Nikos Papageorgiou

Oxidative stress and inflammatory process in patients with atrial fibrillation: The role of left atrium distension

BACKGROUNDnAtrial fibrillation has been associated with increased oxidative stress, elevated inflammatory status and endothelial dysfunction. However, the underlying mechanisms regulating the expression of inflammatory markers or oxidative stress status are unclear. We searched for clinical determinants of oxidative stress status, endothelial function and inflammatory process in patients with chronic atrial fibrillation.nnnMETHODSnSixty nine patients with chronic atrial fibrillation at a stable clinical state were recruited. Ejection fraction of the left ventricle and the dimensions of the left atrium were determined echocardiographically. Flow mediated dilatation (FMD) was evaluated in the brachial artery, while serum oxidized LDL (ox-LDL), matrix metalloproteinase-9 (MMP-9), soluble CD40-ligand (sCD40L) and C-reactive protein (CRP) were measured.nnnRESULTSnFMD was correlated with CRP (r=-0.423, p=0.028), independently of other clinical parameters (beta(SE): -0.0039(0.00159), p=0.022). Ox-LDL was significantly correlated with left atrium diameter(r=0.358, p=0.005) independently of other clinical variables (beta(SE):1.288(0.455), p=0.007). The only independent predictors of MMP-9 were sCD40L (beta(SE):17.232(7.654), p=0.028), CRP (beta(SE):4.249(2.186), p=0.05) and gender (beta(SE):204.657(68.153), p=0.004), but not left atrium dimensions. Independent predictors of CRP were hypertension (beta(SE): 8.531(3.973), p=0.036), sCD40L (beta(SE): 0.779(0.408), p=0.06) and age (beta(SE): 0.381(0.201), p=0.063).nnnCONCLUSIONSnThere is a strong link between inflammation and endothelial function, in patients with atrial fibrillation. The maximum diameter of left atrium is the only independent predictor of oxidized LDL, suggesting that left atrium distension may predict oxidative stress status in these patients.

The role of endothelial progenitor cells in vascular repair after arterial injury and atherosclerotic plaque development.

Endothelial progenitor cells (EPCs) are under investigation due to their association with vascular injury. In response to chemotactic stimuli they are mobilized from bone-marrow and nonbone marrow sites, they migrate, adhere and home to the injured vessel. Numerous molecular and cellular pathways participate and converge to the EPCs mediated vascular repair. However, the exact phenotypic properties, modes of functions and effects in vascular diseases and particularly in atherosclerosis are under investigation. EPCs represent a heterogeneous group of cells in different stages of differentiation, from hematopoietic bone marrow progenitors to mature endothelial cells that participate in adult vascular repair under ischemic or apoptotic stimuli. This review aims to provide an integrative view of EPC-mediated vascular repair.

An Aspect Oriented Approach for Implementing Situational Driven Adaptation of BPMN2.0 Workflows

To address the issue of business process adaptation, we focus on handling adaptation needs as cross-cutting concerns because they rely or must affect many parts of a business process. Our research objective is to enhance aspect-oriented business process management with event-driven capabilities for discovering situations requiring adaptations. To this end, we develop an aspect-oriented extension to BPMN2.0 and we couple it with an event-driven approach for detecting and reasoning about situations that require adaptation of business processes. We use event processing in order to monitor the process execution environment and, when execution violates some quality “threshold” or a problem arises, to detect it and trigger lookup for a suitable process adaptation, using a reasoning mechanism. We demonstrate that our approach is able to address simultaneously adaptation on process model and execution level.

Event-driven adaptive collaboration using semantically-enriched patterns

Collaboration is essential for value creation in the modern business environment, may span across organizational and geographical boundaries and is often used for mission critical tasks. Collaborative environments are subject to continuous changes because participation is dynamic and business goals may be evolving. In such dynamic environments there is a need for adapting the ways of collaboration to reflect the current conditions. By focusing on collaboration in dynamic environments, we explore the utilization of collaboration patterns as models for recurring high-value collaborative tasks, which can be intelligently identified, retrieved and enacted when needed. In this paper, we propose Collaboration Pattern Assistant, an information system which is built around the concept of collaboration patterns and is based on an innovative coupling of ontologies with an event driven architecture. The advantages of using ontologies to represent collaboration patterns lie in their ability to model effectively related concepts and interrelations, to map to collaboration services provided by different suppliers, to use reasoning to check values for validity and consistency, as well as to derive new facts based on the existing ones. The adoption of an event driven architecture enables collaboration support which can respond to continuously changing circumstances by processing effectively and reacting to events generated by on-going collaborations.

A review of patterns in collaborative work

Patterns, repeatable processes for recurring high-value tasks, have great potential for assisting computer-mediated collaboration. In this paper we focus on patterns for collaborative work as a means to capture best practices about recurring collaborative problems and solutions amongst dispersed groups. We present a comparative review of relevant research and commercial efforts related to patterns that can be used to facilitate collaboration.

An Architecture for Collaboration Patterns in Agile Event-Driven Environments

Collaboration in Virtual Organizations is usually informal, dynamic and ad-hoc. In this paper, we introduce Collaboration Patterns as a mechanism to facilitate knowledge-based collaborations. We also propose an event-driven architecture for modeling, recommending and enacting such Collaboration Patterns.

A Collaboration Pattern Model for Virtual Organisations

Collaboration, either inter or intra-organization is a critical business function that demands skills and knowledge spanning a wide range of domains including social, business and technical domains. Collaboration patterns can be a means to capture best practices about recurring collaborative problems and solutions. Many forms of patterns have been proposed addressing specific aspects of collaboration such as business interaction design and workflow. In this paper we propose a novel collaboration pattern model that aims to constitute a framework capable to describe recurring collaborative activities taking place in the context of virtual organisations.

Dynamic event subscriptions in distributed event based architectures

Highlights? Approach for recommending dynamically subscriptions to event sources. ? Goal-driven, hierarchical extension of Event Condition Action rules. ? Run-time enablement and disablement of Event Condition Action rules. The burst of wireless sensors networks transmitting events paved the way for infrastructures that link uniquely identifiable things to their virtual representations in the Internet. As the Internet of Things gains momentum for leveraging and offering information access to service-based applications and users, challenges associated with efficiently publishing, subscribing, processing and reacting to events emerge. This work focuses on the challenge of enabling efficient active capability in large, distributed event infrastructures. We aim to support dynamic recommendations of new event streams to which a service should subscribe for a meaningful period of time, in order to take advantage of situational information. We present a goal-driven, ECA-based hierarchical model, called Situation-Action-Network (SAN) and we implement the Event Subscription Recommender (ESR) software that uses SANs in order to produce dynamically new event subscriptions or cancel existing ones before they become obsolete, based on detected situations. We evaluated ESR in a scenario that involves events transmitted by marine vessels in order to efficiently enforce safety regulations on behalf of port authorities. The results of this evaluation were compared against a traditional ECA-based system and we found that ESR outperformed existing systems with respect to subscription efficiency.

A Real-Time Architecture for Proactive Decision Making in Manufacturing Enterprises

We outline a new architecture for supporting proactive decision making in manufacturing enterprises. We argue that event monitoring and data processing technologies can be coupled with decision methods effectively providing capabilities for proactive decision-making. We present the main conceptual blocks of the architecture and their role in the realization of the proactive enterprise. We illustrate how the proposed architecture supports decision-making ahead of time on the basis of real-time observations and anticipation of future undesired events by presenting a practical condition-based maintenance scenario in the oil and gas industry. The presented approach provides the technological foundation and can be taken as a blueprint for the further development of a reference architecture for proactive applications.

A goal driven dynamic event subscription approach

As the Internet of Things gained momentum for leveraging and offering information access to service-based applications and users, a number of new challenges have been identified in terms of efficiently publishing, subscribing, processing and reacting to events. This work focuses on the challenge of enabling efficient active capability in large, distributed event infrastructures such as so-called event marketplaces. We present a goal-driven, ECA-based hierarchical model, called Situation-Action-Network (SAN) and we implement and evaluate the Event Subscription Recommender (ESR) software that uses SANs in order to produce dynamically new event subscriptions based on detected situations.