bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Gas Lift System
Authors: Vincent R. Price , Wilder L.B.
Published: May 2009

A system for intermittent or continuous gas lift which uses rubber balls as pistons to prevent wasteful gas slippage is described. Two parallel strings of tubing are used. The rubber balls are forced down one string and the production is lifted up the other. The rubberballs are separated from the oil and gas at the surface and reinjected with the lift gas by a special mechanism at the surface. Field tests indicate that the pump offers an economical solution for pumping wells where low production, foamy crude, high gas-oil ratio, deep production, or corrosion is a problem. One unique nature of the pump is that adjustments and repairs can be made at the surface by one or two men without the use of heavy equipment.

Introduction

Finding a method to economically produce low fluid level, low production wells is becoming a more urgent problem each year. High lifting costs for wells of this type produced by generally used methods results from these causes: frequent pulling jobs due to rod failures, tubing wear, pump replacement; paraffin troubles; corrosion; low efficiency in handling gassy or foamy crudes; and improperly adjusted equipment. Hydraulic subsurface pumping units and intermittent gas lift alleviate some of these problems, but they are not universally useable because of limitations peculiar to each. In an effort to find a lift system solving as many of the problems of pumping as possible, the Stanolind Research Department made an investigation of several possible methods of lift. One method developed has been called the "ball pump", and will be described here.

The increasing availability of natural gas in oil fields, either from gas wells, or from gas compression plants used for secondary recovery projects, existing rotative gas lift systems, gasoline plants, or transmission facilities, indicated that new development should be directed toward using gas as the lifting medium. By eliminating all reciprocating parts in the hole, gas lift removes the cause of many troubles of conventional pumping. However, existing intermittent gas lift systems have certain weaknesses which need improvement. For instance, though recent development of wire-line removable gas lift valves have lessened the need for pulling tubing for repairs or adjustments, low gas lift efficiency is still a problem. The efficiency is affected by the depth of the lift, the kind of fluid lifted, and the spread between the opening and closing pressures of the working gas lift valve. Paraffin control is also a serious problem.
Legal Aspects Of Offshore Oil
Authors: Smith Emory Clark
Published: May 2009

The Outer Continental Shelf Lands Act and the Submerged Lands Act are discussed. More importantly the leasing and operating regulations for the submerged lands of the outer continental shelf are analyzed in some detail. Geological considerations are used to propound the theory that rather than use the depth formula of 100 fathoms for measuring the continental shelf, it is preferable to place the boundary at the outer margin of the continental shelf or continental borderlands and refer this line to fixed points tied to the primary geodetic net of the littoral continent.

The influence of international law with respect to offshore oil operation sis treated. The test of reasonableness is applied not only to the freedom of the seas doctrine of international law but to the regulations controlling offshore drilling operations.

Introduction

Great areas of legal uncertainty were filled by the passage of the Outer Continental Shelf Lands Act and the Submerged Lands Act by the Congress in 1953. More recently, May 8, 1954, the promulgation of Leasing and Operating Regulations for the Outer Continental Shelf served to further clarify the hazy legal areas. These laws and regulations, instead of being obstacles have become useful instruments to the industry. Where there was justifiable hesitation before, there is now excited activity to hasten offshore oil exploration.

I am certain that those of you whose companies are engaged in this type of operation have found that there still remains a considerable area for improvement in the laws. In other words, things are still far from perfect. The imperfections of the law will constitute no delaying factor to the virile spirit of the industry.

On March 10, 1778, Captain William Bligh wrote in the ship's log: "In the forenoon, we struck sounding at 83 fathoms depth off the coast of Argentine, this I concluded to be near the edge of the bank."

Joseph M. G. Ravenal, the French diplomat, who had much to do with the Treaty of 1783 between the United States and Great Britain, wrote in 1803:"The sea which washes the shore of the state is deemed to form a part thereof. We could add that the bottom of the sea along the coast can be considered as having formed a part of the continent and is therefore still considered as forming such a part."
Calculated Performance Of A Dissolved Gas Drive Reservoir By A Phase Behavior Method
Authors: Brinkman F.H. , Weinaug C.F.
Published: May 2009

A phase behavior approach to the prediction of the performance characteristics of a dissolved gas-drive reservoir is unique in that the problem of choosing flash, differential, or composite solution gas-oil ratios and formation-volume factors has been circumvented. Data required are a compositional analysis of the reservoir fluid, the bubble point of this fluid, and the relative permeability curves for the reservoir work.

Gas-oil ratios and formation-volume factors were calculated under conditions duplicating the performance of the reservoir. A comparison was then made between these results and those obtained by calculations involving a differential, a flash, and a composite process. A vital factor in the solution of the problem is the accuracy of the calculated equilibrium constant. Agreement within three per cent was obtained when a calculated differential formation-volume curve was compared with an experimentally determined curve.

Introduction

Many reservoir engineering calculations depend for their solution on laboratory pressure, volume, and temperature measurements of formation volume factors and solution gas-oil ratios. How to determine these factors experimentally for the best duplication of the conditions under which reservoir oil is produced to the stock tank has been a matter of disagreement and much speculation in the oil industry. Three methods are in general use today: the differential process, which assumes that as the pressure on an oil is lowered, the gas, being liberated from the oil phase, is continuously removed from contact with it; the flash process, which assumes that all the gas, being liberated from the oil phase, remains in contact with it; and the composite process, which assumes that a differential process occurs in the reservoir and a flash process occurs upon the liquid portion being produced to the stock tank. Each laboratory process has decided limitations and does not represent accurately conditions under which reservoir oil is produced.
Fitting Performance of Particle‐size Distribution Models on Data Derived by Conventional and Laser Diffraction Techniques
Authors: Bah Abdul R. , Kravchuk Olena , Kirchhof Gunnar
Published: May 2009

Mathematical description of most classical particle size distribution (PSD) data is often used for estimating soil hydraulic properties. Fast laser diffraction (LD) techniques now provide more detailed PSDs, but deriving a function to characterize the entire range of sizes is a major challenge. The aim of this study was to compare the fitting performance of seven PSD functions with one to four parameters on sieve‐pipette and LD data sets of fine‐textured soils. The fits were evaluated by the adjusted R2, MSE, and Akaike's information criterion. The fractal and exponential functions performed poorly while the performance of the Gompertz model increased with clay content for the LD data sets. The Fredlund function provided very good fits with sieve‐pipette PSDs but not the corresponding LD data sets, probably due to underestimation of the clay fraction in the latter. The two‐parameter lognormal function showed better overall performance and provided very good fits with both sieve‐pipette and LD data sets.
Vertisol Crack Extent Associated with Gilgai and Soil Moisture in the Texas Gulf Coast Prairie
Authors: Kishné A. Sz. , Morgan C. L. S. , Miller W. L.
Published: May 2009

Long‐term observations of in situ crack formation and closure in shrink‐swell soils are rare, but important to understanding hydrology in shrink‐swell soils. To analyze spatial and temporal variability of crack development in a Vertisol with gilgai, soil cracks were measured on a 100‐m2 area of Laewest clay (fine, smectitic, hyperthermic Typic Hapludert) with native tallgrass vegetation on 42 dates from 1989 to 1998. Our objectives were to (i) report the distribution of Vertisol cracking across gilgai microtopography; (ii) estimate crack depth as a function of crack width considering gilgai; (iii) investigate the relationship of surface cracking and soil moisture considering gilgai and hysteresis. All surface cracks were mapped on scaled diagrams with width categorized, and some crack depth measured. Gravimetric soil moisture corresponding to crack measurements was measured on 18 dates, and on an additional 32 dates without crack measurements. Drying, wetting, and uniform soil moisture conditions were classified from the difference in soil moisture from 10‐ to 25‐cm depths. Microtopography was quantified using a digital elevation model. Results showed that crack area density was greatest on microhighs and microslopes, though microlows had the largest cracking potential. The linear correlation between crack depth and width was moderately strong (r2 = 0.5), and not affected significantly by gilgai and hysteresis. However, taking hysteresis into account improved the linear regression models of crack area density versus soil moisture (up to r2 = 0.69) on both microhighs and microlows. Antecedent soil moisture seemed to impact in situ crack area density. Further field studies are recommended.
Direct Steam Distillation as an Alternative to the Illinois Soil Nitrogen Test
Authors: Roberts T. L. , Norman R. J. , Slaton N. A. , Wilson C. E. , Ross W. J. , Bushong J. T.
Published: May 2009

Development of the Illinois Soil N Test (ISNT) has rejuvenated the search for a soil‐based N test to measure potentially mineralizable soil N. Accurate quantification of amino sugar N has been achieved using the ISNT, but issues concerning sample variability and analysis time have led to the discovery of a 10 mol L−1 NaOH direct steam distillation (DSD) procedure. Our primary objective was to determine if DSD could be used as a reliable alternative to the ISNT. Laboratory experiments were conducted to compare the two methods based on recovery of N from pure organic compounds, specificity tests to determine amine group hydrolysis, and recovery of 15N‐labeled glucosamine N added to soils. Both methods recovered appreciable amounts of amino sugar N from pure compounds and the ISNT had a higher recovery of N from all amino sugar compounds. Recovery of N from glutamine and asparagine was higher using DSD. Direct 15N techniques for recovery of glucosamine N added to six soils showed no significant difference between the two methods within a soil, but resulted in significant differences among soils. Glucosamine‐15N recovery significantly and positively correlated with soil total N. Although the ISNT and DSD measure different amounts of amino sugar N and transition amino acid N, they recover relatively the same amount of hydrolyzable N for a given soil, indicating that differences between the methods may not be that significant as both appear to quantify a pool of potentially mineralizable N. Direct steam distillation appears to be a viable alternative to the ISNT in correlation and calibration of crop response for N‐fertilizer recommendations due to the short analysis time per sample (∼6 min) and the accurate estimation of potentially mineralizable N.
Correlation and Calibration of Soil Potassium Availability with Rice Yield and Nutritional Status
Authors: Slaton Nathan A. , Golden Bobby R. , Norman Richard J. , Wilson Charles E. , DeLong Russell E.
Published: May 2009

Soil testing is an important tool for estimating soil K availability and determining how much fertilizer must be applied to realize crop yield potential and minimize fertilizer costs. Our primary objectives were to correlate relative rice (Oryza sativa L.) yield with Mehlich‐3 and 1 mol L−1 HNO3 extractable K, define sufficient whole‐plant K concentrations at panicle differentiation (PD) and early heading (HDG), and calibrate K‐fertilizer rates with Mehlich‐3 soil K in the direct‐seeded, delayed‐flood rice production system. Potassium rate experiments were established at 32 site‐years on silt loams in eastern Arkansas. Relationships between selected parameters were evaluated with linear, curvilinear, and linear‐plateau models. The relationships between relative yield regressed against Mehlich‐3 and HNO3 extractable K were significant and curvilinear. The final curvilinear models for Mehlich‐3 and HNO3 K explained 63 and 43% of yield variability among site‐years, with predicted critical soil concentrations to produce 95% relative yield of 99 and 390 mg K kg−1, respectively. Linear‐plateau models provided comparable critical soil K concentrations. Rice having whole‐plant K concentrations of 23.1 g kg−1 at PD and 13.0 g kg−1 at HDG were predicted to produce 95% relative yield. The predicted K‐fertilizer rates required to optimize rice grain yield depended on the model and ranged from 51 to 90, 41 to 70, 30 to 55, and 20 to 35 kg K ha−1 for soil having Mehlich‐3 soil K concentrations of 60, 70, 80, and 90 mg K kg−1, respectively. The suggested Mehlich‐3 soil and plant K critical concentrations should be appropriate for other U.S. mid‐South rice‐producing areas using similar cultural production practices.
Lean and the Psychosocial Work Environment
Authors: Hasle Peter
Published: May 2009

Lean has become an important element in production development, both in the private and the
public sector, but it is also a controversial concept with strong sponsors – proponents as well as opposers.
Does lean lead to intensification of work and increased stress or is it a new possibility for employee
participation and improvement in the psychosocial work environment? A review of the literature does not
give a clear answer. Both outcomes seem to be possible. However, the change process involved in the
implementation of lean appears to be important for the outcome both in terms of productivity and in
terms of the psychosocial work environment. Understanding the role of organizational social capital is
crucial to the possibilities for a successful lean implementation, and it is necessary to have a simultaneous
focus on the improvement of the management–employee collaboration and the application of lean tools
and methods at the same time.
Leaders Embracing Change: Managing Healthy Change Processes
Authors: Oystein Saksvik Per , Danielsen Tvedt Sturle
Published: May 2009

The objective of the chapter is to explore how lower-level leaders, i.e., middle managers, deal
with organizational change processes and to identify their behavior as in accordance with the claims of a
new Work Environment Act in Norway, which defines an optimal and healthy organizational change
process. The chapter builds on our own findings that healthy leader behavior in an organizational change
context is characterized by the embracing of change. In this chapter, we present and discuss the context
of change in Scandinavia and Norway, the impact of the change process, and the relation between change
and leadership theories and perspectives. We also suggest a comprehensive model of healthy
organizational change.
Resistance to Organizational Change: Individual Reactions to Change on the Emotional, Attitudinal, and Behavioral Levels
Authors: Berg Saksvik Ingvild , Hetland Hilde
Published: May 2009

Individual differences in perception of organizational change are assumed to affect both the
change process, and it’s results. Research indicates that some individuals seem to resist most
organizational changes. This chapter presents a recent approach to dispositional resistance to change, and
discusses the concept’s relation to other individual difference variables, as well as practical implications
of focusing on dispositional resistance to change in an organizational change process.
Studying Organizational Change from a Multilevel Perspective
Authors: Rennesund Aslaug
Published: May 2009

During the last ten years, there has been a slow, but promising, increase in the number of
studies that apply a multilevel, or cross-level, perspective when aiming to explain significant variations in
employee behavior, such as job satisfaction and organizational commitment. These studies typically
investigate their outcome variables by focusing on antecedents at both the individual and the
organizational levels in the same methodological framework or research model. Within the subfield of
organizational change studies, the picture seems to be somewhat less promising, and multilevel, or crosslevel,
organizational change studies seem to be outnumbered by equivalent studies that are being
conducted within subfields like leadership and occupational health. When addressing organizational
change, researchers seem to agree that prerequisites for managing healthy or successful change initiatives
may reside both in the employees and in the organization, but still they tend to limit their research to just
one conceptual and analytical level, and do not often explore how phenomena may work together across
these levels in order to ensure healthy change. The aim of this chapter is to demonstrate why and how
organizational change should be studied within a methodological framework that takes into account the
multilevel nature of organizational change. The chapter is structured around two main questions: a) why
should organizational change be studied within a multilevel perspective?, and b) drawing on some of the
most recent studies within organizational change, what issues related to organizational change could be
studied within this methodological framework? The first part of the chapter discusses conceptual and
methodological reasons why organizational change should be studied from a multilevel perspective, by
providing a brief and easily accessible introduction to the philosophical and methodological literature that
exists on the topic. The second part of the chapter presents change topics that might be particularly
interesting to explore by means of a multilevel framework. The presentation is based on several empirical
studies that have been published in the period from 1999 to 2008, and focuses on the relationship that
may exist between the characteristics of the change effort, the individual or collective change capabilities
in the organization, and two individual outcome variables that have been associated with successful
change initiatives, namely job satisfaction and organizational commitment. The categories developed by
Armenakis and Bedeian (1999) are used as an important framework in this discussion.
Early and Aggressive Initiation of Insulin Therapy for Type 2 Diabetes: What Is the Evidence?
Authors: Niswender Kevin
Published: May 2009

IN BRIEF

Type 2 diabetes is a progressive disease in which b[beta symbol]-cell function continually declines and eventually fails, ultimately requiring nearly all patients to be placed on insulin therapy. An increasing body of evidence suggests that early intensive glycemic control reduces long-term vascular outcomes and potentially may prolong b[beta symbol]-cell lifespan and function. Herein, evidence in favor of early insulin therapy on disease progression and long-term outcomes will be reviewed and placed into clinical context.
On uncertainty relations in noncommutative phase space
Authors: Guo Guangjie , Long Chaoyun , Qin Shuijie
Published: May 2009

The uncertainty relations are discussed on a noncommutative plane when noncommutativity of momentum spaces is considered. It is possible to construct normalizable states by simultaneously saturating two coordinate-momentum uncertainty relations. However, under the natural condition θη ≪ 4ħ2 one can not construct a normalizable state by simultaneously saturating any other pairs out of four basic nontrivial uncertainty relations.
Development of an Integrated Framework for Assessing and Improving the Performance of Manufacturing Industries in Developing Countries
Authors: Syan Chanan , Ramoutar Krystal
Published: May 2009

Development of an Integrated Framework for Assessing and Improving the Performance of Manufacturing Industries in Developing Countries

In developing countries, there is an overwhelming challenge to diversify the economy from the primary sectors to more value adding and income generating sustainable secondary or manufacturing sectors. As global competitiveness intensifies, it is imperative that manufacturing organizations in developing countries can compete at a global level. This research focuses on Trinidad and Tobago (T&T) and the wider Caribbean region. However, its applicability and relevance is extensive. This paper investigates the manufacturing techniques/practices currently implemented in T&T with focus on companies that are compliant with quality and health and safety policies. This study advocates the need for a strategic approach for the successful implementation of world-class manufacturing (WCM) techniques/practices in T&T manufacturing industry. The methodology as well as research instruments developed and used are presented.
Entomopter Maneuverability Exchanged by Deformations Control of Flexible Flapping Wings
Authors: Kowalczyk Grzegorz , Lewitowicz Jerzy , Sibilski Krzysztof
Published: May 2009

Entomopter Maneuverability Exchanged by Deformations Control of Flexible Flapping Wings

In the background of preparing this paper lies our believe that transferring ideas from the more matured disciple like aircraft technology to emerging animal technology should be beneficial for the later one and vice-versa. One integrated idea, of special interest to both disciplines, is theactive flexible wingconcept. In this paper we developed aeroelastic analysis for a flexible wing for an imposed harmonic flapping motion about the root chord of the wing. A Matlab code was written based on the analysis. This code was used to find the average lift and thrust of a wing of known aerodynamic and structural properties.
Knowledge-Based Collaborative Lean Manufacturing Management (KBCLMM) System
Authors: Nawawi Mohd , Khan Mohammed , Hussain Khalid
Published: May 2009

Knowledge-Based Collaborative Lean Manufacturing Management (KBCLMM) System

The objective of this research paper is to demonstrate the application of hybrid Knowledge-Based System, Gauging Absences of Pre-Requisites (GAP), and Analytic Hierarchy Process (AHP) approaches for selecting the improvement programs for Collaborative Lean Manufacturing Management (CLMM) System. In this research, a generic Knowledge-Based System is developed to measure the level of CLMM adoption in automotive manufacturers compared to the ideal system. Using the embedded GAP and AHP technique, the key lean manufacturing improvement programs can be prioritised by using both qualitative and quantitative criteria. The analysis covers the planning stage of the KBCLMM. The utilisation of the approach is demonstrated with an illustrative example.
Atlantoaxial stabilization in rheumatoid arthritis
Authors: Papadopoulos Stephen M. , Dickman Curtis A. , Sonntag Volker K. H.
Published: May 2009

✓ Atlantoaxial subluxation in patients with rheumatoid arthritis is common. Operative stabilization is clearly indicated when signs and symptoms of spinal cord compression occur. However, many recommend early operative fusion before evidence of appreciable neural compression occurs because 1) the myelopathy in these patients may be irreversible; 2) the overall prognosis is poor once symptoms of cord compression are present; and 3) the risk of sudden death associated with atlantoaxial subluxation is increased even in asymptomatic patients. The authors believe that rheumatoid arthritis patients in relatively good health without advanced multisystem disease and less than 65 years of age should be considered for operative stabilization if mobile atlantoaxial subluxation is greater than 6 mm. Seventeen patients with severe rheumatoid arthritis and atlantoaxial subluxation treated with a posterior arthrodesis are presented. A new method of fusion, devised by the senior author (V.K.H.S.), was utilized in all cases. Indications for operative therapy in these patients included evidence of spinal cord compression in 11 patients (65%) and mobile atlantoaxial subluxation greater than 6 mm but no signs or symptoms of cord compression in six patients (35%). Thirteen patients developed a stable osseous fusion, two patients a well-aligned fibrous union, one patient a malaligned fibrous union, and one patient died prior to evaluation of fusion stability.

The details of the operative technique and management strategies are presented. Several technical advantages of this method of fusion make this approach particularly useful in patients with rheumatoid arthritis. Because of multisystem involvement of this disease, a high rate of osseous fusion is often difficult to achieve.
Long-term effects of nimodipine on cerebral infarcts and outcome after aneurysmal subarachnoid hemorrhage and surgery
Authors: Öhman Juha , Servo Antti , Heiskanen Olli
Published: May 2009

✓ A total of 213 patients with verified aneurysmal subarachnoid hemorrhage (SAH) of Grades I to III (Hunt and Hess classification) were enrolled in a double-blind placebo-controlled trial to determine the effect of intravenous nimodipine on delayed ischemic deterioration and computerized tomography (CT)-visualized infarcts after SAH and surgery. The administration of the drug or matching placebo was started immediately after the radiological diagnosis of a ruptured aneurysm had been made. Of the 213 patients enrolled in the study, 58 were operated on early (within 72 hours after the bleed: Days 0 to 3), 69 were operated on subacutely (between Days 4 and 7), and 74 had late surgery (on Day 8 or later). Eleven patients died before surgery was undertaken and one was not operated on. A follow-up examination with CT scanning, performed 1 to 3 years after the SAH (mean 1.4 years), revealed no significant differences in the overall outcome between the groups. However, nimodipine treatment was associated with a significantly lower incidence of deaths caused by delayed cerebral ischemia (p = 0.01) and significantly lower occurrence of cerebral infarcts visualized by CT scanning in the whole population (p = 0.05), especially in patients without an associated intracerebral hemorrhage on admission CT scan (p = 0.03).
Risks factors for cerebral infarction in good-grade patients after aneurysmal subarachnoid hemorrhage and surgery: a prospective study
Authors: Öhman Juha , Servo Antti , Heiskanen Olli
Published: May 2009

✓ A prospective series of 265 patients with aneurysmal subarachnoid hemorrhage (SAH) of Grades I to III (Hunt and Hess classification) upon admission were evaluated as to neurological outcome and computerized tomography (CT) findings 1 to 3 years (mean 1.4 years) after the SAH and surgery. A total of 73 patients underwent acute surgery (within 72 hours after the bleed: Days 0 to 3), 86 were operated on subacutely (between Days 4 and 7), and 91 had late surgery (on Day 8 or later). Fifteen patients died before surgery was undertaken and another 20 patients died during the follow-up period. A total of 104 patients received nimodipine and the rest of the patients received either placebo (109 patients) or no medication (52 patients). A logistical regression analysis revealed the following prognostic factors for cerebral infarction, in order of importance: the amount of blood on the primary CT scan; postoperative angiographic vasospasm; the timing of the operation; and a history of hypertension. The use of nimodipine was associated with a significant reduction of cerebral infarcts visualized by CT scanning in patients who received intermediate or late surgery. In patients who underwent acute surgery no significant difference between the incidence of cerebral infarcts was observed.
Correlates of survival and the Daumas-Duport grading system for astrocytomas
Authors: Kim Tai Seung , Halliday Andrea L. , Hedley-Whyte E. Tessa , Convery Karen
Published: May 2009

✓ In order to examine the correlation between prognosis and the histological features of nuclear atypia, mitosis, endothelial proliferation, and necrosis in supratentorial adult astrocytomas, the authors reviewed 251 such cases treated at the Massachusetts General Hospital between 1972 and 1980. One point was given for the presence of each feature. The total number of features was translated into a grade as follows: none of the four features = Grade 1 (one patient), one feature = Grade 2 (36 patients), two features = Grade 3 (33 patients), and three or four features = Grade 4 (181 patients). The period of survival was significantly associated with grade, the presence or absence of each of the four histological features, patient's age, type of operation, radiation therapy, and extent of tumor (log rank, p < 0.05). The variables associated with grade were age (p < 0.001) and radiation therapy (p < 0.02). After adjustment for these variables using a Cox proportional-hazards model, the difference in overall survival time between patients in Grades 2 and 3 was not statistically significant. When comparable groups of patients were examined in terms of age or receipt of radiation therapy, the median survival times differed markedly. Patients 50 years of age or less had a median survival time of 68 months (Grade 2 tumors), 29 months (Grade 3 tumors), and 13 months (Grade 4 tumors). Patients over 50 years of age had a median survival time of 6 months (Grade 2 and 4 tumors) and 9 months (Grade 3 tumors). Those patients who had received radiation therapy had a median survival time of 68 months (Grade 2 tumors), 21 months (Grade 3 tumors), and 11 months (Grade 4 tumors). Those patients who did not receive radiation therapy had a median survival time of 1 month (Grade 2 tumors) and 2 months (Grade 3 and 4 tumors); over half of these patients died within 2 months of surgery. This grading system, originally proposed by Daumas-Duport, et al., is simple, objective, and reproducible, and correlates well with survival times. The authors recommend that astrocytomas be graded on a scale of 1 to 4, with Grade 1 reserved for the rare adult supratentorial astrocytoma with none of the four histological features.
Idiopathic and glucocorticoid-induced spinal epidural lipomatosis
Authors: Haddad Souheil F. , Hitchon Patrick W. , Godersky John C.
Published: May 2009

✓ Pathological overgrowth of the epidural fat in the spine has been described and reported nearly exclusively in patients either with Cushing's syndrome or on chronic intake of glucocorticoids for a variety of clinical disorders. The authors report four patients with documented spinal lipomatosis (three pathologically and one radiologically). Only one of these patients received corticosteroids, and none had an underlying endocrinological abnormality. All four patients were adult males with a mean age at onset of symptoms of 43 years (range from 18 to 60 years). The symptoms ranged from simple neurogenic claudication and radicular pain to frank myelopathy. Myelography followed by computerized tomography were instrumental in the diagnosis of the first three patients; the fourth was diagnosed by magnetic resonance imaging. The thoracic spine was involved in two cases and the lumbosacral area in the other two. The different treatment modalities were tailored according to the symptomatology of the patients. These included weight reduction of an overweight patient with minimal neurological findings in one case and decompressive laminectomy and fat debulking to achieve adequate cord decompression in the remaining three cases. Two patients improved significantly, the condition of one stabilized, and the fourth required a second decompression at other spinal levels. The various modalities of treatment and their potential complications are discussed.
The effect of glucose administration on carbohydrate metabolism after head injury
Authors: Robertson Claudia S. , Goodman J. Clay , Narayan Raj K. , Contant Charles F. , Grossman Robert G.
Published: May 2009

✓ The role of intravenous infusion of glucose in limiting ketogenesis and the effect of glucose on cerebral metabolism following severe head injury were studied in 21 comatose patients. The patients were randomly assigned to alimentation with or without glucose. Systemic protein wasting, arterial concentrations of energy substrates, and cerebral metabolism of these energy substrates were monitored for 5 days postinjury. Both groups were in negative nitrogen balance, and had wasting of systemic proteins despite substantial protein intake. Blood and cerebrospinal fluid (CSF) glucose concentrations were highest on Day 1, but remained higher than normal fasting levels on all days of study, even in the patients who received no exogenous glucose. Although there were no differences in blood or CSF glucose concentrations in the two groups of patients, the glucose group had higher plasma insulin levels, with a mean ± standard deviation of 14.8 ± 7.3 µU/ml compared to 10.3 ± 4.2 µU/ml in the saline group. The blood concentrations of β-hydroxybutyrate, acetoacetate, pyruvate, glycerol, and the free fatty acids were higher in the saline group than in the glucose group. Cerebral oxygen consumption was similar in the two groups, while the cerebral metabolism of glucose and of the ketone bodies was dependent on whether glucose was administered. In the glucose group, glucose was the only energy substrate utilized by the brain. In the saline group, the ketone bodies β-hydroxybutyrate and acetoacetate replaced glucose to the extent of 16% of the brain's total energy production. Cerebral lactate production and CSF lactate concentration were lower in the saline group. These studies suggest that administration of glucose during the early recovery period of severe head injury is a major cause of suppressed ketogenesis, and may increase production of lactic acid by the traumatized brain by limiting the availability of nonglycolytic energy substrates.
Management of meralgia paresthetica
Authors: Williams Paul H. , Trzil Kenneth P.
Published: May 2009

✓ Meralgia paresthetica is a syndrome of pain or dysesthesia, or both, in the anterolateral thigh caused by entrapment or neurinoma formation of the lateral femoral cutaneous nerve. Conservative treatment was successful in relieving symptoms in 91% of 277 patients with this syndrome; however, 24 patients required surgical treatment for intractable symptoms. Although neurolysis with transposition is the most common procedure, sectioning of the lateral femoral cutaneous nerve was performed in 24 cases and was successful in 23. One patient had early symptomatic relief, but subsequently developed different neurological signs and symptoms because of an undetected pelvic neoplasm.

Anatomical variations of the nerve and neurinomas, which occur frequently, are easily handled with sectioning but may lead to recurrence with neurolysis and transposition.
Treatment of severe intraventricular hemorrhage by intraventricular infusion of urokinase
Authors: Todo Tomoki , Usui Masaaki , Takakura Kintomo
Published: May 2009

✓ Six patients with severe intraventricular hemorrhage were treated with direct intraventricular infusion of urokinase. In each case, hemorrhage extended into all ventricular chambers, and a cast formation and expansion of the third and fourth ventricles were found. Immediately after the therapy was started (within 7 days from onset of symptoms), reduction of intraventricular hematoma volume was observed on computerized tomography. On average, both the third and fourth ventricles became clear on the third day after hemorrhage; there was one exception, a case of ruptured aneurysm. Five of the six patients showed excellent or good outcome, although two developed delayed hydrocephalus. No infection or rebleeding was observed. The outcome in a retrospectively studied group of five patients not treated with urokinase is also reported. The authors conclude that this relatively easy method of treatment will greatly improve the prognosis of severe intraventricular hemorrhage.
Effects of tromethamine and hyperventilation on brain injury in the cat
Authors: Yoshida Kazuo , Marmarou Anthony
Published: May 2009

✓ The metabolic brain acidosis after trauma has been thought to be harmful and to contribute to neurological deterioration. Amelioration of the brain acidosis either by systemic buffering agents or by hyperventilation has been proposed as a method of treatment. The objective of this study was to explore with magnetic resonance (MR) spectroscopy the metabolic changes in brain that occur with the use of hyperventilation, THAM (tromethamine; tris[hydroxymethyl]aminomethane), and a combination (THAM and hyperventilation) therapy in experimental fluid-percussion injury.

Brain lactate, brain pH, inorganic phosphate (Pi), and adenosine triphosphate levels were measured by 1H and 31P MR spectroscopy. Arterial and cerebrovenous lactate and water content in brain tissue was determined in 29 cats using the specific gravimetric technique. Following injury, the phosphocreatine (PCr)/Pi ratio, which is an index of cerebral energy depletion, decreased to 76% in four untreated animals, to 79% in 11 THAM-treated animals, to 68% in seven animals receiving hyperventilation, and to 66% in seven animals with combination THAM and hyperventilation therapy. The PCr/Pi ratio returned to a normal level in 8 hours in animals treated with THAM and THAM in combination with hyperventilation. The brain lactate index increased to 157% in the hyperventilation group after trauma. In cats receiving THAM plus hyperventilation, the brain lactate index was reduced to 142%, while the minimum rise of 126% was associated with treatment of THAM alone. In the THAM-treatment and combination-treatment groups, the water content of the white and gray matter was significantly decreased compared with that in untreated cat brains.

Prolonged hyperventilation provided relative ischemia in brain tissue and promoted more production of brain lactate, no recovery of the PCr/Pi ratio, and no decrease in brain edema. On the other hand, administration of THAM decreased production of brain lactate and brain edema and promoted the recovery of cerebral energy dysfunction. It was found that THAM ameliorates the deleterious effects of hyperventilation by minimizing energy disturbance and that it also decreases brain edema. The authors conclude that THAM may be effective in reducing brain tissue acidosis and helpful as a metabolic stabilizing agent following severe head injury.
Tumor-associated neurological dysfunction prevented by lazaroids in rats
Authors: King Wesley A. , Black Keith L. , Ikezaki Kiyonobu , Conklin Scott , Becker Donald P.
Published: May 2009

✓ The efficacy of U-74006F and U-78517F in the treatment of blood-tumor barrier permeability and tumor-associated neurological dysfunction was evaluated in a brain-tumor model in rats. U-74006F is a 21-aminosteroid and U-78517F is a 2-methylamino chroman. Rats with stereotactically implanted Walker 256 tumors were treated with methylprednisolone, U-74006F, U-78517F, or vehicle (0.05 N HCl) on Days 6 through 10 following implantation. Neurological function and vascular permeability were assessed on Day 10. Methylprednisolone and U-74006F were equally effective at preventing neurological dysfunction compared to the control group (p < 0.01); U-78517F was slightly less effective than U-74006F and methylprednisolone but was significantly better than vehicle in preventing neurological dysfunction. Delivery of methylprednisolone resulted in a significant decrease in tumor vascular permeability (p < 0.006) while U-74006F and U-78517F had no effect on permeability. This suggests that U-74006F and U-78517F prevented tumor-associated neurological dysfunction by a mechanism other than decreasing permeability in tumor capillaries, and that U-74006F or U-78517F could prove useful in the treatment of brain tumors.
Epidermoid cysts of the brain stem
Authors: Obana William G. , Wilson Charles B.
Published: May 2009

✓ The authors report the cases of three patients with epidermoid cysts which insinuated themselves into the brain stem. In all three patients, the tumor occupied the pons, although in one it was predominantly located in the medulla. The cyst contents and nonadherent tumor capsule were removed in all three patients, but no attempt was made to remove tumor densely adherent to the brain stem. One patient's cyst was removed in one operation, but maximal resection in the other two required two operations. After surgery, sixth nerve function completely returned in one patient; another patient had a stable pontine gaze palsy but developed new facial weakness; and the third patient had stable cranial nerve deficits with a diminished hemiparesis. The last patient developed a pseudomeningocele and communicating hydrocephalus, and required a lumboperitoneal shunt. In all three patients, computerized tomography scans demonstrated hypodense tumors not enhanced by contrast material. Magnetic resonance imaging was performed on two patients; in both, the tumors showed increased signal intensity relative to brain on T1-weighted images and decreased signal intensity relative to brain on T2-weighted studies. Magnetic resonance imaging, the most accurate modality for localizing these lesions and determining their extent, was also invaluable for postoperative monitoring and follow-up evaluation. Safe and adequate resection includes decompression of cyst contents and removal of nonadherent portions of the cyst capsule. Cyst wall adherent to the brain stem, however, should not be removed.
Basilar impression in osteogenesis imperfecta tarda
Authors: Kurimoto Masanori , Ohara Susumu , Takaku Akira
Published: May 2009

✓ A case is presented of basilar impression secondary to osteogenesis imperfecta tarda, associated with hemifacial spasm and brain-stem compression syndrome. The symptoms improved with posterior fossa decompression and posterior fusion.
Central corpectomy for cervical spondylotic myelopathy: a consecutive series with long-term follow-up evaluation
Authors: Saunders Richard L. , Bernini Philip M. , Shirrefks Thomas G. , Reeves Alexander G.
Published: May 2009

✓ Since 1984, a consecutive series of patients with cervical spondylotic myelopathy has been treated by central corpectomy and strut grafting. This report focuses on 40 cases operated on between 1984 and 1987 and followed from 2 to 5 years. The perioperative complication rate was 47.5%, with a 7.5% incidence of persistent sequelae: severe C-5 radiculopathy in one patient, swallowing dysfunction in one, and hypoglossal nerve palsy in one. No single factor (age, duration of symptoms, or severity of myelopathy) was absolutely predictive of outcome; however, syndromes of short duration had the best likelihood of cure. Similar outcomes were associated, individually, with long duration of symptoms, age over 70 years, and severe myelopathy. After factoring a 5% regression of improvement, the long-term cure rate was 57.5% and the failure rate was 15%. Myelopathy worsening was not documented.
Intracranial arachnoid cysts in children. A comparison of the effects of fenestration and shunting
Authors: Ciricillo Samuel F. , Cogen Philip H. , Harsh Griffith R. , Edwards Michael S. B.
Published: May 2009

✓ The best operative intervention for children with arachnoid cysts remains the subject of controversy. Recent reports stress that craniotomy for cyst fenestration is associated with a low incidence of morbidity and mortality and may leave the child shunt-independent. The cases of 40 pediatric patients with arachnoid cysts treated between 1978 and 1989 are reported. Five children with mild symptoms and small cysts that remained stable on follow-up studies have not required surgical intervention. Of 15 patients with cysts initially treated by fenestration, 10 (67%) showed no clinical or radiographic improvement postoperatively and have undergone cyst-peritoneal (eight patients) or ventriculoperitoneal (VP) shunting (one patient), or revision of a VP shunt placed for hydrocephalus before cyst fenestration (one patient). Two other patients with existing VP shunts required no further procedures. Thus, only three (20%) of 15 patients initially treated by fenestration remain shunt-independent after a median follow-up period of 8 years. The 20 other patients were initially treated by cyst shunting and all improved postoperatively; shunt revision has been necessary in six (30%) of these 20 patients because of cyst recurrence, Cyst location influenced the success of shunt treatment; none of the seven middle cranial fossa cysts treated by shunting have required revision, but results with cysts in other locations were less favorable. In all locations, though, shunting was more successful than fenestration. It is concluded that cyst-peritoneal or cyst-VP shunting is the procedure of choice for arachnoid cysts in most locations, including those in the middle cranial fossa.
Multiple adenomas of the human pituitary
Authors: Kontogeorgos George , Kovacs Kalman , Horvath Eva , Scheithauer Bernd W.
Published: May 2009

✓ In a review of autopsy material from two centers, 20 pituitary glands were found containing multiple adenomas. In total, 44 adenomas were identified histologically; 16 glands contained double tumors and in four glands triple adenomas were found. Size was measured in 30 tumors, all of which were microadenomas. Thirty-four adenomas were located in the lateral wings and 10 lay in the median wedge. Forty-one tumors were chromophobic and three were basophilic. Immunocytochemical analysis of the 44 tumors demonstrated the presence of prolactin in 11, adrenocorticotropic hormone in three, growth hormone in one, and α-subunit as well as follicle-stimulating hormone and luteinizing hormone in one.

Of the 20 patients studied, there were 11 men and nine women, with an average age of 69 years. All patients died from various nonendocrine causes. With the exception of one patient who appeared mildly acromegalic, no correlation was observed between pituitary morphology and clinical data. This study found a 10.4% frequency of adenomas in pituitaries studied randomly at autopsy. Multiple tumors were encountered in 0.9% of cases. Despite its low frequency, adenoma multiplicity may underlie surgical failure in cases in which one adenoma is removed and the other is left behind.