method uses stochastic simultaneous perturbation of all parameters to generate a down hill search direction at each iteration. The theoretical basis for this probabilistic perturbation is that the expectation of the search direction generated is the steepest descent direction.
We present modifications for improvement in the convergence behavior of the SPSA algorithm for history matching and compare its performance to the steepest descent, gradual deformation and LBFGS algorithm. Although the convergence properties of the SPSA algorithm are not nearly as good as our most recent implementation of a quasi-Newton method (LBFGS), the SPSA algorithm is not simulator specific and it requires only a few hours of work to combine SPSA with any commercial reservoir simulator to do automatic history matching.
To the best of our knowledge, this is the first introduction of SPSA into the history matching literature. Thus, we make considerable effort to put it in a proper context.
Evaporative Cleanup of Water Blocks in Gas Wells
Authors: Mahadevan Jagannathan , Sharma Mukul M. , Yortsos Yannis C. 
Published: June 2007

Summary
The flow of a gas toward the wellbore of a production well will result in the evaporative cleanup of water blocks, which occurs primarily because of gas expansion. This paper presents for the first time a model for calculating the rate at which such water blocks are removed, for either fractured or unfractured gas wells. The model can be used to compute the impact of evaporative cleaning on well productivity.
The removal of water first occurs by gas displacement. Evaporative cleanup is caused by gas expansion. The resulting saturation profile is qualitatively different for low-or high-permeability rocks. As a consequence, the increase in gas relative permeability, or the well productivity, with time can vary depending on the rock permeability and the well drawdown. High-permeability (e.g., fractured) rocks clean up significantly faster. By contrast, low-permeability unfractured wells may require a very long time to clean up. Large pressure drawdowns, as well as the use of more volatile fluids, such as alcohols, also result in faster cleanup.
A distinctive feature of the work presented is that the model equations are formulated and solved completely without the assumption of skin factors for the damage zone. Thus, the prediction of cleanup rates can be made more accurately.
Semianalytical Stream-Function Solutions on Unstructured Grids for Flow in Heterogeneous Media
Authors: Hazlett R. D. , Babu D. K. , Lake L. W. 
Published: June 2007

Summary
This paper outlines a Boundary Element Method (BEM) for a piece-wise analytic solution of the Laplace (Poisson) equation for pseudosteady-state, single-phase flow on unstructured, rectangular grids. The method models flow through a reservoir that has been segmented into interacting homogeneous rectangular regions; no further discretization of the solution space analogous to grid refinement in numerical schemes is required for improved accuracy. Rather, boundary discretization allows for continuation of pressure and flux. Previous work on pressure distribution modeling is extended to analytically capture the stream function. Stream-function solutions can then form the basis for other performance measures, such as improved oil recovery efficiency estimation or tracer flow analysis. Moving beyond structured grids into unstructured grid geometry allows for advanced flexibility in problem development and improved efficiency in solution construction. The analytic approach avoids the need for numerical differentiation of the pressure field and particle tracking methods to recover streamlines. Capturing flow in highly heterogeneous media, without local grid refinement, is demonstrated to showcase the robustness of the technique in handling complex reservoir architecture, of particular interest in optimal well positioning and optimal wellpattern development.
An Improved Model for Estimating Flow Impairment by Perforation Damage
Authors: Hagoort Jacques 
Published: June 2007

Summary
In this work, we present two simple formulas for the skin of a perforated well caused by perforation damage: one for the reduction in permeability, and one for the increase in non-Darcy flow coefficient (beta factor). They are based on the inflow performance of a single perforation obtained by means of a prolate-spheroidal flow model. This model rigorously accounts for the flow convergence toward a perforation, especially near the tip of the perforation. It provides a more realistic description of the inflow than a radial flow model, the basis for the existing skin formulas proposed by McLeod (1983). In the case of perforations with a large aspect ratio and a thin damaged zone, the formula for the skin due to permeability reduction reduces to McLeod's formula. The formula for the non-Darcy skin yields a significantly larger skin than predicted by the radial flow model, up to a factor 1.4 for large aspect ratios. Finally, we demonstrate that perforated wells are much more liable to non-Darcy flow than openhole wells, in particular if the perforations are severely damaged.
UV/H2O2 degradation of endocrine-disrupting chemicals in water evaluated via toxicity assays
Authors: Linden Karl G. , Rosenfeldt Erik J. , Kullman Seth W. 
Published: June 2007

Due to rising concern regarding the presence of endocrine-disrupting chemicals (EDCs) in surface water and groundwater throughout the United States, Asia and Europe, treatment of these chemicals in drinking water and wastewater to protect human health and the environment is an area of great interest. Many conventional treatment schemes are relatively ineffective in removing EDCs from water and wastewater. This is concerning because these chemicals are biologically active at very low concentrations and effects of mixtures are relatively unknown.
17-α-oestradiol (E2) and 17-β-ethinyl-oestradiol (EE2), suspected EDCs, were degraded significantly by the UV/H2O2 AOP. The UV/H2O2 processes using either low or medium pressure lamps were degraded EDCs by between 80 and 99.3% at a 15 ppm H2O2 concentration and a UV dose of 1,000 mJ/cm2. Significantly greater removal was noted when the removal was based on total oestrogenic activity using a yeast oestrogen screen (YES) assay. These data indicated that a dose of less than 200 mJ/cm2 completely removed oestrogenic activity in lab water. Values for natural waters were slightly higher.
A steady state model was developed to determine EDC destruction efficiency in waters of differing quality. The model effectively predicted destruction in water, where concentrations of all scavenging species were known. Based on these results it was concluded than complete destruction of oestrogenic activity was possible under practical advanced oxidation conditions for a variety of water qualities.
Ozonation and combined ozone/H2O2, UV/ozone and UV/H2O2 for treatment of fuel oxygenates MTBE, ETBE, TAME, and DIPE from water – a comparison of removal efficiencies
Authors: Baus C. , Sona M. , Brauch H.-J. 
Published: June 2007

Methyl tert-butylether (MTBE) used as fuel oxygenate poses problems for water suppliers since it is persistent in the aquatic environment and the removal efficiency by conventional water treatment methods (aeration or activated carbon filtration) is rather low. Substitution by other ether compounds such as ethyl tert-butylether (ETBE), tert-amylmethylether (TAME) or di-isopropylether (DIPE) is discussed, however, their environmental behaviour is similar to that of MTBE. Experiments investigating the elimination efficiency of AOP were carried out in tap water and water from Lake Constance.
The elimination efficiency for all treatment processes was found to follow the order:
For all compounds under investigation, neither pure ozonation nor UV irradiation yield a considerable concentration decline. Only the formation of highly reactive OH radicals shows a potential for removing the ethers from water. Therefore the addition of H2O2 in equimolar ratio prior to ozone admixing proved to be quite efficient. The application of combined UV/H2O2 showed good results in all cases; the best concentration decline was achieved with UV/ozone. The rate of elimination of the three substitutes for MTBE (ETBE, TAME and DIPE) is higher in all processes; nevertheless, no complete removal could be achieved. Therefore, from the point of view of water suppliers, the use of other ethers as substitute for MTBE is posing the same problems as MTBE.