bluuebunny/crossref_metadata_2025 huggingface dataset:
Why Dual Porosity Models are not Applicable for Simulation of the Near-Wellbore Zone of Gas Condensate Well for Naturally Fractured Reservoirs
Authors: Rudenko D. , Shandrygin A. , Zyryanova A.
Published: October 2008

The peculiarities of retrograde condensation in the near wellbore region in naturally fractured formation were studied with the use of dual-porosity/dual permeability models and the direct numerical simulation based on the "Sugar Cube"19 representation of the fractured porous media. Serious spatial inhomogeneity of the saturation distribution in porous matrix blocks was demonstrated. Dual porosity/permeability models are obviously unable to reproduce spatial condensate distribution in near wellbore zone of the reservoir but after proper tuning these models can be used for the simulation of the well production profile in naturally fractured reservoir and of the flow picture in the near wellbore zone in general.
Definition of Oil Displacement Mechanism at Field Development
Authors: Karnauhov Mihail , Gaponova Larisa , Klimov Mihail , Piankova Elena
Published: October 2008

The definition of oil displacement mechanism is one of major questions in problem of reservoir processes: or as mixed oil-water flow, when oil and water phase relative permeability (kro and krw) of water flood zones are specified; or as piston flow, when takes place frontal drive of oil by stream of approaching water.

Phase relative permeability for water and oil are usually defined on the basis of learning filtering of oil-water mixtures through a core. Just on the basis of such experiments the curves of phase relative permeability to oil and water are performed, which then used in the different design documents and projects of field development.

At the same time it is known, for example, that using modern methods of engineering inclusive reservoir simulation model are large difficulties at history matching with applying of such relative permeability curves of filtered fluids. Frequently forced variation of parameters of filtering at history matching results in concurrence of calculated and actual indexs to development at final parameters of filtering much distinguished from source, obtained in laboratory conditions.

It is necessary to mark also, that in the literature last years many papers have appeared that the core is a poor material that only on its basis to plan field development because of unrepresentative of coring, as a result of which it does not mirror property of all reservoir system; high created gradients of stresses at studies in laboratory conditions as contrasted to actual; strictly oriented directivity of flow of fluid through a core with impossibility of an estimation of anisotropy of formations on permeability and etc.

In a paper the features of extraction of oil reserves on some fields of Western Siberia are reviewed. Is shown, that as a whole on fields there are complex processes of fluid flow, where are formed as regions of water inrushes with consequent catastrophic watering out of individual wells, and zones of oil displacement with waterless wells, working a long time, and recovery of reserves in such zones much greater, than initial oil reserves in drained areas of these wells. It is impossible to explain by widespread assumptions about influencing reformative phase relative permeability or complex heterogeneity of oil reservoir. Formed zones of oil displacement to durable waterless operation of wells, as a rule, are connected with frontal drive. The examples of operation of some horizontal wells with high oil recovery factor (more than 0.5) in area of their drainage. The results of numerous production and injection well testing and conducting of hydrolistenings testify to such nature of water-oil displacement.

The concrete offers on rational field development methods are made, when the piston condition of water-oil displacement is organized predominantly.
Features of Oil Fields Development by the System of Multilateral Horizontal Wells, Practical Experience
Authors: Klimov Mikhail , Karnauhov Mikhail
Published: October 2008

This paper summarizes practical results of oil fields development by multilateral horizontal wells. By the example of Severo-Yangtinskoe and Chatylkynskoe oil fields the whole cycle of works from well-planning to development monitoring is described.

Severo-Yangtinskoe is one of the newest oil fields operated by the Company. Field Development Project regulating its development was drawn up and approved in Central Development Commission in 2006 after that production drilling of the main object began. All project decisions are based on reservoir simulation model. According to FDP, development scheme involves irregular placement of horizontal and subvertical wells.

Severo-Yangtinskoe reserves may be classified as difficult to recover; in practice it is problematic to involve such a deposit into development by conventional subvertical well schemes. During the two-year period of field development 8 horizontal wells have been successfully drilled and put on production, of which 3 are multilateral, that is the latest well completion technology probe-tested in the Company. This technology has been put into practice on the other Company's oil fields. Present work demonstrates and proves the advantages of complex reservoirs development by dual horizontal wells.

Chatylkynskoe oil field is also one of the newest Company's assets. FDP regulating the development was composed and defended in Central Development Commission in 2006. The pilot project specifies horizontal wells application as well as marginal waterflooding by deviated wells for the field development. The main reservoir has significant thickness, but its geological structure is complicated by tectonic disturbances and heterogeneity. All the decisions worked out are based on a reservoir simulation modeling. During the period 2006 – 2008 7 horizontal wells have been successfully drilled, 5 of which are dual wells.
Solution of Problems of Water-Gas Influence (WGI) on the Layer Using Jet and Electrical Centrifugal Pumping Technology
Authors: Drozdov A. N. , Telkov V. P. , Egorov Yu. A. , Verbitsky V. S. , Dengaev A. V. , Lambin D. N. , Krasilnikov I. A.
Published: October 2008

Waterflooding – is currently the most popular method of oilfield development, but very often it does not guarantee high development effectiveness. This fact is the significant problem taking into account that the amount of hard to recover reserves is being increased constantly. The combined water and gas injection to the layer enables us to essentially increase the oil recovery ratio. Use of associated gas for water-gas influence also enables us to solve a problem of its utilization.

About 100 field applications of WGI are known since this technology was used in North Pembina (Canada 1957 year) for the first time, and only single cases failed.

Today, different technologies of WGI are applied that can be classified in two ways: alternate or simultaneous injection of water and gas (WAG or SWAG Injection). However, traditional ways of applying WGI were not widespread in Russian oil fields, but instead significant amounts of associated gas were flared.

WAG compressor technology requires the purchasing of import equipment, essential investments in the initial stage, and high operating costs. Besides compressor stations, the construction of gas treatment plants is required.

The separation of rich fraction from associated gas is required for the proper work functioning of compressors. These fractions are not always utilized and than the usage of dry gas for WGI it is less effective in terms of increasing oil recovery.
TNK-BP Idle Well Stock Reactivation Program
Authors: Manapov T. , Alekseeva V. , Zhigalov V. , Aksenov M.
Published: October 2008

Large inactive well stock is one of the factors complicating current Russian oil field development process. As per 1 January 2008, the Russian Federation IWS amounted to over 26000 oil wells. Long-continued inactivity of a large well number reduces potential of development optimization and oil recovery enhancement methods, deteriorates production and economic performance, increases environmental impact risks.

IWS re-activation requires complex well servicing involving water isolation, fishing, sidetracking etc. Therefore, idle stock reactivation efficiency, as a rule, is lower than that of active well interventions. In these conditions particular emphasis is placed on selection of methodology for dealing with IWS, which considers retention of the project development system, achievement of maximum oil recovery factor and improvement of the field development cost-performance ratio.

A comprehensive TNK-BP Idle Well Stock Reactivation Program was developed within the frame of Company's strategy, to reach the following objectives:

– by end of 2013, to reduce IWS to the amount close to the standard (10%); – complete license obligations fulfillment in the part of drilled well-stock utilization, including solutions of the approved project process documentation; – application of advanced technology to re-activate idle wells and enhance their performance.

The article considers results of comprehensive Idle Well Stock Reactivation Program implementation, describes examples of idle well reactivation and design technology / project development system recovery technology implementation, and identifies ways to improve performance. It is demonstrated that even in conditions of high depletion ratio and extremely high watercut, substantiated use of modern technologies allows to guarantee efficient production of remaining oil reserves.
A Sedimentologic Model for Lower Cretaceous Sediments Within the Northern Portion of the Surgut Arch as Exemplified by the BS102 Zone
Authors: Supolkina I. V. , Saratinyan L. V. , Kozhevskikh A. S. , Gorbunov A. A.
Published: October 2008

Due to decrease in oil reserves caused by their depletion new exploration activities and development targets are required. One of such development targets is the BS10 zone. The origin of the BS102 zone is the object of the present report.

The BS102 zone confined to Lower Cretaceous sediments is the most productive among pay zones within the northern part of the Syrgur arch. In terms of geology the zone is very complicated. Exploratory drilling in the Severo-Konitlorskoye, Severo-Kochevskoye, Kochevskoye and Tevlinsko-Russkinskoye oil fields made possible to reveal different water-oil-contacts of different level. This means that hydrocarbon accumulations in the BS102 zone are hydrodynamically separated. Due to variations in depositional environments the deposits of the zone are characterized by lithology substitution, pinchind-out, variations in thickness of lens-shaped bodies the zone is composed of as well as variations in reservoir properties.

The study area is located in the Surgut region of the Khanty-Mansi Autonomous okrug, 150 km north of the city of Surgut. From a tectonic point of view the area is confined to the northwestern part of the Kogalym uplift which is supposed to be the 2nd structure order. In the north this structure complicates the Surgut arch - the 1st order structure. The area is investigated by various types of exploratory activities. They include geomorphologic, airborne magnetic surveys, exploratory and development drilling, and 2D, 3D seismic surveys.
Reservoir Parameters Evaluation Based on Production Data Analysis
Authors: Khasanov Mars , Krasnov Vitaly , Guk Viatcheslav
Published: October 2008

Evaluation of reservoir properties such as permeability, formation pressure and skin factor by means of welltest data interpretation is widespread. Usually these tests are implemented using pressure build up technique which leads to production losses. This fact makes regular well tests conductions to be undesirable by operators.

Another opportunity for reservoir parameters evaluation is given by transient period of well operation, the one starts after a new well start up and lasts until the pressure disturbance reaches the boundaries. In case when transient period lasts long enough (Priobskaya field) and production regimes are logged regularly, using this data seems to be reasonable.

A new approach to permeability, reservoir pressure and skin factor evaluation by production data analysis is presented in this study. This approach is based on broadening of the NODAL analysis concept onto transient case. The system operational point on the NODAL analysis plot is an intersection of inflow performance relationship curve and lift performance curve. During the transient flow regime, inflow performance curve changes with time. This allows developing expression for productivity index variation with time as dependent on permeability and skin factor. Matching the model curve of rate-time dependence to the actual curve allows resolving a system of equations containing reservoir parameters as unknowns.

Proposed method is approximate. A comparison to the rigorous solution for linear inner boundary condition is given. The results of calculation by proposed method were shown to be in good agreement to the ones obtained with the analytical solution. The case study including comparison to the build-up test also showed good performance of proposed method.

Implementation of the method proposed in this study allows, in particular, performing identification of transient regime, defining and ascribing production change to influencing factors and planning production optimization.
Hydrodynamic Reservoir Simulation of Prediction Cases
Authors: Moiseevich Olenchikov Dmitry , Rustamovna Kruglikova Ludmila
Published: October 2008

In the report the analysis of the basic difficulties of prediction cases hydrodynamic modeling is executed. It is offered to describe prediction cases not in terms of simulator key words, but in terms of events and patterns of actions. It will raise the quality of prediction cases and will reduce time necessary for its designing. Also it will free the reservoir management engineer of necessity of detailed studying numerous simulator key words.
Main Tendencies of the Sweep Efficiency Improvement Evolution in Russia
Authors: Shandrygin A. N. , Lutfullin A.
Published: October 2008

The sweep efficiency enhancement technologies applied in Russia were analyzed. It was shown that the most common sweep efficiency enhancement techniques are sidetracking, non-stationary flooding and different flow-diverting technologies, based on chemicals injection, restricted by volume. In some cases, hydraulic fracturing can be considered also as a means to improve the sweep efficiency by treatment. The case histories of all treatment techniques specified in the paper are presented and trends of their development in the future are identified.
Hierarchy of the Integrated Models
Authors: Khasanov M. M. , Afanasiev I. S. , Latypov A. R. , Pavlov V. A. , Antonenko D. A. , Surtaev V. N.
Published: October 2008

The end of an «easy oil times», realization of expensive projects on developing fields in the remote from infrastructure areas, with severe climate and complicated topographical conditions, raised new challenges for the field development engineering. First of all, it is related to a necessity of developing a general of field preparation prior to the detailed design and construction works.

A standard approach to field development projects is based on a series of calculations on different scenarios for reservoir development, facilities construction together with economical evaluation. As practice shows, selection of optimal reservoir development scenario, irrespective of surface facilities issues, or selection of optimum surface facilities case, calculated without taking into account reservoir performance, eventually, do not provide optimal economic indicators for the entire system. Considering this interrelation, it is not possible to transfer sensitivity analysis for parameters of one system into another and, ultimately, economical indicators of the project.

All this confirms that the effective, self-consistent solutions can be developed only using the integrated approach considering all aspects, affecting technological and economical field development indicators. To fulfill these objectives, Rosneft Oil Company implemented the integrated approach to field development engineering.

In this article, we introduce a concept of the integrated model hierarchy, allowing classification and reservoir model construction and design process facilitation depending on problem complexity. Various models application is demonstrated on the example of one of the largest Rosneft's new fields.
High GLR ESP Technologies Comparison, Field Test Results
Authors: Bedrin V. G. , Khasanov M. M. , Khabibullin R. A. , Krasnov V. A. , Pashali A. A. , Litvinenko K. V. , Elichev V. A. , Prado M.
Published: October 2008

One of limitations of achieving full potential in pumped wells is due to the presence of excessive free gas at pump intake. The presence of free gas at pump intake has several effects on the pump performance. A reduction in the pressure drop developed by the pump is usually observed when pumping multiphase flow mixtures. This performance reduction sometimes may be severe, resulting in unstable pump operation, production losses and may lead to premature equipment failure.

Electric submersible centrifugal pumps (ESP) are commonly used in Russia and other parts of the world for oil production. Currently operators are being required to produce wells under non conventional and challenging operational conditions. One of such conditions is the use of ESP in wells with a high free gas liquid ratio that requires the use of special technology. Under those circumstances it is very important to understand more profoundly the processes of ESP operation as any mistake in the equipment design may have severe economical consequences. One of the crucial information needed is the technical limiting operational conditions for different ESP technologies when handling high gas liquid ratio mixtures.

Determination of the technical operational envelope is itself a challenge. Experimental work conducted in Universities and industry research centers are very important for an understanding of the problem and advance of the technologies. But it is difficult to recreate in the lab the same conditions that exist in a well bore. Working with actual fluids at high temperatures and pressures are still challenging conditions to be reproduced in the lab. Therefore theoretical models, experimental correlations manufactures technical guidelines need to be verified against the conditions existing in a real oil well.

This work presents the conclusions of the use of state of the art engineering methods describing the reservoir-pump-production system to analyze the performance of gas handling technologies based on real well field test results. The field tests were conducted under the New Technologies System project of Rosneft Oil Company. Field tests estimated technical limits for ESP gas handling technologies for up to 75% of volumetric gas fraction at pump intake conditions, as well as confirmed the possibility of oil production enhancement with the tests (the NPV for 11 ESP tested was more than 40 mln. rubles in 2007). It is estimated that more than a 100 wells would benefit from ESP gas handling technologies in Purneftegas alone, yielding significant economic impact for the company, increasing oil production by more than 700 tons/day.
Modeling of Hydraulically Fractured Wells in Full Field Reservoir Simulation Model
Authors: Gataullin Timur
Published: October 2008

Many methods of fractured well representation in simulation model are known. Some of them are too complex to use in large simulation model where more then one well are fractured, some don't represent a fractured well behaviour. In this work a choise of a fractured well representation in simulation model have been proceded from the practical point of view. A method of fractured well simulation model assessment in situation with lacking production history was created. It is based on comparison of productivity and transient pressure behaviour with results of analytical model of Cinco-Ley and Samaniego.
The Straddle Packer Application as a Way to Reduce Multi-zone Fracturing Cycle Duration
Authors: Pestrikov A. V. , Kuznetsov V. A. , Grigorichev D. B.
Published: October 2008

Nowadays, hydraulic fracturing is one of the most effective ways of low-permeability layered reservoirs management. About half of the oil reserves, remained in Western Siberia today, are concentrated in such reservoirs. The field experience and engineering calculations show that without fracturing the largest part of this oil would be left in the Earth forever. That is why we can classify hydraulic fracturing as a method of oil recovery enhancement.

The reduction of multi-zone fracturing time cycle is an important part of asset management and cost optimization for the large multi-layer oil fields developing with the help of hydraulic fracturing.
Application of Low Frequency Passive Seismic Technology for Hydrocarbon Exploration at Complicated Subsurface Structures
Authors: Irrnyakov Eugene , Mikhailov Sergy , Khabibullin Ilnur
Published: October 2008

In last several years there is an increasing interest in phenomenon of low frequency (1-10Hz) spectral anomalies above the hydrocarbon reservoirs. The practical application of this phenomenon is an opportunity for a direct hydrocarbon exploration. In this paper we report the preliminary results of the Low Frequency Passive Seismic survey, which have been performed in Russian Federation, Republic of Tatarstan (Volga-Urals oil province) in the eastern board of the Mellikesskaya hollows. The subsurface structure of the survey area is complicated by Visean ridges, Bobrikovian sediments of terrigenous facies with excellent productivity properties. At such complicated structures the conventional seismic fails, so the Low Frequency Passive Seismic Technology has been chosen as an exploration tool. Using high-sensivity broadband seismometers we have performed a registration of seismic wave field at 64 points of the survey area. To estimate the production properties of an oil saturated area we have calibrated spectral properties of seismic signal at points, penetrated by wells. There is an excellent agreement of the survey results with five new wells, which has been drilled after the survey, so the Low Frequency Passive Seismic Technology also can be applied at complicated subsurface structures where conventional seismic fails.
Effects of PKC and PKA Inhibitors on the cAMP-Stimulant-Induced Enhancement of Tetrodotoxin-Resistant Na+ (Nav1.8) Currents
Authors: Matsumoto Shigeji , Yoshida Shinki , Ikeda Mizuho , Saiki Chikako , Takeda Mamoru
Published: October 2008

The protein kinase C (PKC) inhibitor bisindolymaleimide Ro-31-8425 (Ro-31-8425) decreases the peak tetrodotoxin-
resistant (TTX-R) Na+ (Nav1.8) current in nodose ganglion (NG) neurons, and this decrease is not altered by simultaneous
application of 8-bromo-cAMP (8-Br-cAMP), phorbol 12-myristate 13-acetate (PMA, a PKC activator) or
forskolin (a cAMP analogue). Intracellular application of the endogenous protein kinase A (PKA) inhibitor, protein kinase
inhibitor (PKI) abolishes the increase in the peak Nav1.8 current that occurs in response to the applications of 8-BrcAMP,
PMA, forskolin, or prostaglandin E2 (PGE2, an adenyl cyclase activator). At a higher concentration (0.5 mM)
compared with a sufficient concentration (0.01 mM) to block the cAMP-stimulant Nav1.8 current, PKI still attenuated the
Ro-31-8425-induced decrease in peak Nav1.8 current. When we considered these results together, cAMP-stimulantinduced
modification of Nav1.8 currents is mediated by the activation of both PKA and PKC, and PKC may be located
upstream of PKA.
Effect of Bilateral Mandibular Osteodistration on the Condylar Cartilage: An Experimental Study on Rabbits
Authors: Elgazzar Reda F , El-Bialy Tarek H , Megahed Eman
Published: October 2008

Although various aspects of bone formation during distraction osteogenesis have been studied extensively, there are only limited experimental data concerning the influence of hyper-physiologic mandibular distraction rate on structural alterations in the temporomandibular joint (TMJ) condylar cartilage. The purpose of this study was to evaluate the effect of bilateral distraction osteogenesis of the mandibular body, at a hyper-physiologic rate and length, on the integrity of the condylar cartilage in rabbits. MATERIALS AND METHODS: Eighteen healthy adult male rabbits weighing 2 to 3 kg were assigned to 1 of 2 groups: the control group (n = 2 rabbits, 4 joints) or the study group (n = 16 rabbits, 32 joints) four rabbits (8 joints) in each subgroup according to the post-distraction period (1,2,3 or 4 weeks). In the control group, rabbits received sham surgery (Osteotomy without distraction) and then left to live for 4 weeks under the same condition of the study group then euthanized using intravenous overdose of pentobarbital sodium. In the study group, an extra oral custom-made distracter was employed to achieve bilateral mandibular hyper physiologic distraction (1.5 mm twice daily for 5 days) distraction. All animals were evaluated clinically and histomorphometrically and results analyzed by MINITABE 13.1 statistical package using ANOVA test. RESULTS: Animals underwent distraction showed obvious changes in condylar surface contour related to length of the follow up period, compared to the control; these changes seemed to be partly reversible. The most pronounced observation was the irregularities and resorption in the anterior part of the condylar cartilage and the subcondylar bone. Moreover, at the first two weeks, the area of resorption was invaded by large number of osteoclasts and chronic inflammatory cells which declined later in the 3rd and 4th weeks and replaced with osteoblastic activities. CONSLUSION: These experimental data showed that distraction rate of 3 mm per day may lead to degenerative or even early arthritic changes in the TMJ condylar cartilage in the 1st and 2nd post-distraction weeks. However, all condyles showed adaptive and remodeling sings in the following 3rd and 4th weeks.
LINEAR ARRAY Human Papillomavirus Genotyping Test Amenable to Automation by Implementation of GT-Blot 48 – A Pilot Study
Authors: Schmid Michael , Schalasta Gunnar , Speicher Andrea , Enders Gisela
Published: October 2008

Objectives:

Persistent infection with high-risk human papillomavirus is associated with the development of
cervical intraepithelial neoplasia and a key factor in progression to invasive cancer. The Linear Array HPV genotyping
test (LA) is a valuable diagnostic tool enabling type-specific detection of DNA from 37 anogenital high- and low-risk
HPV genotypes. Its value, however, is hampered by the underlying labour-intensive manual line blot technology. This
study was designed to improve the suitability of LA in routine use by implementing the GT-Blot 48 instrument as an alternative
instead of using the proposed manual detection protocol.

Methods:

Automation of LA processing was evaluated by comparing GT-blot 48 processed strips to the manufacturer recommended
manual protocol. For type-specificity we compared the performance of GT-blot 48 processed strips with that
of PapilloCheck, another PCR-based HPV typing assay. Furthermore, the performance of HPV DNA detection by GTblot
48 processed strips to that by Hybrid Capture 2 (hr-HC2) assay was compared, using samples from 122 women attending
routine cervical examination.

Results:

GT-blot 48 processed strips and the manual method demonstrate equal performance. The overall agreement of
HPV prevalence between automated LA and PapilloCheck was 96.6% (kappa = 0.92). A 91.2% concordance was observed
between automated LA and hr-HC2 (kappa = 0.82).

Conclusions:

Automated LA processing is a valuable alternative to the manual method. Results are highly comparable
with those obtained by hr-HC2 and PapilloCheck. Implementation of GT-blot 48 is a reliable easy-to-use format, which
offers increased time efficiency and the additional benefit of high-throughput with standardized processing.
The Relationship between the Mean Surface Air Temperature in Egypt and NAO Index and ENSO
Authors: Hafez Y.Y. , Robaa S.M.
Published: October 2008

The relationship between the NAO index and ENSO and the mean surface air temperature over Egypt has been investigated. The NCEP/NCAR reanalysis data of the monthly mean surface air temperature over Egypt for the period (1948-2005) have been used in this study. The corresponding monthly mean values of NAO index, SOI, and El-Nino3 have been also used. Monte Carlo methodology as a linear correlation analysis has been used to obtain the correlation coefficient between the mean surface air temperature over Egypt and NAO, SOI, and El-Nino3 through the period (1948-2005). The results show that surface air temperature in Egypt is significantly correlated with the climatic index NAO and ENSO only for a south western part of Egypt. There is a significant negative correlation (-0.6) between surface air temperature over south west part of Egypt in winter season and NAO index. The relationship between EL-Nino3 and surface air temperature has contradicted the relationship with SOI. Whereas, a significant positive correlation (+0.6) between surface air temperature over south west part of Egypt and EL-Nino3 in autumn season. Surface air temperature correlated with SOI by a significant negative correlation (-0.5) during the same season over south west of Egypt. It is concluded that the surface air temperature is significantly correlated with NAO index and ENSO over the south west part of Egypt.
Evaluation of Three Practical Methods for Estimating Daily Solar Radiation in Dry Climates
Authors: Castellví F.
Published: October 2008

Three practical methods for estimating daily solar radiation in dry climates with air temperature and precipitation data as input were evaluated. The three equations only partially explained second order statistics such as variance and different correlations, so the interdependence with primary weather variables such as the daily maximum and minimum temperatures was not fully captured. The equations, however, may be useful for calculations that require solar radiation as input, such as the daily reference evapotranspiration according to Priestley-Taylor equation using the FAO guidelines expert consultation.
Post-Operative Pain After Knee Arthroscopy and Related Factors
Authors: Drosos G.I , Stavropoulos N.I , Katsis A , Kesidis K , Kazakos K , Verettas D.-A
Published: October 2008

The aim of this study was to explore the intensity of post-arthroscopy knee pain during the first 24 hours, and to study the influence of pre-operative pain, tourniquet time and amount of surgical trauma on post-arthroscopy pain. In 78 male patients that underwent elective arthroscopic menisectomy or diagnostic arthroscopy of the knee, preoperative and post-operative pain were registered using the Visual Analogue Scale. Variance for repeated measures and for independent observations was analysed. Supplementary analgesia was required for 23% of the patients, more often in the recovery room and between 2 and 8 hours postoperatively. Of all factors analyzed, only time was statistically significant in determining the level of post-operative pain. Supplementary analgesia was required only in patients that underwent operative arthroscopy, and more often in patients with tourniquet time of more than 40 minutes. In conclusions, post-operative time is the most significant factor related to the post-arthroscopy knee pain.
The Use of Pinus radiata Sawdust or Bark, or Zeolite to Reduce E. coli in Stand-Off Pads or Associated Drainage
Authors: Donnison A.M. , Ross C.M.
Published: October 2008

Cow dung slurry containing a total of 7.4 × 105 E. coli was applied to laboratory-scale microcosms of Pinus
radiata sawdust or bark. Rainfall was simulated by application of water at rates of 25 mm h-1 or 50 mm h-1 over 30 minutes.
For sawdust 5% and 11% (respectively) of the E. coli were transferred to drainage compared to 12% and 28% for
bark. After collection of drainage less than 10% of the retained E. coli were recovered from sawdust compared to about
90% for bark. Stand-off pad drainage (102 E. coli 100 mL-1) was passed through laboratory-scale microcosms at 0.42 mL
min-1 for 4 weeks. The E. coli concentration was reduced by 1.5 log10 for sawdust microcosms but there was no significant
reduction for bark and zeolite. P. radiata sawdust seems an unfavourable environment for E. coli and its use in stand-off
pads could reduce transmission of faecal microbes from dairy farms to waterways.
Taxes under Obama and McCain
Authors: Gale William G. , Harris Benjamin
Published: October 2008

The bottom line on the tax plans of Obama and McCain are that Obama has bigger tax cuts for middle income families and modest tax hikes for the wealthy, as compared with McCain's $125,000 per family tax cut for those earning over $600,000. Neither candidate is paying enough attention to the long term need to raise taxes, according to William Gale and Benjamin Harris.
The incidence of heparin-induced thrombocytopenia Type II in patients with subarachnoid hemorrhage treated with heparin versus enoxaparin
Authors: Kim Grace H. , Hahn David K. , Kellner Christopher P. , Komotar Ricardo J. , Starke Robert , Garrett Matthew C. , Yao Jiang , Cleveland Justin , Mayer Stephan A. , Connolly E. Sander
Published: October 2008

Object

Heparin-induced thrombocytopenia Type II (HIT II) is a serious complication that occurs in 0.2–3% of patients treated with heparin and is associated with a high risk of thrombotic events. One center recently reported an incidence of HIT II of 15% in a population of patients with aneurysmal subarachnoid hemorrhage (aSAH). Because these patients are typically exposed to heparin during angiography, controversy exists regarding whether prophylaxis with enoxaparin rather than heparin affords any reduction in the risk of developing HIT II. In this study, the authors investigated the effect of heparin compared with enoxaparin on the incidence of HIT II in patients with aSAH.

Methods

The authors reviewed the medical records of 300 patients treated for aSAH who received thromboprophylaxis with either heparin or enoxaparin, and identified patients who developed HIT II. The incidences of HIT II in the 2 treatment groups were then compared.

Results

One hundred sixty-six patients with aSAH were treated with heparin, and 134 patients were treated with enoxaparin. Sixteen (5.3%) of 300 patients met the diagnostic criteria for HIT II. Of those treated with heparin, 8 (4.8%) of 166 developed HIT II, compared with 8 (6%) of 134 treated with enoxaparin (difference not significant).

Conclusions

The authors report a lower incidence of HIT II in patients with aSAH than has previously been reported. The data also suggest that patients with aSAH who receive heparin are at no greater risk of developing HIT II than those who receive enoxaparin. This finding challenges the merit of choosing enoxaparin rather than heparin for thromboprophylaxis in patients with a SAH.
Relationship between supratentorial arachnoid cyst and chronic subdural hematoma: neuroradiological evidence and surgical treatment
Authors: Domenicucci Maurizio , Russo Natale , Giugni Elisabetta , Pierallini Alberto
Published: October 2008

Object

Arachnoid cysts are relatively common congenital intracranial mass lesions that arise during the development of the meninges. They can be complicated by the formation of an ipsilateral chronic subdural hematoma (CSDH) after minor cranial trauma. Treatment of these coexisting conditions remains controversial. In this study the authors describe the anatomical, clinical, and neuroradiological features and outcome in a series of patients whose CSDH associated with arachnoid cysts were managed surgically by draining the hematoma alone and leaving the cyst intact. The authors based this surgical management on histological and neuroradiological observations concerning these associated medical conditions.

Methods

A series of 8 patients with CSDHs associated with arachnoid cysts underwent surgery to drain the hematoma though a bur hole. The arachnoid cyst was left intact. Postoperative follow-up included CT scanning and T1- and T2-weighted MR imaging.

Results

Clinical, anatomical, and radiological observations suggest that because separate membranes cover arachnoid cysts and the related hematoma, arachnoid cysts remain unaffected by the subdural bleeding. In the present study, these observations received support from the neuroimaging appearances, suggesting that arachnoid cysts related to hematoma contained only blood breakdown products from the hematoma that had filtered through the reciprocal dividing membranes.

Conclusions

Arachnoid cysts associated with SDH are anatomically separate conditions whose neurological symptoms respond to surgical drainage of the CSDH alone.
William S. Halsted and Harvey W. Cushing: reflections on their complex association
Authors: Voorhees Jennifer R. , Tubbs R. Shane , Nahed Brian , Cohen-Gadol Aaron A.
Published: October 2008

William Stewart Halsted, the father of modern surgery, and Harvey Williams Cushing, the father of neurosurgery, are remembered for their countless innovations and contributions to the discipline of surgery. Between 1896 and 1912, they worked together at Johns Hopkins Hospital making many of their respective achievements possible. In the later years, their complex relationship, somewhat strained during Cushing's residency, grew into a mutual respect and deep appreciation for one another. In this offering, the authors attempt to elucidate the evolution of this complex relationship.
Is the distance between mammillary bodies predictive of a thickened third ventricle floor?
Authors: Iaccarino Corrado , Tedeschi Enrico , Rapanà Armando , Massarelli Ilario , Belfiore Giuseppe , Quarantelli Mario , Bellotti Alfredo
Published: October 2008

Object

The aim of this study was to correlate intraoperative endoscopic third ventriculostomy (ETV) findings in hydrocephalic patients with the MR imaging appearance of the mammillary bodies (MBs), the fundamental anatomical landmarks of the third ventricle floor (TVF) region.

Methods

The authors reviewed brain MR images and intraoperative ETV records in 23 patients with hydrocephalus as well as MR imaging data from 120 randomized control volunteers of various ages to define the normal intermammillary distance (IMD).

Results

In control volunteers, no measurable IMD (“kissing” configuration) was observed in 91 (85%) of 107 cases, and there was mild MB splitting (mean ± standard deviation, 0.18 ± 0.12 cm) in only 16 cases with age-related cerebral atrophy. Among the 21 patients with complete MR imaging and ETV data sets, 12 ETV procedures were hindered by anatomical anomalies such as a thickened TVF or an “upward ballooning” phenomenon. On preoperative MR imaging in these 12 patients, there was an increased IMD (0.55 ± 0.41 cm) compared with that in the remaining 9 patients (0.27 ± 0.25 cm) who had a normal thin TVF during ETV and in the control group (0.03 ± 0.08 cm). Magnetic resonance imaging and ETV data concordantly displayed nonsplit MBs in 6 of 9 cases with a thin TVF and split MBs in 10 of 12 cases with a thick TVF.

Conclusions

The normal configuration of MBs is no measurable IMD, with mild splitting occurring in patients with age-related brain atrophy. In hydrocephalic patients, a thickened TVF was present almost exclusively with an increased IMD on preoperative MR imaging and separated MBs on endoscopic viewing. Large retrospective series are needed to confirm that a preoperative increased IMD is predictive of a thickened TVF during ETV.
The role of a single nucleotide polymorphism of MDM2 in glioblastoma multiforme
Authors: Khatri Rina G. , Navaratne Kapila , Weil Robert J.
Published: October 2008

Object

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults, with a 5-year survival rate of < 5%. Aberrant function of TP53 is common in GBM. Although mutational inactivation of p53 is found in many cases, there remain tumors in which genetic alterations of p53 are absent. Negative regulators of the TP53 pathway such as MDM2, which directly inhibits TP53 expression and activity, may influence the pathogenesis of GBM. To understand its potential function in gliomagenesis, the authors analyzed a novel single nucleotide polymorphism (SNP) in the MDM2 promoter that enhances MDM2 expression.

Methods

The investigators isolated DNA from 98 patients with GBM and 102 healthy, cancer-free controls. A polymerase chain reaction analysis was performed to determine the MDM2 SNP309 genotype by using distinct primer pairs for the wild-type (T) and mutant (G) alleles.

Results

The frequency of the mutant MDM2 polymorphism was found to be higher (p = 0.0092) in patients with GBM (54.6%) compared with healthy controls (41.2%); the TT and GG genotypes were more common in healthy controls and patients with GBM (p = 0.0004 and p = 0.02, respectively). Although there was no association between the MDM2 SNP309 and overall survival, the GG genotype was associated with development of GBM at a younger age in patients with tumors harboring wild-type p53, which may mitigate the effect of the MDM2 SNP.

Conclusions

Although the MDM2 SNP309 does not portend decreased survival, the increased incidence of the mutant G allele in patients with GBM and its influence on age of onset suggest a potential role in the molecular pathogenesis of GBM, and may be a therapeutic target.
Brainstem glioma progression in juvenile and adult rats
Authors: Liu Qing , Liu Ran , Kashyap Meghana V. , Agarwal Rajnee , Shi Xiang'en , Wang Chung-cheng , Yang Shao-Hua
Published: October 2008

Object

Brainstem gliomas are common in children and have the worst prognosis of any brain tumor in this age group. On the other hand, brainstem gliomas are rare in adults, and the authors of some clinical studies have suggested that this lesion behaves differently in adults than in children. In the present study, the authors test an orthotopic C6 brainstem glioma model in juvenile and adult rats, and investigate the biological behavior of this lesion in the 2 age groups.

Methods

The C6 glioma cells were stereotactically implanted into the pons of juvenile or adult male rats. Neurological presentation and survival time were recorded. Tumor proliferation and the number of apoptotic cells in brainstem gliomas of young and adult rats were determined by immunohistochemical staining with Ki 67 and terminal deoxynucleotidyl transferase 2′-deoxyuridine 5′-triphosphate-mediated nick-end labeling assay.

Results

Striking differences in the onset of neurological signs, duration of symptoms, survival time, tumor growth pattern, tumor proliferation, and number of apoptotic cells were found between the gliomas in the 2 groups of rats. The lesions were relatively focal in adult rats but more diffuse in young rats. Furthermore, brainstem gliomas in adult rats were less proliferative and had more apoptotic cells than those in young rats.

Conclusions

The authors found that the C6 brainstem glioma model in young and adult rats closely imitates the course of brainstem glioma in humans both in neurological findings and histopathological characteristics. Their findings also suggest that the different growth pattern and invasiveness of these lesions in children compared with that in adults could be due to different cellular environments in the 2 age groups, and warrants further investigation into the difference in the host response to brainstem gliomas in children and adults.
Convection-enhanced delivery of polyethylene glycol–coated liposomal doxorubicin: characterization and efficacy in rat intracranial glioma models
Authors: Kikuchi Toshio , Saito Ryuta , Sugiyama Shin-ichirou , Yamashita Yoji , Kumabe Toshihiro , Krauze Michal , Bankiewicz Krystof , Tominaga Teiji
Published: October 2008

Object

The characteristics of polyethylene glycol–coated liposomal doxorubicin (PLD), the only liposomal drug now clinically available for intravenous injection, were investigated after convection-enhanced delivery (CED) into the rat brain parenchyma.

Methods

The distribution, tissue retention, and toxicity profile were evaluated after CED into the rat brain parenchyma. The antitumor efficacy was also determined in rodent intracranial U-251MG and U-87MG glioma models.

Results

Convection-enhanced delivery of PLD achieved wider distributions and delayed onset of toxicity in the brain parenchyma compared with CED of free doxorubicin infusion. Fluorescence generated from doxorubicin infused as PLD was detected until at least 30 days after infusion. Local toxicity was not observed when a 10% dilution of the commercially available PLD solution was used (0.2 mg/ml doxorubicin), but was significant at higher concentrations. Results after 10% PLD was delivered locally with CED demonstrated significant survival prolongation in both intracranial U-251MG and U-87MG xenograft models.

Conclusions

Convection-enhanced delivery of PLD achieved extensive tissue distribution and sustained drug release. Convection-enhanced delivery of PLD is a promising chemotherapy for the treatment of malignant gliomas.
Detection of infusate leakage in the brain using real-time imaging of convection-enhanced delivery
Authors: Varenika Vanja , Dickinson Peter , Bringas John , LeCouteur Richard , Higgins Robert , Park John , Fiandaca Massimo , Berger Mitchel , Sampson John , Bankiewicz Krystof
Published: October 2008

Object

The authors have shown that convection-enhanced delivery (CED) of gadoteridol-loaded liposomes (GDLs) into different regions of normal monkey brain results in predictable, widespread distribution of this tracking agent as detected by real-time MR imaging. They also have found that this tracking technique allows monitoring of the distribution of similar nanosized agents such as therapeutic liposomes and viral vectors. A limitation of this procedure is the unexpected leakage of liposomes out of targeted parenchyma or malignancies into sulci and ventricles. The aim of the present study was to evaluate the efficacy of CED after the onset of these types of leakage.

Methods

The authors documented this phenomenon in a study of 5 nonhuman primates and 7 canines, comprising 54 CED infusion sessions. Approximately 20% of these infusions resulted in leakage into cerebral ventricles or sulci. All of the infusions and leakage events were monitored with real-time MR imaging. The authors created volume-distributed versus volume-infused graphs for each infusion session. These graphs revealed the rate of distribution of GDL over the course of each infusion and allowed the authors to evaluate the progress of CED before and after leakage.

Results

The distribution of therapeutics within the target structure ceased to increase or resulted in significant attenuation after the onset of leakage.

Conclusions

An analysis of the cases in this study revealed that leakage undermines the efficacy of CED. These findings reiterate the importance of real-time MR imaging visualization during CED to ensure an accurate, robust distribution of therapeutic agents.