bluuebunny/crossref_metadata_2025 huggingface dataset:
Ozonated sesame oil enhances cutaneous wound healing in SKH1 mice
Authors: Valacchi Giuseppe , Lim Yunsook , Belmonte Giuseppe , Miracco Clelia , Zanardi Iacopo , Bocci Velio , Travagli Valter
Published: December 2010

Ozone is well recognized as a bactericidal agent and its beneficial effect on wound healing could be a consequence of this property. Because ozone itself does not penetrate the cells but immediately reacts with polyunsaturated fatty acids, its effects should be the results of oxidative reaction. For this reason, ozonated oils could be a way to deliver ozone messengers to the skin. This paper evaluated the therapeutic effects of three different grades of ozonated sesame oil in acute cutaneous wounds made in the skin of SKH1 mice. Specifically, wound closure rate, histological parameters, and the level of key proteins such as vascular endothelial growth factors and cyclin D1 have been analyzed in relation to the peroxide level present in the ozonated oil. Treatment with moderately ozonated sesame oil—expressed as peroxide value about 1,500)—has a faster wound closure rate in the first 7 days than treatment with oil containing either lower or higher peroxide value, and even with controls. Moreover, under the same treatment, an earlier and higher response of cells involved in wound repair, a higher angiogenesis, as well as an enhanced vascular endothelial growth factors and cyclin D1 expression were observed. The present study shows the validity of ozonated sesame oil in cutaneous wound healing and emphasizes the importance of the ozonation grade.
IMPACTS OF MESOGRAZERS ON EPIPHYTE AND ENDOPHYTE GROWTH ASSOCIATED WITH CHEMICALLY DEFENDED MACROALGE FROM THE WESTERN ANTARCTIC PENINSULA: A MESOCOSM EXPERIMENT1
Authors: Aumack Craig F. , Amsler Charles D. , McClintock James B. , Baker Bill J.
Published: December 2010

It has been hypothesized that the extensive mesograzer community along the western Antarctic Peninsula regulates epiphytic algae as well as emergent filaments from endophytic species. Should grazing limit growth of fouling or potentially pathogenic microphytes, then Antarctic macrophytes may actually benefit from the remarkably high densities of mesograzer amphipods that occur in these waters. Although initially counterintuitive, the negative impacts of epi/endophyte fouling may outweigh stresses caused by limited amphipod grazing on chemically defended macrophytes by reducing stress from endo/epiphyte biomass. If so, then alleviating mesograzing stress should result in significant increases in endo/epiphytic biomass. To test this hypothesis, a mesocosm experiment was conducted. Individuals representing four common species of Antarctic macroalgae were placed in flow‐through seawater mesocosms. Amphipods were added to five mesocosms at simulated natural densities, while the other five remained herbivore free. At the end of 7 weeks, endo/epiphytic growth on individual macrophytes was quantified. Most species of macroalgae demonstrated noticeably higher instances of endophyte coverage, epiphytic diversity, and diatom colonization in consumer‐free mesocosms than in the presence of amphipods. These data suggest that macroalgae along the western Antarctic Peninsula rely on grazers to control populations of potentially harmful epiphytes. We hypothesize that the chemically defended macroalgal flora lives in mutualism with high densities of mesograzers, providing amphipods with shelter from predation while continually being cleaned of potentially harmful endo/epiphytes.
Rejuvenation improves roller pump–induced physical stress resistance of fresh and stored red blood cells
Authors: Gelderman Monique P. , Vostal Jaroslav G.
Published: December 2010

BACKGROUND: Retrospective studies on transfusion recipients suggested that transfusion of older red blood cells (RBCs) was associated with higher morbidity. Similar studies were also done on cardiac surgery patients who were placed on cardiac bypass pumps. It is possible that stored RBCs are more fragile and could be more easily damaged by these pumps, thus leading to additional morbidity.

STUDY DESIGN AND METHODS: Fresh and stored (42 days) RBCs, rejuvenated and nonrejuvenated, were compared in resistance to physical stress, induced by a roller pump, and osmotic fragility changes during physical stress to model RBCs going through cardiac bypass instruments. In addition, posttransfusion in vivo recovery was evaluated in an immunodeficient mouse model to minimize species differences between transfusion product and recipient.

RESULTS: Fresh RBCs were more resistant to both osmotic and physical stress than stored cells. After 2 hours of physical stress, the osmotic stress resistance of fresh cells declined and was the same as for stored cells. Rejuvenated fresh cells did not demonstrate a decline in osmotic resistance during the stress test and both fresh and stored cells had the same improved resistance to osmotic stress before and after the physical stress. Rejuvenation slightly improved recovery of fresh RBCs but almost doubled the recovery of stored cells in the mouse model.

CONCLUSIONS: Our studies suggest that rejuvenation improves roller pump–induced physical and osmotic stress resistance of stored RBCs.
Not so simple after all: searching for ecological advantages of compound leaves
Authors: Warman Laura , Moles Angela T. , Edwards Will
Published: December 2010

Leaves come in many sizes and shapes, and the relationships between leaf traits and the environments they occur in are better understood every day. However we still know very little about the ecological consequences of plants having either compound or simple leaves. We attempted to address this knowledge gap by comparing chemical and physical characteristics (leaf area, length:width ratio, water content, leaf mass per area, ‘toughness’ and C:N ratio), as well as rates of herbivory between compound and simple leaves across 34 species in adjacent rainforest, open woodland and wet sclerophyll (tall open forest) vegetation in northeastern Australia. We found C:N ratio to be lower in simple leaves, but this was the only leaf trait that differed significantly between leaf types and did not stand up under phylogenetic analysis. Overall, we found no differences in herbivory between simple and compound leaves. While it remains unclear what the advantages of having one leaf type over another might be, the differences do not seem to lie in construction, or in vulnerability to herbivores, at least in the Australian Wet Tropics.
X-ray flares from propagation instabilities in long gamma-ray burst jets
Authors: Lazzati D. , Blackwell C. H. , Morsony B. J. , Begelman M. C.
Published: December 2010

We present a numerical simulation of a gamma-ray burst jet from a long-lasting engine in the core of a 16 solar mass Wolf–Rayet star. The engine is kept active for 6000 s with a luminosity that decays in time as a power law with index −5/3. Even though there is no short time-scale variability in the injected engine luminosity, we find that the jet's kinetic luminosity outside the progenitor star is characterized by fluctuations with relatively short time-scale. We analyse the temporal characteristics of those fluctuations and we find that they are consistent with the properties of observed flares in X-ray afterglows. The peak-to-continuum flux ratio of the flares in the simulation is consistent with some, but not all, the observed flares. We propose that propagation instabilities, rather than variability in the engine luminosity, are responsible for the X-ray flares with moderate contrast. Strong flares such as the one detected in GRB 050502B, instead, cannot be reproduced by this model and require strong variability in the engine activity.
Climate Change and Agriculture: The Policy Challenge for the 21st Century?  Changement climatique et agriculture : le défi du 21ème siècle pour l’action publique?  Klimawandel und Landwirtschaft: Die politische Herausforderung für das 21. Jahrhundert?
Authors: Huang Hsin , Legg Wilfrid , Cattaneo Andrea
Published: December 2010

Climate Change and Agriculture: The Policy Challenge for the 21st Century?

Climate change will have significant impacts on agriculture. Farmers and the agri‐food supply chain will have to adapt, while at the same time providing food for a growing population. Agriculture can be expected to contribute to meeting targets to reduce greenhouse gas emissions, although the sector did not figure significantly at the UN Climate Change Conference in Copenhagen in December 2009. The ongoing or expected international climate change, food security and trade commitments present both challenges and opportunities for the agri‐food sector, as agriculture is one of the few sectors that can contribute to both mitigation and sequestration of carbon emissions. Accounting for agriculture’s carbon footprint is a key issue given the possibility of including agriculture in greenhouse gas reduction commitments. However, the range and variability of estimates, and the complexity and uncertainty of accounting for indirect land use change remain to be resolved. Policies will play a role in enhancing the ability of agriculture to adapt to climate change, in reducing greenhouse gases, while contributing to other environmental goals. There is an urgent need to consider whether an international agreement would be the channel to enable appropriate national policy actions to be taken in the context of a global framework to reduce emissions from agriculture in the most efficient and least‐cost manner.
The Positive Contribution of Agriculture and Forestry to Combating Climate Change  La contribution positive de l’agriculture et de la sylviculture à la lutte contre le changement climatique  Der positive Beitrag von Land‐ und Forstwirtschaft zur Bekämpfung des Klimawandels
Authors: Andúgar Antonia
Published: December 2010

The Positive Contribution of Agriculture and Forestry to Combating Climate Change

Significant reductions in greenhouse gas (GHG) emissions can be achieved whilst at the same time developing the production potential of EU agriculture and forestry through increased productivity. Therefore, research and investment in innovation and new technologies are needed. Agriculture and forestry are uniquely placed in being able to reduce GHG emissions whilst adapting their own businesses and facilitating society’s adaptation to climate change. Farmers in the EU‐27 have already contributed to a significant decrease in GHG emissions of 20 per cent between 1990 and 2006. The implementation of the EU’s climate and energy package must not jeopardise the economic viability and competitiveness nor the social component of agricultural and forestry activities. Beyond their productive role, environmental benefits, landscape preservation and employment opportunities are delivered by both sectors. However, several factors hamper their contribution to combating climate change: and there is a risk that measures put in place to reduce GHG emissions will result in the delocalisation of agricultural production outside the EU. There is limited capacity of autonomous farm level adaptation. It is vital, therefore, that we have a strong Common Agricultural Policy to support farmers in improving their resilience to climatic variability and in contributing to climate change mitigation, which will deliver cost‐saving benefits for society as a whole.
Moving Ahead in Madrid: Aspirations and Expectations in the Spanish Second Generation
Authors: Portes Alejandro , Aparicio Rosa , Haller William , Vickstrom Erik
Published: December 2010

This paper examines determinants of aspirations and expectations among children of immigrants based on a statistically representative sample of 3,375 second generation youths interviewed in 101 public and private secondary schools in metropolitan Madrid. We review the past literature on status attainment in general and aspirations and expectations, in particular, and draw from it a set of six hypotheses to guide the analysis. Most theoretical statements in this field have been developed on the basis of U.S. data; studies in other immigrant-receiving countries, especially outside the Anglophone world, have been scarce. The study thus provides an opportunity to test and refine existing hypotheses in a different national context. We present breakdowns of educational and occupational aspirations and expectations by gender, parental education and type of school attended. This is followed by multivariate regressions of all four dependent variables on these three plus other predictors suggested by the research literature. This analysis ends with structural equation models – recursive and non-recursive – that provide an integrated theoretical statement of the causal structure of ambition in the Spanish context. Implications of our findings for theory and policy are examined. Suggestions for future research in this field are discussed.
Determinants of International Migration Flows to and from Industrialized Countries: A Panel Data Approach beyond Gravity
Authors: Kim Keuntae , Cohen Joel E.
Published: December 2010

We quantified determinants of international migratory inflows to 17 Western countries and outflows from 13 of these countries between 1950 and 2007 in 77,658 observations from multiple sources using panel-data analysis techniques. To construct a quantitative model that could be useful for demographic projection, we analyzed the logarithm of the number of migrants (inflows and outflows separately) as dependent variables in relation to demographic, geographic, and social independent variables. The independent variables most influential on log inflows were demographic [log population of origin and destination and log infant mortality rate (IMR) of origin and destination] and geographic (log distance between capitals and log land area of the destination). Social and historical determinants were less influential. For log outflows from the 13 countries, the most influential independent variables were log population of origin and destination, log IMR of destination, and log distance between capitals. A young age structure in the destination was associated with lower inflows while a young age structure in the origin was associated with higher inflows. Urbanization in destination and origin increased international migration. IMR affected inflows and outflows significantly but oppositely. Being landlocked, having a common border, having the same official language, sharing a minority language, and colonial links also had statistically significant but quantitatively smaller effects on international migration. Comparisons of models with different assumed correlation structures of residuals indicated that independence was the best assumption, supporting the use of ordinary-least-squares estimation techniques to obtain point estimates of coefficients.
Transatlantic Opinion on Immigration: Greater Worries and Outlier Optimism
Authors: Gustin Delancey , Ziebarth Astrid
Published: December 2010

This article outlines some of the key findings of the 2008 and 2009 Transatlantic Trends: Immigration 1 public opinion study. The countries surveyed include the United States, the United Kingdom, France, Germany, Italy, the Netherlands, and, for 2009 only, Spain and Canada. 2 Some of the findings are highlighted in this article, including the limited effect of the economic crisis on attitudes; approval ratings of governments’ migration management; political support for U.S. immigration reform components; Canada's outlier optimism; increasing Dutch skepticism; and support for the resettlement of migrants displaced by the effects of worldwide climate change.
Molecular Weight and Structure of Water Soluble (1→3), (1→4)‐β‐Glucans Affect Pasting Properties of Oat Flours
Authors: Liu Yanjun , White Pamela J.
Published: December 2010

Abstract:  Seven experimental oat lines with high (5.9% to 7.2%), medium (5.3% to 5.5%), and low (4.4%) β‐glucan concentrations were evaluated for the effects of β‐glucan molecular weight (MW) and structure on viscosities of oat‐flour slurries. The MW of β‐glucans was determined by size‐exclusion high‐performance liquid chromatography. The structural features of β‐glucans were measured by using fluorophore‐assisted capillary‐electrophoresis after complete hydrolysis with lichenase. The oat‐slurry viscosities were measured on a Rapid Visco Analyser under 4 conditions: (1) without starch (amylolysis, removal of starch by α‐amylase); (2) without β‐glucan (removal of β‐glucan by lichenase); (3) natural action of enzymes (autolysis, in sodium buffer); and (4) inhibition of enzymes (in silver nitrate solution). Excluding one line (regression outlier), significant correlations (P < 0.05) between peak MW of β‐glucan and viscosities of oat slurries were obtained under inhibition. The ratio of degree of polymerization (DP) 3/DP4 negatively correlated with viscosity under amylolysis, autolysis, and inhibition (P < 0.05). The amount of DP ≥ 5 negatively correlated with pasting final viscosity after β‐glucan removal by lichenase (P < 0.05). Positive correlations (P < 0.05) between the ratio of β‐(1→4)/β‐(1→3) linkages and viscosities under autolysis and inhibition were found. Overall, these findings demonstrated that the peak MW, ratio of DP3/DP4, amount of DP ≥ 5, and ratio of β‐(1→4)/β‐(1→3) linkages of β‐glucans impacted pasting properties of oat‐flour slurries.
Are Initial Returns and Underwriting Spreads in Equity Issues Complements or Substitutes?
Authors: Kim Dongcheol , Palia Darius , Saunders Anthony
Published: December 2010

The objective of this paper is to analyze the joint behavior of underwriting spreads and initial returns on equity issues for a large sample of issues over a 21‐year period. Traditional empirical approaches to the determination of these direct and indirect issuing costs view them as independent. Using a three‐stage least squares approach, we find these costs to be positively and significantly related. In the case of seasoned equity offerings, our results are robust to replacing initial returns with the offer price discount. We also find that low quality issuers are charged higher underwriting spreads and initial returns when compared to high quality issuers.
Retail Trading and IPO Returns in the Aftermarket
Authors: Chan Yue‐Cheong
Published: December 2010

Using trade size from the Trade and Quote (TAQ) data set as a proxy for individual versus institutional trading, this paper finds that the effects of trading of these two types of investors on initial public offering (IPO) returns on the first trading day depend on the hotness of the IPO. My regression results reveal that IPOs’ open‐to‐close returns are positively related to small trade participation, small trade purchases, and small trade order imbalance in the hot IPO sample, but not in the cold and neutral IPO samples. In addition, the aftermarket prices of cold and neutral IPOs are primarily driven by the trading of institutional investors, who are less likely to be driven by sentiment.
Merger‐Motivated IPOs
Authors: Hovakimian Armen , Hutton Irena
Published: December 2010

In this paper, we find support for initial public offerings (IPOs) motivated by subsequent acquisition activity. Over a third of newly public firms enter the market for corporate control as acquirers within three years of the IPO. We find that IPOs facilitate acquisitions in a number of ways. Newly public firms benefit from the cash raised in the IPO, from subsequent access to public financing, and from ability to pay with publicly traded stock for acquisitions. IPO firms also benefit by obtaining market feedback and by taking advantage of high post‐IPO stock values in making stock‐based acquisitions at favorable terms.
Gains from Mergers and Acquisitions Around the World: New Evidence
Authors: Alexandridis G. , Petmezas D. , Travlos N.G.
Published: December 2010

Using a global M&A data set, this paper provides evidence that the empirical observations relating public acquisitions to, at best, zero abnormal returns, and their stock‐financed subset to negative abnormal returns for acquiring firms around the deal announcement are not unanimous across countries. Acquirers beyond the most competitive takeover markets (the United States, United Kingdom, and Canada) pay lower premia and realize gains, while share‐for‐share offers are at least non‐value‐destroying for their shareholders. In contrast, target shareholders within these markets gain significantly less, implying that the benefits generated are more evenly split between the involved parties.
Emerging from Chapter 11 Bankruptcy: Is It Good News or Bad News for Industry Competitors?
Authors: Zhang Gaiyan
Published: December 2010

A firm under Chapter 11 bankruptcy protection may emerge from bankruptcy in a more advantageous competitive position within its industry to the detriment of their industry rivals. Using a sample of 264 firms that emerged from Chapter 11 bankruptcy during the period 1999‐2006, I find that its industry competitors demonstrate negative postemergence long‐term equity returns and deteriorating financial performance. Additional tests indicate that this outcome is less likely due to overall industry distress. Competitors tend to be more adversely affected if they are in more concentrated industries, if they have lower credit quality, when a more efficient firm emerges, and when the duration of bankruptcy is longer. This study suggests a need to reconsider Chapter 11's role in promoting competition and allocation of resources given its negative externalities on industry competitors.
Structural Response to Sloshing Excitation in Membrane LNG Tank
Authors: Graczyk Mateusz , Moan Torgeir
Published: December 2010

Sloshing in LNG membrane tanks may cause large pressures on the tank structure. To keep the cargo at the required low temperature, the tank structure is covered with an insulation, which has a much less strength than steel. The containment system is a very complex structure, which consists of different materials and requires a careful analysis with due consideration of the load process and dynamic effects in the response. The structural response of the membrane tank wall is investigated in this paper by finite element analyses. First, a modal composition of the structural response is studied. It is shown that many modes contribute to the response, which makes it difficult to establish the simplified DLF approach. The dynamic structural response to a typical sloshing impact is investigated in detail. An important observation is that, although the containment system has traditionally been modeled with a rigid support, the steel plate that supports the insulation may be flexible under the relevant load conditions. It is shown that the flexibility of the steel plate causes significant stress variation in the insulation. Different response patterns of the Mark III containment system are presented, and mechanisms that cause large stress concentrations and different response patterns in the static and dynamic cases are discussed. The scaling issue in view of the response is also investigated. Various scaling formulations may apply in post-processing sloshing experiments. While the Froude law yields conservative scaling for pressure magnitude, its conservatism for scaling the time needs to be investigated in view of the relevant dynamic response. By analyzing the structural response to the differently scaled loads, it is found that the Froude approach is conservative, but the scatter of results may be very large.
Modeling the Seasonality of Extreme Waves in the Gulf of Mexico
Authors: Jonathan Philip , Ewans Kevin
Published: December 2010

Statistics of storm peaks over threshold depend typically on a number of covariates including location, season, and storm direction. Here, a nonhomogeneous Poisson model is adopted to characterize storm peak events with respect to season for two Gulf of Mexico locations. The behavior of storm peak significant wave height over threshold is characterized using a generalized Pareto model, the parameters of which vary smoothly with season using a Fourier form. The rate of occurrence of storm peaks is also modeled using a Poisson model with rate varying with season. A seasonally varying extreme value threshold is estimated independently. The degree of smoothness of extreme value shape and scale and the Poisson rate with season are regulated by roughness-penalized maximum likelihood; the optimal value of roughness is selected by cross validation. Despite the fact that only the peak significant wave height event for each storm is used for modeling, the influence of the whole period of a storm on design extremes for any seasonal interval is modeled using the concept of storm dissipation, providing a consistent means to estimate design criteria for arbitrary seasonal intervals. The characteristics of the 100 year storm peak significant wave height, estimated using the seasonal model, are examined and compared with those estimated ignoring seasonality.
Polymer Rigidity Control for Endoscopic Shaft-Guide ‘Plastolock’ — A Feasibility Study
Authors: Loeve Arjo J. , Bosma Johannes H. , Breedveld Paul , Dodou Dimitra , Dankelman Jenny
Published: December 2010

Flexible endoscopes are used for diagnostic and therapeutic interventions in the human body for their ability to be advanced through tortuous trajectories. However, this very same property causes difficulties as well. For example, during surgery, a rigid shaft would be more beneficial since it provides more stability and it allows for better surgical accuracy. In order to keep the flexibility and to obtain the rigidity when needed, a shaft-guide with controllable rigidity could be used. In this article, we introduce the plastolock shaft-guide concept, which uses thermoplastics that are reversibly switched from rigid to compliant by changing their temperatures from 5°C to 43°C. These materials are used to make a shaft that can be rendered flexible to follow the flexible endoscope and rigid to guide it. To find polymers that are suitable for the plastolock concept, an extensive database and internet search was performed. The results suggest that many suitable materials are available or can be custom synthesized to meet the requirements. The thermoplastic polymer Purasorb® PLC 7015 was obtained and a dynamic mechanical analysis showed that it is suitable for the plastolock concept. A simple production test indicated that this material is suitable for prototyping by molding. Overall, the results in this article show that the plastolock concept can offer simple, scalable solutions for medical situations that desire stiffness at one instance and flexibility at another.
Modeling of Deformation-Accelerated Breakdown of Polylactic Acid Biodegradable Stents
Authors: Soares João S. , Moore James E. , Rajagopal Kumbakonam R.
Published: December 2010

The use of biodegradable polymers in biomedical applications has been successful in nonload bearing applications, such as biodegradable implants for local drug delivery, and in simple load bearing situations such as surgical sutures and orthopedic fixation screws. The desire to incorporate these materials in more complex load bearing situations, such as tissue engineering scaffolds and endovascular or urethral stents, is strong, but the lack of constitutive models describing the evolution of biodegradable polymers over the course of degradation has severely hampered the rational design process for these more complex biodegradable medical applications. With the objective of predicting biodegradable stent behavior, we incorporated constitutive models of biodegradable polymeric materials in a computational setting and the mechanical response of three different stent designs were analyzed as degradation progressed. A thermodynamically consistent constitutive model for materials undergoing deformation-induced degradation was applied to a commonly employed biodegradable polymer system, poly(L-lactic acid), and its specific form was determined by corroboration against experimental data. Depreciation of mechanical properties due to degradation confers time-dependent characteristics to the response of the biodegradable material: the deformation imparted by a constant load increases over time, i.e. the body creeps, and the stress necessary to keep a fixed deformation decreases, i.e. the body relaxes. Biodegradable stents, when subjected to constant pressure in its exterior, deflect inwards and ultimately fail as the structure loses its mechanical integrity. The complex geometry of endovascular stents and their physiological loading conditions lead to inhomogeneous deformations, and consequently, inhomogeneous degradation ensues. Degradation is mostly confined to the bends of the stent rings and junction points, which are the locations that carry most of the deformation, whereas mostly undeformed connector bars remain less degraded. If failure occurs, it will occur most likely at those sensitive locations and large, nondegraded pieces can provoke severe embolic problems. Highly nonuniform degradation indicates that some stent designs are at higher risk for complications. Deformation patterns of stents made of a material that loses its integrity are different than those of permanent stents. Blind adaptation of permanent stent design concepts is ill-suited for biodegradable stent design. The time-dependent aspect of the implant not only must be taken into account but should also be used to interact with the body’s reaction and to enhance healing.
Parametric Investigation of Circumferential Grooves on Compressor Rotor Performance
Authors: Wu Yanhui , Chu Wuli , Zhang Haoguang , Li Qingpeng
Published: December 2010

This paper presents numerical and experimental investigations about grooved casing treatment with the help of a high-speed small-scale compressor rotor. First, the numerical investigation seeks to offer a contribution of understanding the working mechanism by which circumferential grooves improve stall margin. It is found that stall margin gain due to the presence of circumferential grooves arises from the suction-injection effect and the near-tip unloading effect. Based on that, the philosophy of design of experiment is then set up. Finally, parametric studies are carried out through systematical experiments. It is found that the orthogonal experiment and the factorial analyses are successful in identifying the “best casing configuration” in terms of stall margin improvement. However, the ineffectiveness of the deduction from simulations suggests that the secondary flow circulations on stall margin gain should not be neglected, and the overall contribution of each groove to stall margin gain depends on its unloading effect and the compound effect of suction-injection. Further numerical investigation will focus on how to set up quantitative criteria to evaluate the compound effect of suction-injection and the unloading effect on stall margin gain respectively in each groove.
An Implantable Battery System for a Continuous Automatic Distraction Device for Mandibular Distraction Osteogenesis
Authors: Chung M. D. , Rivera R. D. , Feinberg S. E. , Sastry A. M.
Published: December 2010

Distraction osteogenesis is a method of generating new bone formation by the gradual application of tensile stress across an osteotomy site (a complete cut through the bone). Internal or intraoral distraction devices have become the most common clinical apparatus in craniofacial distraction osteogenesis, although actuating the distraction devices relies upon manual length adjustment under patients’ compliance, introducing inconvenience and potential error in the procedure. To realize a fully implantable automatic distraction device, we propose a device design comprising a continuous miniature motor-driven distractor with a controller and an on-board lithium-ion battery. A benchtop prototype was fabricated to demonstrate the device’s structural design capable of transmitting sufficient loads with sufficient strain accuracy; it is capable of using a battery selection algorithm to determine an appropriate electrochemistry, temperature, sealability, and form factor and a control algorithm and a testing protocol with a laboratory-fabricated control circuit. This new distraction osteogenesis device enables completely automated and continuous distraction by the application of a low strain magnitude with multiple steps potentially leading to enhanced osteogenic activity.
Modifications to CHROMagar Acinetobacter for improved selective growth of multi-drug resistantAcinetobacter baumannii
Authors: Wareham D W , Gordon N C
Published: December 2010

Performance of CHROMagar Acinetobacter was assessed for the selective isolation and identification ofAcinetobacter baumannii. The medium was effective in suppressing the growth of other Gram-positive and Gram-negative species while the addition of KPC supplement ensured growth of only carbapenem resistantA baumannii.
P-010 A canine bifurcation giant aneurysm model
Authors: Consigny D , Yasuda R , Strother C , Aagaard-Kienitz B
Published: December 2010

Purpose

To create a reproducible canine model of giant aneurysms.

Materials and methods

Seven mongrel dogs were used for this study. All procedures were performed under an institutional approved protocol. Anesthesia was induced with propofol 10 mg/kg intravenous injection, and maintained using 1–5% isoflurane and 100% oxygen. After the neck was sterilely prepped and draped, bilateral 10 cm incisions were made medial to each external jugular vein. 30 mm segments of both external jugular veins were ligated, removed and placed in heparinized saline (1000 U heparin/100 ml saline). The left common carotid artery (CCA) was ligated proximally and a temporary vascular clamp was placed distally. A tunnel was created under the trachea to pass the left CCA to the right side. Temporary clamps were placed proximally and distally on the right CCA. An 8 mm arteriotomy was made on the right CCA midway between the clamps. The distal segment of the left CCA was then anastomosed to the base of the right CCA. Both external jugular vein segments were opened longitudinally and angled (arrowhead shaped) incisions were made into both vein segments so that they would match the arterial opening where the right and left CCAs had been anastomosed. The opened segments of the jugular veins were then anastomosed to form a single cylinder using a running suture technique. Once this was done the resulting vein pouch was sewn into the opening between the right and left CCA. All vascular sutures were performed using 7-0 prolene suture. The temporary vascular clamps were removed, and if any leaks were seen, additional sutures were used until hemostasis was established (Abstract P-010 figure 1A). Incisions were closed using absorbable suture. The surgical procedure took 2.5 h. Animals were allowed to recover for further studies. Angiograms were preformed 4.5 weeks after the aneurysm creation.

Abstract P-010 Figure 1

Results

Six of seven aneurysms remained fully patent 4.5 weeks post-creation (Abstract P-010 figure 1B). During this interval, animals showed no surgical related complications. No medication was needed to prevent thrombus. Aneurysm dimensions are shown in Abstract P-010 table 1.

Abstract P-010 Table 1

Aneurysm dimensions

Case 1Case 2Case 3Case 4Case 5Case 6Height20.527.424.132.421.522.1Dome width11.611.812.214.812.512.0Neck width10.310.69.914.98.39.3Volume1550.92440.72267.24593.72342.82623.9Ostium area111.399.395.2171.968.892.3Proximal artery diameter3.64.13.73.53.43.7Distal artery diameter (L)3.23.93.33.23.12.7Distal artery diameter (R)3.33.83.33.43.22.8

Conclusion

We successfully developed a reproducible giant aneurysm model using a vein patch technique.
P-011 Percutaneous anterior column stabilization of focal metastatic lesions of the spine: the value of plasma mediated radiofrequency ablation before cement injection
Authors: Georgy B
Published: December 2010

Purpose

Spinal metastatic lesions which are located in the anterior or posterior regions of the vertebral body (Weinstein types III and IV) are usually treated by extensive anterior corpectomy stabilization and posterior fusion. This study assesses the value of creating a cavity in the anterior two-thirds of the vertebral body using plasma mediated radiofrequency ablation prior to cement injection, aiming to stabilize the anterior column through a non-heat-driven method.

Materials and methods

Retrospective assessments of CT images were performed pre- and postprocedure in 24 patients (27 levels). A void was created in the anterior portion of the tumor infiltrated vertebral body using a bipolar plasma mediated radiofrequency based wand (ArthroCare Corporation, Austin, Texas, USA) and bone cement was inserted. Pain was recorded both preprocedure and 2–4 weeks afterwards using a visual analog scale (VAS).

Results

In 11/12 levels with anterior lesions, cement was deposited inside the lesion. Cement was also successfully deposited anterior to the lesion in 13/15 levels with posteriorly located lesions. VAS pain scores were available for 21 patients: 19 reported significant pain relief while two exhibited no change. No clinically significant leakage was observed.

Conclusion

Cavity creation using plasma mediated radiofrequency ablation can be performed percutaneously before standard vertebroplasty and results in more control over cement deposition in the anterior part of the vertebral body, regardless of the lesion location. This approach could treat focal metastatic lesions while avoiding the more invasive standard technique of extensive anterior surgical debulking and reconstruction. In cases displaying neurological deficit, it can complement a simpler posterior decompressive laminectomy and fusion.
P-019 Correlation between blood flow and recurrences in coiled patients
Authors: van den Berg J , Schneiders J , Marquering H , Majoie C , van Bavel E , van den Berg R
Published: December 2010

Introduction

Endovascular treatment with detachable coils has become an established technique for patients with intracranial aneurysms, the drawback being recurrence due to coil compaction or enlargement of a remnant. The contribution of hemodynamics to recurrence is at present unknown. The aim of this study was to explore the relationship between blood flow into the aneurysm and area of recurrence. We hypothesized that the location of the recurrence at first follow-up overlaps with the location of the inflow jet into the original untreated aneurysm.

Materials and methods

Out of 270 patients who received endovascular treatment for an intracranial aneurysm, 19 patients with a recurrence at first follow-up were included. Five patients with a recurrence were excluded because imaging was unsuitable for processing. Virtual surface models of the original untreated aneurysms and surrounding vessels were segmented with the Vascular Modeling ToolKit (VMTK) using three-dimensional imaging obtained before treatment. Recurrence areas were identified on 6 month follow-up three-dimensional time of flight MR angiography. Virtual surface models were also segmented of the lumen of the recurrences. Both surface models were matched using the Iterative Closest Point registration already available in VMTK (Abstract P-019 figure 1).

Abstract P-019 Figure 1

Match between the surface models of the untreated aneurysm and the luminal recurrence. Case No 01001.

After post-processing of the flow, it was possible to visualize the exact location of blood flowing into the aneurysm. This flow profile was matched with the location of the recurrence, with the untreated aneurysm neck as a reference frame. This match allowed for calculation of the overlap between area of recurrence and area of inflow (Abstract P-019 figure 2).

Abstract P-019 Figure 2

Two-dimensional slice perpendicular through the aneurysm neck. Dark grey: blood outflow zone before treatment. Light grey: blood inflow zone before treatment. Black outline: the luminal recurrence. Black area: overlapping zone of original inflow and later recurrence. Overlap: 15.3%. Case No 01005.

Results

The area of recurrence did not show a strong correlation with the initial inflow jet area in the aneurysm. The mean area of overlap of the inflow area and recurrence area as a percentage of the total recurrence area was only 35.45% (CI 22.83 to 48.07). Two cases did not show any overlap and none of the cases had a complete overlap. The range of overlap area was 0.00–96.35%.

Conclusion

Our model, construction using high quality geometry and CFD simulations using Fluent, were accurate. The results in this small sample do not support a relation between location of inflow in an untreated aneurysm and location of recurrence after treatment with coils.
P-005 Anesthetic considerations and the role of blood pressure management in the endovascular treatment of acute ischemic stroke
Authors: Menon B , Davis M , Herrera C , Eesa M , Demchuk A , Goyal M , Archer D , Hill M
Published: December 2010

Introduction

Increasingly used in North America, endovascular thrombolysis for ischemic stroke results in high recanalization rates without a comparable increase in good clinical outcomes. Many neurointerventionalists prefer general anesthesia to keep patients still. The purpose of this study is to identify the role of anesthesia and any other associated periprocedural factors in determining clinical outcomes in patients undergoing endovascular procedures for acute ischemic stroke.

Methods

We retrospectively studied patients who underwent open label intra-arterial procedures for stroke from 2003 to 2009 in our intra-arterial database. Data were collected from chart reviews and automated anesthesia records. We used the Houston Intra-arterial Therapy (HIAT) score (1 point for age >75 years; 1 for National Institutes of Health Stroke Scale (NIHSS) score >18 and 1 point for glucose >150 mg/dl) for adjusting for baseline differences. The primary clinical outcome was modified Rankin Scale 0–2 at 3 months.

Results

96 patients (67 males, median age 65 years) with median NIHSS 17 (range 12–20) were included in the study. The distribution of type of anesthesia was as follows: 48/96 general anesthesia, 44/96 conscious sedation (14) or local anesthesia only (30), and 4/96 undetermined. 7/48 (15%) in the general anesthesia group had good clinical outcome compared with 29/44 (66%) in the local anesthesia/conscious sedation group (RR 0.22; 95% CI 0.11 to 0.45). After adjusting for HIAT score and the presence or absence of any major anesthetic comorbidities, the general anesthesia group had significantly worse clinical outcome (p=0.001). Lower blood pressure correlated with poorer clinical outcomes in both anesthesia groups. The lowest mean systolic blood pressure in the general anesthesia group was 104 mm Hg compared with 135 mm Hg in the local anesthesia/conscious sedation group (p=0.0001).

Conclusion

The use of general anesthesia during endovascular procedures in acute ischemic strokes is associated with poorer clinical outcomes at 3 months. This could be because of lower periprocedural blood pressures.
P-009 Trend towards using mechanical thrombectomy devices in stroke interventions in recent years
Authors: Nanda A , Sharma J , Mehta S , Joshi A , Hsu D
Published: December 2010

Purpose

Mechanical thrombectomy is a promising new modality of interventional stroke treatment. The use of these devices has been steadily increasing over the past 2–3 years.

In recent years, multiple trials have been published establishing the efficacy of mechanical thrombectomy devices in achieving successful vascular recanalization and improved outcomes. We reviewed single institution data analyzing increasing use of mechanical thrombectomy devices and related outcomes in recent years.

Methods

Retrospective chart review was performed on 146 consecutive patients who underwent interventional acute stroke treatment from January 2006 to October 2009. Data were analyzed to compare use of mechanical thrombectomy devices (MERCI and Penumbra) and outcomes for each individual year. The primary outcome measures compared were mortality, recanalization rate and modified Ranking Score (mRS).

Results

For all patients included, data were analyzed for each year separately. In 2006, all patients (n=11) were treated with IA (intra-arterial) tissue plasminogen activator (tPA) (100%) and none received mechanical thrombectomy, with recanalization rates (TIMI=2/3), mortality and mRS ≤2 of 54%, 18% and 45%, respectively. Total patients treated were 49, 47 and 39 in 2007, 2008 and 2009, respectively. In 2007, 44 were treated with IA tPA (89%) and nine (18%) underwent mechanical thrombectomy with recanalization rates (TIMI=2/3), mortality and mRS ≤2 of 65%, 18% and 53%, respectively. In 2008, 34 were treated with IA tPA (72%) and 21 (44%) underwent mechanical thrombectomy with recanalization rates (TIMI=2/3), mortality and mRS ≤2 of 59%, 25% and 48%, respectively. In 2009, 30 were treated with IA tPA (76%) and 28 (71%) underwent mechanical thrombectomy with recanalization rates (TIMI=2/3), mortality and mRS ≤2 of 71%, 23% and 41%, respectively

Conclusion

There is an increasing trend towards using mechanical thrombectomy devices over recent years resulting in better recanalization rates. However, no trend towards improved outcomes or reduced mortality was observed in our single institution series. This could be due to inclusion of patients with older age, higher National Institutes of Health Stroke Scale scores and expanded treatment time windows for interventional stroke therapy in recent years.

Abstract P-009 Figure 1
O-011 Long term outcome in the repair of spinal cord perimedullary arteriovenous fistulae
Authors: Hetts S , Antonietti L , Sheth S , English J , Dowd C , Higashida R , Lawton M , Halbach V
Published: December 2010

Background and purpose

The natural history of perimedullary arteriovenous fistulae (PMAVFs), also known as type IV spinal cord AV fistulae, is incompletely understood. Both open surgical and endovascular approaches have been described as treatment modalities for this disease. The goal of this study was to evaluate the long term outcome of patients with PMAVFs treated at a single tertiary care institution.

Materials and methods

We conducted a retrospective study on 32 patients with PMAVFs, evaluated between 1983 and 2009. Data were gathered by reviewing outpatient clinic notes, operative and radiological reports, and spinal angiograms. The PMAVFs were categorized into one of three types based on the angiographic imaging criteria. Pretreatment and post-treatment ambulation and micturition symptoms were quantified using the Aminoff and Logue scale (ALS).

Results

30 patients underwent corrective procedures, four by embolization alone, 11 by surgery alone and 15 patients received a combination of the two. 28 patients underwent follow-up spinal angiography, with residual shunting noted in six patients. Mean follow-up period was 54 months (range 1–228). Analysis of the ALS scores revealed that treatment of PMAVFs, independent of modality, resulted in significant improvement in ambulation, but inconsistent changes in micturition. In addition, residual fistula at the time of follow-up angiogram was associated with worsened neurologic status or lack of improvement. Outcome analysis based on fistula type showed dramatic improvement in ALS ambulation scores (62%) for type 3 fistulae compared with type 1 and 2 (26%, 27%, respectively).

Conclusion

Significant improvement in ambulation, but not micturition, was observed following treatment. Residual fistula on follow-up angiography was associated with progressive worsening or lack of improvement in neurologic function. Patients with type 3 fistulae were shown to benefit most from treatment, with marked improvement in post-treatment ambulation scores. As endovascular and surgical techniques continue to evolve, further studies are warranted.