Tracking social provenance in chains of retweets

Knowledge and Information Systems - In the era of massive sharing of information, the term social provenance is used to denote the ownership, source or origin of a piece of information which has...     

Coexistence of anti-phospholipid antibodies and endothelial perturbation in systemic lupus erythematosus patients with ongoing prothrombotic state

BACKGROUND: Anti-phospholipid antibodies (aPLs) were associated with an ongoing prothrombotic state in patients with systemic lupus erythematosus (SLE). Because aPLs are able to shift endothelial function toward procoagulant activity in vitro, we investigated the relationship among aPLs, ongoing prothrombotic state, and endothelial perturbation in SLE patients. METHODS AND RESULTS: We measured aPLs, anti-EC antibodies, circulating levels of prothrombin fragment F1 + 2 (F1 + 2), tumor necrosis factor-alpha (TNF-alpha), tissue-type plasminogen activator (TPA), and von Willebrand factor (vWF) in 43 SLE patients and 25 healthy subjects. Patients positive for aPLs (n = 23) had a higher prevalence of anti-EC antibodies (P = .02) and higher levels of F1 + 2 (P = .003) than aPL(-) patients. Endothelial perturbation, defined by elevated plasma levels of both TPA and vWF, was significantly associated with aPL positivity (P = .001). F1 + 2 > 1 nmol/L (mean +/- 2 SD of controls) was detected in all but one patient in whom aPL positivity and endothelial perturbation coexisted and in no aPL(+) patient without endothelial perturbation (P = .0039). F1 + 2 was significantly correlated with vWF (rho = .6, P = .004) and TPA (114 = .70, P = .0006) only in aPL(+) patients. Endothelial perturbation was closely associated with high values of TNF-alpha (P = .0001), anti-phospholipid (P = .001), and anti-EC antibodies (P = .012). In 31 patients without a clinical history of thrombosis followed up for 3 years, aPL(+) patients with endothelial perturbation showed higher F1 + 2 and TNF-alpha values than aPL(+) patients without endothelial dysfunction. CONCLUSIONS: This study shows that in SLE patients, aPL positivity is associated with an ongoing prothrombotic state only in the presence of endothelial perturbation. Our findings also suggest that aPLs and TNF-alpha might cooperate in inducing endothelial perturbation.     

Protection of low density lipoprotein oxidation at chemical and cellular level by the antioxidant drug dipyridamole

1. The oxidative modification of low density lipoprotein (LDL) is thought to be an important factor in the initiation and development of atherosclerosis. Natural and synthetic antioxidants have been shown to protect LDL from oxidation and to inhibit atherosclerosis development in animals. Synthetic antioxidants are currently being tested, by they are not necessarily safe for human use. 2. We have previously reported that dipyridamole, currently used in clinical practice, is a potent scavenger of free radicals. Thus, we tested whether dipyridamole could affect LDL oxidation at chemical and cellular level. 3. Chemically induced LDL oxidation was made by Cu(II), Cu(II) plus hydrogen peroxide or peroxyl radicals generated by thermolysis of 2,2'-azo-bis(2-amidino propane). Dipyridamole, (1-10 microM), inhibited LDL oxidation as monitored by diene formation, evolution of hydroperoxides and thiobarbituric acid reactive substances, apoprotein modification and by the fluorescence of cis-parinaric acid. 4. The physiological relevance of the antioxidant activity was validated by experiments at the cellular level where dipyridamole inhibited endothelial cell-mediated LDL oxidation, their degradation by monocytes, and cytotoxicity. 5. In comparison with ascorbic acid, alpha-tocopherol and probucol, dipyridamole was the more efficient antioxidant with the following order of activity: dipyridamole > probucol > ascorbic acid > alpha-tocopherol. The present study shows that dipyridamole inhibits oxidation of LDL at pharmacologically relevant concentrations. The inhibition of LDL oxidation is unequivocally confirmed by use of three different methods of chemical oxidation, by several methods of oxidation monitoring, and the pharmacological relevance is demonstrated by the superiority of dipyridamole over the naturally occurring antioxidants, ascorbic acid and alpha-tocopherol and the synthetic antioxidant probucol.     

The ESTEEM platform: enabling P2P semantic collaboration through emerging collective knowledge

In this paper, we present Esteem (Emergent Semantics and cooperaTion in multi-knowledgE EnvironMents), a community-based P2P platform for supporting semantic collaboration among a set of independent peers, without prior reciprocal knowledge and no predefined relationships. Goal of Esteem is to go beyond the existing state-of-the-art solutions for P2P knowledge sharing and to provide an integrated platform for both data and service discovery. A distinguishing feature of Esteem is the use of semantic communities to explicitly give shape to the collective knowledge and expertise of peer groups with similar interests. Key techniques of Esteem will be presented in the paper and concern: shuffling-based communication, ontology and service matchmaking, context management, and quality-aware data integration. An application example of data and service discovery in the health-care domain will be presented, by also discussing results of system and user evaluation.     

Modeling temporal dimensions of semistructured data

In this paper we propose a graph-based generic model able to uniformly represent semistructured data and their temporal aspects. In particular, we start from a generic and expressive model proposed in the database literature and consider in a formal and systematic way both valid time and transaction time, together with the set of temporal constraints needed to correctly manage the semantics of the represented time dimension. We then propose operations, which allow the incremental management of the proposed model satisfying the introduced temporal constraints. Moreover, we also deal with the possibility of managing together the two classical time dimensions of valid and transaction times, and formalize the set of constraints needed to correctly handle these temporal aspects together. Some examples taken from a medical scenario will be used to describe the introduced concepts.     

Applying model-checking to solve queries on semistructured data

The large volume and nature of data available to the casual users and programs motivate the increasing interest of the database community in studying flexible and efficient techniques for extracting and querying semistructured data. On the other hand, efficient methods have been discovered for solving the so-called model-checking problem for some modal logics. The aim of this paper is to show how some of these methods can be used for querying semistructured data. For doing that we show that semistructured data can be naturally seen as Kripke Transition Systems. To keep the presentation independent of a specific language, we introduce a graphical query language that includes some of the features of the query languages based on graphs and patterns. We show how to associate CTL formulas to queries of this language. This allows us to see the problems of solving a query as an instance of the model-checking problem for CTL that can be solved in polynomial time. We have tested the method by using a model-checker, and have studied the applicability of the method to some existing languages for semistructured databases.     

Emergent Semantics and Cooperation in Multi-knowledge Communities: the ESTEEM Approach

In the present global society, information has to be exchangeable in open and dynamic environments, where interacting users do not necessarily share a common understanding of the world at hand. This is particularly true in P2P scenarios, where millions of autonomous users (peers) need to cooperate by sharing their resources (such as data and services). We propose the Esteem approach (Emergent Semantics and cooperaTion in multi-knowledgE EnvironMents), where a comprehensive framework and a platform for data and service discovery in P2P systems are proposed, with advanced solutions for trust and quality-based data management, P2P infrastructure definition, query processing and dynamic service discovery in a context-aware scenario. In Esteem, semantic communities are built around declared interests in the form of manifesto ontologies and their autonomous nature is preserved by allowing a shared semantics to naturally emerge from the peer interactions. Inside the borders of semantic communities data and services are discovered, queried and invoked in a resource sharing scenario, where the context in which users interoperate and the trust of exchanged information are also relevant aspects to take into account.     

A data-mining approach to preference-based data ranking founded on contextual information

The term information overload was already used back in the 1970s by Alvin Toffler in his book Future Shock, and refers to the difficulty to understand and make decisions when too much information is available. In the era of Big Data, this problem becomes much more dramatic, since users may be literally overwhelmed by the cataract of data accessible in the most varied forms. With context-aware data tailoring, given a target application, in each specific context the system allows the user to access only the view which is relevant for that application in that context. Moreover, the relative importance of information to the same user in a different context or, reciprocally, to a different user in the same context, may vary enormously; for this reason, contextual preferences can be used to further refine the views associated with contexts, by imposing a ranking on the data of each context-aware view. In this paper, we propose a methodology and a system, PREMINE (PREference MINEr), where data mining is adopted to infer contextual preferences from the past interaction of the user with contextual views over a relational database, gathering knowledge in terms of association rules between each context and the relevant data.     

Neutrophil Gelatinase-Associated Lipocalin as Potential Predictive Biomarker of Melanoma and Non-Melanoma Skin Cancers in Psoriatic Patients: A Pilot Study

Background: Studies have demonstrated a higher risk of nonmelanoma skin cancers (NMSC) and a modestly increased melanoma risk in patients with psoriasis. To date, no biomarkers predictive of evolution have been identified yet. Methods: The aim of this prospective case-control study was to investigate the potential role of neutrophil gelatinase-associated lipocalin (NGAL) as a predictive biomarker of skin cancers in psoriatic patients. Patients with a diagnosis of psoriasis were enrolled, as well as healthy subjects and patients with skin cancers as controls. Plasma protein expression of NGAL, metalloproteinases (MMP)-2, and MMP-9 was performed by an enzyme-linked immunosorbent assay (ELISA). In all the patients who developed skin cancer at follow-up, NGAL, MMP-2, and MMP-9 serum levels were dosed again. Results: Plasma NGAL levels were significantly higher in psoriatic patients with NMSC than without (182.3 ± 36.6 ng/mL vs. 139.9 ± 39.3 ng/mL) (p < 0.001). Plasma NGAL levels were significantly higher (p < 0.00001) in patients with psoriasis and NMSC than in patients with skin tumors without psoriasis (182.3 vs. 122.9). Patients with psoriasis who developed NMSC at follow-up showed increased plasma MMP-9 levels. Conclusion: NGAL seems to play a role in the pathogenesis of NMSC but not melanoma in patients with psoriasis.