bluuebunny/crossref_metadata_2025 huggingface dataset:
Wellhead Managers Improve Operating Efficiencies In the Pembina Field-A Case Study
Authors: Reynolds M. , Sutton J. , Hedberg G.
Published: March 2010

The Pembina field is the largest oilfield in Canada with in excess of 5,000 current operating wells. The field has been on production for more than 40 years and under waterflood since the early 1960s. In spite of its advanced productive life, this field contains a large amount of remaining reserves. Reducing or controlling operating costs today and into the future will be a major challenge due to the advanced age of the wells and facilities.

One of the technologies used to control operating costs in aging fields has been wellhead managers with and without remote control (SCADA). Petro-Canada investigated wellhead automation in a number of mature fields in Canada and the U.S. prior to the implementation of a ten well test project in the Pembina field. There were a number of objectives to be studied during the pilot test:Reduce the number of bottom hole equipment failures related to fluid poundReduce the amount of lost production related to equipment failures with better surveillanceProve the applicability in low oil rate, high water cut wells in a mature waterfloodOptimize the use and reduce the cost of paraffin and scale control chemicalsDemonstrate the effectiveness of using an integrated team of production engineering, field technical and operations staff during the design and implementation phases of the test.

Wellhead managers had proven successful in reducing costs and production losses in other fields, therefore the pilot test was expected to last for a maximum of six months. The main purpose of the test was to gain the field operators' support of the system, as well as quantify the benefits under Pembina operating conditions prior to a field wide expansion of a fully automated SCADA system.

Introduction

The Pembina Cardium Field(1) located in west central Alberta is the largest oilfield in Canada in terms of both areal extent and original oil in place. The portions of the field operated by Petro- Canada are located in the southeastern area near the village of Buck Creek (Figure 1). The first producing wells were drilled in this area in 1954 with first waterflooding started in 1957. By 1961, all Petro-Canada operated areas were under waterflood.

This area was operated by Norcen Energy and predecessor companies up until 1994 when Petro-Canada was elected operator. The Cardium reservoir in this area has responded well to waterflooding and the production trend is characterized as low decline (4 to 7% per year) with a long remaining reserves life index in spite of more than 40 years of past production. The operated properties consist of approximately 120 producing wells, 100 injection wells and 20 suspended wells. Most of the area is on 80 acre well spacing and 160 acre five spot waterflood patterns. There are six separate tank batteries complete with water plants and numerous satellite testing facilities scattered throughout the property.
Barite Segregation In Inclined Boreholes
Authors: Skalle P. , Backe K.R. , Lyomov S.K. , Sveen J.
Published: March 2010

Settling and sagging of barite in inclined boreholes may lead to safety and operational problems. To study the effect of rheology on settling, a laboratory tool was designed, consisting of two connected tubes, one inclined and one vertical. The hydrostatic pressure was measured at the bottom of each pipe. Stable and unstable muds can clearly be differentiated through their pressure behaviour.

Several muds were studied at simulated static and dynamic conditions. The results show that sagging is most severe during laminar flow and also indicate that the rheological parameters may be used for predicting stability problems.

Introduction

In weighted drilling mud barite tends to segregate slowly. In directional drilling operations the settling process is accelerated. Barite settles in the lower side of the borehole and starts sliding when the borehole has an inclination above 30 °. This phenomenon is known as barite sagging. Sagging can lead to drilling and completion problems; a density variation or non-linear hydrostatic pressure gradients which can lead to pressure control problems, while thick and tight barite beds can lead to high torque and drag, stuck pipes and plugged boreholes, and even lost circulation.

The sag problem is related to the so called Boycott effect(1), first described in 1920. Hanson et al.(2) have investigated the phenomenon and found that most of the sagging occurs while the mud is circulating. The same conclusion was reached by Bern et al.,(3) the sagging tendency is highest at low annular velocities. Zamora and Jefferson(4) presented a method for tracking drilling fluid density variations, which helps to detect, but not to predict drilling mud instability. Jamison and Clements(5) developed a test method to characterise settling and sag tendencies in static drilling fluids, however their equipment was not able to distinguish between settling and sliding. They also found that their data, based upon standard API rheological parameters like PV and YP, were unsuitable for prediction of sagging behaviour. It is apparent from previous works that the most difficult part of the problem is the prediction of drilling mud instabilities for both static and flowing drilling fluids. To date there are no API test procedures for sag testing.

A new simple laboratory tool was therefore designed for the purpose to study and develop a method to predict sagging.

Drilling Mud Separation

Settling of Particles

In vertical wells the settling of weighting material is generally not a problem due to the long settling distance. In horizontal wells the distance to the lower side of the wall is only about 0.2 m, which leads to rapid generation of solids beds. The settling velocity of a single spherical particle, vs,l, in a fluid is expressed by Stoke's law(6):

Equation 1 (available in full paper)

A barite particle (ρp = 4,200 kg/m3) with a diameter (dp) of 20 µm in a fluid of density (ρfluid) 1,500 kg/m3 and a viscosity (µ??of 40 cP will settle at a rate of 53 mm/h.
A Practical Well Control Methodology While Drilling Without Returns
Authors: Schneider G. , Osisanya S.O.
Published: March 2010

While drilling in some oil fields of the world, lost circulation may be so severe that normal remedies that might heal the loss zone are not effective. A procedure has been developed to drill "blind" or without returns. The procedure has been refined enough so that stuck drill pipe may be avoided, but the most dangerous aspect of drilling "blind" is the lack of well control. Often when circulation is lost, the well kicks and gas can flow into the wellbore due to drastic reduction in hydrostatic pressure. Furthermore, normal well control operations are ineffective. The procedure generally involves pumping a viscous slug of waterbased gel mud into the annulus and this column of mud is called a "mudcap." This approach depends on whether the lost zone is above or below a gas zone and either approach effectively limits the amount of fluid that can be used.

In order to properly place a mudcap, a better understanding of the relationship between the fluid rheological properties, column height, and the initial shut-in casing pressure is required. In this respect, no quick field procedure has been developed to help rigsite personnel to control these types of wells. A set of charts have been constructed to aid field personnel in blowout prevention, when they are confronted with a gas kick occurring while drilling without returns. This situation is common in many oil fields especially in Middle East and North Africa. The set of charts is based on the slot flow approximation for Bingham fluids. Two sets of charts are developed: one for the case in which pipe is in the hole and the other when the casing is opened.

Each of the charts represents a different annular configuration. These charts make life easier for rig personnel especially in a very stressful situation, and this type of pre-planning should help to avoid costly mistakes in judgment.

Introduction

Solutions for equations describing axial annular flow of Newtonian fluids can be determined directly. However, direct methods for solving annular flow equations for more complex rheological models, such as Bingham-Plastic and Power-Law, usually result in unwieldy expressions. To avoid this the slot flow approximation was developed. This method equates the geometry of an annulus to that of a narrow slot. Depending upon the geometric parameters used in the narrow slot approximation and the degree of accuracy required, some sort of correction for the curvature of annulus may be needed.

Therefore, a suitable expression for the Newtonian curvature correction factor must be developed. Using the same correction factor as for Newtonian fluids, a slot flow approximation of the axial annular flow of Bingham-Plastic fluids should be relatively accurate. The primary purpose of this paper was to develop relations that describe the annular flow of Bingham-Plastic fluids and the pressure gradient necessary to initiate flow. With an expression that relates pressure gradient to the Bingham Plastic yield point, a set of practical charts was developed.
Observations and Design Considerations for In Situ Combustion Projects
Authors: Moore R.G. , Laureshen C.J. , Mehta S.A. , Ursenbach M.G.
Published: March 2010

An important part of any engineer's tool box is a set of simple equations thatwill allow one to quickly assess the performance potential of a given project. For many years, the model of Nelson and McNeil, as well as that of Gates and Ramey, have remained the standards for the preliminary design of in situcombustion projects. However, advances have been made in our understanding ofthe fundamental mechanisms and reaction kinetics of the combustion process, both for heavy and light oils. Combining established procedures with animproved interpretation of the mechanisms forms the basis for this paper. Theinclusion of the negative temperature gradient region, which affects thetransition to the high-temperature combustion mode, is one of the key elementsof these advances.

The paper also addresses the sizing of air injection capacity and itsimportance, as well as the monitoring and analysis of gas-phase combustionproducts. In summary, the paper will provide the engineer with some realisticguidelines for estimating the oil recovery performance of an in situ combustionproject.

Background

In situ combustion is an enhanced recovery process with tremendous theoreticalpotential, but it has failed to perform up to expectations in many of its fieldimplementations. Two decades of research work at the University of Calgary onin situ combustion has focussed on the question "What makes in situ combustionfail?" While many mechanisms have been identified, the most critical withregard to heavy oil is the temperature of the oxidation (combustion)reactions.

Figures 1 and 2 illustrate the importance of the oxidation zone temperature onthe residual oil and oil production for Athabasca bitumen (8 ° API). Figure 1shows high residual hydrocarbon concentrations for temperatures of less than300 ° C, while Figure 2 shows that no tests exhibited significant levels of oilrecovery for reaction temperatures of less than 350 ° C. These data, which werepreviously reported by Moore et al.(1), were determined by heatingpre-mixed Athabasca Oil Sands cores in a one dimensional core holder at a rateof 40 ° C/hr. while flowing an oxygen containing gas. Maximum oil recoveriesfor these ramped temperature oxidation tests were significantly lower thanthose for combustion tube tests due to the oxidation of the oil during theperiod of heating when temperatures were less than 300 ° C. However, thequalitative behaviour was similar in both types of tests.

What these ramped temperature oxidation data show is that the mobilizationefficiency of air is low for oxidation temperatures of less than 300 ° C. However, reaction temperatures in excess of 350 ° C, while necessary, are not asufficient condition to mobilize oil from the region swept by the oxidationzone. It was found that elevated levels of oil recovery were associated with arapid transition of the leading edge temperatures to a value in excess of 350 °C.
Derivative Analysis Without Type Curves
Authors: Mattar L.
Published: March 2010

Modern type curve analysis involves matching the pressures and their semilog derivative on a set of dimensionless type curves, and selecting a match point. Using this point and a specified matching curve, reservoir parameters such as permeability, skin, fracture half length, fracture conductivity, etc., can be calculated.

This paper shows that the same parameters can be obtained without having to use the type curves. In fact, only the semilog derivative of the data is needed on log-log coordinates. The various flow regimes such as wellbore storage, radial, linear, bilinear or spherical flow can be identified by their characteristic slopes (1, 0, 0.5, 0.25, -0.5). By simply placing a straight line with the appropriate slope on the (semilog) derivative points, all the required reservoir parameters can be calculated. This technique is, in actual fact, a combination in one single plot, of all the specialized analyses (which are traditionally done on their own individual scales, semilog, square-root, quad-root, cartesian).

In addition to the semilog derivative data, it is advisable to superimpose a plot of PPD (Primary Pressure Derivative). This enables the analyst to differentiate between reservoir and wellbore effects, and thereby avoid some of the common pitfalls when using real (as opposed to synthetic) data.

Introduction

"Type Curve" analysis has been used in the field of hydrology since the mid 1930s. In the 1970s, type curves(2,3) were introduced to the petroleum industry, and in the early 1980s Bourdet et al.(1) added the "derivative," which helped in making type curve matching more unique.

This article will explain how analysis of well test data can be achieved by using log-log plots and derivative, but without the need for "type curves." In order to understand this new procedure, a review of how type curve analysis works, will first be presented, and then extended to illustrate the new methods.

Type Curve Matching: (The old way)

The theory underlying type curve matching is fully explained in the ERCB (now AEUB) Gas Well Testing manual(2) and Earlougher(3). Basically the process consists of matching field data onto pre-selected dimensionless "type curves," and from the match point, calculating permeability, skin, wellbore storage constant, reservoir size, etc. Once a satisfactory match of the field data and the type curves has been obtained, a "match point" is chosen (any arbitrary point will do), and its coordinates read simultaneously from both the "type curve" scale and the "data" scale. From the coordinates of this arbitrary point, reservoir or wellbore characteristics can be calculated. For example to obtain permeability, read the vertical values ΔpD and Δp of the dimensionless type curve and of the data plot, at the selected common match point. From the definition of dimensionless pressure, the calculation of permeability is easily obtained as follows:

Equation (available in full paper)

In a similar manner, other variables can be calculated, once a match has been obtained.

Traditional type curve analysis has two major drawbacks:
Response to the SEC’s Proposed Rule—Roadmap for the Potential Use of Financial Statements Prepared in Accordance with International Financial Reporting Standards (IFRS) by U.S. Issuers
Authors: Bradshaw Mark , Callahan Carolyn , Ciesielski Jack , Gordon Elizabeth A. , Hodder Leslie , Hopkins Patrick E. , Kohlbeck Mark , Laux Robert , McVay Sarah , Stober Thomas , Stocken Phillip , Yohn Teri Lombardi
Published: March 2010

SYNOPSIS: The Financial Reporting Policy Committee of the Financial Accounting and Reporting Section of the American Accounting Association (hereafter, the AAA FRPC or the committee) is charged with responding to discussion memoranda and exposure drafts on financial accounting and reporting issues. This response is to the SEC’s proposed rule, Roadmap for the Potential Use of Financial Statements Prepared in Accordance with International Financial Reporting Standards (IFRS) by U.S. Issuers. Based on a review of the literature, the AAA FRPC has concluded that a move to an international set of financial reporting standards is a desirable goal. We have also concluded that continued convergence of U.S. GAAP with IFRS by joint relations between the International Accounting Standards Board (hereafter, IASB) and the Financial Accounting Standards Board (hereafter, FASB) is preferable to near-term adoption of IFRS as a strategy for convergence.
A Perspective on the Canadian Accounting Standards Board Exposure Draft on Generally Accepted Accounting Principles for Private Enterprises
Authors: Jamal Karim , Bloomfield Robert , Christensen Theodore E. , Colson Robert H. , Moehrle Stephen , Ohlson James , Penman Stephen , Stober Thomas , Sunder Shyam , Watts Ross L.
Published: March 2010

SYNOPSIS: The Canadian Accounting Standards Board (hereafter, AcSB) recently issued an exposure draft to adopt separate GAAP for private enterprises. This new GAAP is justified as being consistent with the current FASB/IASB conceptual framework, but is sensitive to the different cost-benefit considerations facing private entities. We view this proposal as being innovative and responsive to the differential reporting needs of private entities. In this article we explain our reasoning and conclusions on several issues raised by the exposure draft starting with a discussion about the need for a separate conceptual framework for private enterprises. We sketch a preliminary conceptual framework that could be used to develop and justify the type of changes proposed in this exposure draft. We then discuss key issues raised in the exposure draft such as reliance on historical cost as the key basis of measurement, the significant reduction in disclosure requirements for private enterprises, and stopping the emerging issues committee from providing implementation guidance (no EICs). We also comment on the mechanism for financing the standard-setting board, the need to ensure compatibility between accounting and auditing standards, and a process for adjusting the education system to support this new private enterprise GAAP.
A Research-Based Perspective on the SEC’s Proposed Rule—Roadmap for the Potential Use of Financial Statements Prepared in Accordance with International Financial Reporting Standards (IFRS) by U.S. Issuers
Authors: Jamal Karim , Bloomfield Robert , Christensen Theodore E. , Colson Robert H. , Moehrle Stephen , Ohlson James , Penman Stephen , Stober Thomas , Sunder Shyam , Watts Ross L.
Published: March 2010

SYNOPSIS: The Securities and Exchange Commission (hereafter, SEC) issued a call for comment on a proposal to adopt a roadmap for potential use of international financial reporting standards (hereafter, IFRS) by U.S. companies. We comment on five key issues raised by the SEC proposal. First, we propose that the need for a global regulator is overstated. A global regulator is unlikely to help achieve the stated goals of comparability and consistency of financial reporting on a global basis. We favor allowing U.S. companies to choose use of U.S. GAAP or IFRS rather than mandating one global monopoly set of standards. Second, we agree that the focus on auditing is a very relevant issue that deserves more attention from standard setters. Gains from adopting principles-based accounting standards such as IFRS are likely to be realized only if auditors are also principles-based. Third, while we have serious concerns about governance and financing mechanisms of the International Accounting Standards Board (hereafter, IASB), we recommend that all regulatory actions cannot be held to a standstill while structural changes are made to the IASB. Fourth, we are not in favor of requiring reconciliation schedules from U.S. companies using IFRS. We view such reconciliations as being costly and unnecessary. Fifth, we recommend that the SEC pay more explicit attention to the educational and professional judgment consequences of its proposals.
Response to the Financial Accounting Standards Board’s and the International Accounting Standard Board’s Joint Discussion Paper Entitled Preliminary Views on Financial Statement Presentation
Authors: Moehrle Stephen , Stober Thomas , Jamal Karim , Bloomfield Robert , Christensen Theodore E. , Colson Robert H. , Ohlson James , Penman Stephen , Sunder Shyam , Watts Ross L.
Published: March 2010

SYNOPSIS: The Financial Accounting Standards Board (hereafter, FASB) and the International Accounting Standard Board (hereafter, IASB) issued a joint discussion paper titled Preliminary Views on Financial Statement Presentation. The Boards are seeking comments on whether their proposed model for financial statement presentation would improve the usefulness of the financial statement information for financial decision makers. This paper sets forth the American Accounting Association Financial Accounting Standards Committee (hereafter, the committee) summary comments as well as responses to several of the FASB’s and IASB’s (hereafter, jointly mentioned, the Boards) specific objectives and principles-related questions. Overall, the committee believes that the model has several appealing features, but also has several potential problems. Many of the problems discussed related to potential learning impediments for users to adapt to the new presentation format.
An Analysis of the Underlying Causes Attributed to Restatements
Authors: Plumlee Marlene , Yohn Teri Lombardi
Published: March 2010

SYNOPSIS: The dramatic increase in the number of restatements filed over the past years has been attributed to numerous causes, including the complexity of the accounting standards, internal control reviews, changes in materiality thresholds, the overly conservative nature of auditors, earnings management, increased transaction complexity, and the second-guessing of management judgments by a variety of interested parties. However, empirical evidence on the underlying causes of restatements has been lacking. This study provides such evidence by directly addressing these questions: (1) To what causes do companies attribute restatements? (2) To what characteristics of the accounting standards do companies attribute restatements? Relying on the restating companies’ disclosures about restatements, we find that companies most often attribute restatements to basic internal company errors unrelated to any specific characteristic of the accounting standards. We also find that, for those restatements attributed to some characteristic of the accounting standards, the primary contributing factor is the lack of clarity in applying the standards and/or the proliferation of the literature because the original standard lacked clarity. These findings should interest standard setters and regulators addressing the proliferation of restatements and academics using restatements as proxies for constructs of interest in research.
A Risk Model to Opine on Internal Control
Authors: Akresh Abraham D.
Published: March 2010

SYNOPSIS: In recent years, auditors have reported on the effectiveness of internal control, usually as part of integrated audits. The audit risk model currently in auditing standards was designed for financial statement audits, not internal control audits—a key part of integrated audits. Because the audit of processes (internal control) is conceptually different from the audit of outputs (financial statements), the auditor needs a different risk model to provide a conceptual framework for internal control audits. The model I propose1 provides the auditor a method to determine the appropriate nature, timing, and extent of testing in an integrated audit. My model is focused on the risk of material weakness, rather than the risk of material misstatement. I also show how the auditor would use two different models in an integrated audit.
The PCAOB Meets the Constitution: The Supreme Court to Decide on the PCAOB’s Conformity with the Separation of Powers Doctrine and Appointments Clause
Authors: King Ronald R.
Published: March 2010

SYNOPSIS: This commentary provides an overview of the case currently before the U.S. Supreme Court that alleges constitutional problems with the Public Company Accounting Oversight Board (PCAOB). The PCAOB, a Board designed to oversee auditing for publicly traded firms, was created by Congress when it passed the Sarbanes-Oxley Act of 2002 (hereafter, SOX). To enhance PCAOB’s independence from political pressures, Congress established it as a private-sector, non-profit organization, and gave oversight powers to the Securities and Exchange Commission (hereafter, SEC), an independent agency. The plaintiffs in this case allege that Congress empowered the PCAOB with broad executive powers, yet limited the President’s ability to appoint Board members (thus violating the appointments clause of the Constitution) and to control and/or remove Board members (thus violating the separation of powers doctrine of the Constitution). The Supreme Court’s decision about the constitutionality of the PCAOB is important because of its potential impact on (1) the future of auditing oversight; (2) the validity of SOX; and (3) the future of independent agencies in general. From a policy point of view, the case highlights the importance of the combination of independence and accountability for auditing and accounting standard setting and practice.
Transparency Unveiled: Financial Crisis Prevention through Accounting Reform
Authors: Mosso David
Published: March 2010

SYNOPSIS: In this commentary, I propose a new accounting model, in which accounting reports measure wealth and provide information that can diagnose financial health. I argue that my proposed model addresses the major weaknesses of the existing choice-based GAAP model, and the proposed model has the potential to support a much more effective and efficient standard-setting process.
Case-control study to evaluate risk factors for the development of sepsis (neutropenia and fever) in dogs receiving chemotherapy
Authors: Sorenmo Karin U. , Harwood Lisa P. , King Lesley G. , Drobatz Kenneth J.
Published: March 2010

Objective—To identify risk factors for development of sepsis in dogs treated with chemotherapeutics and to evaluate the impact of sepsis on outcome.

Design—Case-control study.

Animals—Client-owned dogs with various cancers undergoing standard chemotherapeutic treatment at the University of Pennsylvania veterinary hospital.

Procedures—39 dogs with sepsis (cases) were identified through a search of the medical record database. Controls (n = 77) were randomly selected from dogs admitted during the same time period. Variables analyzed included patient demographics, tumor type, stage, remission status, treatment phase, chemotherapeutics used, and outcome.

Results—Dogs that weighed less and dogs with lymphoma were significantly more likely to become septic, compared with larger dogs or dogs with solid tumors. Septic dogs were also significantly more likely to have received doxorubicin (odds ratio [OR], 12.5; 95% confidence interval [CI], 2.4 to 66.0) or vincristine (OR, 9.0; 95% CI, 1.6 to 52.0) than controls. Of the 39 cases, 28 (71.8%) were in the induction phase of their protocol, and 19 of 39 (48.7%) became septic after receiving the chemotherapeutic drug for the first time. Median survival time of the cases (253 days) was not significantly different from that of the controls (371 days).

Conclusions and Clinical Relevance—Dogs that weighed less were at increased risk for chemotherapy-induced sepsis. Tumor type and chemotherapeutic drug used were also important risk factors. These results may lead to the implementation of prophylactic measures, especially when doxorubicin or vincristine is used in the induction phase in small dogs with lymphoma.
Evaluation of outcomes in dogs treated for pyothorax: 46 cases (1983–2001)
Authors: Boothe Harry W. , Howe Lisa M. , Boothe Dawn M. , Reynolds Loren A. , Carpenter Mark
Published: March 2010

Objective—To determine the effect of treatment approach on outcome and the appropriateness of initial empirical antimicrobial treatment in dogs with pyothorax.

Design—Retrospective case series.

Animals—46 dogs with pyothorax confirmed by either (n = 15) or both (31) of the following: intracellular bacteria in pleural fluid or tissue (41) and bacteria recovered via culture of pleural fluid (36).

Procedures—Medical records of dogs treated for pyothorax from 1983 through 2001 were reviewed. Data on signalment, history, clinical signs, and treatment and results of diagnostic imaging and cytologic and microbiological evaluations were obtained. Follow-up was performed via reexamination (n = 15) and contact with referring veterinarians (26) and owners (24).

Results—46 dogs were treated with at least 1 antimicrobial and thoracocentesis (n = 7; noninvasive group), a thoracostomy tube (26; invasive group) with or without pleural lavage and heparin, or a thoracotomy (13; surgical group) and thoracostomy tube with or without pleural lavage and heparin. Pyothorax recurred in 7 dogs, and 5 of the 7 died or were euthanatized. In the respective groups, the short-term survival rate was 29%, 77%, and 92% and the long-term survival rate was 29%, 71%, and 70%. Pleural lavage and heparin treatment increased the likelihood of short- and long-term survival. Results of antimicrobial susceptibility testing suggested empirical antimicrobial selection was associated with a 35% risk of inefficacy.

Conclusions and Clinical Relevance—In the dogs with pyothorax in this study, favorable treatment effects were achieved with surgery (for short-term survival) and pleural lavage and heparin treatment (for short- and long-term survival). Findings failed to support the hypothesis that invasive (surgical) versus noninvasive treatment of pyothorax in dogs leads to a better long-term outcome.
Mycophenolate mofetil treatment in dogs with serologically diagnosed acquired myasthenia gravis: 27 cases (1999–2008)
Authors: Dewey Curtis W. , Cerda-Gonzalez Sofia , Fletcher Daniel J. , Harb-Hauser Marcella F. , Levine Jonathan M. , Badgley Britton L. , Olby Natasha J. , Shelton G. Diane
Published: March 2010

Objective—To compare clinical outcome in dogs with serologically diagnosed acquired myasthenia gravis (MG) treated with pyridostigmine bromide (PYR) with that of dogs treated with mycophenolate mofetil (MMF) and PYR (MMF + PYR).

Design—Retrospective case series.

Animals—27 dogs.

Procedures—Medical records from August 1999 through February 2008 were reviewed to identify dogs with serologically diagnosed acquired MG treated with PYR or MMF + PYR. Data collected for each dog included signalment, whether the dog had megaesophagus or pneumonia (or both), thyroid hormone concentration, remission, time to remission, and survival time. Rates for detection of clinical signs and survival time were compared. Survival time was estimated via the Kaplan-Meier method. Influence of drug treatment protocol on likelihood of remission, time to remission, and survival time was examined. Effects of MMF treatment, megaesophagus, pneumonia, and low serum thyroid hormone concentration on time to remission and survival time were also analyzed.

Results—12 dogs were treated with PYR, and 15 were treated with MMF + PYR. Mortality rates were 33% (PYR) and 40% (MMF + PYR). There was pharmacological remission in 5 and 6 dogs in the PYR and MMF + PYR groups, respectively. No significant differences were detected between treatment groups for remission rate, time to remission, or survival time. Megaesophagus, pneumonia, and low serum thyroid hormone concentration had no significant effect on time to remission or survival time for either treatment group.

Conclusions and Clinical Relevance—The results did not support routine use of MMF for the treatment of dogs with acquired MG.
Tobacco use and secondhand smoke exposure during pregnancy in low‐ and middle‐income countries: the need for social and cultural research
Authors: NICHTER MIMI , GREAVES LORRAINE , BLOCH MICHELE , PAGLIA MICHAEL , SCARINCI ISABEL , TOLOSA JORGE E. , NOVOTNY THOMAS E.
Published: March 2010

Tobacco use is a leading cause of death and of poor pregnancy outcome in many countries. While tobacco use is decreasing in many high‐income countries, it is increasing in many low‐ and middle‐income countries (LMICs), where by the year 2030, 80% of deaths caused by tobacco use are expected to occur. In many LMICs, few women smoke tobacco, but strong evidence indicates this is changing; increased tobacco smoking by pregnant women will worsen pregnancy outcomes, especially in resource‐poor settings, and threatens to undermine or reverse hard‐won gains in maternal and child health. To date, little research has focused on preventing pregnant women's tobacco use and secondhand smoke (SHS) exposure in LMICs. Research on social and cultural influences on pregnant women's tobacco use will greatly facilitate the design and implementation of effective prevention programs and policies, including the adaptation of successful strategies used in high‐income countries. This paper describes pregnant women's tobacco use and SHS exposure and the social and cultural influences on pregnant women's tobacco exposure; it also presents a research agenda put forward by an international workgroup convened to make recommendations in this area.
Active versus expectant management for preterm prelabor rupture of membranes at 34‐36 weeks of completed gestation: comparison of maternal and neonatal outcomes
Authors: KAYEM GILLES , BERNIER‐DUPREELLE AURÉLIE , GOFFINET FRANÇOIS , CABROL DOMINIQUE , HADDAD BASSAM
Published: March 2010

Objective. To compare maternal and neonatal outcomes in deliveries managed by a policy of expectant management and active management of women with preterm prelabor rupture of membranes (pPROM), at 34‐36 completed weeks of gestation. Design. Retrospective multicenter cohort study. Setting. Three tertiary care teaching hospitals in France. Population. Women with pPROM were identified from the databases of three perinatal centers. Methods. Maternal and neonatal complications were compared according to the hospital policy in effect at pPROM – expectant or active management. Main outcome measures. Clinical chorioamnionitis, neonatal morbidity including neonatal infection, respiratory problems, and metabolic disorders. Results. During the seven‐year study period, 634 women were admitted for pPROM at 34‐36 completed weeks of gestation, 241 of whom were included in the study: 126 in the group with a policy of expectant management and 115 in the active management group. The incidence of clinical chorioamnionitis was 4.8% in the former and 0.9% in the latter (p = 0.07). Neonatal oxygen was still needed at 24 hours significantly more often in the active than in the expectant management group (7.0 vs. 1.6%, p = 0.05). However, after adjustment for gestational age at birth, only delivery at 34 weeks of gestation remained associated with the need for neonatal oxygen at 24 hours. The rate of hypoglycemia or hypocalcemia was 5.6% in the expectant management group versus 12.3% in the active management group (p = 0.07). There were no neonatal deaths. Conclusion. A policy of active management, especially at 34 weeks of gestation, was associated with greater neonatal morbidity, whereas an expectant management policy tended to be associated with an increased rate of clinical chorioamnionitis.
Psychoprophylaxis during labor: associations with labor‐related outcomes and experience of childbirth
Authors: BERGSTRÖM MALIN , KIELER HELLE , WALDENSTRÖM ULLA
Published: March 2010

Objective. To study whether use of psychoprophylaxis during labor affects course of labor and experience of childbirth in nulliparous women. Design. Cohort study. Setting. Women were recruited from 15 antenatal clinics in Sweden between October 2005 and January 2007. Sample. A total of 857 nulliparous women with a planned vaginal delivery. Methods. Using data from a randomized controlled trial of antenatal education where the allocated groups were merged, we compared course of labor and experience of childbirth between women who used psychoprophylaxis during labor and those who did not. Data were collected by questionnaires in mid‐pregnancy and three months after birth, and from the Swedish Medical Birth Register. Logistic regression was used to assess associations. Main outcome measures. Mode of delivery, augmentation of labor, length of labor, Apgar score, pain relief and experience of childbirth as measured by the Wijma Delivery Experience Questionnaire. Results. Use of psychoprophylaxis during labor was associated with a lower risk of emergency cesarean section (adjusted odds ratio (OR) 0.57; 95% confidence interval (CI) 0.37–0.88), but an increased risk of augmentation of labor (adjusted OR 1.68; 95% CI 1.23–2.28). No statistical differences were found in length of labor (adjusted OR 1.32; 95% CI 0.95–1.83), Apgar score < 7 at five minutes (adjusted OR 0.82; 95% CI 0.33–2.01), epidural analgesia (adjusted OR 1.13; 95% CI 0.84–1.53) or fearful childbirth experience (adjusted OR 1.04; 95% CI 0.62–1.74). Conclusion. Psychoprophylaxis may reduce the rate of emergency cesarean section but may not affect the experience of childbirth.
Ecological Systems as Complex Systems: Challenges for an Emerging Science
Authors: Anand Madhur , Gonzalez Andrew , Guichard Frédéric , Kolasa Jurek , Parrott Lael
Published: March 2010

Complex systems science has contributed to our understanding of ecology in important areas such as food webs, patch dynamics and population fluctuations. This has been achieved through the use of simple measures that can capture the difference between order and disorder and simple models with local interactions that can generate surprising behaviour at larger scales. However, close examination reveals that commonly applied definitions of complexity fail to accommodate some key features of ecological systems, a fact that will limit the contribution of complex systems science to ecology. We highlight these features of ecological complexity—such as diversity, cross-scale interactions, memory and environmental variability—that continue to challenge classical complex systems science. Further advances in these areas will be necessary before complex systems science can be widely applied to understand the dynamics of ecological systems.
Yield Implications of Site Preparation Treatments for Lodgepole Pine and White Spruce in Northern British Columbia
Authors: Cortini Francesco , Comeau Philip G. , Boateng Jacob O. , Bedford Lorne
Published: March 2010

We evaluated the effects of site preparation treatments on growth of lodgepole pine and white spruce in north-eastern British Columbia, Canada. These treatments can provide yield gains of up to 10 percent for lodgepole pine and white spruce at 60 and 80 years, respectively (estimated using TASS). Stands of these two species are showing a Type 1 response. Using growth multipliers, based on measurements collected at ages 10 to 20 results in inflated estimates of potential yield responses while the age-shift method provides the most appropriate estimates of yield gains when measured during the first 20 years of growth.
A New View of Alcohol Metabolism and Alcoholism—Role of the High-Km Class Ⅲ Alcohol Dehydrogenase (ADH3)
Authors: Haseba Takeshi , Ohno Youkichi
Published: March 2010

The conventional view is that alcohol metabolism is carried out by ADH1 (Class I) in the liver. However, it has been suggested that another pathway plays an important role in alcohol metabolism, especially when the level of blood ethanol is high or when drinking is chronic. Over the past three decades, vigorous attempts to identify the enzyme responsible for the non-ADH1 pathway have focused on the microsomal ethanol oxidizing system (MEOS) and catalase, but have failed to clarify their roles in systemic alcohol metabolism. Recently, using ADH3-null mutant mice, we demonstrated that ADH3 (Class III), which has a high Km and is a ubiquitous enzyme of ancient origin, contributes to systemic alcohol metabolism in a dose-dependent manner, thereby diminishing acute alcohol intoxication. Although the activity of ADH3 toward ethanol is usually low in vitro due to its very high Km, the catalytic efficiency (kcat/Km) is markedly enhanced when the solution hydrophobicity of the reaction medium increases. Activation of ADH3 by increasing hydrophobicity should also occur in liver cells; a cytoplasmic solution of mouse liver cells was shown to be much more hydrophobic than a buffer solution when using Nile red as a hydrophobicity probe. When various doses of ethanol are administered to mice, liver ADH3 activity is dynamically regulated through induction or kinetic activation, while ADH1 activity is markedly lower at high doses (3–5 g/kg). These data suggest that ADH3 plays a dynamic role in alcohol metabolism, either collaborating with ADH1 or compensating for the reduced role of ADH1. A complex two-ADH model that ascribes total liver ADH activity to both ADH1 and ADH3 explains the dose-dependent changes in the pharmacokinetic parameters (b, CLT, AUC) of blood ethanol very well, suggesting that alcohol metabolism in mice is primarily governed by these two ADHs. In patients with alcoholic liver disease, liver ADH3 activity increases, while ADH1 activity decreases, as alcohol intake increases. Furthermore, ADH3 is induced in damaged cells that have greater hydrophobicity, whereas ADH1 activity is lower when there is severe liver disease. These data suggest that chronic binge drinking and the resulting liver disease shifts the key enzyme in alcohol metabolism from low-Km ADH1 to high-Km ADH3, thereby reducing the rate of alcohol metabolism. The interdependent increase in the ADH3/ADH1 activity ratio and AUC may be a factor in the development of alcoholic liver disease. However, the adaptive increase in ADH3 sustains alcohol metabolism, even in patients with alcoholic liver cirrhosis, which makes it possible for them to drink themselves to death. Thus, the regulation of ADH3 activity may be important in preventing alcoholism development.
Tissue Equivalents Based on Cell-Seeded Biodegradable Microfluidic Constructs
Authors: Borenstein Jeffrey T. , Megley Katie , Wall Kimberly , Pritchard Eleanor M. , Truong David , Kaplan David L. , Tao Sarah L. , Herman Ira M.
Published: March 2010

One of the principal challenges in the field of tissue engineering and regenerative medicine is the formation of functional microvascular networks capable of sustaining tissue constructs. Complex tissues and vital organs require a means to support oxygen and nutrient transport during the development of constructs both prior to and after host integration, and current approaches have not demonstrated robust solutions to this challenge. Here, we present a technology platform encompassing the design, construction, cell seeding and functional evaluation of tissue equivalents for wound healing and other clinical applications. These tissue equivalents are comprised of biodegradable microfluidic scaffolds lined with microvascular cells and designed to replicate microenvironmental cues necessary to generate and sustain cell populations to replace dermal and/or epidermal tissues lost due to trauma or disease. Initial results demonstrate that these biodegradable microfluidic devices promote cell adherence and support basic cell functions. These systems represent a promising pathway towards highly integrated three-dimensional engineered tissue constructs for a wide range of clinical applications.
Application of Nanodiamonds in Biomolecular Mass Spectrometry
Authors: Kong Xianglei , Cheng Ping
Published: March 2010

The combination of nanodiamond (ND) with biomolecular mass spectrometry (MS) makes rapid, sensitive detection of biopolymers from complex biosamples feasible. Due to its chemical inertness, optical transparency and biocompatibility, the advantage of NDs in MS study is unique. Furthermore, functionalization on the surfaces of NDs expands their application in the fields of proteomics and genomics for specific requirements greatly. This review presents methods of MS analysis based on solid phase extraction and elution on NDs and different application examples including peptide, protein, DNA, glycan and others. Owing to the quick development of nanotechnology, surface chemistry, new MS methods and the intense interest in proteomics and genomics, a huge increase of their applications in biomolecular MS analysis in the near future can be predicted.
Structure and Function of Lactate Dehydrogenase from Hagfish
Authors: Nishiguchi Yoshikazu , Ito Nobue , Okada Mitsumasa
Published: March 2010

The lactate dehydrogenases (LDHs) in hagfish have been estimated to be the prototype of those in higher vertebrates. The effects of high hydrostatic pressure from 0.1 to 100 MPa on LDH activities from three hagfishes were examined. The LDH activities of Eptatretus burgeri, living at 45–60 m, were completely lost at 5 MPa. In contrast, LDH-A and -B in Eptatretus okinoseanus maintained 70% of their activities even at 100 MPa. These results show that the deeper the habitat, the higher the tolerance to pressure. To elucidate the molecular mechanisms for adaptation to high pressure, we compared the amino acid sequences and three-dimensional structures of LDHs in these hagfish. There were differences in six amino acids (6, 10, 20, 156, 269, and 341). These amino acidresidues are likely to contribute to the stability of the E. okinoseanus LDH under high-pressure conditions. The amino acids responsible for the pressure tolerance of hagfish are the same in both human and hagfish LDHs, and one substitution that occurred as an adaptation during evolution is coincident with that observed in a human disease. Mutation of these amino acids can cause anomalies that may be implicated in the development of human diseases.
Cyanobacterial Cyclopeptides as Lead Compounds to Novel Targeted Cancer Drugs
Authors: Sainis Ioannis , Fokas Demosthenes , Vareli Katerina , Tzakos Andreas , Kounnis Valentinos , Briasoulis Evangelos
Published: March 2010

Cyanobacterial cyclopeptides, including microcystins and nodularins, are considered a health hazard to humans due to the possible toxic effects of high consumption. From a pharmacological standpoint, microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cellular damage following uptake via organic anion-transporting polypeptides (OATP). Their intracellular biological effects involve inhibition of catalytic subunits of protein phosphatase 1 (PP1) and PP2, glutathione depletion and generation of reactive oxygen species (ROS). Interestingly, certain OATPs are prominently expressed in cancers as compared to normal tissues, qualifying MC as potential candidates for cancer drug development. In the era of targeted cancer therapy, cyanotoxins comprise a rich source of natural cytotoxic compounds with a potential to target cancers expressing specific uptake transporters. Moreover, their structure offers opportunities for combinatorial engineering to enhance the therapeutic index and resolve organ-specific toxicity issues. In this article, we revisit cyanobacterial cyclopeptides as potential novel targets for anticancer drugs by summarizing existing biomedical evidence, presenting structure-activity data and discussing developmental perspectives.