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Delak B.,Technology Park Ljubljana | Bajec M.,University of Ljubljana
Information Systems Management | Year: 2013

The IS field lacks a scientifically based analytical tool for delivering IS due diligence. Due Diligence is the activity of identifying and measuring the risks and increasing the likelihood of productive investment. In this article, we propose a framework for IS due diligence development based on our generalized experiences conducting IS due diligence in more than 60 banks and financial organizations in Europe. © 2013 Copyright Taylor & Francis Group, LLC.

Radic N.,Technology Park Ljubljana | Radic N.,University of Ljubljana | Strukelj B.,University of Ljubljana | Strukelj B.,Jozef Stefan Institute
Phytomedicine | Year: 2012

Over more than 20 years, the endophytic fungi have been explored as "biofactories" of novel bioactive substances, and they have not disappointed. Among the extracts and pure substances obtained from the culture broths or fungal biomass, some have exerted antibacterial activity ranging from moderate to powerful when tested on the bacterial strains resistant to the antibiotics currently in use. In this article we review the accumulated data on endophytic fungi isolated from plants that produce metabolites with antibacterial activity against human pathogenic bacteria. © 2012 Elsevier GmbH.

Parpura V.,Center for Glial Biology in Medicine | Parpura V.,Ikerbasque | Parpura V.,University of Split | Parpura V.,University of Alabama at Birmingham | And 16 more authors.
Journal of Neurochemistry | Year: 2012

Neuroglial cells define brain homeostasis and mount defense against pathological insults. Astroglia regulate neurogenesis and development of brain circuits. In the adult brain, astrocytes enter into intimate dynamic relationship with neurons, especially at synaptic sites where they functionally form the tripartite synapse. At these sites, astrocytes regulate ion and neurotransmitter homeostasis, metabolically support neurons and monitor synaptic activity; one of the readouts of the latter manifests in astrocytic intracellular Ca 2+ signals. This form of astrocytic excitability can lead to release of chemical transmitters via Ca 2+-dependent exocytosis. Once in the extracellular space, gliotransmitters can modulate synaptic plasticity and cause changes in behavior. Besides these physiological tasks, astrocytes are fundamental for progression and outcome of neurological diseases. In Alzheimer's disease, for example, astrocytes may contribute to the etiology of this disorder. Highly lethal glial-derived tumors use signaling trickery to coerce normal brain cells to assist tumor invasiveness. This review not only sheds new light on the brain operation in health and disease, but also points to many unknowns. © 2012 International Society for Neurochemistry.

Parpura V.,University of Alabama at Birmingham | Baker B.J.,University of Alabama at Birmingham | Jeras M.,University of Ljubljana | Jeras M.,Technology Park Ljubljana | And 2 more authors.
Neurochemistry International | Year: 2010

Astrocytes can be considered as signal integrators in central nervous system activity. These glial cells can respond to signals from the heterocellular milieu of the brain and subsequently release various molecules to signal to themselves and/or other neighboring neural cells. An important functional module that enables signal integration in astrocytes is exocytosis, a Ca2+-dependent process consisting of vesicular fusion to the plasma membrane. Astrocytes utilize regulated exocytosis to release various signaling molecules stored in the vesicular lumen. Here we review the properties of exocytotic release of three classes of gliotransmitters: (i) amino acids, (ii) nucleotides and (iii) peptides. Vesicles may carry not only lumenal cargo, but also membrane-associated molecules. Therefore, we also discuss exocytosis as a delivery mechanism for transporters and receptors to the plasma membrane, where these proteins are involved in astrocytic intercellular signaling. © 2010 Elsevier Ltd.

Parpura V.,University of Alabama at Birmingham | Zorec R.,University of Ljubljana | Zorec R.,Technology Park Ljubljana
Brain Research Reviews | Year: 2010

Gliotransmitters are chemicals released from glial cells fulfilling a following set of criteria: (i) they are synthesized by and/or stored in glia; (ii) their regulated release is triggered by physiological and/or pathological stimuli; (iii) they activate rapid (milliseconds to seconds) responses in neighboring cells; and (iv) they play a role in (patho)physiological processes. Astrocytes can release a variety of gliotransmitters into the extracellular space using several different mechanisms. In this review, we focus on exocytotic mechanism(s) underlying the release of three classes of gliotransmitters: (i) amino acids, such as, glutamate and d-serine; (ii) nucleotides, like adenosine 5'-triphosphate; and (iii) peptides, such as, atrial natriuretic peptide and brain-derived neurotrophic factor. It is becoming clear that astrocytes are endowed with elements that qualify them as cells communicating with neurons and other cells within the central nervous system by employing regulated exocytosis. © 2009 Elsevier B.V.

Pohleven J.,Jozef Stefan Institute | Kos J.,Jozef Stefan Institute | Strukelj B.,Jozef Stefan Institute | Jeras M.,Technology Park Ljubljana
Immunology | Year: 2011

A novel lectin, isolated from the basidiomycete mushroom Clitocybe nebularis and termed C. nebularis lectin (CNL), exhibits an immunostimulatory effect on the most potent antigen-presenting cells, the dendritic cells (DCs). Treatment of human monocyte-derived DCs with CNL in doses from 1 to 10μg/ml resulted in a dose-dependent induction of overall DC maturation characteristics. Exposure of DCs to CNL for 48hr resulted in extensive up-regulation of co-stimulatory molecules CD80 and CD86, as well as of the maturation marker CD83 and HLA-DR molecules. Such CNL-matured DCs (CNL-DCs) were capable of inducing a T helper type 1-polarized response in naive CD4 +CD45RA + T cells in 5-day allogeneic co-cultures. The allostimulatory potential of CNL-DCs was significantly increased relative to untreated controls, as was their capacity to produce several pro-inflammatory cytokines such as interleukin-6, interleukin-8 and tumour necrosis factor-α. By using a specific Toll-like receptor 4 (TLR4) signalling inhibitor, CLI-095, as well as Myd88 inhibitory peptide, we have shown that DC activation by CNL is completely dependent on the TLR4 activation pathway. Furthermore, activation of TLR4 by CNL was confirmed via TLR4 reporter assay. Measurement of p65 nuclear factor-κB and p38 mitogen-activated protein kinase (MAPK) phosphorylation levels following CNL stimulation of DCs revealed primarily an increase in nuclear factor-κB activity, with less effect on the induction of p38 MAPK signalling than of lipopolysaccharide-matured DCs. The CNL had the ability to activate human DCs in such a way as to subsequently direct T helper type 1 T-cell responses. Our results encourage the use of mushroom-derived lectins for use in therapeutic strategies with aims such as to strengthen anti-tumour immune responses. © 2011 The Authors. Immunology © 2011 Blackwell Publishing Ltd.

Grabec I.,Technology Park Ljubljana
Nonlinear Phenomena in Complex Systems | Year: 2010

Statistical modeling of physical laws connects experiments with mathematical descriptions of natural phenomena. Most general modeling is based on nonparametric estimation of the probability density from statistical samples of measured variables. For this purpose a kernel estimator is utilized in the article. As an objective kernel the scattering function determined by calibration of the instrument is introduced. This function provides for a definition of experimental information and redundancy of experimentation in terms of information entropy. The redundancy increases with the number of experiments, while the experimental information converges to a value that describes the complexity of the data. The difference between the redundancy and the experimental information is proposed as the model cost function. From its minimum, a proper number of data needed for modeling is estimated. As an optimal, nonparametric estimator of the relation between measured variables the conditional average extracted from the kernel estimator is proposed. The modeling is demonstrated on noisy chaotic data.

Grabec I.,Technology Park Ljubljana
Neural Networks | Year: 2013

This article deals with experimental description of physical laws by probability density function of measured data. The Gaussian mixture model specified by representative data and related probabilities is utilized for this purpose. The information cost function of the model is described in terms of information entropy by the sum of the estimation error and redundancy. A new method is proposed for searching the minimum of the cost function. The number of the resulting prototype data depends on the accuracy of measurement. Their adaptation resembles a self-organized, highly non-linear cooperation between neurons in an artificial NN. A prototype datum corresponds to the memorized content, while the related probability corresponds to the excitability of the neuron. The method does not include any free parameters except objectively determined accuracy of the measurement system and is therefore convenient for autonomous execution. Since representative data are generally less numerous than the measured ones, the method is applicable for a rather general and objective compression of overwhelming experimental data in automatic data-acquisition systems. Such compression is demonstrated on analytically determined random noise and measured traffic flow data. The flow over a day is described by a vector of 24 components. The set of 365 vectors measured over one year is compressed by autonomous learning to just 4 representative vectors and related probabilities. These vectors represent the flow in normal working days and weekends or holidays, while the related probabilities correspond to relative frequencies of these days. This example reveals that autonomous learning yields a new basis for interpretation of representative data and the optimal model structure. © 2012 Elsevier Ltd.

Grabec I.,Technology Park Ljubljana
Nonlinear Phenomena in Complex Systems | Year: 2011

Redundancy of experimental data is the basic statistic from which the complexity of a natural phenomenon and the proper number of experiments needed for its exploration can be estimated. The redundancy is expressed by the entropy of information pertaining to the probability density function of experimental variables. Since the calculation of entropy is inconvenient due to integration over a range of variables, an approximate expression for redundancy is derived that includes only a sum over the set of experimental data about these variables. The approximation makes feasible an efficient estimation of the redundancy of data along with the related experimental information and information cost function. From the experimental information the complexity of the phenomenon can be simply estimated, while the proper number of experiments needed for its exploration can be determined from the minimum of the cost function. The performance of the approximate estimation of these statistics is demonstrated on two-dimensional normally distributed random data.

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