bluuebunny/crossref_metadata_2025 huggingface dataset:
Well Testing Technical Challenges in Deep Water Wells
Authors: Chassagne Alain , Louis Alain
Published: June 2009

After an encouraging exploration well discovery, there is an increasing trend to reduce the number of appraisal wells prior to development.

Simultaneously, management teams require early development studies, which call for a reliable set of reservoir and fluid data.

Service Companies offer today a vast catalogue of tools and techniques, allowing complete data acquisition, but tremendous drilling rig day rates and potential risks associated with dynamically positioned vessels, currently restrain operators from carrying out a thorough implementation of these testing techniques.

This paper discusses the challenge of data acquisition in deep water appraisal wells; it evidences the feasibility of an optimised program, by an early preparation (scenarios, equipment, modelling,..) and a multidisciplinary approach by the operator. A mutual understanding between the operator and the service companies, helps set the priorities of the well test as per its objectives, and stick to it in case of problem. There may not be another well to allow the access to this data, so let's get it right the first time !…

This paper is divided into three sections.

The first section is a review of the crucial data that must be acquired in order to enable preliminary studies, static and dynamic modelling, and to lead to production profile forecast. The related operating procedures, necessary to ensure good data quality are reviewed, and potential risks of any kind (to both data and safety) are highlighted.

The second section of the paper presents field examples from West Africa deep water wells, indicating the limits of the testing operations, as well as the high level of preparation required.

The last section is focused on the necessary technical innovations in well testing technology and procedures. In this particular area, the partnership with Service Companies, to meet operator's requirements and constraints, is discussed in detail.
Safety Performance: An Operations Approach to Management
Authors: Lane Ian , Watkiss Richard
Published: June 2009

This paper presents a case history of a turnaround in safety performance coincident with the introduction of the Step Change Initiative in the North Sea, from an operations rather than a safety specialist's approach. The safety record on 5 platform drilling facilities in the North Sea during 1996 was exemplary, but deteriorated markedly during 1997. Possible factors including management focus, industry activity levels and the impact of workscope are all discussed, concluding that whilst all may have had an impact none could confidently be targeted as the primary cause.

In an effort to reverse the trend, input was sought from the workforce with the aim of building on existing (and previously effective) safety tools rather than introducing a raft of new initiatives. Shortfalls in the identification of hazard and the management of risk were identified. Improvements in this area including focused crew involvement (via Tool Box Talks, Theoretical Maximum Performance Techniques, and other means), rig equipment upgrading and formal procedures were made. Other key changes included higher visibility of leadership from both KCA and the Client, Shell, and the contentious issue of incentivisation. In all, a 24 point action plan was devised and implemented whilst it was being developed, under the main headers of leadership, risk management and workforce involvement. Early results show an extremely positive trend, not only on the 5 "worst" afflicted installations but across the whole of KCA (LTIF/NLTIF per 200,000 man hours) — (SeeFig. 1). Fig 1KCA Drilling LTIF / NLTIF per 200,000 Manhours
How to manage wellbore stability in the Vicking Graben tertiary shales by using mud systems environmentally friendly?
Authors: Charlez Ph. A. , Pradet V. , Onaisi A. , Gregoire M.
Published: June 2009

This paper deals with the drilling of the 17"1/2 section of the Dunbar field (Viking Graben - North Sea). In the past, this formation was systematically drilled with a conventional WBM in underbalanced conditions (mud weight less than formation pore pressure estimated at 1.4SG). With such a mud system, the well was highly unstable particularly in the Eocene shales (very large amounts of cavings were produced, calliper was very overgauged) and the final trip was particularly tight. Following three remedial side tracks experienced over the last two years, an extensive study has been carried out. The main recommendations were to drill the Eocene in overbalanced conditions (MW>1.4SG) with a Silicate Mud. The results obtained on two wells slightly inclined (20° and 35° inclination at the 13"3/8 casing shoe) were very encouraging. By contrast to previous underbalanced experience, the hole was perfectly in gauge and trips much easier (regular wiper trips to be performed). However, even in the case of a perfectly stable rock and to ensure a good hole cleaning, the wells had to be circulated at a high rate and a sufficiently thick rheology.

These results have then been confirmed on a third well (64° at the 13"3/8 casing shoe) with a maximum mud weight equal to 1.45SG. However, this MW was not sufficient for 72° inclination (the well was too unstable and had to be abandoned).
Deterministic Versus Probabilistic Volume Estimates for Reservoirs Without a Known Downdip Limit
Authors: Jordan D. G. , Collarini C. R.
Published: June 2009

The Society of Petroleum Engineers and the World Petroleum Congresses issued revised reserve definitions in 1997 which allow reserves to be estimated using either deterministic or probabilistic methods.1 In the case of reservoirs defined by only a lowest-known hydrocarbon (LKH), the deterministic method limits the proved area to "the area defined by fluid contacts", i.e., the area above the LKH. Likewise, deterministically derived proved plus probable reserves are often considered to extend downdip to one sand thickness below the LKH, and there is little guidance on the limits of possible reserves. Probabilistic methods use 90%, 50%, and 10% confidence levels to determine proved, probable, and possible reserves, respectively, but with no guidance as to what distributions should be used.

Three reservoirs were examined and their estimated reservoir volumes compared using deterministic methods and probabilistic methods where various levels of information about the location of the reservoir limits were known. In certain cases, the estimated proved, probable, and possible volumes using the two methods varied significantly. Various distributions were used for the probabilistic methods, with significant variation in results.
Structural Breaks and Exports in the Philippines
Authors: Kumar Saten
Published: June 2009

This paper estimates the export demand equation for the Philippines using the Gregory and Hansen procedure. We allowed for structural breaks within the Gregory and Hansen framework and obtained a cointegrating relationship between real exports, real income and relative prices. Our preferred model is the level shift where all the coefficients are significant and plausible. The income elasticity of export demand is around unity and the relative price elasticity is around -1.2.
Removal of Dyes from the Textile Industry by Adsorption in Fixed Bed Columns: A Sustainable Process
Authors: Vasques Andressa Regina , Guelli Ulson de Souza Selene Maria Arruda , Valle José Alexandre Borges , Ulson de Souza Antônio Augusto
Published: June 2009

The capacity and mechanism of mono and bi-functional reactive dye adsorption utilizing a new adsorbent obtained from the dried residual sludge (~10% w.w.) of a textile wastewater treatment system was studied. With the focus on determining the efficiency of the adsorbent in the dye removal, the adsorption isotherms were determined for the reactive dyes RR2 and RR141, at different temperatures and salt concentrations. The experiments were carried out in fixed bed adsorption columns, which were defined as the best adsorption experimental condition for both of the dyes through the parameter qm (mg/g), obtained by the adjustment of Langmuir isotherms. Breakthrough curves for the dyes RR2 and RR141 were obtained varying the height to which the fixed bed columns were packed with adsorbent (15, 30 and 45 cm) and varying the adsorbate feed rate in the column (8, 12 and 16 ml/min). For the dye RR2 the maximum adsorption capacity was 53.48 mg/g and for the dye RR141 it was 78.74 mg/g.
Mesenchymal Stem Cells Prevent the Rejection of Fully Allogenic Islet Grafts by the Immunosuppressive Activity of Matrix Metalloproteinase-2 and -9
Authors: Ding Yunchuan , Xu Danmei , Feng Gang , Bushell Andrew , Muschel Ruth J. , Wood Kathryn J.
Published: June 2009

OBJECTIVE

Mesenchymal stem cells (MSCs) are known to be capable of suppressing immune responses, but the molecular mechanisms involved and the therapeutic potential of MSCs remain to be clarified.

RESEARCH DESIGN AND METHODS

We investigated the molecular mechanisms underlying the immunosuppressive effects of MSCs in vitro and in vivo.

RESULTS

Our results demonstrate that matrix metalloproteinases (MMPs) secreted by MSCs, in particular MMP-2 and MMP-9, play an important role in the suppressive activity of MSCs by reducing surface expression of CD25 on responding T-cells. Blocking the activity of MMP-2 and MMP-9 in vitro completely abolished the suppression of T-cell proliferation by MSCs and restored T-cell expression of CD25 as well as responsiveness to interleukin-2. In vivo, administration of MSCs significantly reduced delayed-type hypersensitivity responses to allogeneic antigen and profoundly prolonged the survival of fully allogeneic islet grafts in transplant recipients. Significantly, these MSC-mediated protective effects were completely reversed by in vivo inhibition of MMP-2 and MMP-9.

CONCLUSIONS

We demonstrate that MSCs can prevent islet allograft rejection leading to stable, long-term normoglycemia. In addition, we provide a novel insight into the mechanism underlying the suppressive effects of MSCs on T-cell responses to alloantigen.
Immune Mediators in Patients With Acute Diabetic Foot Syndrome
Authors: Weigelt Christian , Rose Bettina , Poschen Ulrike , Ziegler Dan , Friese Gerd , Kempf Kerstin , Koenig Wolfgang , Martin Stephan , Herder Christian
Published: June 2009

OBJECTIVE

Subclinical inflammation is an important risk factor for type 2 diabetes and diabetes complications. However, data on the association between inflammation and acute diabetic foot syndrome are scarce. The aim of this study was to compare systemic immune mediators in diabetic patients with and without an ulcer and to identify modulating factors.

RESEARCH DESIGN AND METHODS

Circulating levels of acute-phase proteins, cytokines, and chemokines were measured in diabetic patients with an ulcer (n = 170) and without an ulcer (n = 140). Of the patients, 88% had type 2 diabetes.

RESULTS

Patients with an acute foot ulcer had higher levels of C-reactive protein (CRP), fibrinogen, interleukin (IL)-6, macrophage migration inhibitory factor, macrophage inflammatory protein-1α, and interferon-γ–inducible protein-10 as well as lower levels of RANTES (regulated on activation normal T-cell expressed and secreted) (all P < 0.01). No differences were found for IL-8, IL-18, and monocyte chemoattractant protein-1. Most of these associations persisted after adjustment for demographic and anthropometric data, metabolic confounders, and diabetes complications. In multivariate models, size of ulcer according to the University of Texas classification but not the grade of infection was independently associated with three markers of subclinical inflammation (CRP, IL-6, and fibrinogen).

CONCLUSIONS

We demonstrate in our cross-sectional study that acute foot ulcers and their severity are associated with a marked upregulation of acute-phase proteins, cytokines, and chemokines independently of the concomitant infection. Further studies should investigate whether an activation of the immune system precedes the development of foot ulcer and whether anti-inflammatory therapies might be effective.
Short-Term Aerobic Exercise Reduces Arterial Stiffness in Older Adults With Type 2 Diabetes, Hypertension, and Hypercholesterolemia
Authors: Madden Kenneth M. , Lockhart Chris , Cuff Darcye , Potter Tiffany F. , Meneilly Graydon S.
Published: June 2009

OBJECTIVE

The relationship between increased arterial stiffness and cardiovascular mortality is well established in type 2 diabetes. We examined whether aerobic exercise could reduce arterial stiffness in older adults with type 2 diabetes complicated by comorbid hypertension and hyperlipidemia.

RESEARCH DESIGN AND METHODS

A total of 36 older adults (mean age 71.4 ± 0.7 years) with diet-controlled or oral hypoglycemic–controlled type 2 diabetes, hypertension, and hypercholesterolemia were recruited. Subjects were randomly assigned to one of two groups: an aerobic group (3 months vigorous aerobic exercise) and a nonaerobic group (no aerobic exercise). Exercise sessions were supervised by a certified exercise trainer three times per week, and a combination of cycle ergometers and treadmills was used. Arterial stiffness was measured using the Complior device.

RESULTS

When the two groups were compared, aerobic training resulted in a decrease in measures of both radial (−20.7 ± 6.3 vs. +8.5 ± 6.6%, P = 0.005) and femoral (−13.9 ± 6.7 vs. +4.4 ± 3.3%, P = 0.015) pulse-wave velocity despite the fact that aerobic fitness as assessed by Vo2max did not demonstrate an improvement with training (P = 0.026).

CONCLUSIONS

Our findings indicate that a relatively short aerobic exercise intervention in older adults can reduce multifactorial arterial stiffness (type 2 diabetes, aging, hypertension, and hypercholesterolemia).
Asian Americans: Diabetes Prevalence Across U.S. and World Health Organization Weight Classifications
Authors: Oza-Frank Reena , Ali Mohammed K. , Vaccarino Viola , Narayan K.M. Venkat
Published: June 2009

OBJECTIVE

To compare diabetes prevalence among Asian Americans by World Health Organization and U.S. BMI classifications.

RESEARCH DESIGN AND METHODS

Data on Asian American adults (n = 7,414) from the National Health Interview Survey for 1997–2005 were analyzed. Diabetes prevalence was estimated across weight and ethnic group strata.

RESULTS

Regardless of BMI classification, Asian Indians and Filipinos had the highest prevalence of overweight (34–47 and 35–47%, respectively, compared with 20–38% in Chinese; P < 0.05). Asian Indians also had the highest ethnic-specific diabetes prevalence (ranging from 6–7% among the normal weight to 19–33% among the obese) compared with non-Hispanic whites: odds ratio (95% CI) for Asian Indians 2.0 (1.5–2.6), adjusted for age and sex, and 3.1 (2.4–4.0) with additional adjustment for BMI.

CONCLUSIONS

Asian Indian ethnicity, but not other Asian ethnicities, was strongly associated with diabetes. Weight classification as a marker of diabetes risk may need to accommodate differences across Asian subgroups.
Third ventricle colloid cysts: a consecutive 12-year series
Authors: Mathiesen Tiit , Grane Per , Lindgren Lars , Lindquist Christer
Published: June 2009

✓ A continuous follow-up review of colloid cysts including aspects of natural history and evaluation of treatment options is necessary to optimize individual treatment. Thirty-seven consecutive patients with colloid cyst of the third ventricle seen at Karolinska Hospital between 1984 and 1995 were reviewed. Five patients were admitted in a comatose state, and two died despite emergency ventriculostomy. Three had recurrent cysts following previous aspiration procedure. During the study period, patients underwent a total of 10 ventriculostomies, 10 aspirations, 26 microsurgical operations, and two shunt operations.

Twenty-four of 26 microsurgical operations were transcallosal and two were transcortical. Twenty-four operations (22 transcallosal and two transfrontal approaches) without permanent morbidity were performed by four surgeons. Transient memory deficit from forniceal traction was noted in 26%. The remaining two transcallosal operations, which led to permanent morbidity or mortality, were performed by two different surgeons. Aspiration of cysts performed by four different surgeons carried a 40% risk of transient memory deficit (10% permanent) and an 80% recurrence rate. One patient was found to be cured on radiological studies obtained at the 5-year follow-up review.

Seven cysts were followed by means of radiological studies with no treatment for 6 to 37 months. Five of these cysts grew, indicating that younger patients with colloid cysts will probably need surgical treatment.

The main causes of unfavorable results were: 1) failure to investigate symptoms that proved fatal; 2) subtotal resection; and 3) surgical complications. Transcallosal microsurgery produced excellent results when performed by experienced surgeons. A colloid cyst of the foramen of Monro is a disease that should be detected before permanent neurological damage has occurred. Permanent morbidity or mortality should not be accepted in modern series of third ventricle colloid cysts.
Medulloblastoma: is the 5-year survival rate improving?
Authors: David Karoly M. , Casey Adrian T. H. , Hayward Richard D. , Harkness William F. J. , Phipps Kim , Wade Angie M.
Published: June 2009

✓ A series of 80 cases of medulloblastomas in children undergoing operation and postoperatively followed between 1980 and 1990 at Great Ormond Street Hospital for Children (GOSH) has been reviewed and compared to an earlier series reported from the same institution by McIntosh. The overall 5-year survival rate for the present series was 50%, although three patients died after surviving 5 years. The operative mortality rate was 5%. Survival analysis revealed that the presence or absence of spinal metastases and the necessity for some form of cerebrospinal fluid diversion within 30 days of the operation independently significantly affected survival in this series. Those patients with no spinal metastasis and total tumor removal had a 5-year survival rate of 73%, making this the most favorable subgroup in the series. Patient age and gender, duration of symptoms, Chang T stages, tumor volume, extent of resection, and postoperative chemotherapy were not significant variables.

Although these results are better than those reported in the earlier GOSH series, they are not significantly different from the results of the second 5-year cohort of patients described in that article. Radiotherapy remains the greatest advance in treatment, although it is hoped that further improvement will result from the various chemotherapy protocols now being studied and from increasing knowledge of the biological behavior of these tumors.
Utility of relative cerebral blood volume mapping derived from perfusion magnetic resonance imaging in the routine follow up of brain tumors
Authors: Siegal Tali , Rubinstein Rina , Tzuk-Shina Tzahala , Gomori John M.
Published: June 2009

✓ It was recently demonstrated that imaging of brain tumors by relative cerebral blood volume (CBV) maps reconstructed from dynamic magnetic resonance (MR) data provide similar diagnostic information compared to positron emission tomography (PET) or 201Tl single-photon emission computerized tomography (201Tl-SPECT) scans. The authors used relative CBV mapping for routine follow-up evaluation of patients with brain tumors and compared its sensitivity to diagnostic MR imaging, 201Tl-SPECT and clinical assessment.

Fifty-nine patients were prospectively followed using 191 concomitant studies of dual section relative CBV maps, MR imaging, 201Tl-SPECT, and neurological evaluations. Studies were repeated every 2 to 3 months (median three evaluations/patient). The relative CBV maps were graded as relative CBV 0 to 4, where Grades 3 and 4 are indicative of proliferating tumors (four = rapid leak). There were 44 high-grade and 15 low-grade tumors followed during treatment. During the follow-up period a change in relative CBV grade was observed in 56% of the patients, revealing an increasing grade in 72% of them. The rapid leak phenomenon was detected in 35% of all studies and in 81% of those with a worsening relative CBV grade. Tumor progression was detected earlier by relative CBV maps as follows: earlier than MR imaging in 32% of the studies (earlier by a median of 4.5 months; p < 0.01); earlier than 201Tl-SPECT in 63% (median 4.5 months; p < 0.01), and earlier than clinical assessment in 55% (median 6 months; p < 0.01). In 82% of studies with positive MR imaging but negative 201Tl-SPECT, the lesions were smaller than 1.5 cm. The relative CBV maps clearly delineated the appearance of rapid leak in these lesions.

Routine use of relative CBV maps that can be implemented on any high-field MR unit and added to the regular MR evaluation provides useful functional information in patients with brain tumors. When used as an adjunct follow-up evaluation it proved more sensitive than the other modalities for early prediction of tumor growth. It is very sensitive to small regional changes, unlike functional imaging such as PET or SPECT scans. Based on previous experience with 76 regional CBV studies, the authors conclude that regional CBV mapping correlates with active tumor and it may separate enhancing scar and radiation injury from infiltrative tumor. A new effect named the rapid leak phenomenon was also observed; this phenomenon, as identified on the regional CBV maps, correlates with high malignancy.
Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa
Authors: Nishikawa Misao , Sakamoto Hiroaki , Hakuba Akira , Nakanishi Naruhiko , Inoue Yuichi
Published: June 2009

✓ To investigate overcrowding in the posterior cranial fossa as the pathogenesis of adult-type Chiari malformation, the authors studied the morphology of the brainstem and cerebellum within the posterior cranial fossa (neural structures consisting of the midbrain, pons, cerebellum, and medulla oblongata) as well as the base of the skull while taking into consideration their embryological development. Thirty patients with Chiari malformation and 50 normal control subjects were prospectively studied using neuroimaging. To estimate overcrowding, the authors used a “volume ratio” in which volume of the posterior fossa brain (consisting of the midbrain, pons, cerebellum, and medulla oblongata within the posterior cranial fossa) was placed in a ratio with the volume of the posterior fossa cranium encircled by bony and tentorial structures. Compared to the control group, in the Chiari group there was a significantly larger volume ratio, the two occipital enchondral parts (the exocciput and supraocciput) were significantly smaller, and the tentorium was pronouncedly steeper. There was no significant difference in the posterior fossa brain volume or in the axial lengths of the hindbrain (the brainstem and cerebellum). In six patients with basilar invagination the medulla oblongata was herniated, all three occipital enchondral parts (the basiocciput, exocciput, and supraocciput) were significantly smaller than in the control group, and the volume ratio was significantly larger than that in the Chiari group without basilar invagination.

These results suggest that in adult-type Chiari malformation an underdeveloped occipital bone, possibly due to underdevelopment of the occipital somite originating from the paraxial mesoderm, induces overcrowding in the posterior cranial fossa, which contains the normally developed hindbrain. Basilar invagination is associated with a more severe downward herniation of the hindbrain due to the more severely underdeveloped occipital enchondrium, which further exacerbates overcrowding of the posterior cranial fossa.
Diagnosis of root avulsions in traumatic brachial plexus injuries: value of computerized tomography myelography and magnetic resonance imaging
Authors: Carvalho Gustavo Adolpho , Nikkhah Guido , Matthies Cordula , Penkert Götz , Samii Madjid
Published: June 2009

✓ Surgical management and prognosis of traction injuries of the brachial plexus depend on the accurate diagnosis of root avulsion from the spinal cord. Myelography, computerized tomography (CT) myelography, and recently magnetic resonance (MR) imaging have become the main radiological methods for preoperative diagnosis of cervical root avulsions. Most of the previous studies on the accuracy of CT myelography and MR imaging studies have correlated the radiological findings with the extraspinal surgical findings at brachial plexus surgery. Surgical experience shows that in many cases extraspinal findings diverge from intradural determinations. Consequently, only correlation with the intradural surgical findings will allow assessment of the factual accuracy of CT myelography and MR imaging studies.

In a prospective study, 135 cervical roots (C5–8) were evaluated by CT myelography and/or MR imaging and further explored intradurally via a hemilaminectomy. The accuracy of the preoperative CT myelography—based diagnosis in relation to the intraoperative findings was 85%. On the other hand, MR imaging demonstrated an accuracy of only 52%. The most common reasons for false-positive or false-negative findings were: 1) partial rootlet avulsion; 2) intradural fibrosis; and 3) dural cystic lesions. Computerized tomography myelography scans using 1- to 3-mm axial slices prove to be the most reliable method to evaluate preoperatively the presence of complete or partial root avulsion in traumatic brachial plexus injuries.

Because extradural judgment of cervical root avulsion can be unreliable, accurate assessment of intraspinal root avulsion enormously simplifies the decision concerning the choice of donor nerves for transplantation and/or neurotization during brachial plexus surgery.
Utilization of type I collagen gel, demineralized bone matrix, and bone morphogenetic protein-2 to enhance autologous bone lumbar spinal fusion
Authors: Helm Gregory A. , Sheehan Jonas M. , Sheehan Jason P. , Jane John A. , diPierro Charles G. , Simmons Nathan E. , Gillies George T. , Kallmes David F. , Sweeney Thomas M.
Published: June 2009

✓ Autologous bone grafts are currently considered “gold standard” material for achieving long-term spinal arthrodesis. The present study was performed to determine whether demineralized bone matrix (DBM), type I collagen gels, or bone morphogenetic protein-2 (BMP-2) can improve autologous bone spinal fusions. Using a unilateral decompression—contralateral fusion technique in dogs, each of these materials was added to an autologous bone graft. Volumetric analysis, histological analysis, and biomechanical testing were performed to assess the effectiveness of each material. The DBM had an inhibitory effect on solid bone fusion of the spine, whereas the type I collagen gels improved the bony interface between the graft and the host spine. The BMP-2 strongly enhanced the amount of bone deposition at the fusion site and increased the number of intervertebral levels that were solidly fused. This study strongly supports the use of BMP-2 as an additive to autologous bone grafts in spine stabilization.
Specific repression of the preproendothelin-1 gene in intracranial arteriovenous malformations
Authors: Rhoten R. L. Patrick , Comair Youssef G. , Shedid Daniel , Chyatte Douglas , Simonson Michael S.
Published: June 2009

✓ Cerebrovascular arteriovenous malformations (AVMs) display abnormal vascular development and dysautoregulation of blood flow. Genetic mechanisms that contribute to the pathogenesis and phenotype of cerebral AVMs are unknown. As a first step in understanding the pathophysiology of AVMs, the authors investigated the hypothesis that endothelial dysfunction—specifically, deregulation of endothelin-1 (ET-1) secretion—contributes to the abnormal vascular phenotype and the lack of hemodynamic autoregulation elaborated by these lesions. Endothelin-1 peptide and preproendothelin-1 (ppET1) messenger RNA were not detected in the intranidal vasculature of all 17 patients with AVMs studied, but were prominently expressed in human control subjects with normal cerebrovasculature (p < 0.01). Although AVM vasculature lacked ET-1, its expression was prominent in vasculature distant from these lesions, suggesting local repression of the ppET-1 gene. Local repression of ET-1 was specific to AVMs; ET-1 in vascular malformations of patients with Sturge—Weber disease was actually elevated compared to normal controls (p < 0.01). Repression of the ppET-1 gene was an intrinsic phenotype of AVM endothelial cells and was not due to factors in the AVM microenvironment. The authors also showed that ETA receptor expression was low in AVM vasculature compared to normal controls. Together, these results demonstrate that the ppET-1 gene is locally repressed in AVM lesions and suggest a role for abnormal ppET-1 gene regulation in the pathogenesis and clinical sequelae of cerebral AVMs.
Progesterone and estrogen receptors in meningiomas: prognostic considerations
Authors: Hsu Dora W. , Efird Jimmy T. , Hedley-Whyte E. Tessa
Published: June 2009

✓ Meningiomas often contain steroid hormone receptors, but the correlation of receptor presence with patient outcome or mitotic index is unclear. Intracranial meningiomas from 70 patients (27 males and 43 females, mean age 52.9 + 1.7 years [mean ± standard error of the mean], range 15–78 years) were evaluated immunocytochemically for female sex hormone receptors using specific monoclonal antibodies. Prognostic correlations were determined using statistical analyses that included clinical and histological variables. Twenty-eight tumors were benign, 27 had atypical features, and 15 were malignant. Thirty tumors were meningotheliomatous, 11 were fibroblastic, 28 were transitional, and one was secretory. Twenty-nine of the 70 primary tumors recurred (mean interval to recurrence 50.1 ± 10 months). The mean progression-free follow-up period for patients without recurrence was 82.1 ± 7.7 months. Nuclear staining for the progesterone receptor (PR) was found in 58 cases (83%) and PR status was scored as 0 (0% nuclei positive), 1 (< 1%), 2 (1–9%), 3 (10–49%), or 4 (> 50%). Only six tumors (8.6%) contained nuclear estrogen receptor (ER) staining, which was limited to a small number of nuclei (< 1%). Fisher's exact test (two-tailed) showed an inverse correlation between tumor grade and PR staining score (p ≤ 0.001), with 96% of benign and 40% of malignant meningiomas containing PR-positive nuclei. No correlation between age or histological subtype and PR score was detected. Meningiomas from female patients had more PRs (p ≤ 0.05). Analysis of variance revealed that the mitotic index (total counts of mitoses per 10 high-power fields) for tumors with 0 PR staining (18 ± 4.4) was higher (p ± 0.0001) than for those with PR scores of 1 to 4 (4.3 ± 1.9, 5.1 ± 2, 2.2 ± 0.8, and 1.7 ± 0.9, respectively). Univariate analysis indicated that the absence of PR, high mitotic index, and higher tumor grade were significant factors for shorter disease-free intervals. Multivariate analysis showed that a three-factor interaction model, with a PR score of 0, mitotic index greater than 6, and malignant tumor grade, was a highly significant predictor (p ≤ 0.0001) for worse outcome in patients harboring meningiomas. These data indicate that the presence of PRs, even in a small number of tumor cells, is a favorable prognostic factor for meningiomas.
Analysis of proliferation markers and p53 expression in gliomas of astrocytic origin: relationships and prognostic value
Authors: Cunningham Julie M. , Kimmel David W. , Scheithauer Bernd W. , O'Fallon Judith R. , Novotny Paul J.
Published: June 2009

✓ Consecutive paraffin sections of 105 astrocytomas and 15 oligoastrocytomas were examined for expression of p53, MIB-1 (Ki-67), and proliferating cell nuclear antigen (PCNA). The tumors had been examined previously for genetic abnormalities and by flow cytometry. Regardless of the tumor's stage and grade and the patient's age and gender, p53 expression was found in 40% of tumors. Although p53 expression was associated with a loss on chromosome 17p and was more frequent in aneuploid tumors, it had no association with survival time. The MIB-1 and PCNA labeling indices increased with increasing tumor grade but showed no association with other clinicopathological parameters. In individual tumors, there was poor concordance between any of the variables (MIB-1, PCNA, and p53). Results for p53 and MIB-1 were similar for both astrocytomas and oligoastrocytomas. The MIB-1 and PCNA values appeared to have prognostic utility in univariate analysis but not after adjusting for patient age and tumor grade. The poor concordance between MIB-1 and PCNA in individual tumors indicates that any one means of assessing proliferative potential in gliomas may not be reliable.
Effect of hemodilution with diaspirin cross-linked hemoglobin on intracranial pressure, cerebral perfusion pressure, and fluid requirements after head injury and shock
Authors: Chappell James E. , Shackford Steven R. , McBride Whitney J.
Published: June 2009

✓ Hemodilution has been shown to increase cerebral blood flow (CBF) and reduce lesion volume in models of occlusive cerebral ischemia, but it has not been evaluated in the setting of head trauma and shock in which ischemia is thought to play a role in the evolution of secondary injury. In a porcine model of brain injury and shock the authors compared hemodilution with diaspirin cross-linked hemoglobin (DCLHb) to a standard resuscitation regimen using Ringer's lactate solution and shed blood. After creation of a cryogenic brain injury followed by hemorrhage, the animals received a bolus of either 4 ml/kg of Ringer's lactate solution (Group 1, six animals) or DCLHb (Group 2, six animals), followed by infusion of Ringer's lactate solution to restore mean arterial pressure (MAP) to baseline. Group 1 received shed blood 1 hour after hemorrhage (R1) in the form of packed red blood cells. Group 2 received shed blood only for an Hb count of less than 5 g/dl. The animals were monitored for 24 hours. At R1, Group 2 had a significantly greater cerebral perfusion pressure ([CPP] 88 ± 5.7 vs. 68 ± 2.4 mm Hg, p < 0.05). By 3 hours after hemorrhage (R3) Group 2 had a significantly lower Hb concentration (8.5 ± 0.4 vs. 12.1 ± 0.3 g/dl, p < 0.05) and a significantly lower intracranial pressure ([ICP] 9 ± 0.8 vs. 14 ± 0.6 mm Hg, p < 0.05). The total 24-hour fluid requirement was significantly less in Group 2 (10,654 ± 505 ml vs. 15,542 ± 1094 ml, p < 0.05) There was no difference between the groups regarding levels of regional CBF in the injured hemisphere. Cerebral O2 delivery was not significantly different between groups at any time. Lesion volume as determined at postmortem examination was not significantly different between the groups. The increased MAP and CPP and lower ICP observed in the Group 2 animals indicate that hemodilution with DCLHb may be beneficial in the treatment of head injury and shock.
Duraplasty with biosynthetic cellulose: an experimental study
Authors: Mello Luis Renato , Feltrin Leonir T. , Fontes Neto Paulo T. , Ferraz Fernando A. P.
Published: June 2009

✓ In the search for a new synthetic substitute for the dura mater, the authors conducted a research study using 32 mongrel dogs divided into three groups. Group I animals (21 dogs) underwent a right-sided parietooccipital craniotomy and substitution of two 1-cm pieces of dura mater by two different grafts: one piece of biosynthetic cellulose (50 µ thick) and one fragment of temporal fascia. The animals were observed for 30, 90, or 180 days. Group II animals (five dogs) underwent a somewhat larger craniotomy, removal of a 2-cm piece of dura mater, and lesioning of the cortex made by a thin sharp forceps, which caused bleeding that was controlled by application of a thin film of cellulose (10 µ thick). Duraplasty was performed using a 50-µ-thick cellulose membrane to complete the procedure and the animals were observed over a period of 270 days. Group III animals (six dogs) underwent smaller (1-cm diameter) bilateral parietal craniectomy, which included additional covering of the dura on the left side with 50-µ-thick cellulose and a suture of temporalis muscle. This group was observed for 40, 60, 80, or 120 days.

Transient mild clinical symptoms were observed during the early postoperative period. At autopsy, macroscopic examination demonstrated good acceptance of the grafts with few and moderate extradural fibrosis, which caused adherence of the implants to the bone fragment. No adherence to the cortex was observed. Microscopic examination demonstrated absence of graft adherence to the cortical surface even when the cortex was injured. The cellulose was enveloped by two layers of connective tissue, the external layer being thicker than the internal one. Cellulose fibers increased in thickness over time until 30 days and then decreased in thickness until 270 days. This decrease in thickness between 30 to 270 days was statistically significant (p < 0.05). The physical properties of biosynthetic cellulose and the low cellular reaction to its implantation qualify this material as a dural substitute. Additional long-term studies must be undertaken to complete this report.
Hyperactive pectoralis reflex as an indicator of upper cervical spinal cord compression
Authors: Watson Joseph C. , Broaddus William C. , Smith Maurice M. , Kubal Wayne S.
Published: June 2009

✓ Myelopathy from cervical spondylosis is often accompanied by hyperreflexia of the upper-extremity deep tendon reflexes (DTRs). Reflexes such as the pectoralis jerk and the deltoid jerk may only be apparent in the context of hyperreflexia. Although the nerve roots involved in the reflex arcs are well described, levels of cervical spinal cord compression that lead to the hyperreflexia are not as clear. This is of particular significance for patients with multilevel cervical spondylosis in determining the levels responsible for their symptoms. The authors examined 15 consecutive patients who presented for treatment of cervical myelopathy. The clinical examination was then correlated with levels of cervical spinal cord compression by cervical magnetic resonance imaging or computerized tomography with intrathecal contrast enhancement. The presence of a prominent pectoralis jerk was seen only in patients with spinal cord compression at the C2–3 and/or C3–4 levels (nine patients). No patient with compression at or below the C4–5 disc space without coexisting compression at a higher level had hyperactive pectoralis reflexes. This association between the C3–4 level and a hyperactive pectoralis reflex was significant (p < 0.004, Fisher's exact test). The deltoid reflex was tested in the last nine consecutive patients. It was present in patients with compression of the upper spinal cord at levels C3–4 and C4–5 (four of five patients) but appeared in only one of four patients with compression below C4–5. This association did not attain statistical significance. The presence of a hyperactive pectoralis reflex is specific for lesions of the upper cervical spinal cord. Examination of upper-extremity DTRs may be helpful in planning the appropriate levels for surgical decompression in patients with multilevel spondylosis and myelopathy.
Skull base chordomas: a management challenge
Authors: Al-Mefty Ossama , Borba Luis A. B.
Published: June 2009

✓ Because of their critical location, invasive nature, and aggressive recurrence, skull base chordomas are challenging and, at times, frustrating tumors to treat. Both radical surgical removal and high-dose radiation therapy, particularly proton beam therapy, reportedly are effective in tumor control and improve survival rates. The authors posit that these tumors are best treated with radical surgery and proton—photon beam therapy. During the last 5 years, they treated 25 patients (15 females and 10 males) who harbored pathologically diagnosed skull base chordomas. The mean age of the patients was 38.4 years (range 8–61 years). Previous surgery or radiation therapy was performed at other institutions in seven and two patients, respectively. The authors performed 33 surgical procedures on 23 patients. Radical removal (defined as absence of residual tumor on operative inspection and postoperative imaging) was achieved in 10 patients; subtotal resection (defined as resection of > 90% of the tumor) was achieved in 11 patients; and partial resection (defined as resection of < 90% of the tumor) was achieved in two patients. Radical surgical removal included not only the excision of soft-tumor tissue, but also extensive drilling of the adjacent bone. Adjuvant therapy consisted of postoperative combined proton—photon beam therapy (given to 17 patients and planned for one patient) and conventional radiation therapy (two patients); three patients received no adjunct therapy. To date, four patients have died. One patient who had undergone previous surgery and sacrifice of the internal carotid artery died postoperatively from a massive stroke; one patient died from adenocarcinoma of the pancreas without evidence of recurrence; and two patients died at 25 and 39 months of recurrent tumor. Permanent neurological complications included third cranial nerve palsy (one patient) and hemianopsia (one patient); radiation necrosis occurred in three patients. Of the 21 patients followed for more than 3 months after surgery, 16 have had no evidence of recurrence and five (including the two mortalities noted above) have had recurrent tumors (four diagnosed clinically and one radiologically). The mean disease-free interval was 14.4 months. A longer follow-up period will, hopefully, support the early indication that radical surgical removal and postoperative proton—photon beam therapy is an efficacious treatment. The use of skull base approaches based on the tumor classification introduced in this paper is associated with low mortality and morbidity rates.
Sensory effects of microvascular decompression in trigeminal neuralgia
Authors: Miles John B. , Eldridge Paul R. , Haggett Carol E. , Bowsher David
Published: June 2009

✓ Nineteen patients with “idiopathic” trigeminal neuralgia, who had not undergone any previous interventional procedures, possessed a vessel or vessels compressing the preganglionic nerve root that was demonstrated by magnetic resonance tomographic angiography. Pain was relieved immediately in all of these patients after they underwent microvascular decompression without observed nerve damage.

Although preoperative measurement of sensory perception thresholds showed elevations in the thresholds for touch (von Frey filaments) and warmth and coolness sensations, these thresholds normalized during the postoperative period. An apparent deficit in the pinprick (sharpness) sensation appeared postoperatively, but the deficit gradually regressed and completely disappeared by 1 year after surgery; this phenomenon may have been a statistical anomaly. The patients' pain disappeared immediately postoperatively and remained absent throughout the follow-up period.

The authors conclude that damage to the nerve or nerve root is not essential for the relief of trigeminal neuralgia.
Treatment of syringomyelia associated with arachnoid scarring caused by arachnoiditis or trauma
Authors: Klekamp Jörg , Batzdorf Ulrich , Samii Madjid , Bothe Hans Werner
Published: June 2009

✓ The authors conducted a retrospective study of 107 patients treated for syringomyelia associated with arachnoid scarring between 1976 and 1995 at the Departments of Neurosurgery at the Nordstadt Hospital in Hannover, Germany, and the University of California in Los Angeles, California. Twenty-nine patients have not been surgically treated to date because of their stable neurological status. Seventy-eight patients with progressive neurological deficits underwent a total of 121 surgical procedures and were followed for a mean period of 32 (±37) months. All patients demonstrated arachnoid scarring at a level close to the syrinx. In 52 patients the arachnoid scarring was related to spinal trauma, whereas 55 had no history of trauma and developed arachnoid scarring as a result of an inflammatory reaction. Of these, 15 patients had undergone intradural surgery, eight had suffered from spinal meningitis, three had undergone peridural anesthesia, and one each presented with a history of osteomyelitis, spondylodiscitis, and subarachnoid hemorrhage. No obvious cause for the inflammatory reaction resulting in arachnoid scarring could be ascertained for the remaining 26 patients.

The postoperative neurological outcome correlated with the severity of arachnoid pathology and the type of surgery performed. Shunting of the syrinx to the subarachnoid, pleural, or peritoneal cavity was associated with recurrence rates of 92% and 100% for focal and extensive scarring, respectively. Successful long-term management of the syrinx required microsurgical dissection of the arachnoid scar and decompression of the subarachnoid space with a fascia lata graft. This operation stabilized the preoperative progressive neurological course in 83% of patients with a focal arachnoid scar. For patients with extensive arachnoid scarring over multiple spinal levels or after previous surgery, clinical stabilization was achieved in only 17% with this technique.
Progressive loss of glutamic acid decarboxylase, parvalbumin, and calbindin D28K immunoreactive neurons in the cerebral cortex and hippocampus of adult rat with experimental hydrocephalus
Authors: Tashiro Yuzuru , Chakrabortty Shushovan , Drake James M. , Hattori Toshiaki
Published: June 2009

✓ The authors investigated functional neuronal changes in experimental hydrocephalus using immunohistochemical techniques for glutamic acid decarboxylase (GAD) and two neuronal calcium-binding proteins: parvalbumin (PV) and calbindin D28K (CaBP).

Hydrocephalus was induced in 16 adult Wistar rats by intracisternal injection of a kaolin solution, which was confirmed microscopically via atlantooccipital dural puncture. Four control rats received the same volume of sterile saline. Immunohistochemical staining for GAD, PV, and CaBP, and Nissl staining were performed at 1, 2, 3, and 4 weeks after the injection. Hydrocephalus occurred in 90% of kaolin-injected animals with various degrees of ventricular dilation. In the cerebral cortex, GAD-, PV-, and CaBP-immunoreactive (IR) interneurons initially lost their stained processes together with a concomitant loss of homogeneous neuropil staining, followed by the reduction of their total number. With progressive ventricular dilation, GAD- and PV-IR axon terminals on the cortical pyramidal cells disappeared, whereas the number of CaBP-IR pyramidal cells decreased, and ultimately in the most severe cases of hydrocephalus, GAD, PV, and CaBP immunoreactivity were almost entirely diminished. In the hippocampus, GAD-, PV-, and CaBP-IR interneurons demonstrated a reduction of their processes and terminals surrounding the pyramidal cells, with secondary reduction of CaBP-IR pyramidal and granular cells. On the other hand, Nissl staining revealed almost no morphological changes induced by ischemia or neuronal degeneration even in the most severe cases of hydrocephalus.

Hydrocephalus results in the progressive functional impairment of GAD-, PV-, and CaBP-IR neuronal systems in the cerebral cortex and hippocampus, often before there is evidence of morphological injury. The initial injury of cortical and hippocampal interneurons suggests that the functional deafferentation from intrinsic projection fibers may be the initial neuronal event in hydrocephalic brain injury. Although the mechanism of this impairment is still speculative, these findings emphasize the importance of investigating the neuronal pathophysiology in hydrocephalus.