Risk of intracerebral aneurysm rupture during carotid revascularization

ObjectiveRobust guidelines exist for the treatment of carotid stenosis and intracranial aneurysms independently, however, the management of tandem carotid stenosis and intracranial aneurysms remains uncertain. Although the prevalence of tandem pathologies is small (1.9%-3.2%), treating carotid stenosis can alter intracranial hemodynamics potentially predisposing to aneurysm rupture. In this review, our aim was to assess the safety of intervention in this cohort, by analyzing outcomes from the published literature.MethodsThe preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used to conduct the review. Articles from 1947 to 2012 were searched using EMBASE Classic and EMBASE (November, 1947 -March, 2012) and Ovid MEDLINE(R) In-Process and other NonIndexed Citations and Ovid MEDLINE(R) on Ovid SP, http://ClinicalTrials.gov, http://controlled-trials.com and the Cochrane review database using a predefined search strategy.ResultsOne hundred forty-one patients from 27 articles were included. Interventions ranged from single (n = 104, 74%), staged (n = 26, 18%) to simultaneous procedures (n = 11, 8%). The largest cohort of patients was treated by carotid endarterectomy alone (n = 92, 66%). The majority of patients presented with a symptomatic carotid stenosis and an asymptomatic ipsilateral intracranial aneurysm (n = 70, 50%). Five subarachnoid hemorrhages occurred (4% [5/140], three within 30 days of the procedure and two thereafter) of which two were fatal. All five occurred in patients who underwent carotid endarterectomy as a single procedure (5%). Two of the five patients presented with ruptured posterior communicating artery aneurysms.ConclusionsPublished reports of perioperative aneurysm rupture are rare in individuals with tandem carotid stenosis and intracranial aneurysms. This is the first analysis of all published cases. However, it is limited by the small number of studies and the possible underreporting due to publication bias and underdiagnosis where angiography was not performed. Although we report a low incidence of subarachnoid hemorrhage, analysis of registry data with a larger cohort is warranted to confirm these findings

Innate immunity and monocyte-macrophage activation in atherosclerosis

Innate inflammation is a hallmark of both experimental and human atherosclerosis. The predominant innate immune cell in the atherosclerotic plaque is the monocyte-macrophage. The behaviour of this cell type within the plaque is heterogeneous and depends on the recruitment of diverse monocyte subsets. Furthermore, the plaque microenvironment offers polarisation and activation signals which impact on phenotype. Microenvironmental signals are sensed through pattern recognition receptors, including toll-like and NOD-like receptors - the latter of which are components of the inflammasome - thus dictating macrophage behaviour and outcome in atherosclerosis. Recently cholesterol crystals and modified lipoproteins have been recognised as able to directly engage these pattern recognition receptors. The convergent role of such pathways in terms of macrophage activation is discussed in this review

ELECTROMYOGRAPHICAL ANALYSIS OF HAMSTRING RESISTANCE TRAINING EXERCISES

This study evaluated the EMG activity of the hamstring and quadriceps muscle groups during resistance training exercises commonly used for training the hamstrings. Subjects included 34 collegiate athletes. Hamstring and quadriceps MVIC and 6 repetition maximum loads were determined. Data were collected 72 hours later, during the performance of 6 randomly ordered exercises, including back squats, seated leg curls, stiff leg dead lifts, single leg dead lifts, good mornings, and “Russian curls.” Data were analyzed using RMS values normalized to MVIC. A one way repeated measures ANOVA revealed that significant differences existed between several exercises. Additionally, the ratio of hamstring to quadriceps co-activation was significantly different between all exercises

Distributed ice thickness and glacier volume in southern South America

South American glaciers, including those in Patagonia, presently contribute the largest amount of meltwater to sea level rise per unit glacier area in the world. Yet understanding of the mechanisms behind the associated glacier mass balance changes remains unquantified partly because models are hindered by a lack of knowledge of subglacial topography. This study applied a perfect-plasticity model along glacier centre-lines to derive a first-order estimate of ice thickness and then interpolated these thickness estimates across glacier areas. This produced the first complete coverage of distributed ice thickness, bed topography and volume for 617 glaciers between 41°S and 55°S and in 24 major glacier regions. Maximum modelled ice thicknesses reach 1631 m ± 179 m in the South Patagonian Icefield (SPI), 1315 m ± 145 m in the North Patagonian Icefield (NPI) and 936 m ± 103 m in Cordillera Darwin. The total modelled volume of ice is 1234.6 km3 ± 246.8 km3 for the NPI, 4326.6 km3 ± 865.2 km3 for the SPI and 151.9 km3 ± 30.38 km3 for Cordillera Darwin. The total volume was modelled to be 5955 km3 ± 1191 km3, which equates to 5458.3 Gt ± 1091.6 Gt ice and to 15.08 mm ± 3.01 mm sea level equivalent (SLE). However, a total area of 655 km2 contains ice below sea level and there are 282 individual overdeepenings with a mean depth of 38 m and a total volume if filled with water to the brim of 102 km3. Adjusting the potential SLE for the ice volume below sea level and for the maximum potential storage of meltwater in these overdeepenings produces a maximum potential sea level rise (SLR) of 14.71 mm ± 2.94 mm. We provide a calculation of the present ice volume per major river catchment and we discuss likely changes to southern South America glaciers in the future. The ice thickness and subglacial topography modelled by this study will facilitate future studies of ice dynamics and glacier isostatic adjustment, and will be important for projecting water resources and glacier hazards

Heterotrophy mitigates the response of the temperate coral

Anthropogenic increases in atmospheric carbon dioxide concentration have caused global average sea surface temperature (SST) to increase by approximately 0.11°C per decade between 1971 and 2010 - a trend that is projected to continue through the 21st century. A multitude of research studies have demonstrated that increased SSTs compromise the coral holobiont (cnidarian host and its symbiotic algae) by reducing both host calcification and symbiont density, among other variables. However, we still do not fully understand the role of heterotrophy in the response of the coral holobiont to elevated temperature, particularly for temperate corals. Here, we conducted a pair of independent experiments to investigate the influence of heterotrophy on the response of the temperate scleractinian coral Oculina arbuscula to thermal stress. Colonies of O. arbuscula from Radio Island, North Carolina, were exposed to four feeding treatments (zero, low, moderate, and high concentrations of newly hatched Artemia sp. nauplii) across two independent temperature experiments (average annual SST (20°C) and average summer temperature (28°C) for the interval 2005-2012) to quantify the effects of heterotrophy on coral skeletal growth and symbiont density. Results suggest that heterotrophy mitigated both reduced skeletal growth and decreased symbiont density observed for unfed corals reared at 28°C. This study highlights the importance of heterotrophy in maintaining coral holobiont fitness under thermal stress and has important implications for the interpretation of coral response to climate change

Hyperstrong Radio-Wave Scattering in the Galactic Center. II. A Likelihood Analysis of Free Electrons in the Galactic Center

The scattering diameters of Sgr A* and several nearby OH masers (~ 1" at 1 GHz) indicate that a region of enhanced scattering is along the line of sight to the Galactic center. We combine radio-wave scattering data and free-free emission and absorption measurements in a likelihood analysis that constrains the following parameters of the GC scattering region: The GC-scattering region separation, d; the angular extent of the region, \psi_l; the outer scale on which density fluctuations occur, l_0; and the gas temperature, T. The maximum likelihood estimates of these parameters are d = 133_{-80}^{+200} pc, 0.5 degrees <= \psi_l <~ 1 degrees, and (l_0/1 pc)^{2/3}T^{-1/2} = 10^{-7 +/- 0.8}. As host media for the scattering, we consider the photoionized surface layers of molecular clouds and the interfaces between molecular clouds and the 10^7 K ambient gas. We are unable to make an unambiguous determination, but we favor an interface model in which the scattering medium is hot (T ~ 10^6 K) and dense (n_e ~ 10 cm^{-3}). The GC scattering region produces a 1 GHz scattering diameter for an extragalactic source of 90", if the region is a single screen, or 180", if the region wraps around the GC, as appears probable. We modify the Taylor-Cordes model for the Galactic distribution of free electrons in order to include an explicit GC component. Pulsars seen through this region will have a dispersion measure of approximately 2000 pc cm^{-3}, of which 75% arises from the GC component. We stress the uniqueness of the GC scattering region, probably resulting from the high-pressure environment in the GC.Comment: 39 pages with 9 PostScript figures; LaTeX2e with AASTeX macro aaspp4, to be published in Ap

Lipotoxicity and immunometabolism in ischemic acute kidney injury: current perspectives and future directions

Dysregulated lipid metabolism is implicated in the pathophysiology of a range of kidney diseases. The specific mechanisms through which lipotoxicity contributes to acute kidney injury (AKI) remain poorly understood. Herein we review the cardinal features of lipotoxic injury in ischemic kidney injury; lipid accumulation and mitochondrial lipotoxicity. We then explore a new mechanism of lipotoxicity, what we define as “immunometabolic” lipotoxicity, and discuss the potential therapeutic implications of targeting this lipotoxicity using lipid lowering medications

Origin and implications of early diagenetic quartz in the Mississippian Bowland Shale formation, Craven Basin, UK

Silica cementation exerts a key control on the compaction and geotechnical properties of mudstones, and by extension, the style of hydrocarbon and/or mineral systems present in a given sedimentary basin. Integrated microscopic and bulk geochemical observations demonstrate that siliceous mudstones in the Bowland Shale Formation, a target for UK shale gas extraction, exhibit abundant dispersed, discrete, μm-scale quartz cements, and exhibit silica enrichment (‘excess’) above a local detrital Si/Al threshold of 2.5. Dissolution of siliceous radiolarian tests during early diagenesis is identified as the main source of silica (opal A) required for quartz precipitation, either via opal CT or directly to quartz, and potentially generated as a product of anoxic marine ‘weathering’ (dissolution) of reactive silicates during early diagenesis. Excess silica correlates with free hydrocarbons (S1) normalised to total organic carbon (oil saturation index; OSI); we propose early diagenetic quartz precipitation suppressed pore collapse (‘buttress effect’), retaining the pore space capacity to host oil. Quartz precipitation was likely catalysed, for example via low porewater pH, elevated Al and/or Fe oxide content, and/or abundant labile organic matter. Juxtaposition of siliceous mudstones and mudstones lacking quartz cement indicates silica was immobile beyond the bed scale. Thus metre-scale siliceous packages likely represent more prospective units within the Bowland Shale (in terms of unconventional hydrocarbons), on the basis of early diagenetic biogenic-derived quartz cementation leading to improved hydrocarbon storage capacity coupled to enhanced brittleness. These findings are relevant for shale oil and shale gas systems, specifically where oil retained in pores subsequently cracks to generate gas. These findings also suggest the Bowland Shale is a sub-class of black shale, defined by the potential to host a relatively large volume of early diagenetic fluids, derived from anoxic bottom waters, which were potentially S- and/or metal-bearing. This is potentially relevant for understanding the genesis of adjacent and related Pb-Zn mineral deposits