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The intervertebral disc (IVD) is a complex biological structure that ensures the spine strength, stability, mobility, and flexibility. This is achieved due to its biphasic nature which is attained by its solid phase (annulus fibrosus) and fluid phases (nucleus pulposus). Hence, the IVD biomechanical response to long-term loads, which is critical as it affects hydration, and nutrients-water transport influencing disc height reduction, has been further explored and mathematically modelled in this paper. An in-vitro study was performed on seven human lumbar spine specimens (L4-5), to assess if the classical rheological models and Nutting's power law can model in a simple way the intermediate characteristics between solid and fluid of the IVD. Creep tests were conducted by applying a static compression load of 500 N for 15 min. A correlation analysis was done (Pearson, p < 0.05) between the model parameters and the maximum value of Disc Height Reduction, followed by a linear regression analysis. In summary, the long-term IVD mechanical behavior was modeled in a simple way, emphasizing that yet there is no mathematical certainty about this mechanical behavior. Hence, a future aim might be to develop intervertebral disc prostheses capable of replicating only the disc mechanical response, without necessarily considering the microscopic-level biological drivers. Therefore, a future goal is to fully understand and model the disc's mechanical response toward the design of new disc prostheses that would consider only the macroscopic aspect, without considering the biological aspects.Article highlights: Intervertebral disc (IVD) biomechanics under long-term lads is still not yet fully understood. Creep curves of IVD were modelled through rheological models and Nutting’s power law. A simplified model should be pursued to describe the IVD biomechanics, to support research into IVD replacement devices. [ABSTRACT FROM AUTHOR]

We consider steady-state single-phase confined flow through a subsurface porous layer containing a displaced, fully conductive fault causing a sudden jump in the flow path, and we employ (semi-)analytical techniques to compute the corresponding pressures and fault stresses. In particular, we obtain a new solution for the pressure field with the aid of conformal mapping and a Schwarz–Christoffel transformation. Moreover, we use an existing technique to compute the poro-elastic stress field with the aid of inclusion theory. The additional resistance to fluid flow provided by a displaced fault, relative to the resistance in a layer without a fault, is a function of dip angle, fault throw divided by reservoir height, and reservoir width divided by reservoir height. Fluid flow has a larger effect on fault stresses in case of injection than in case of depletion, where injection with up-dip flow results in increased zones of fault slip near the bottom of the reservoir. Opposedly, injection with down-dip flow results in increased slip near the top of the reservoir. An order-of-magnitude estimate of the effect of steady-state flow across displaced faults in the Groningen natural gas reservoir shows that the effect on fault stresses is probably negligible. A similar estimate of the effect in low-enthalpy geothermal doublets indicates that steady-state flow may possibly play a small role, in particular close to the injector, but site-specific assessments will be necessary to quantify the effect. Article Highlights: We present a semi-analytical method to compute the pressure and flow fields in reservoirs with a displaced fault. In case of reservoir depletion, the effect of steady-state flow on the induced fault stresses is expected to be negligible. In case of fluid injection, steady-state flow may significantly affect the induced fault stresses and the potential slip patches. [ABSTRACT FROM AUTHOR]

Background: Incisional hernia prevention strategies related to fascial closure technique during laparotomy are well described yet poorly implemented in practice. The factors hindering the surgeon's adoption of evidence-based techniques for fascial closure are poorly understood and characterized. Methods: Using an exploratory sequential mixed methods design, we first collected 139 responses to a validated quantitative survey based on a Theoretical Domain Framework for adoption of healthcare practices. Mean scores from survey responses were tabulated, and the findings were used to develop an interview guide for subsequent qualitative individual semi-structured phone interviews. Fourteen practicing surgeons were purposively sampled from social media outlets and our institution. The interviews were recorded and transcribed verbatim for coding and thematic analysis using NVivo 12 Plus. Data from the surveys and interviews were integrated using joint displays. Results: Quantitative and qualitative analyses from surveys and semi-structured interviews revealed various themes related to surgeon decision-making related to fascial closure technique. Surgeons cited limitations of prior studies, applicability of findings, anecdotal experiences, and situation-specific environments that influence their decision-making. Peer influence and lack of training also affected surgeons' perspectives on integrating small bite technique into practice. Conclusion: Trial design limitations, peer influence, and patient-specific factors impacted surgeon decision-making in the choice of fascial closure technique. Future clinical trials in diverse patient populations may improve surgeons' confidence in implementing technique for fascial closure. [ABSTRACT FROM AUTHOR]

Ecological theory predicts close relationships between macroclimate and functional traits. Yet, global climatic gradients correlate only weakly with the trait composition of local plant communities, suggesting that important factors have been ignored. Here, we investigate the consistency of climate-trait relationships for plant communities in European habitats. Assuming that local factors are better accounted for in more narrowly defined habitats, we assigned > 300,000 vegetation plots to hierarchically classified habitats and modelled the effects of climate on the community-weighted means of four key functional traits using generalized additive models. We found that the predictive power of climate increased from broadly to narrowly defined habitats for specific leaf area and root length, but not for plant height and seed mass. Although macroclimate generally predicted the distribution of all traits, its effects varied, with habitat-specificity increasing toward more narrowly defined habitats. We conclude that macroclimate is an important determinant of terrestrial plant communities, but future predictions of climatic effects must consider how habitats are defined. Climatic variables are useful but often weak predictors of plant functional trait variation across ecosystems. Here the authors investigate how assigning plant communities to a habitat hierarchy improves the explanatory power of climate-trait relationships at the continental scale. [ABSTRACT FROM AUTHOR]

Copyright of Huisarts En Wetenschap is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Marine ecosystems and their associated biodiversity sustain life on Earth and hold intrinsic value. Critical marine ecosystem services include maintenance of global oxygen and carbon cycles, production of food and energy, and sustenance of human wellbeing. However marine ecosystems are swiftly being degraded due to the unsustainable use of marine environments and a rapidly changing climate. The fundamental challenge for the future is therefore to safeguard marine ecosystem biodiversity, function, and adaptive capacity whilst continuing to provide vital resources for the global population. Here, we use foresighting/hindcasting to consider two plausible futures towards 2030: a business-as-usual trajectory (i.e. continuation of current trends), and a more sustainable but technically achievable future in line with the UN Sustainable Development Goals. We identify key drivers that differentiate these alternative futures and use these to develop an action pathway towards the desirable, more sustainable future. Key to achieving the more sustainable future will be establishing integrative (i.e. across jurisdictions and sectors), adaptive management that supports equitable and sustainable stewardship of marine environments. Conserving marine ecosystems will require recalibrating our social, financial, and industrial relationships with the marine environment. While a sustainable future requires long-term planning and commitment beyond 2030, immediate action is needed to avoid tipping points and avert trajectories of ecosystem decline. By acting now to optimise management and protection of marine ecosystems, building upon existing technologies, and conserving the remaining biodiversity, we can create the best opportunity for a sustainable future in 2030 and beyond. [ABSTRACT FROM AUTHOR]

Purpose: Traumatic abdominal injury is associated with significant mortality, especially in hemodynamically unstable patients. Trauma management now supports more conservative surgical management with judicious non-operative management. The aim of this study is to use STAG data to characterize abdominal trauma outcomes, focusing on factors that may influence mortality. Methods: A retrospective analysis of prospectively collected STAG data was queried using AIS codes for Scottish abdominal trauma patients between 2011 and 2015. Patients were divided into non-survivor and survivor groups, reflecting mortality. Following this, outcomes and injury patterns of patients undergoing operative or non-operative management were compared between groups. Results: A total of 1226 were analyzed. The mean age of the cohort was 42.47 ± 19.42 years, with most patients suffering blunt injuries. Non-survivors had more severe injuries to the liver, diaphragm, pancreas, vasculature, and pelvis (p < 0.001, p = 0.005, p = 0.025, p < 0.001, and p < 0.001, respectively). Survivors more often received CT scanning (0.09 [0.03–0.27]) and underwent surgical intervention (57.4% vs 39.7%; p = 0.001). Non-survivors more often had a shorter time till operative intervention (2.6 h vs 6.3 h, p < 0.001). Conclusions: About 7% of patients in the STAG registry display abdominal injury. Mortality was found to have strong associations with older age, hemodynamic instability, poor neurological status, and head and neck injury. Outcomes may improve with the anticipated creation of the Scottish Trauma System. [ABSTRACT FROM AUTHOR]

We explore and develop a Proper Orthogonal Decomposition (POD)-based deflation method for the solution of ill-conditioned linear systems, appearing in simulations of two-phase flow through highly heterogeneous porous media. We accelerate the convergence of a Preconditioned Conjugate Gradient (PCG) method achieving speed-ups of factors up to five. The up-front extra computational cost of the proposed method depends on the number of deflation vectors. The POD-based deflation method is tested for a particular problem and linear solver; nevertheless, it can be applied to various transient problems, and combined with multiple solvers, e.g., Krylov subspace and multigrid methods. [ABSTRACT FROM AUTHOR]

Background: Complex lower limb trauma is a challenging problem. Achieving optimal long-term outcomes requires multi-disciplinary input, while patients are in hospital, and after discharge. The aim of this study was to evaluate the long-term health services resource use of patients with such injuries, in the context of a publicly funded health system. Methods: This is a population-based retrospective cohort study. Data were obtained from the Information Services Division (ISD) Scotland. We included patients with isolated lower extremity injuries, sustained between 1997 and 2015, with follow-up to 2017. Cases were identified defined by ICD-10 and OPCS-4 procedural codes and divided into two groups, complex and simple injuries and analysed for their subsequent contacts with the health service. Results: There were 42,601 patients with isolated lower limb injuries. 2976 (7.0%) had suffered complex injuries. The in-hospital mortality of these patients was 1.9%. 538 (18.1%) of the patients who sustained complex injuries underwent reconstructive surgery. Just over half attended an orthopaedic outpatient clinic in the first year, and 31.7% attended a plastic surgery clinic. Very few patients attended pain management clinics, or other clinics that might provide pain services. Conclusions: Only a small proportion of patients who undergo reconstructive surgery are followed up by specialist services. The reasons for such low follow-up rates are not obvious. Our findings raise the question of whether the health service in Scotland has sufficient resources to optimise functional outcome in this patient group. Level of evidence: Level III, risk / prognostic study [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the feasibility of enrolling patients in a randomized controlled trial (RCT) comparing endovascular coils (EC) and vascular plugs (VP) for proximal splenic artery embolization (pSAE) in high-grade splenic trauma, and to collect data to inform the design of a larger clinical effectiveness trial. Methods: Single-center, prospective, RCT of patients with Grade III–V splenic injuries selected for nonoperative management. Patients were randomized to pSAE with EC or VP. The main outcome was feasibility. We also evaluated technical success, time to stasis, complications, mortality, and splenectomy rates, by estimating rates and 95% confidence intervals. Results: 46 of 50 eligible patients were enrolled (92%, 95% CI 90–100%). Overall, splenic salvage was 98% (45/46; 95% CI 94–100%). Primary technical success was observed in 22 EC patients (96%; 95% CI 87–100%) and 20 VP patients (87%; 95% CI 73–100%). Bayesian analysis suggests a > 80% probability that primary technical success is higher for EC. Two complications (one major and one minor) occurred in the EC group (9%; CI 0–20%) and one major complication occurred in the VP group (4%; CI 0–13%). Conclusions: Randomized comparisons of endovascular devices used for pSAE after trauma are feasible. pSAE using either EC or VP results in excellent rates of splenic salvage in trauma patients with high-grade splenic injuries. These high rates of splenic salvage and low rates of complications make their use as a primary outcome in a future trial problematic. Consideration should be given to technical parameters as a primary outcome for future trials. [ABSTRACT FROM AUTHOR]

In data assimilation problems, various types of data are naturally linked to different spatial resolutions (e.g., seismic and electromagnetic data), and these scales are usually not coincident to the subsurface simulation model scale. Alternatives like upscaling/downscaling of the data and/or the simulation model can be used, but with potential loss of important information. Such alternatives introduce additional uncertainties which are not in the nature of the problem description, but the result of the post processing of the data or the geo-model. To address this issue, a novel multiscale (MS) data assimilation method is introduced. The overall idea of the method is to keep uncertain parameters and observed data at their original representation scale, avoiding upscaling/downscaling of any quantity. The method relies on a recently developed mathematical framework to compute adjoint gradients via a MS strategy in an algebraic framework. The fine-scale uncertain parameters are directly updated and the MS grid is constructed in a resolution that meets the observed data resolution. This formulation therefore enables a consistent assimilation of data represented at a coarser scale than the simulation model. The misfit objective function is constructed to keep the MS nature of the problem. The regularization term is represented at the simulation model (fine) scale, whereas the data misfit term is represented at the observed data (coarse) scale. The computational aspects of the method are investigated in a simple synthetic model, including an elaborate uncertainty quantification step, and compared to upscaling/downscaling strategies. The experiment shows that the MS strategy provides several potential advantages compared to more traditional scale conciliation strategies: (1) expensive operations are only performed at the coarse scale; (2) the matched uncertain parameter distribution is closer to the "truth"; (3) faster convergence behavior occurs due to faster gradient computation; and (4) better uncertainty quantification results are obtained. The proof-of-concept example considered in this paper sheds new lights on how one can reduce uncertainty within fine-scale geo-model parameters with coarse-scale data, without the necessity of upscaling/downscaling the data nor the geo-model. The developments demonstrate how to consistently formulate such a gradient-based MS data assimilation strategy in an algebraic framework which allows for implementation in available computational platforms. [ABSTRACT FROM AUTHOR]

A generic framework for the computation of derivative information required for gradient-based optimization using sequentially coupled subsurface simulation models is presented. The proposed approach allows for the computation of any derivative information with no modification of the mathematical framework. It only requires the forward model Jacobians and the objective function to be appropriately defined. The flexibility of the framework is demonstrated by its application in different reservoir management studies. The performance of the gradient computation strategy is demonstrated in a synthetic water-flooding model, where the forward model is constructed based on a sequentially coupled flow-transport system. The methodology is illustrated for a synthetic model, with different types of applications of data assimilation and life-cycle optimization. Results are compared with the classical fully coupled (FIM) forward simulation. Based on the presented numerical examples, it is demonstrated how, without any modifications of the basic framework, the solution of gradient-based optimization models can be obtained for any given set of coupled equations. The sequential derivative computation methods deliver similar results compared to FIM methods, while being computationally more efficient. [ABSTRACT FROM AUTHOR]

In reservoir engineering, it is attractive to characterize the difference between reservoir models in metrics that relate to the economic performance of the reservoir as well as to the underlying geological structure. In this paper, we develop a dissimilarity measure that is based on reservoir flow patterns under a particular operational strategy. To this end, a spatial-temporal tensor representation of the reservoir flow patterns is used, while retaining the spatial structure of the flow variables. This allows reduced-order tensor representations of the dominating patterns and simple computation of a flow-induced dissimilarity measure between models. The developed tensor techniques are applied to cluster model realizations in an ensemble, based on similarity of flow characteristics. [ABSTRACT FROM AUTHOR]

Advanced data acquisition and process modelling technology provide 'real-time' data and decision support capacity for different aspects of the resource extraction process. Closed-loop approaches have recently been applied to utilize information extracted from these data in combination with advanced computing technology for improved production control in mineral resource extraction. Similar techniques have been developed in the petroleum industry combining computer-assisted model updating with model-based production optimization. This contribution reviews recent developments and methods applied, highlights differences and assesses the potential value addition for both application domains. The focus here is on the two main constituents of closed-loop concepts, data assimilation and optimization. Technological readiness of the constituents is assessed, and gaps for further technology development are identified. The value added is illustrated by means of selected cases. [ABSTRACT FROM AUTHOR]

Many aspects of reservoir management can be expected to benefit from the application of computational optimization procedures. The focus of this review paper is on well control optimization, which entails the determination of well settings, such as flow rates or bottom hole pressures, that maximize a particular objective function. As is the case with most reservoir-related optimizations, this problem is in general computationally demanding since function evaluations require reservoir simulation runs. Here we describe reduced-order modeling procedures, which act to accelerate these simulation runs, and discuss their use within the context of well control optimization. The techniques considered apply proper orthogonal decomposition (POD), which enables the representation of reservoir states (e.g., pressure and saturation in every grid block) in terms of a highly reduced set of variables. Two basic approaches are described-the direct application of POD-based reduction at each Newton iteration, and a trajectory piecewise linearization (POD-TPWL) procedure that applies POD to a linearized representation of the governing equations. Both procedures require one or more pre-processing 'training' simulation runs using the original full-order model. The use of both gradient-based optimization methods (including adjoint procedures) and direct search approaches with reduced-order models is described. Several concepts relevant to the general topic, including adjoint formulations and controllability, are also reviewed. Numerical results are presented for both approaches. In particular, the POD-TPWL procedure is applied to a computationally demanding bi-objective optimization problem, where it is shown to provide reasonable accuracy and a high degree of speedup. [ABSTRACT FROM AUTHOR]

In many social insects, fertility of the reproductive caste is communicated via cuticular chemistry. Changes in cuticular profiles have been correlated to ovarian development. However, an effect of insemination has been neglected in the majority of studies so far. In Bombus terrestris, we stimulated virgin queens to found colonies without being inseminated and compared their cuticular hydrocarbon profile (CHC) to other females in different insemination and breeding statuses. The analysis of the CHC profiles showed an effect of both insemination and ovarian development on the cuticular profile. Thus, insemination besides ovarian development might be received by workers in bumblebees as a potential cue for fertility. [ABSTRACT FROM AUTHOR]

This work proposes a new hierarchical multiscale optimization technique to improve the performance of life-cycle production optimization. This approach represents a combination of two previous multiscale approaches presented in the literature and is theoretically motivated by the concept of refinement indicators. The new algorithm is applied to two example problems, and its performance is compared with other life-cycle production optimization algorithms that have been proposed in the literature including the two hierarchical multiscale optimization methods on which it is based. In a separate paper (Oliveira and Reynolds ), the proposed algorithm is successfully applied to a field case. [ABSTRACT FROM AUTHOR]

OBJECTIVES:This multicenter, phase 3 trial evaluated oral lubiprostone for constipation associated with non-methadone opioids in patients with chronic noncancer-related pain.METHODS:Adults with opioid-induced constipation (OIC; <3 spontaneous bowel movements [SBMs] per week) were randomized 1:1 to double-blind lubiprostone 24 μg or placebo twice daily for 12 weeks. The primary end point was the overall SBM response rate. Responders had at least moderate response (≥1 SBM improvement over baseline frequency) in all treatment weeks with available observed data, as well as full response (≥3 SBMs per week) for at least 9 of the 12 treatment weeks.RESULTS:In total, 431 patients were randomized; 212 each received lubiprostone and placebo, and 7 were not treated. Overall, the SBM response rate was significantly higher for patients treated with lubiprostone vs. placebo (27.1 vs. 18.9%, respectively; P=0.030). Overall mean change from baseline in SBM frequency was significantly greater with lubiprostone vs. placebo (3.2 vs. 2.4, respectively; P=0.001). The median time to first SBM was significantly shorter with lubiprostone vs. placebo (23.5 vs. 37.7 h, respectively; P=0.004). Compared with placebo, the patients treated with lubiprostone exhibited significant improvements in straining (P=0.004), stool consistency (P<0.001), and constipation severity (P=0.010). No significant differences were observed in quality-of-life measures or the use of rescue medication; however, the percentage of patients who used rescue medication was consistently lower in the lubiprostone group than in the placebo group at months 1 (34.9 vs. 37.7%), 2 (23.4 vs. 26.6%), and 3 (20.5 vs. 22.0%). Adverse events (AEs) >5% were diarrhea, nausea, vomiting, and abdominal pain (lubiprostone: 11.3, 9.9, 4.2, and 7.1%, respectively; placebo, 3.8, 4.7, 5.2, and 0%, respectively). None of the serious AEs (lubiprostone, 3.3%; placebo, 2.8%) were related to lubiprostone.CONCLUSIONS:Lubiprostone significantly improved symptoms of OIC and was well tolerated in patients with chronic noncancer pain. [ABSTRACT FROM AUTHOR]

An adjoint formulation for the gradient-based optimization of oil-gas compositional reservoir simulation problems is presented. The method is implemented within an automatic differentiation-based compositional flow simulator (Stanford's Automatic Differentiation-based General Purpose Research Simulator, AD-GPRS). The development of adjoint procedures for general compositional problems is much more challenging than for oil-water problems due to the increased complexity of the code and the underlying physics. The treatment of nonlinear constraints, an example of which is a maximum gas rate specification in injection or production wells, when the control variables are well bottom-hole pressures, poses a particular challenge. Two approaches for handling these constraints are presented-a formal treatment within the optimizer and a simpler heuristic treatment in the forward model. The relationship between discrete and continuous adjoint formulations is also elucidated. Results for four example cases of increasing complexity are presented. Improvements in the objective function (cumulative oil produced) relative to reference solutions range from 4.2 to 11.6 %. The heuristic treatment of nonlinear constraints is shown to offer a cost-effective means for obtaining feasible solutions, which are, in some cases, better than those obtained using the formal constraint handling procedure. [ABSTRACT FROM AUTHOR]

Reservoir simulation models are frequently used to make decisions on well locations, recovery optimization strategies, etc. The success of these applications is, among other aspects, determined by the controllability and observability properties of the reservoir model. In this paper, it is shown how the controllability and observability of two-phase flow reservoir models can be analyzed and quantified with aid of generalized empirical Gramians. The empirical controllability Gramian can be interpreted as a spatial covariance of the states (pressures or saturations) in the reservoir resulting from input perturbations in the wells. The empirical observability Gramian can be interpreted as a spatial covariance of the measured bottom-hole pressures or well bore flow rates resulting from state perturbations. Based on examples in the form of simple homogeneous and heterogeneous reservoir models, we conclude that the position of the wells and of the front between reservoir fluids, and to a lesser extent the position and shape of permeability heterogeneities that impact the front, are the most important factors that determine the local controllability and observability properties of the reservoir. [ABSTRACT FROM AUTHOR]

Background: Deterioration of left ventricular (LV) function after myocardial infarction (MI) is a major cause of heart failure. Myocardial perfusion performance may play an important role in deterioration or improvement in LV function after MI. The aim of this study was to evaluate the myocardial perfusion reserve (MPR) and stress perfusion in deteriorating and non-deteriorating LV segments in patients after MI by PET and MRI, respectively. Methods: Regional wall thickening of 352 segments in 22 patients was assessed at 4 and 24 months after MI by cardiac MRI. PET was performed to evaluate MPR and adenosine stress N-ammonia perfusion 24 months after MI. Segments were divided into four groups according to deterioration or improvement in wall thickening. Results: Normal functional segments at 4 months after MI that remained stable had a significantly higher mean MPR and mean stress perfusion PET value than deteriorated segments ( p < 0.001). Furthermore, dysfunctional segments that improved had a significantly higher mean stress perfusion PET value than dysfunctional segments that remained dysfunctional ( p < 0.001). Conclusion: This study demonstrated the additional value of myocardial perfusion assessment in relation to the functional integrity of the injured myocardium. Segmental functional LV improvement after MI was associated with better regional myocardial perfusion characteristics. Furthermore, the amount of wall thickening reduction was associated with regional myocardial perfusion abnormalities in patients after MI. [ABSTRACT FROM AUTHOR]

Background: Home parenteral nutrition (HPN) is a life-saving therapy for patients with diseases that preclude adequate oral or enteral food intake. HPN has a large impact on daily life. Many patients suffer from fatigue and depression, and they experience limits in social activities. This all contributes to a lower quality of life. Purpose: Fatigue is the most frequently mentioned problem in Dutch HPN patients. Therefore, we studied the prevalence, course and predictors of fatigue in these patients. Methods: Patients completed questionnaires at baseline and follow-up (12 months later). Measurements included fatigue, depression, functional impairment, social support, self-efficacy, coping, anxiety and acceptance. Laboratory measures, including total bilirubin, creatinine, albumin and haemoglobin levels, were obtained from the medical records. Descriptive statistics, correlations and linear regression analysis were performed. Results: The response rate was 71% ( n = 75). Sixty-five per cent of the patients were severely fatigued ( n = 49). Eighty-nine per cent experienced persistent fatigue. Baseline fatigue predicted 57% of the variance of fatigue at follow-up, and avoidance was responsible for 3% of the variance. No significant correlations between fatigue and laboratory measures were found. A cross-sectional analysis showed that 46% of the variance of fatigue was explained by functional impairment, self-efficacy and depression. Conclusion: Severe fatigue is a persistent problem for HPN patients. Baseline fatigue was the strongest predictor of fatigue at follow-up. Functional impairment, self-efficacy and depression are strongly related to fatigue. Early recognition and treatment of fatigue are important. [ABSTRACT FROM AUTHOR]

Gradient-based history matching algorithms can be used to adapt the uncertain parameters in a reservoir model using production data. They require, however, the implementation of an adjoint model to compute the gradients, which is usually an enormous programming effort. We propose a new approach to gradient-based history matching which is based on model reduction, where the original (nonlinear and high-order) forward model is replaced by a linear reduced-order forward model and, consequently, the adjoint of the tangent linear approximation of the original forward model is replaced by the adjoint of a linear reduced-order forward model. The reduced-order model is constructed with the aid of the proper orthogonal decomposition method. Due to the linear character of the reduced model, the corresponding adjoint model is easily obtained. The gradient of the objective function is approximated, and the minimization problem is solved in the reduced space; the procedure is iterated with the updated estimate of the parameters if necessary. The proposed approach is adjoint-free and can be used with any reservoir simulator. The method was evaluated for a waterflood reservoir with channelized permeability field. A comparison with an adjoint-based history matching procedure shows that the model-reduced approach gives a comparable quality of history matches and predictions. The computational efficiency of the model-reduced approach is lower than of an adjoint-based approach, but higher than of an approach where the gradients are obtained with simple finite differences. [ABSTRACT FROM AUTHOR]

Copyright of TSG: Tijdschrift Voor Gezondheidswetenschappen is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

NSAIDs are among the most often used drugs worldwide. Numerous NSAID users are at risk for developing gastrointestinal complications. The purpose of this review was to identify and stratify risk factors for gastrointestinal complications in NSAID users documented in guidelines and consensus agreements, and to collect recommendations regarding over-the-counter (OTC) NSAID use. To facilitate this, a PubMed search from 1 January 1999 until 1 March 2009 was performed, resulting in the inclusion of nine English-language guidelines in our analysis. Risk factors were defined as 'definite' if mentioned in all guidelines; otherwise they were defined as 'controversial' risk factors. 'Definite' risk factors were a history of (complicated) peptic ulcer disease, older age (cut-off range 60-75 years), concomitant anticoagulant or corticosteroid use and multiple NSAID use, including low-dose aspirin (acetylsalicylic acid). 'Controversial' risk factors were high-dose NSAID use, concomitant clopidogrel or selective serotonin reuptake inhibitor use, a history of gastrointestinal symptoms, rheumatoid arthritis disability and cardiovascular disease. Infection with Helicobacter pylori was identified as an additive risk factor. Risk factors in OTC NSAID users were difficult to identify in the current literature. Risk factors were not all uniformly present in analysed guidelines and consensus agreements. We identified a history of (complicated) peptic ulcer disease, older age, concomitant anticoagulant or corticosteroid use and multiple NSAID use, including low-dose aspirin, as definite gastrointestinal risk factors in NSAID users. [ABSTRACT FROM AUTHOR]

Copyright of Huisarts En Wetenschap is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cyclooxygenases (COX) catalyze the conversion of arachidonic acid to prostaglandins (PGs). COX-inhibiting drugs, such as nonsteroidal anti-inflammatory drugs (NSAIDs), increase the risk for peptic ulcer disease. As a corollary, COX gene polymorphisms could be important in the pathogenesis of peptic ulcer disease because these affect prostaglandin formation and impair its protective effect at the level of the gastric mucosa. This study was designed to investigate the association between the functional single-nucleotide polymorphism, A-842G/C50T, in the COX-1 gene and peptic ulcer bleeding. We obtained DNA samples from 106 patients who underwent upper gastrointestinal endoscopy because of bleeding peptic ulcer disease and from 88 healthy control subjects. Genetic polymorphism in A-842G/C50T was determined by PCR followed by restriction-fragment-length-polymorphism analysis. Adjusted logistic regression analysis was performed to evaluate the associations. Risk factors associated with peptic ulcer bleeding were male gender (odds ratio, 4.78; 95% confidence interval, 2.6-8.8) and NSAID/aspirin-use (odds ratio, 38.39; 95% confidence interval, 14.2-103.6). The A-842G/C50T heterozygote was less frequent in peptic ulcer bleeding (n = 7) compared with healthy control subjects (n = 11). The adjusted risk for peptic ulcer bleeding among individuals who were heterozygote for the A-842G/C50T polymorphism was 0.75 (range, 0.19-3.01) compared with wild type. The COX-1 A-842G/C50T SNP does not influence the risk for developing peptic ulcer bleeding. [ABSTRACT FROM AUTHOR]

Purpose. 2-(18F)- Fluoro-2-deoxy-D)-glucose positron emission tomography (FDG-PET) is an imaging technique which enables detection of malignancies. FDG-PET has been established as a tool for the diagnosis of pancreatic carcinoma (CA). Early detection is mandatory as cure can only he achieved in non-advanced disease. This is, however, very difficult with conventional radiological techniques. Patients with chronic pancreatitis (CP) are at risk of developing CA. A simple, reliable screening method for malignant degeneration is highly desirable. We set out to investigate whether FDG-PET is able to detect CA in the setting of CP and can fulfiI a potential role in the early detection of CA in CP. Methods. FDG-PFT was performed in 77 CP patients and in six patients with CP complicated by CA (CP + CA). We included 26 CA patients as a positive control. A positive scan was defined as focal FDG accumulation in the pancreas region. Results. In 67 of the 77 CP (87%) patients, pancreatic FDG accumulation was absent. Six patients had significant accumulation. In CA, 24/26 patients had a positive PET. Five out of the six patients with CP + CA had local uptake, while minor uptake was seen in one patient. FDG-PET was positive in almost all CA patients and CP + CA patients. FDG-PET was negative in the large majority (87%) of CP patients, which suggests that a positive PET scan in CP patients must lead to efforts to exclude a malignancy. Conclusion. These data suggest that FDG-PET has a potential role as a diagnostic tool for detecting CA in long-standing CP. [ABSTRACT FROM AUTHOR]

Pollution by heavy metals over large areas and long periods of time may cause chronic damage to living organisms and must be carefully controlled. One way to determine the extent of environmental contamination is by measuring the levels of contaminants in plants. The use of mosses as biomonitors is a convenient method to determine levels of (atmospheric) deposition, as terrestrial mosses obtain most of their supply of mineral elements from precipitation and dry deposition of airborne particles. Mosses have therefore received increasing attention as a suitable tool for monitoring regional patterns of elemental deposition from the atmosphere in large-scale studies in various countries, in areas close to industrial installations as well as in areas not expected to be contaminated. Although this technique is widely known, ecological studies of this type have rarely been done in Portugal. The aim of this paper is to evaluate and compare the spatial distribution of heavy metals in Hypnum cupressiforme, Pleurozium schreberi, Dicranum scoparium and Polytrichum piliferum collected from the Serra da Estrela natural park in Portugal and in the Veluwezoom natural park in the Netherlands. The selected species are the most widely used bryophytes for biomonitoring in the boreal region. The popularity of these species for this purpose is due to their wide ecological amplitude and distribution. At 54 sampling sites in both nature parks, samples of Hypnum cupressiforme, Pleurozium schreberi, Dicranum scoparium and Polytrichum piliferum were collected. Plant digests were analysed for Al, Ba, Ca, Cr, Fe, K, Mg, Mn, Ni, Sr, V, Zn, Pb, Cu, Cd, N and P. Differentiations between sampling sites in terms of concentrations of elements in mosses were evaluated by ANOVA and the least significant difference was calculated. The normality of the analysed features was checked with the chi square test. After standardization, the matrix of 54 samples and 10 heavy metals was subjected to numerical classification to detect groups of samples with similar patterns of metal concentrations. The clustering algorithm was prepared with Ward’s method, and the City Block Manhattan method was used for the similarity measure. Metals and samples were also subjected to ordination to reveal possible gradients of heavy metal levels, using PCA. Correlations were calculated between concentrations of metals and factors 1 and 2, allowing the dependence between the concentration of metals and factors (factor loading) to be estimated. All species examined in both areas contained elevated levels of Mn and Pb. For each particular species, concentrations of N, P and Pb were significantly higher at Serra da Estrela, while concentrations of Cu were significantly higher at the Veluwezoom. Mosses from Portugal and the Netherlands differed significantly mainly in the concentrations of Al, Ba, Cr, Fe, Mn, Ni, Pb and V. This differentiation did not exceed that within the mosses from Portugal. Mosses from Portugal and the Netherlands differ significantly mainly in the concentrations of Al, Ba, Cr, Fe, Mn, Ni, Pb and V. This differentiation does not exceed the differentiation within the mosses from Portugal. Further research is required into the origin and deposition of the polluting elements in other environmental compartments. [ABSTRACT FROM AUTHOR]

The distal gut hormone peptide YY (PYY) mediates feedback inhibition of gastric acid secretion, gastrointestinal motility, and pancreatic enzyme output. To investigate the influence of maldigestion on PYY, we determined plasma PYY levels in patients with celiac disease under basal conditions and in response to intraduodenal fat. Basal PYY was increased in untreated celiac patients (N = 13) compared to patients on a gluten free diet (N = 9) [15.6 (11.8-27.0) pM vs 12.2 (10.1-13.1) pM; P < 0.05] and compared to control subjects (N = 15) [9.5 (8.3-10.4) pM; P < 0.001]. Integrated PYY in response to intraduodenally infused predigested fat (1071+/-293 pM 80 min) was significantly (P < 0.05) greater than in response to undigested fat (322+/-223 pM 80 min) in six untreated celiacs. Plasma concentrations of PYY and cholecystokinin were strongly correlated (r = 0.79; P < 0.001). We conclude that basal PYY levels in untreated celiac disease are elevated, that predigestion of fat enhances PYY release in these patients, and that PYY secretion is correlated with CCK release. [ABSTRACT FROM AUTHOR]

Previously we demonstrated an inverse relation between cancer of the gastrointestinal tract and glutathione S-transferase activity of the gastrointestinal mucosa. Chronic infection with H. pylori has been associated with an increased risk of gastric cancer. The aim of this study was to investigate the levels of glutathione and glutathione S-transferase activity in H. pylori-infected and noninfected antral mucosa. Glutathione and glutathione S-transferases were measured in antral biopsies of patients with nonulcer dyspepsia without H. pylori infection (A), with prior H. pylori infection who became H. pylori negative after eradication therapy (B) and with proven H. pylori infection (C). Glutathione concentration and glutathione S-transferase activity in group A were 31.0 (range 6.0-59.6) nmol/mg protein and 810 (range 165-1312) nmol/min/mg protein, in group B 27.0 (range 5.0-53.8) nmol/mg protein and 745 (range 403-1199) nmol/min/mg protein, and in group C 18.5 (range 1.6-55.8) nmol/mg protein and 572 (range 144-1047) nmol/min/mg protein, respectively. The glutathione and glutathione S-transferase values were significantly lower in patients infected with H. pylori than in patients who were H. pylori negative. [ABSTRACT FROM AUTHOR]

The vestibulo-ocular pathways have been examined in embryonic chicks using horseradish peroxidase or dil as retrograde and anterograde tracers. The vestibular neurons project to the rostral, external eye motor nuclei over one or the other of three separate pathways; the ipsilateral and controlateral medial longitudinal fascicle and the contralateral brachium conjunctivum. The brachium conjunctivum component originates dorsally in the superior vestibular region and projects to the contralateral inferior oblique and superior rectus motor nuclei. An ipsilateral component of the medial longitudinal fascicle is labeled from more ventral sites in the vestibulo-cerebellar process and terminates in the ipsilateral superior oblique and inferior rectus nuclei. The contralateral medial longitudinal fascicle component originates still more ventrally and terminates in the contralateral superior oblique and inferior rectus motor nuclei. Accordingly, the vestibulo-ocular pathways in chickens operate predominantly on synergistic pairs of external eye muscles. These selective terminal fields are established within a day or two after the first terminals invade the eye motor nuclei during embryo-genesis. [ABSTRACT FROM AUTHOR]

Impaired postprandial gallbladder emptying in celiac disease has been attributed to an absence of appropriate cholecystokinin release. To determine if a flat jejunal mucosa in celiac patients is related to a reduced cholecystokinin-secreting capacity, increasing doses of bombesin were infused into six patients with celiac disease and a flat jejunal mucosa (group A), in seven celiac patients with a normal jejunal mucosa while on a gluten-free diet (group B), and in seven healthy controls (group C). Bombesin induced significant (P < 0.05) increments of plasma CCK to a maximum value of 1.0 +/- 0.3 pM in group A, to 1.5 +/- 0.3 pM in group B, and to 1.2 +/- 0.3 pM in group C (NS between groups), that were accompanied by significant (P < 0.05) gallbladder emptying responses of 70 +/- 4% in group A, 47 +/- 10% in group B and 65 +/- 5% in group C. Dose-response relationships were not different between groups. We conclude that there is no major impairment of gallbladder responsiveness to bombesin or of cholecystokinin-secreting capacity in patients with a flat jejunal mucosa due to celiac disease. [ABSTRACT FROM AUTHOR]

Several major pancreatic resections have been proven effective for the relief of pain caused by chronic pancreatitis. Distinct morbidity, however, and interference with gastrointestinal hormone response patterns have been documented. We have tested the effect of the duodenumpreserving resection of the head of the pancreas on basal and meal-stimulated (TMA) blood glucose and plasma insulin, glucagon, pancreatic polypeptide (PP), and cholecystokinin levels (CCK) in dogs (n =9). Intravenous glucose tolerance tests (IVGTT) were performed in addition. Tests were performed before and at six and 12 wk after operation. Results of TMA were expressed in basal and integrated levels for glucose, insulin and glucagon. PP and CCK responses were expressed in incremental levels, results of IVGTT as K-values and integrated insulin response. Basal glucagon, insulin, and PP levels (mean ± SEM) decreased from 86 ± 23 to 44 ± 10 pg/mL, from 14 ± 3 to 8±1 μU/mL, and from 75 ±11 to 24±3 pM, respectively (p<.05), basal CCK values were not affected. Incremental PP response decreased from 363 ±39 to 10±4 pM at 12 wk. Incremental CCK, integrated insulin, and glucagon values showed no significant changes. K-values dropped from 3.5 ±0.3 to 1.5 ±0.2 at six weeks, and glucose-induced integrated insulin from 1488 ±235 to 701 ± 108. All parameters measured stabilized as of six weeks after operation. It is concluded that duodenumpreserving resection of the pancreatic head leads to vagal denervation of the pancreas and accelerated gastric emptying. Probably as a result of the unaffected CCK response, no quantitative changes in integrated insulin and glucagon response were observed after operation. The decrease in glucose tolerance may be caused by a combination of decreased islet-mass and qualitative changes in insulin delivery, as a result of distinctive histological changes after ductal injection with Tissucol. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to determine if there is an abnormality of circulating gastrointestinal hormones in patients with severe idiopathic constipation. Methods: Twelve patients, all female (median age 34 yr) and 12 healthy controls (eight female, median age 32 yr) were studied. A radioisotope-labeled solid/liquid meal was ingested, and the serum hormone response, as well as the relationship between serum hormones and rates of gastric emptying and small intestinal transit, were studied for 180 min postprandially. Results: Somatostatin levels were higher in patients with constipation (basal level, controls vs patients, 31 vs 57 pmol/L, p < 0.05, median values; peak level, 48 vs 60, p < 0.05). Patients showed a significantly lower somatostatin integrated incremental meal response (2182 vs 104, p < 0.05). No correlation was found between the somatostatin levels and rates of upper gastrointestinal transit in patients. Pancreatic glucagon was significantly decreased (p = 0.04). Enteroglucagon levels were significantly lower (p < 0.05) in patients between 30 and 60 min after the meal. The peak found after the meal in normal subjects was absent. Basal levels of pancreatic glucagon correlated with small bowel transit by two different measures: head of meal (r = 0.69, p = 0.03) and cecal filling at the time of 50% gastric emptying (r = 0.84, p = 0.002). No significant differences between the two groups could he found for basal and peak levels at different times and integrated incremental response to the meal for insulin, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1 (GLP-1), cholecystokinin (CCK), gastrin, pancreatic polypeptide (PP), motilin, neurotensin, and peptide tyrosine tyrosine (PYY). Conclusion: Patients with severe idiopathic constipation have specific abnormalities of circulating gut hormones that most likely play a role in gastrointestinal motility and that may he of pathophysiological... [ABSTRACT FROM AUTHOR]

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