bluuebunny/crossref_metadata_2025 huggingface dataset:
Hyperglycemia in apolipoprotein E-deficient mouse strains with different atherosclerosis susceptibility
Authors: Li Jing , Wang Qian , Chai Weidong , Chen Mei-Hua , Liu Zhenqi , Shi Weibin
Published: December 2011

Background

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of atherosclerotic vascular disease, but it is unknown whether the other way around is true too. C57BL/6 (B6) and BALB/cJ (BALB) are two mouse strains that differ markedly in their susceptibility to atherosclerosis. In this study we investigated the development of diet-induced T2DM in these two strains.

Methods and Results

When deficient in apolipoprotein E (apoE-/-) and fed a Western diet for 12 weeks, atherosclerosis-susceptible B6 mice developed significant hyperglycemia. In contrast, atherosclerosis-resistant BALB apoE-/- mice had much lower plasma glucose levels than B6.apoE-/- mice on either chow or Western diet and during an intraperitoneal glucose tolerance test. In response to glucose BALB.apoE-/- mice displayed both the first and second phases of insulin secretion but the second phase of insulin secretion was absent in B6.apoE-/- mice. In response to insulin B6.apoE-/- mice showed a deeper and longer-lasting fall in blood glucose levels while BALB.apoE-/- mice showed little reduction in glucose levels. Pancreatic islet area of BALB.apoE-/- mice on light microscopy nearly doubled the area of B6.apoE-/- mice. Most circulating proinflammatory cytokines were lower in BALB.apoE-/- than in B6.apoE-/- mice on the Western diet, as determined by protein arrays. Increased macrophage infiltration in islets was observed in B6.apoE-/- mice by immunostaining for Mac2 and also by flow cytometry.

Conclusion

This study demonstrates that defects in insulin secretion rather than defects in insulin resistance explain the marketed difference in susceptibility to T2DM in the B6.apoE-/- and BALB.apoE-/- mouse model. A smaller islet mass and more prominent islet inflammation may explain the vulnerability of B6.apoE-/- mice to diet-induced diabetes.
The signaling pathway of Campylobacter jejuni-induced Cdc42 activation: Role of fibronectin, integrin beta1, tyrosine kinases and guanine exchange factor Vav2
Authors: Krause-Gruszczynska Malgorzata , Boehm Manja , Rohde Manfred , Tegtmeyer Nicole , Takahashi Seiichiro , Buday Laszlo , Oyarzabal Omar A , Backert Steffen
Published: December 2011

Background

Host cell invasion by the foodborne pathogen Campylobacter jejuni is considered as one of the primary reasons of gut tissue damage, however, mechanisms and key factors involved in this process are widely unclear. It was reported that small Rho GTPases, including Cdc42, are activated and play a role during invasion, but the involved signaling cascades remained unknown. Here we utilised knockout cell lines derived from fibronectin-/-, integrin-beta1-/-, focal adhesion kinase (FAK)-/- and Src/Yes/Fyn-/- deficient mice, and wild-type control cells, to investigate C. jejuni-induced mechanisms leading to Cdc42 activation and bacterial uptake.

Results

Using high-resolution scanning electron microscopy, GTPase pulldowns, G-Lisa and gentamicin protection assays we found that each studied host factor is necessary for induction of Cdc42-GTP and efficient invasion. Interestingly, filopodia formation and associated membrane dynamics linked to invasion were only seen during infection of wild-type but not in knockout cells. Infection of cells stably expressing integrin-beta1 variants with well-known defects in fibronectin fibril formation or FAK signaling also exhibited severe deficiencies in Cdc42 activation and bacterial invasion. We further demonstrated that infection of wild-type cells induces increasing amounts of phosphorylated FAK and growth factor receptors (EGFR and PDGFR) during the course of infection, correlating with accumulating Cdc42-GTP levels and C. jejuni invasion over time. In studies using pharmacological inhibitors, silencing RNA (siRNA) and dominant-negative expression constructs, EGFR, PDGFR and PI3-kinase appeared to represent other crucial components upstream of Cdc42 and invasion. siRNA and the use of Vav1/2-/- knockout cells further showed that the guanine exchange factor Vav2 is required for Cdc42 activation and maximal bacterial invasion. Overexpression of certain mutant constructs indicated that Vav2 is a linker molecule between Cdc42 and activated EGFR/PDGFR/PI3-kinase. Using C. jejuni mutant strains we further demonstrated that the fibronectin-binding protein CadF and intact flagella are involved in Cdc42-GTP induction, indicating that the bacteria may directly target the fibronectin/integrin complex for inducing signaling leading to its host cell entry.

Conclusion

Collectively, our findings led us propose that C. jejuni infection triggers a novel fibronectin→integrin-beta1→FAK/Src→EGFR/PDGFR→PI3-kinase→Vav2 signaling cascade, which plays a crucial role for Cdc42 GTPase activity associated with filopodia formation and enhances bacterial invasion.
Complement activating antibodies to myelin oligodendrocyte glycoprotein in neuromyelitis optica and related disorders
Authors: Mader Simone , Gredler Viktoria , Schanda Kathrin , Rostasy Kevin , Dujmovic Irena , Pfaller Kristian , Lutterotti Andreas , Jarius Sven , Di Pauli Franziska , Kuenz Bettina , Ehling Rainer , Hegen Harald , Deisenhammer Florian , Aboul-Enein Fahmy , Storch Maria K , Koson Peter , Drulovic Jelena , Kristoferitsch Wolfgang , Berger Thomas , Reindl Markus
Published: December 2011

Background

Serum autoantibodies against the water channel aquaporin-4 (AQP4) are important diagnostic biomarkers and pathogenic factors for neuromyelitis optica (NMO). However, AQP4-IgG are absent in 5-40% of all NMO patients and the target of the autoimmune response in these patients is unknown. Since recent studies indicate that autoimmune responses to myelin oligodendrocyte glycoprotein (MOG) can induce an NMO-like disease in experimental animal models, we speculate that MOG might be an autoantigen in AQP4-IgG seronegative NMO. Although high-titer autoantibodies to human native MOG were mainly detected in a subgroup of pediatric acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) patients, their role in NMO and High-risk NMO (HR-NMO; recurrent optic neuritis-rON or longitudinally extensive transverse myelitis-LETM) remains unresolved.

Results

We analyzed patients with definite NMO (n = 45), HR-NMO (n = 53), ADEM (n = 33), clinically isolated syndromes presenting with myelitis or optic neuritis (CIS, n = 32), MS (n = 71) and controls (n = 101; 24 other neurological diseases-OND, 27 systemic lupus erythematosus-SLE and 50 healthy subjects) for serum IgG to MOG and AQP4. Furthermore, we investigated whether these antibodies can mediate complement dependent cytotoxicity (CDC). AQP4-IgG was found in patients with NMO (n = 43, 96%), HR-NMO (n = 32, 60%) and in one CIS patient (3%), but was absent in ADEM, MS and controls. High-titer MOG-IgG was found in patients with ADEM (n = 14, 42%), NMO (n = 3, 7%), HR-NMO (n = 7, 13%, 5 rON and 2 LETM), CIS (n = 2, 6%), MS (n = 2, 3%) and controls (n = 3, 3%, two SLE and one OND). Two of the three MOG-IgG positive NMO patients and all seven MOG-IgG positive HR-NMO patients were negative for AQP4-IgG. Thus, MOG-IgG were found in both AQP4-IgG seronegative NMO patients and seven of 21 (33%) AQP4-IgG negative HR-NMO patients. Antibodies to MOG and AQP4 were predominantly of the IgG1 subtype, and were able to mediate CDC at high-titer levels.

Conclusions

We could show for the first time that a subset of AQP4-IgG seronegative patients with NMO and HR-NMO exhibit a MOG-IgG mediated immune response, whereas MOG is not a target antigen in cases with an AQP4-directed humoral immune response.
Transgenic neuronal overexpression reveals that stringently regulated p23 expression is critical for coordinated movement in mice
Authors: Gong Ping , Roseman Jelita , Fernandez Celia G , Vetrivel Kulandaivelu S , Bindokas Vytautas P , Zitzow Lois A , Kar Satyabrata , Parent Angèle T , Thinakaran Gopal
Published: December 2011

Background

p23 belongs to the highly conserved p24 family of type I transmembrane proteins, which participate in the bidirectional protein transport between the endoplasmic reticulum and Golgi apparatus. Mammalian p23 has been shown to interact with γ-secretase complex, and modulate secretory trafficking as well as intramembranous processing of amyloid precursor protein in cultured cells. Negative modulation of β-amyloid production by p23 in cultured cell lines suggested that elevation of p23 expression in neurons might mitigate cerebral amyloid burden.

Results

We generated several lines of transgenic mice expressing human p23 in neurons under the control ofThy-1.2promoter. We found that even a 50% increase in p23 levels in the central nervous system of mice causes post-natal growth retardation, severe neurological problems characterized by tremors, seizure, ataxia, and uncoordinated movements, and premature death. The severity of the phenotype closely correlated with the level of p23 overexpression in multiple transgenic lines. While the number and general morphology of neurons in Hup23 mice appeared to be normal throughout the brain, abnormal non-Golgi p23 localization was observed in a subset of neurons with high transgene expression in brainstem. Moreover, detailed immunofluorescence analysis revealed marked proliferation of astrocytes, activation of microglia, and thinning of myelinated bundles in brainstem of Hup23 mice.

Conclusions

These results demonstrate that proper level of p23 expression is critical for neuronal function, and perturbing p23 function by overexpression initiates a cascade of cellular reactions in brainstem that leads to severe motor deficits and other neurological problems, which culminate in premature death. The neurological phenotype observed in Hup23 mice highlights significant adverse effects associated with manipulating neuronal expression of p23, a previously described negative modulator of γ-secretase activity and β-amyloid production. Moreover, our report has broader relevance to molecular mechanisms in several neurodegenerative diseases as it highlights the inherent vulnerability of the early secretory pathway mechanisms that ensure proteostasis in neurons.
Unraveling the biological functions of Smad7 with mouse models
Authors: Zhu Lu , Chen Susie , Chen Yan
Published: December 2011

Smad7 is a key negative regulator of the transforming growth factor β (TGF-β) signaling and plays an important role in modulating a large array of biological processes. The physiological actions of Smad7 have been extensively investigated by using various mouse models. These studies have pinpointed numerous important in vivo functions of Smad7, including its activity in early embryonic development, fibrosis of many organs, skin cell differentiation, regulation of immune response and inflammation, tumorigenesis, and metabolic control. As most biological activities modulated by Smad7 are closely related to human disorders, it is anticipated that Smad7 will continue to be an intriguing molecule that will be vigorously investigated in the future to strengthen our understanding about the pathogenesis of human diseases.
Effect of Early Palliative Care on Chemotherapy Use and End-of-Life Care in Patients With Metastatic Non–Small-Cell Lung Cancer
Authors: Greer Joseph A. , Pirl William F. , Jackson Vicki A. , Muzikansky Alona , Lennes Inga T. , Heist Rebecca S. , Gallagher Emily R. , Temel Jennifer S.
Published: December 2011

Purpose

Prior research shows that introducing palliative care soon after diagnosis for patients with metastatic non–small-cell lung cancer (NSCLC) is associated with improvements in quality of life, mood, and survival. We sought to investigate whether early palliative care also affects the frequency and timing of chemotherapy use and hospice care for these patients.

Patients and Methods

This secondary analysis is based on a randomized controlled trial of 151 patients with newly diagnosed metastatic NSCLC presenting to an outpatient clinic at a tertiary cancer center from June 2006 to July 2009. Participants received either early palliative care integrated with standard oncology care or standard oncology care alone. By 18-month follow-up, 133 participants (88.1%) had died. Outcome measures included: first, number and types of chemotherapy regimens, and second, frequency and timing of chemotherapy administration and hospice referral.

Results

The overall number of chemotherapy regimens did not differ significantly by study group. However, compared with those in the standard care group, participants receiving early palliative care had half the odds of receiving chemotherapy within 60 days of death (odds ratio, 0.47; 95% CI, 0.23 to 0.99; P = .05), a longer interval between the last dose of intravenous chemotherapy and death (median, 64.00 days [range, 3 to 406 days] v 40.50 days [range, 6 to 287 days]; P = .02), and higher enrollment in hospice care for longer than 1 week (60.0% [36 of 60 patients] v 33.3% [21 of 63 patients]; P = .004).

Conclusion

Although patients with metastatic NSCLC received similar numbers of chemotherapy regimens in the sample, early palliative care optimized the timing of final chemotherapy administration and transition to hospice services, key measures of quality end-of-life care.
Conophylline Suppresses Pancreatic Stellate Cells and Improves Islet Fibrosis in Goto-Kakizaki Rats
Authors: Saito Rie , Yamada Satoko , Yamamoto Yoritsuna , Kodera Tsutomu , Hara Akemi , Tanaka Yuji , Kimura Fumihiko , Takei Izumi , Umezawa Kazuo , Kojima Itaru
Published: December 2011

Activin A is a differentiation factor for β-cells and is effective to promote β-cell neogenesis. Activin A is also an autocrine activator of pancreatic stellate cells, which play a critical role in fibrogenesis of the pancreas. Conophylline (CnP) is a natural compound, which reproduces the effect of activin on β-cell differentiation and promotes β-cell neogenesis when administered in vivo. However, its effect on stellate cells is not known. We therefore investigated the effect of CnP on stellate cells both in vitro and in vivo. Unlike activin A, CnP inhibited activation of cultured stellate cells and reduced the production of collagen. We then analyzed the involvement of stellate cells in islet fibrosis in Goto-Kakizaki (GK) rats, a model of type 2 diabetes mellitus. In pancreatic sections obtained from 6-wk-old GK rats, CD68-positive macrophages and glial fibrillary acidic protein- and α-smooth muscle actin-positive stellate cells infiltrated into islets. Later, the number of macrophages was increased, and the α-smooth muscle actin staining of stellate cells became stronger, indicating the involvement of stellate cells in islet fibrosis in GK rats. When CnP was administered orally for 4 wk, starting from 6 wk of age, invasion of stellate cells and macrophages was markedly reduced and islet fibrosis was significantly improved. The insulin content was twice as high in CnP-treated rats. These results indicate that CnP exerts antifibrotic actions both in vitro and in vivo and improves islet fibrosis in Goto-Kakizaki rats.
Thermal Response of Steel Columns Exposed to Localized Fires-Numerical Simulation and Comparison with Experimental Results
Authors: Zhang Chao , Li Guo-Qiang
Published: December 2011

The popular CFD code FDS is adopted to predict the thermal behaviors of steel columns exposed to localized fires. Two real localized fire tests (one surrounded fire test that the column is inside the fire source and one adjacent fire test that the column is adjacent to the fire source) are modeled in FDS. The effects of input parameters such as grid size and number of solid angles on the accuracy of the numerical results have been investigated. Experimental results concerning heat fluxes and temperatures are compared with the numerical results. Good agreements between the predicted and measured results are found in surrounded fire case, whilst acceptable predictions are given in adjacent fire case.
Nurse Staffing in Medical Units: A Queueing Perspective
Authors: Véricourt Francis de , Jennings Otis B.
Published: December 2011

In this paper, we present a closed queueing model to determine efficient nurse staffing policies. We explicitly model the workload experienced by s nurses within a single medical unit with n homogeneous patients as a closed M/M/s//n queueing system, where each patient alternates between requiring assistance and not. The performance of the medical unit is based on the probability of excessive delay, the relative frequency with which the delay between the onset of patient neediness and the provision of care from a nurse exceeds a given time threshold. Using new many-server asymptotic results, we find that effective staffing policies should deviate from threshold-specific nurse-to-patient ratios by factors that take into account the total number of patients present in the unit. In particular, our staffing rule significantly differs from California Bill AB 394, legislation that mandates fixed nurse-to-patient staffing ratios. Simulations show that our results are robust to delay-dependent service times, generally distributed service times, and nonhomogeneous patients, i.e., those with different acuity levels.
A Study of Interactions in the Risk Assessment of Complex Engineering Systems: An Application to Space PSA
Authors: Borgonovo E. , Smith C. L.
Published: December 2011

Risk managers are often confronted with the evaluation of operational policies in which two or more system components are simultaneously affected by a change. In these instances, the decision-making process should be informed by the relevance of interactions. However, because of system and model complexity, a rigorous study for determining whether and how interactions quantitatively impact operational choices has not been developed yet. In light of the central role played by the multilinearity of the decision support models, we investigate the presence of interactions in multilinear functions first. We identify interactions that can be a priori excluded from the analysis. We introduce sensitivity measures that apportion the model output change to individual factors and interaction contributions in an exact fashion. The sensitivity measures are linked to graphical representation methods as tornado diagrams and Pareto charts, and a systematic way of inferring managerial insights is presented. We then specialize the findings to reliability and probabilistic safety assessment (PSA) problems. We set forth a procedure for determining the magnitude of changes that make interactions relevant in the analysis. Quantitative results are discussed by application to a PSA model developed at NASA to support decision making in space mission planning and design. Numerical findings show that suboptimal decisions concerning the components on which to focus managerial attention can be made, if the decision-making process is not informed by the relevance of interactions.
Use of Topical Tranexamic Acid or Aminocaproic Acid to Prevent Bleeding After Major Surgical Procedures
Authors: Ipema Heather J , Tanzi Maria G
Published: December 2011

OBJECTIVE:

To evaluate the literature describing topical use of tranexamic acid or aminocaproic acid for prevention of postoperative bleeding after major surgical procedures.

DATA SOURCES:

Literature was retrieved through MEDLINE (1946-September 2011) and International Pharmaceutical Abstracts(1970-September 2011) using the terms tranexamic acid, aminocaproic acid, antifibrinolytic, topical, and surgical. In addition, reference citations from publications identified were reviewed.

STUDY SELECTION AND DATA EXTRACTION:

All identified articles in English were evaluated. Clinical trials, case reports, and meta-analyses describing topical use of tranexamic acid or aminocaproic acid to prevent postoperative bleeding were included.

DATA SYNTHESIS:

A total of 16 publications in the setting of major surgical procedures were included; the majority of data were for tranexamic acid. For cardiac surgery, 4 trials used solutions containing tranexamic acid (1-2.5 g in 100-250 mL of 0.9% NaCl), and 1 trial assessed a solution containing aminocaproic acid (24 g in 250 mL of 0.9% NaCl). These solutions were poured into the chest cavity before sternotomy closure. For orthopedic procedures, all of the data were for topical irrigation solutions containing tranexamic acid (500 mg-3 g in 50-100 mL of 0.9% NaCl) or for intraarticular injections of tranexamic acid (250 mg to 2 g in 20-50 mL of 0.9% sodium chloride, with or without carbazochrome sodium sulfate). Overall, use of topical tranexamic acid or aminocaproic acid reduced postoperative blood loss; however, few studies reported a significant reduction in the number of packed red blood cell transfusions or units given, intensive care unit stay, or length of hospitalization.

CONCLUSIONS:

Topical application of tranexamic acid and aminocaproic acid to decrease postsurgical bleeding after major surgical procedures is a promising strategy. Further data are needed regarding the safety of this hemostatic approach.
Exogenous Glucagon-Like Peptide-1 for Hyperglycemia in Critically Ill Patients
Authors: Pinelli Nicole R , Jones Mathew C , Monday Lea M , Smith Zachary , Rhoney Denise H
Published: December 2011

OBJECTIVE:

To review literature evaluating the safety and efficacy of exogenous glucagon-like peptide-1 (GLP-1) for hyperglycemia in critically ill patients.

DATA SOURCES:

PubMed was queried (inception to September 3, 2011), using the search term glucagon-like peptide-1. The search was limited to studies published in English and conducted in humans. Regular and late-breaking abstracts from the American Diabetes Association Scientific Sessions in 2009 and 2010 were also searched using the same search term.

STUDY SELECTION AND DATA EXTRACTION:

All abstracts were screened for eligibility, which consisted of studies reporting the effects of intravenous GLP-1 administration on glycemic control in critically ill patients. Data extracted from eligible trials included study and population characteristics, measures of glycemic efficacy, and safety.

DATA SYNTHESIS:

Our search resulted in the identification of 2105 potentially relevant articles; of those, 7 were reviewed. All included publications evaluated the use of intravenous GLP-1 (1.2-3.6 pmol/kg/min) compared with insulin or placebo infused for 4.5-72 hours in critically ill patients. The majority (n = 4) of studies included only patients from a surgical intensive care setting, and 71% (n = 5) of trials included those with a history of diabetes. Relative to insulin or placebo, GLP-1 therapy effectively lowered blood glucose concentrations in all trials. Out of 81 total study participants receiving GLP-1, only 4 had documented hypoglycemia (<60 mg/dL), 4 reported nausea, and 2 experienced vomiting. No other serious adverse events were reported.

CONCLUSIONS:

All trials reviewed suggest that GLP-1 may be a promising agent for the management of hyperglycemia in critically ill patients, regardless of diabetes status. Additional studies in more heterogeneous intensive care settings comparing GLP-1 with insulin, the current standard of care, are necessary. These studies should evaluate long-term safety and effectiveness of GLP-1 therapy on morbidity and mortality outcomes in critically ill populations.
Estimating Glomerular Filtration Rates by Use of Both Cystatin C and Standardized Serum Creatinine Avoids Ethnicity Coefficients in Asian Patients with Chronic Kidney Disease
Authors: Teo Boon Wee , Xu Hui , Wang Danhua , Li Jialiang , Sinha Arvind Kumar , Shuter Borys , Sethi Sunil , Lee Evan J C
Published: December 2011

BACKGROUND

The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is most accurate for estimating glomerular filtration rate (GFR) but requires an adjustment for African-American patients. Estimation equations are also improved with the use of serum cystatin C combined with standardized creatinine. Combination equations have been derived by the CKD-EPI and Chinese investigators. We investigated whether these cystatin C–based equations improve estimation adequately, so that adjustments for ethnicity are not required in a multiethnic Asian population with chronic kidney disease (CKD).

METHODS

This was a cross-sectional study of 232 stable CKD patients who underwent GFR measurements using 3-sample plasma clearances of 99mTc-DTPA, and for whom serum cystatin C and creatinine were quantified.

RESULTS

For all patients, the median biases with cystatin C equations were generally greater than with the CKD-EPI equation, and precision and root mean square error (RMSE) were not significantly better. However, the combination serum creatinine and cystatin C equation improved the precision, RMSE, and percentage of estimated GFR to within 15% and 30% of the measured GFR (57.3% vs 50.0%, 88.4% vs 82.8%, respectively). The derived ethnicity coefficients for the combination equation were all >1 (1.009–1.082) but small, suggesting that coefficients are not required. The Chinese-specific equations were more biased and performed more poorly than the CKD-EPI equation.

CONCLUSIONS

The use of a cystatin C and creatinine combination equation for estimating GFR in a multiethnic Asian population with CKD does not require ethnicity coefficients because the derived coefficients are very close to each other.
Implant Placement and Immediate Loading With Fixed Restorations in Augmented Sockets. Five-Year Results. A Case Report
Authors: Zafiropoulos Gregory-George K. , Deli Giorgio , Vittorini Gianluca , Hoffmann Oliver
Published: December 2011

In this report, a case is presented in which a patient received eight implants 10 months after tooth extraction and socket preservation. The implants were placed in both arches (maxilla = 4, mandible = 4) and immediately loaded using fixed partial restorations; they remained functional over 5 years. No changes in bleeding on probing or plaque index were observed; however, a 1.5-mm probing attachment level loss was observed during the first 3 years (mean: 0.25 mm/year) with no subsequent changes.
Systematics and evolution of Paleozoic and Mesozoic damselfly-like Odonatoptera of the ‘protozygopteran’ grade
Authors: Nel André , Bechly Günter , Prokop Jakub , Béthoux Olivier , Fleck Gunther
Published: December 2011

The Paleozoic to Mesozoic grade ‘Protozygoptera’ is revised. It appears to be composed of two main lineages, namely the superfamily Permagrionoidea, and the Archizygoptera. The latter taxon forms a monophyletic group together with Panodonata (=crown-Odonata plus their closest stem-relatives). Therefore, the ‘Protozygoptera’ as previously understood is paraphyletic. Diagnostic characters of the ‘Protozygoptera’, Permagrionoidea, and Archizygoptera are re-evaluated. The Permolestidae is considered as a junior synonym of the Permagrionidae. The following new taxa are described: Permolestes sheimogorai new species, Permolestes soyanaiensis new species, Epilestes angustapterix new species, Solikamptilon pectinatus new species (all in Permagrionidae); Lodeviidae new family (for Lodevia); Luiseiidae new family (including Luiseia breviata new genus and species); Kennedya azari new species, Kennedya pritykinae new species, Kennedya ivensis new species, Progoneura grimaldii new species (all in Kennedyidae); Engellestes chekardensis new genus and species (in Bakteniidae); and Azaroneura permiana new genus and species (in Voltzialestidae). The Kaltanoneuridae and Oboraneuridae are revised. The evolution of protozygopteran Odonatoptera during the transition from the Permian to the Triassic is discussed. The larger taxa of the permagrionoid lineage apparently did not cross through the Permian–Triassic boundary, unlike the more gracile Archizygoptera. This last group shows a remarkable longevity from the late Carboniferous to the Early Cretaceous. It also presents a great taxonomic and morphological stability, with genera ranging from the Permian to the Triassic, and a wing venation pattern nearly unchanged from the late Carboniferous to the Late Triassic. The mass extinction at the end of the Permian period seemingly had a minor effect on these tiny and delicate insects.
Multiple-Mixing-Cell Method for MMP Calculations
Authors: Ahmadi Kaveh , Johns Russell T.
Published: December 2011

The minimum miscibility pressure (MMP) is a key parameter governing the displacement efficiency of gasfloods. There are several methods to determine the MMP, but the most accurate methods are slim-tube experiments, analytical methods, and numerical-simulation/cell-to-cell methods. Slim-tube experiments are important to perform because they use actual crude oil, but they are costly and time consuming. Analytical methods that use the method of characteristics (MOC) are very fast and help to understand the structure of gasfloods. MOC, however, relies on finding the unique and correct set of key tie lines in the displacements, which can be difficult. Slim-tube simulation methods and their simplified cell-to-cell derivatives require tedious fluid and rock inputs, and their MMP estimates can be clouded by dispersion.

This paper presents a simple and accurate multiple-mixing-cell method for MMP calculations that corrects for dispersion, and is faster and less cumbersome than 1D simulation methods. Unlike previous mixing-cell methods, our cell-to-cell mixing model uses a variable number of cells, and is independent of gas/oil ratio, volume of the cells, excess oil volumes, and the amount of gas injected. The new method only relies on robust P/T flash calculations using any cubic equation-of-state (EOS). The calculations begin with only two cells and perform additional cell-to-cell contacts between resulting equilibrium-phase compositions based on equilibrium gas moving ahead of the equilibrium liquid phase. We show for a variety of oil and gas compositions that all key tie lines can be found to the desired accuracy, and that they are nearly identical to those found using analytical MOC methods. Our approach, however, is more accurate and robust than those from MOC because we do not make approximations regarding shocks along nontie-line paths, and the unique set of key tie lines converges automatically.

The MMP using our mixing-cell method can be calculated in minutes using an Excel spreadsheet and is estimated from a novel bisection method of the minimum tie-line lengths observed in the cells at four or five pressures. Our multiple-mixing-cell method can calculate either the MMP or the minimum miscibility for enrichment (MME) independent of the number of components in the gas or oil. Our approach further supports the notion that the MMP is independent of fractional flow because we obtain the same key tie lines independent of how much fluid is moved from one cell to another.
Dynamic Data Integration and Quantification of Prediction Uncertainty Using Statistical-Moment Equations
Authors: Likanapaisal P.. , Li L.. , Tchelepi H.A.. A.
Published: December 2011

The use of a probabilistic framework for dynamic data integration (history matching) has become accepted practice. In this framework, one constructs an ensemble of reservoir models, in which each realization honors the available (static and dynamic) information. The variations in the flow performance across the ensemble provide an assessment of the prediction uncertainty due to incomplete knowledge of the reservoir properties (e.g., permeability distribution). Methods based on Monte Carlo simulation (MCS) are widely used because of the generality and simplicity of MCS. As a black-box approach, only pre- and post-processing of conventional flow simulations are needed. To achieve reasonable accuracy in estimating the statistical moments of flow-performance predictions, however, large numbers of realizations are usually necessary. Here, we use a different, and direct, approach for model calibration and uncertainty quantification. Specifically, we describe a statistical-moment-equations (SMEs) framework for both the forward and inverse problems associated with immiscible two-phase flow. In the SME method, the equations governing the statistical moments of the quantities of interest (e.g., pressure and saturation) are derived and solved directly. We assume that statistical information and a few measurements are available for the permeability field. As for the dynamic properties, we assume that measurements of pressure, saturation, and flow rate are available at a few locations and at several times. For the forward problem, the flow (pressure and total-velocity) SMEs are solved on a regular grid, while a streamline-based strategy is used to solve the transport SMEs. We use a kriging-based inversion algorithm, in which the first two statistical moments of permeability are conditioned directly using the available dynamic data. We analyze the behaviors of the saturation moments and their evolution as they are conditioned on measurements, in both space and time. Moreover, we discuss the relationship between the widely used MCS-based Kalman-filter approach and our SME inversion scheme.
Non-Darcy Porous-Media Flow According to the Barree and Conway Model: Laboratory and Numerical-Modeling Studies
Authors: Lai Bitao , Miskimins Jennifer L. , Wu Yu-Shu
Published: December 2011

This paper presents the results of our new experimental studies conducted for high flow rates through proppant packs, which show that the Barree and Conway (2004) flow model is capable of overcoming limitations of the Forchheimer non-Darcy equation at very high flow rates. To quantify the non-Darcy flow behavior using the Barree and Conway model, a numerical model is developed to simulate non-Darcy flow. In addition, an analytical solution is presented for steady-state linear non-Darcy flow and is used to verify the numerical-simulation results. The numerical model incorporates the Barree and Conway model into a general-purpose reservoir simulator for modeling multidimensional, single-phase non-Darcy flow in porous and fractured media and supplements the laboratory findings. The numerical model is then used to perform sensitivity analysis of the Barree and Conway flow model's parameters and to investigate transient behavior of non-Darcy flow at an injection well.
Practical Solutions for Pressure-Transient Responses of Fractured Horizontal Wells in Unconventional Shale Reservoirs
Authors: Brown M.. , Ozkan E.. , Raghavan R.. , Kazemi H..
Published: December 2011

This paper presents an analytical trilinear-flow solution to simulate the pressure-transient and production behaviors of fractured horizontal wells in unconventional shale reservoirs (Ozkan et al. 2009). The model is simple, but versatile enough to incorporate the fundamental petrophysical characteristics of shale reservoirs, including the intrinsic properties of the matrix and the natural fractures. Special characteristics of fluid exchange among various reservoir components may also be considered. Computational convenience of the trilinear-flow solution makes it a practical alternative to more rigorous but computationally intensive and time-consuming solutions. Another advantage of the trilinear-flow solution is the convenience in deriving asymptotic approximations that provide insight about potential flow regimes and the conditions leading to these flow regimes. Though linear- and bilinear-flow regimes have been noted for fractured horizontal wells in the literature on the basis of their diagnostic features, they have not been associated with particular reservoir characteristics and flow relationships. The trilinear-flow solution also provides a suitable algorithm for the regression analysis of pressure-transient tests in shale reservoirs.
CO2 Injection Performance in the Fruitland Coal Fairway, San Juan Basin: Results of a Field Pilot
Authors: Oudinot Anne Y. , Koperna George J. , Philip Zeno G. , Liu Ning , Heath Jason E. , Wells Arthur , Young Genevieve B. , Wilson Tom
Published: December 2011

The Pump Canyon CO2-enhanced coalbed methane (ECBM)/ sequestration demonstration in New Mexico has the primary objective of demonstrating the feasibility of CO2 sequestration in deep, unmineable coal seams through a small-scale geologic sequestration pilot. This project is not the first of its kind; several small- or large-scale pilots were already conducted previously in the United States [Allison Unit (Reeves et al. 2003) in the San Juan, Appalachian, and Warrior basins] as well as internationally [the Recopol (Reeves and Oudinot 2002) project in Poland, and the Yubari project in Japan, Canada, and Australia]. Additional pilots are currently under way.

At the project site, a new CO2-injection well was drilled within an existing pattern of coalbed-methane-production wells. Primarily operated by ConocoPhillips, these wells produce from the Late Cretaceous Fruitland coals. CO2 injection into these coal seams was initiated in late July 2008 and ceased in August 2009. A variety of monitoring, verification, and accounting (MVA) methods were employed to track the movement of the CO2 in order to determine the occurrence of leakage. Within the injection well, MVA methods included continuous measurement of injection volumes, pressures, and temperatures. The offset production wells sampled gas-production rates, pressures, and gas composition through CO2 sensors, tracers in the injected CO2, time-lapse vertical seismic profiling, and surface tiltmeter arrays. A detailed study of the overlying Kirtland shale was also conducted to investigate the integrity of this primary caprock. This information was used to develop a detailed geologic characterization and reservoir model that has been used to further understand the behavior of this reservoir.

The CO2-injection pilot has ended with no significant CO2 buildup occurring in the offset production wells. However, a small but steady increase in CO2 and N2 at two of the offset wells may have been an indication of imminent breakthrough. More recent gas samples are, however, showing a decrease in CO2 and N2 content at those wells. This paper describes the project, covering the regulatory process and injection-well construction, the different techniques used to monitor for CO2 leakage, and the results of the modeling work.
Analysis of Data From the Barnett Shale Using Conventional Statistical and Virtual Intelligence Techniques
Authors: Awoleke Obadare O. , Lane Robert H.
Published: December 2011

A Barnett shale water-production data set from approximately 11,000 completions was analyzed using conventional statistical techniques. Additionally, a water/hydrocarbon ratio and first-derivative diagnostic-plot technique developed elsewhere for conventional reservoirs was extended to analyze Barnett shale water-production mechanisms. To determine hidden structure in well and production data, self-organizing maps and the k-means algorithm were used to identify clusters in data. A competitive-learning-based network was used to predict the potential for continuous water production from a new well, and a feed-forward neural network was used to predict average water production for wells drilled in Denton and Parker Counties, Texas, of the Barnett shale.

Using conventional techniques, we concluded that for wells of the same completion type, location is more important than time of completion or hydraulic-fracturing strategy. Liquid loading has potential to affect vertical more than horizontal wells. Different features were observed in the spreadsheet diagnostic plots for wells in the Barnett shale, and we made a subjective interpretation of these features. We find that 15% of the horizontal and vertical wells drilled in Denton County have a load-water-recovery factor greater than unity. Also, 15 and 35% of the horizontal and vertical wells drilled, respectively, in Parker County have a load-recovery factor greater than unity.The use of both self-organizing maps and the k-means algorithm showed that the data set is divided into two main clusters. The physical properties of these clusters are unknown but interpreted to represent wells with high water throughput and those with low water throughput. Expected misclassification error for the competitive-learning-based tool was approximately 10% for a data set containing both vertical and horizontal wells. The average prediction error for the neural-network tool varied between 10 and 26%, depending on well type and location.Results from this work can be used to mitigate risk of water problems in new Barnett shale wells and predict water issues in other shale plays. Engineers are provided a tool to predict potential for water production in new wells. The method used to develop this tool can be used to solve similar challenges in new and existing shale plays.
Laminar and Turbulent Friction Factors for Annular Flow of Drag-Reducing Polymer Solutions in Coiled-Tubing Operations
Authors: Ogugbue Chinenye C. , Shah Subhash N.
Published: December 2011

The challenge of theoretical and numerical studies of annular fluid flow with varying eccentricity is mainly a result of the required coordinate systems. Computational-fluid-dynamics (CFD) modeling provides the state-of-the-art approach of investigating fluid flow in such complex geometries. In this study, results from a series of numerical simulations for the fully developed laminar flow of non-Newtonian power-law fluids in concentric and eccentric annular geometries are used to investigate the effect of eccentricity, flow-behavior index, and diameter ratio (ratio of the outer diameter of the inner tubing to the inner diameter of the outer tubing) on axial frictional pressure losses.

The frictional pressure-loss gradients predicted by the CFD simulations were verified by comparing with the published studies and flow data from a field-scale experimental setup. At a constant flow rate, it is confirmed that frictional pressure losses decrease with increasing eccentricity. A good agreement was obtained with the Haciislamoglu and Langlinais (1990) correlation, and the results of this study, especially at low values of eccentricity. At very high eccentricities, data from the CFD model yield lower frictional pressure loss compared to Haciislamoglu and Langlinais (1990) correlation. This type of expression is obtained and the improved data of this study is incorporated.

Next, this paper presents the results of an experimental study carried out to investigate frictional pressure-loss behavior of drag- reducing polymer solutions, flowing turbulently through an eccentric annulus. The experimental setup includes 30 ft of 3½×2⅜-in., 200 ft of 3½×1¾-in., 69 ft of 5½ × 4-in., and 79 ft of 5 ×3½-in. fully eccentric annuli. Data analysis enabled the development of a new correlation using fluid apparent viscosity at 511 sec–1, generalized Reynolds number, and diameter ratio, all of which can be easily determined in the field as independent variables. These new correlations for laminar and turbulent flow of drag-reducing polymer solutions present an improvement to existing correlations, and also permit undemanding hydraulic-program calculations for varying annular configurations.
Production-Induced Stress Change in and Above a Reservoir Pierced by Two Salt Domes: A Geomechanical Model and Its Applications
Authors: Schutjens P.M.T.M.. M.T.M. , Snippe J.R.. R. , Mahani H.. , Turner J.. , Ita J.. , Mossop A.P.. P.
Published: December 2011

Production decreases the pore-fluid pressure and increases the effective stress acting on the load-bearing-grain framework that makes up the reservoir. As a result, the reservoir deforms and compacts, and because it is connected to the rocks around it, there will be deformations and displacements in these rocks also. Well known geomechanical effects of production include surface subsidence, wells damaged by shear, and time shifts in 4D seismic. Less well known is how the changes in the stress field itself should be taken into account in operations—e.g., to design infill wells and to plan production stimulation by hydraulic fracturing or waterflooding of the reservoir.

We present a geomechanical model for the initial stress field and production-induced stress changes in and around a steeply dipping hydrocarbon reservoir penetrated by two large salt domes. The model integrates 3D seismic and geological understanding, geomechanical data from wells and analogues, and depletion patterns from fluid-flow (dynamic) simulation. Our model results confirm published models of principal-stress orientation in rocks pierced by salt domes. The depleted-model results show stress changes up to several MPa in magnitude compared with the preproduction stress state, but only limited changes in the stress orientations. The model highlights the influence of structural dip and time-dependent salt/sediment interaction on stress changes.

We then describe the application of the model in wellbore stress analysis for infill wells and in a water-injection scheme that has, we believe, been severely impacted by injection-induced fractures propagating in the reservoir from the injector wells toward the producer wells. We explain how the latter application uses a 3D flow-simulation model coupled to a dynamic fracture-propagation model. The geomechanical model provides key input: stress magnitude and stress orientation. Results are validated against a more conventional analysis of real-time pressure data.

In both applications, the integration of geomechanics in 3D static and dynamic models improved insight into the rock response to drilling and waterflooding, thus helping to optimize production.
Productivity Loss in Gas Wells Caused by Salt Deposition
Authors: Le Duc , Mahadevan Jagannathan
Published: December 2011

Production of gas can result in drying of the near-wellbore region caused by gas expansion, which causes evaporation and hence salt deposition. The deposition of salt leads to a reduction in porosity and permeability of the rock in the near-wellbore region, which then leads to reduction in well productivity. The main objective of this work is to understand the role of capillarity on salt deposition and its impact on well flow efficiency.

We develop and solve the dimensionless-conservation equations for solid-salt saturation using numerical methods under radial-flow conditions. The results of the calculations show that when the capillary effects are strong, the salt accumulates near the wellbore, which leads to plugging and hence higher skin values. The salt saturation continues to evolve until a limiting value, in the rock pores, is reached. Higher values of the limiting saturation lead to a greater reduction in permeability and therefore result in a larger skin value for the gas well. The flow efficiency of a gas well, calculated as a dimensionless ratio of the flow with and without skin, decreases continually and asymptotically approaches a constant value.

In a simulation for a typical field case, we find that the largest increase in skin factor and corresponding decrease in flow efficiency occur in approximately the first 30 days, after which the changes are slower. When connate-water salt concentration is higher, the skin value is much higher and thus the well productivity is lower. Using the model developed in this study, the decline of gas-well productivity caused by salt deposition can be predicted and hence accurate timing of well operations, such as water wash, can be made. Also, the modeling study can be used to select remediation strategies such as wettability alteration to reduce capillarity or application of inhibitors, which can reduce the limiting salt saturation by preventing growth of salt crystals within the reservoir rock.