Can the ischemic penumbra be identified on noncontrast CT of acute stroke?

<p><b>Background and Purpose:</b> Early ischemic changes on noncontrast CT in acute stroke include both hypoattenuation and brain swelling, which may have different pathophysiological significance.</p> <p><b>Methods:</b> Noncontrast CT and CT perfusion brain scans from patients with suspected acute stroke <6 hours after onset were reviewed. Five raters independently scored noncontrast CTs blind to clinical data using the Alberta Stroke Program Early CT Score (ASPECTS). Each ASPECTS region was scored as hypodense or swollen. A separate reviewer measured time to peak and cerebral blood volume in each ASPECTS region on CT perfusion. Time to peak and cerebral blood volume were compared for each region categorized as normal, hypodense, or isodense and swollen.</p> <p><b>Results:</b> Scans of 32 subjects a median 155 minutes after onset yielded 228 regions with both CT perfusion and noncontrast CT data. Isodense swelling was associated with significantly higher cerebral blood volume (P=0.016) and with penumbral perfusion (posttest:pretest likelihood ratio 1.44 [95% CI: 0.68 to 2.90]), whereas hypodensity was associated with more severe time to peak delay and with core perfusion (likelihood ratio 3.47 [95% CI: 1.87 to 6.34]). Neither isodense swelling nor hypodensity was sensitive for prediction of perfusion pattern, but appearances were highly specific (87.2% and 91.0% for penumbra and core, respectively). Intrarater agreement was good or excellent, but interrater agreement for both hypodensity and swelling was poor.</p> <p><b>Conclusions:</b> Regions exhibiting hypoattenuation are likely to represent the infarct core, whereas regions that are isodense and swollen have increased cerebral blood volume and are more likely to signify penumbral perfusion. Although noncontrast CT is not sensitive for detection of core and penumbra, appearances are specific. Some information on tissue viability can therefore be obtained from noncontrast CT.</p&gt

Lightweight Multilingual Software Analysis

Developer preferences, language capabilities and the persistence of older languages contribute to the trend that large software codebases are often multilingual, that is, written in more than one computer language. While developers can leverage monolingual software development tools to build software components, companies are faced with the problem of managing the resultant large, multilingual codebases to address issues with security, efficiency, and quality metrics. The key challenge is to address the opaque nature of the language interoperability interface: one language calling procedures in a second (which may call a third, or even back to the first), resulting in a potentially tangled, inefficient and insecure codebase. An architecture is proposed for lightweight static analysis of large multilingual codebases: the MLSA architecture. Its modular and table-oriented structure addresses the open-ended nature of multiple languages and language interoperability APIs. We focus here as an application on the construction of call-graphs that capture both inter-language and intra-language calls. The algorithms for extracting multilingual call-graphs from codebases are presented, and several examples of multilingual software engineering analysis are discussed. The state of the implementation and testing of MLSA is presented, and the implications for future work are discussed.Comment: 15 page

Lightweight Call-Graph Construction for Multilingual Software Analysis

Analysis of multilingual codebases is a topic of increasing importance. In prior work, we have proposed the MLSA (MultiLingual Software Analysis) architecture, an approach to the lightweight analysis of multilingual codebases, and have shown how it can be used to address the challenge of constructing a single call graph from multilingual software with mutual calls. This paper addresses the challenge of constructing monolingual call graphs in a lightweight manner (consistent with the objective of MLSA) which nonetheless yields sufficient information for resolving language interoperability calls. A novel approach is proposed which leverages information from a compiler-generated AST to provide the quality of call graph necessary, while the program itself is written using an Island Grammar that parses the AST providing the lightweight aspect necessary. Performance results are presented for a C/C++ implementation of the approach, PAIGE (Parsing AST using Island Grammar Call Graph Emitter) showing that despite its lightweight nature, it outperforms Doxgen, is robust to changes in the (Clang) AST, and is not restricted to C/C++.Comment: 10 page

Evolution and diversity of secretome genes in the apicomplexan parasite Theileria annulata

<b>BACKGROUND</b>: Little is known about how apicomplexan parasites have evolved to infect different host species and cell types. Theileria annulata and Theileria parva invade and transform bovine leukocytes but each species favours a different host cell lineage. Parasite-encoded proteins secreted from the intracellular macroschizont stage within the leukocyte represent a critical interface between host and pathogen systems. Genome sequencing has revealed that several Theileria-specific gene families encoding secreted proteins are positively selected at the inter-species level, indicating diversification between the species. We extend this analysis to the intra-species level, focusing on allelic diversity of two major secretome families. These families represent a well-characterised group of genes implicated in control of the host cell phenotype and a gene family of unknown function. To gain further insight into their evolution and function, this study investigates whether representative genes of these two families are diversifying or constrained within the T. annulata population. <b>RESULTS</b>: Strong evidence is provided that the sub-telomerically encoded SVSP family and the host-nucleus targeted TashAT family have evolved under contrasting pressures within natural T. annulata populations. SVSP genes were found to possess atypical codon usage and be evolving neutrally, with high levels of nucleotide substitutions and multiple indels. No evidence of geographical sub-structuring of allelic sequences was found. In contrast, TashAT family genes, implicated in control of host cell gene expression, are strongly conserved at the protein level and geographically sub-structured allelic sequences were identified among Tunisian and Turkish isolates. Although different copy numbers of DNA binding motifs were identified in alleles of TashAT proteins, motif periodicity was strongly maintained, implying conserved functional activity of these sites. <b>CONCLUSIONS</b>: This analysis provides evidence that two distinct secretome genes families have evolved under contrasting selective pressures. The data supports current hypotheses regarding the biological role of TashAT family proteins in the management of host cell phenotype that may have evolved to allow adaptation of T. annulata to a specific host cell lineage. We provide new evidence of extensive allelic diversity in representative members of the enigmatic SVSP gene family, which supports a putative role for the encoded products in subversion of the host immune response

Twistor theory on a finite graph

We show how the description of a shear-free ray congruence in Minkowski space as an evolving family of semi-conformal mappings can naturally be formulated on a finite graph. For this, we introduce the notion of holomorphic function on a graph. On a regular coloured graph of degree three, we recover the space-time picture. In the spirit of twistor theory, where a light ray is the more fundamental object from which space-time points should be derived, the line graph, whose points are the edges of the original graph, should be considered as the basic object. The Penrose twistor correspondence is discussed in this context

Portal vein thrombosis after laparoscopic splenectomy: an ongoing clinical challenge.

ObjectivesPortal vein thrombosis (PVT) following open splenectomy is a potentially lethal complication with an incidence of up to 6%. The objective of this report is to describe our management of a recent laparoscopic case, discuss current therapies, and consider antiplatelet therapy for prophylaxis.MethodsMedical records, laboratory studies, and imaging studies pertaining to a recent case of a laparoscopic splenectomy were examined. Current literature related to this topic was reviewed.ResultsA 16-year-old girl underwent laparoscopic splenectomy for idiopathic thrombocytopenic purpura. Her preoperative platelet count was 96K. She was discharged on postoperative day 1 after an uneventful operation including division of the splenic hilum with an endoscopic linear stapler. On postoperative day 20, she presented with a 5-day history of epigastric pain, nausea, and low-grade fevers without peritoneal signs. Her white blood cell count was 17.3; her platelets were 476K. Computed tomography demonstrated thrombosis of the splenic, superior mesenteric, and portal veins propagating into the liver. Heparinization was begun followed by an unsuccessful attempt at pharmacologic and mechanical thrombolysis by interventional radiology. Over the next 5 days, her pain resolved, she tolerated a full diet, was converted to oral anticoagulation and sent home. Follow-up radiographic studies demonstrated the development of venous collaterals and cavernous transformation of the portal vein.DiscussionNo standard therapy for PVT exists; several approaches have been described. These include systemic anticoagulation, systemic or regional medical thrombolysis, mechanical thrombolysis, and surgical thrombectomy. Unanswered questions exist about the most effective acute therapy, duration of anticoagulation, and the potential efficacy of routine prophylaxis with perioperative antiplatelet agents. PVT following splenectomy occurs with both the open and laparoscopic approach

Telomeres and genomic evolution

The terminal regions of eukaryotic chromosomes, composed of telomere repeat sequences and sub-telomeric sequences, represent some of the most variable and rapidly evolving regions of the genome. The sub-telomeric regions are characterized by segmentally duplicated repetitive DNA elements, interstitial telomere repeat sequences and families of variable genes. Sub-telomeric repeat sequence families are shared among multiple chromosome ends, often rendering detailed sequence characterization difficult. These regions are composed of constitutive heterochromatin and are subjected to high levels of meiotic recombination. Dysfunction within telomere repeat arrays, either due to disruption in the chromatin structure or because of telomere shortening, can lead to chromosomal fusion and the generation of large-scale genomic rearrangements across the genome. The dynamic nature of telomeric regions, therefore, provides functionally useful variation to create genetic diversity, but also provides a mechanism for rapid genomic evolution that can lead to reproductive isolation and speciation. This article is part of the theme issue ‘Understanding diversity in telomere dynamics'

Raptors on the East Coast: A Shift in the Timing of Autumn Migration

I tested whether or not raptors on the east coast are shifting the timing of their autumn migration. I analyzed 38 years of passage data at three count sites across New England: Hawk Mountain, Quaker Ridge, and Lighthouse Point. I studied four raptors with diverse natural history traits: Red-tailed Hawk (Buteo jamaicensis), Northern Harrier (Circus cyaneus), Sharp-shinned Hawk (Accipiter striatus), and Broad-winged Hawk (Buteo platypterus). I also investigated possible factors associated with any documented shift, including climate, distance of migration, diet, and population trend. Long-distance migrants should advance their migration and short-distance migrants should delay their migration, as reported for numerous taxa, including raptors, in Europe. Raptors that feed primarily on birds should advance their migration. Species advancing their migration should advance it further in warm years, while species delaying their migration should delay it further in warm years. Finally, I predicted that species in decline would show little or no shift in migration timing; species unable to adjust to climate change may be at a disadvantage. The Red-tailed Hawk and Northern Harrier delayed their autumn migrations past these three count sites, while the Sharp-shinned Hawk advanced and the Broad-winged Hawk showed no shift in its migration phenology. Some of these results match my predictions based on the raptors\u27 life history traits, but some do not, suggesting that North American raptors are responding to climate change differently from European raptors. The Broad-winged Hawk is the only raptor among the four species I studied that is not shifting and it is currently declining in population in the Northeast. This species may be more hard-wired to migrate at roughly the same time every year, and that inability to shift may be contributing to population decline