Showing papers by "University of Rijeka published in 2008"

Modeling long-range cross-correlations in two-component ARFIMA and FIARCH processes

Abstract: We investigate how simultaneously recorded long-range power-law correlated multivariate signals cross-correlate. To this end we introduce a two-component ARFIMA stochastic process and a two-component FIARCH process to generate coupled fractal signals with long-range power-law correlations which are at the same time long-range cross-correlated. We study how the degree of cross-correlations between these signals depends on the scaling exponents characterizing the fractal correlations in each signal and on the coupling between the signals. Our findings have relevance when studying parallel outputs of multiple component of physical, physiological and social systems.

Acquisition of the vacuolar ATPase proton pump and phagosome acidification are essential for escape of Francisella tularensis into the macrophage cytosol.

Abstract: The Francisella tularensis-containing phagosome (FCP) matures to a late-endosome-like phagosome prior to bacterial escape into the cytosols of macrophages, where bacterial proliferation occurs. Our data show that within the first 15 min after infection of primary human monocyte-derived macrophages (hMDMs), approximately 90% of the FCPs acquire the proton vacuolar ATPase (vATPase) pump and the lysomotropic dye LysoTracker, which concentrates in acidic compartments, similar to phagosomes harboring the Listeria monocytogenes control. The acquired proton vATPase pump and lysomotropic dye are gradually lost by 30 to 60 min postinfection, which coincides with bacterial escape into the cytosols of hMDMs. Colocalization of phagosomes harboring the iglD mutant with the vATPase pump and the LysoTracker dye was also transient, and the loss of colocalization was faster than that observed for the wild-type strain, which is consistent with the faster escape of the iglD mutant into the macrophage cytosol. In contrast, colocalization of both makers with phagosomes harboring the iglC mutant was persistent, which is consistent with fusion to the lysosomes and failure of the iglC mutant to escape into the macrophage cytosol. We have utilized a fluorescence microscopy-based phagosome integrity assay for differential labeling of vacuolar versus cytosolic bacteria, using antibacterial antibodies loaded into the cytosols of live hMDMs. We show that specific inhibition of the proton vATPase pump by bafilomycin A1 (BFA) blocks rapid bacterial escape into the cytosols of hMDMs, but 30% to 50% of the bacteria escape into the cytosol by 6 to 12 h after BFA treatment. The effect of BFA on the blocking of bacterial escape into the cytosol is completely reversible, as the bacteria escape after removal of BFA. We also show that the limited fusion of the FCP to lysosomes is not due to failure to recruit the late-endosomal fusion regulator Rab7. Therefore, within few minutes of its biogenesis, the FCP transiently acquires the proton vATPase pump to acidify the phagosome, and this transient acidification is essential for subsequent bacterial escape into the macrophage cytosol.

Influence of corruption on economic growth rate and foreign investment

Abstract: We analyze the dependence of the Gross Domestic Product (GDP) per capita growth rates on changes in the Corruption Perceptions Index (CPI). For the period 1999–2004 for all countries in the world, we find on average that an increase of CPI by one unit leads to an increase of the annual GDP per capita growth rate by 1.7%. By regressing only the European countries with transition economies, we find that an increase of CPI by one unit generates an increase of the annual GDP per capita growth rate by 2.4%. We also analyze the relation between foreign direct investments received by different countries and CPI, and we find a statistically significant power-law functional dependence between foreign direct investment per capita and the country corruption level measured by the CPI. We introduce a new measure to quantify the relative corruption between countries based on their respective wealth as measured by GDP per capita.

Exploring the Relationship Between Environmental Orientation and Brand Value : Is There Fire or Only Smoke?

Abstract: This paper investigates whether a firm's environmental orientation influences corporate brand value. In the discussion on sustainable development, corporate participation is a given, and increasingly firms are adopting environmental policies and practices. This paper observes corporate environmentalism from two perspectives: environmental embeddedness – the level to which environmental values are incorporated in brand identity; and environmental performance – the level of a firm's accordance with environmental policies and good practices. Cross-analysis of these two perspectives generates four types of corporate environmental orientation: leaders, performers, advocates and laggards. The results do not provide conclusive evidence for whether consumers reward environmental leaders and punish environmental laggards by converting their environmental opinions into brand perceptions and purchasing decisions. It is believed that the hypothesized relationships are moderated and mediated by other stimuli, so managers are advised not to negate corporate social responsibility, but rather to invest wisely in environmental activities and its communication. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.

Passive Immunization Reduces Murine Cytomegalovirus-Induced Brain Pathology in Newborn Mice

Abstract: Human cytomegalovirus (HCMV) is the most frequent cause of congenital viral infections in humans and frequently leads to long-term central nervous system (CNS) abnormalities that include learning disabilities, microcephaly, and hearing loss. The pathogenesis of the CNS infection has not been fully elucidated and may arise as a result of direct damage of CMV-infected neurons or indirectly secondary to inflammatory response to infection. We used a recently established model of mouse CMV (MCMV) infection in newborn mice to analyze the contribution of humoral immunity to virus clearance from the brain. In brains of MCMV-infected newborn mice treated with immune serum, the titer of infectious virus was reduced below detection limit, whereas in the brains of mice receiving control (nonimmune) serum significant amounts of virus were recovered. Moreover, histopathological and immunohistological analyses revealed significantly less CNS inflammation in mice treated with immune serum. Treatment with MCMV-specific monoclonal antibodies also resulted in the reduction of virus titer in the brain. Recipients of control serum or irrelevant antibodies had more viral foci, marked mononuclear cell infiltrates, and prominent glial nodules in their brains than mice treated with immune serum or MCMV-specific antibodies. In conclusion, our data indicate that virus-specific antibodies have a protective role in the development of CNS pathology in MCMV-infected newborn mice, suggesting that antiviral antibodies may be an important component of protective immunological responses during CMV infection of the developing CNS.

Altered development of the brain after focal herpesvirus infection of the central nervous system.

Abstract: Human cytomegalovirus infection of the developing central nervous system (CNS) is a major cause of neurological damage in newborn infants and children. To investigate the pathogenesis of this human infection, we developed a mouse model of infection in the developing CNS. Intraperitoneal inoculation of newborn animals with murine cytomegalovirus resulted in virus replication in the liver followed by virus spread to the brain. Virus infection of the CNS was associated with the induction of inflammatory responses, including the induction of a large number of interferon-stimulated genes and histological evidence of focal encephalitis with recruitment of mononuclear cells to foci containing virus-infected cells. The morphogenesis of the cerebellum was delayed in infected animals. The defects in cerebellar development in infected animals were generalized and, although correlated temporally with virus replication and CNS inflammation, spatially unrelated to foci of virus-infected cells. Specific defects included decreased granular neuron proliferation and migration, expression of differentiation markers, and activation of neurotrophin receptors. These findings suggested that in the developing CNS, focal virus infection and induction of inflammatory responses in resident and infiltrating mononuclear cells resulted in delayed cerebellar morphogenesis.

RoboNet-II: Follow-up observations of microlensing events with a robotic network of telescopes

Abstract: RoboNet-II uses a global network of robotic telescopes to perform follow-up observations of microlensing events in the Galactic Bulge. The current network consists of three 2m telescopes located in Hawaii and Australia (owned by Las Cumbres Observatory) and the Canary Islands (owned by Liverpool John Moores University). In future years the network will be expanded by deploying clusters of 1m telescopes in other suitable locations. A principal scientific aim of the RoboNet-II project is the detection of cool extra-solar planets by the method of gravitational microlensing. These detections will provide crucial constraints to models of planetary formation and orbital migration. RoboNet-II acts in coordination with the PLANET microlensing follow-up network and uses an optimization algorithm ("web-PLOP") to select the targets and a distributed scheduling paradigm (eSTAR) to execute the observations. Continuous automated assessment of the observations and anomaly detection is provided by the ARTEMiS system.

Correlation of serum IL-6, IL-8 and IL-10 levels with clinicopathological features and prognosis in patients with diffuse large B-cell lymphoma

Abstract: Cytokines play important roles in the pathogenesis of lymphomas. This study aimed to determine the relationship(s) between serum levels of interleukin (IL)-6, IL-8 and IL-10, measured by enzyme-immunoassay, and the clinical characteristics and outcomes in 46 untreated patients with diffuse large B-cell lymphoma (DLBCL). Serum IL-6, IL-8 and IL-10 levels were higher in DLBCL patients than in control subjects. Elevated levels of IL-6, IL-8 and IL-10 correlated with more adverse disease features. Consequently, patients with elevated IL-6, IL-8 and IL-10 levels prior to treatment had a lower response to therapy. Furthermore, those with elevated IL-6 and IL-10 levels had poor median, 3-year and 5-year survival, while elevated serum IL-8 level did not correlate with overall survival. Worse survival was also confirmed in patients with combined elevated pretreatment serum levels of IL-6, IL-8 and IL-10 (none, one, two or three elevated). Multivariate analysis identified elevated values of IL-6 and IL-10 and response to therapy as significant predictors for overall survival. Serum levels of IL-6, IL-8 and IL-10 before treatment of patients with newly diagnosed DLBCL may give some insight into the possible prognosis and thus facilitate the decisions regarding therapeutic approaches for individual patients.

CD8+ T Lymphocytes Control Murine Cytomegalovirus Replication in the Central Nervous System of Newborn Animals

Abstract: Human CMV infection of the neonatal CNS results in long-term neurologic sequelae. To define the pathogenesis of fetal human CMV CNS infections, we investigated mechanisms of virus clearance from the CNS of neonatal BALB/c mice infected with murine CMV (MCMV). Virus titers peaked in the CNS between postnatal days 10-14 and infectious virus was undetectable by postnatal day 21. Congruent with virus clearance was the recruitment of CD8(+) T cells into the CNS. Depletion of CD8(+) T cells resulted in death by postnatal day 15 in MCMV-infected animals and increased viral loads in the liver, spleen, and the CNS, suggesting an important role for these cells in the control of MCMV replication in the newborn brain. Examination of brain mononuclear cells revealed that CD8(+) T cell infiltrates expressed high levels of CD69, CD44, and CD49d. IE1(168)-specific CD8(+) T cells accumulated in the CNS and produced IFN-gamma and TNF-alpha but not IL-2 following peptide stimulation. Moreover, adoptive transfer of brain mononuclear cells resulted in decreased virus burden in immunodepleted MCMV-infected syngeneic mice. Depletion of the CD8(+) cell population following transfer eliminated control of virus replication. In summary, these results show that functionally mature virus-specific CD8(+) T cells are recruited to the CNS in mice infected with MCMV as neonates.

Dominant-Negative FADD Rescues the In Vivo Fitness of a Cytomegalovirus Lacking an Antiapoptotic Viral Gene

Abstract: Genes that inhibit apoptosis have been described for many DNA viruses. Herpesviruses often contain even more than one gene to control cell death. Apoptosis inhibition by viral genes is postulated to contribute to viral fitness, although a formal proof is pending. To address this question, we studied the mouse cytomegalovirus (MCMV) protein M36, which binds to caspase-8 and blocks death receptor-induced apoptosis. The growth of MCMV recombinants lacking M36 (ΔM36) was attenuated in vitro and in vivo. In vitro, caspase inhibition by zVAD-fmk blocked apoptosis in ΔM36-infected macrophages and rescued the growth of the mutant. In vivo, ΔM36 infection foci in liver tissue contained significantly more apoptotic hepatocytes and Kupffer cells than did revertant virus foci, and apoptosis occurred during the early phase of virus replication prior to virion assembly. To further delineate the mode of M36 function, we replaced the M36 gene with a dominant-negative FADD (FADD DN ) in an MCMV recombinant. FADD DN was expressed in cells infected with the recombinant and blocked the death-receptor pathway, replacing the antiapoptotic function of M36. Most importantly, FADD DN rescued ΔM36 virus replication, both in vitro and in vivo. These findings have identified the biological role of M36 and define apoptosis inhibition as a key determinant of viral fitness.

Murine cytomegalovirus regulation of NKG2D ligands.

Abstract: Human cytomegalovirus (HCMV) is a ubiquitous pathogen that causes morbidity risk in immunologically suppressed and immunodeficient patients including congenital infections. Approaches to curb the consequences of HCMV infections are restricted by a lack of complete understanding of viral pathogenesis. The infection of mice with murine cytomegalovirus (MCMV) as a model of HCMV infection has been particularly useful in elucidating the role of innate and adaptive immune response mechanisms. A large number of cytomegalovirus genes modulate the innate and the adaptive host immune response. The products of several MCMV genes are involved in subverting the natural killer (NK) cell response by down-modulating cellular ligands for the NKG2D receptor expressed on NK cells and CD8(+) T cells. Mutant viruses lacking these immunoevasion genes are attenuated with respect to virus growth in vivo. Given the importance of the NKG2D receptor in controlling both NK- and T cell-mediated immunity, it is of tremendous importance to understand the molecular mechanisms and consequences of viral regulation of the NKG2D ligands.

Potentially inappropriate prescribing to hospitalised patients.

Abstract: Purpose The objective of this study was to evaluate the prevalence of potential drug–drug interactions (DDIs) in hospitalised patients in correlation with patient's age and number of drugs prescribed and to determine the prevalence of inappropriate drugs prescribed to elderly patients. Methods Drugs prescribed during 1 day to all hospitalised patients at seven wards of Department of Medicine in University Hospital Rijeka were recorded by reviewing patient medical charts. Potential DDIs were evaluated using a list of potentially harmful drug combinations compiled from the literature. Beers criteria were used to identify potentially inappropriate medications in patients aged 65 years or older. Results The study included 225 patients that received a total of 1301 drugs. Twenty-two percent of the patients receiving drug therapy were prescribed drug combinations that are potentially harmful. The most common potentially harmful drug combination was an ACE inhibitor with a potassium supplement (33.9% of all combinations). In the multivariate analysis, age and number of drugs are significantly associated with potential DDIs (r = 0.8629). One quarter of elderly patients received a drug potentially inappropriate considering their age. The most commonly prescribed potentially inappropriate drug was amiodarone, followed by diazepam. Conclusion Polypharmacy and older age have been proven to be important risk factors for potential drug interactions. We identified a high rate of prescribing potentially inappropriate medications among elders. Results of this study indicate that particular caution should be given when prescribing drugs to patients already receiving drugs and to elderly patients, considering the risk of drug-related problems. Copyright © 2007 John Wiley & Sons, Ltd.

Business ethics in tourism – As a dimension of TQM

Abstract: The aim of the paper is to emphasize ethics as a dimension of TQM, as well as a dimension of the quality of a community and the quality of life and work. This paper focuses on business ethics and the social responsibility of business enterprises and tourism. After providing the definitions of ethics, business ethics and the social responsibility of business, the paper gives an example of ethics and social responsibility in the tourism and hotel industry, which is one of the world’ s greatest industries and also a social phenomenon with a great tendency to further expand and develop. The ethical components of the tourism and hotel industry are important due to the industry’ s great international importance.The main goal of managers is to generate profits, but only within the legal framework and bearing in mind the rule: “ Never cheat the customer.” Business ethics prescribes profit making, but with respect for ethical principles and standards. Business ethics increases the reputation and market competitiveness of an enterprise. Croatia wants to join the European Union. The prerequisite is to meet European standards in all fields of work and life and all social areas. Among those standards are also business standards and business ethics. One of the weaknesses of Croatian economy and society is a high corruption index. The aim of this paper is to prove the importance of business ethics in tourism in helping Croatia approximate EU standards.

Murine Cytomegalovirus m38.5 Protein Inhibits Bax-Mediated Cell Death

Abstract: Many viruses encode proteins that inhibit the induction of programmed cell death at the mitochondrial checkpoint. Murine cytomegalovirus (MCMV) encodes the m38.5 protein, which localizes to mitochondria and protects human HeLa cells and fibroblasts from apoptosis triggered by proteasome inhibitors but not from Fas-induced apoptosis. However, the ability of this protein to suppress the apoptosis of murine cells and its role during MCMV infection have not been investigated previously. Here we show that m38.5 is expressed at early time points during MCMV infection. Cells infected with MCMVs lacking m38.5 showed increased sensitivity to cell death induced by staurosporine, MG132, or the viral infection itself compared to the sensitivity of cells infected with wild-type MCMV. This defect was eliminated when an m38.5 or Bcl-XL gene was inserted into the genome of a deletion mutant. Using fibroblasts deficient in the proapoptotic Bcl-2 family proteins Bak and/or Bax, we further demonstrated that m38.5 protected from Bax- but not Bak-mediated apoptosis and interacted with Bax in infected cells. These results consolidate the role of m38.5 as a viral mitochondrion-localized inhibitor of apoptosis and its functional similarity to the human cytomegalovirus UL37x1 gene product. Although the m38.5 gene is not homologous to the UL37x1 gene at the sequence level, m38.5 is conserved among rodent cytomegaloviruses. Moreover, the fact that MCMV-infected cells are protected from both Bak- and Bax-mediated cell death suggests that MCMV possesses an additional, as-yet-unidentified mechanism to block Bak-mediated apoptosis.

A Signal Denoising Method Based on the Improved ICI Rule

Abstract: In this letter, we have proposed a signal denoising method based on a modification of the intersection of confidence intervals (ICI) rule. The ICI rule is complemented by the relative intersection of confidence intervals length which is used as an additional criterion for adaptive filter support selection. It is shown that the proposed method outperforms the original ICI method equipped with the local polynomial approximation (LPA), as well as various conventional wavelet shrinkage methods.

Viral inhibitors of NKG2D ligands: Friends or foes of immune surveillance?

Abstract: NKG2D is a potent activating receptor on NK cells and a co-stimulatory receptor on CD8+ T cells. Through its ability to recognize a panel of ligands inducible by stress or infection, it plays an important role in the control of viral infections. The viruses have evolved robust mechanisms to counteract NKG2D-dependent immune response. The functions of these viral inhibitors are well characterized during the early days post-infection but less so during the chronic viral infection.

Decidual natural killer cell tuning by autologous dendritic cells.

Abstract: Problem Dendritic cells (DC)/natural killer (NK) cells interactions in the deciduas of early human pregnancies were analyzed in vitro. Method of study Phenotype, cytokine expression and/or cytolytic mediators' expression were measured by flow cytometry in NK and DC from the freshly isolated decidual mononuclear cells or after their purification and co-culture in vitro. Proliferation of 5(6)-Carboxyfluorescein diacetate N-succinimidyl ester (CFSE)-labeled CD56(+) cells was analyzed by flow cytometry after the co-culture with CD1a(+) or CD83(+) DC. Results Decidual CD1a(+) cells show less mature phenotype with no expression of CD197, lower expression of CD80 and CD86 and higher expression of CD206 and CD195 in comparison to CD83(+) cells. Interleukin (IL)-15, interferon-gamma and tumor necrosis factor-alpha productions were higher in immature than mature DC, whereas IL-10 and IL-18 were equally produced in both subpopulations. Immature DC increase perforin, FasL and TRAIL protein expression and proliferation of NK cells, but decrease their intracellular IL-15 production. Mature DC caused less efficient proliferation of NK cells, and did not affect cytokine and cytolytic mediator expression. Conclusion These results suggest that decidual CD1a(+) cells regulate and shape NK cell function more profoundly than CD83(+) cells in decidua.

Croatian physicians’ and nurses’ experience with ethical issues in clinical practice

Abstract: To assess ethical issues in everyday clinical practice among physicians and nurses of the University Hospital Rijeka, Croatia. We surveyed the entire population of internal medicine, oncology and intensive care specialists and associated nurses employed at the University Hospital Rijeka, Croatia (N=532). An anonymous questionnaire was used to explore the type and frequency of ethical dilemmas, rank of their difficulty, access and usage of ethics support services, training in ethics, and confidence about knowledge in ethics. Physicians (N=113, female 55%) ranged in age from 27 to 61, nurses (N=251, female 95%) ranged in age from 20 to 52. Most often ethical dilemmas were: uncertain or impaired decision-making capacity (physicians 66%, nurses 47%, P=0, 008), limitation of therapy at the end of life (physicians 60%, nurses 31%, P<0, 001), and disagreements among family members (physicians 47%, nurses 31%, P=0, 025). Most difficult ethical dilemmas were euthanasia/PAS (physicians 49%, nurses 52%) and limitation of therapy at the end of life (physicians 14%, nurses 18%). Only a minority reported ever using any kind of ethics support services (physicians 12%, nurses 3%, P=0, 001), or being very confident about knowledge in ethics (physicians 5%, nurses 6%). Similar ethical difficulties are present in clinical practice of both physicians and nurses, with important differences in access and usage of ethics support services. A need for systematic ethics educational activities was identified. Inclusion of individual ethics consultants in Croatian healthcare ethics support services is strongly advised.

Limits on additional planetary companions to OGLE 2005-BLG-390L

Abstract: Aims. We investigate constraints on additional planets orbiting the distant M-dwarf star OGLE 2005-BLG-390L, around which photometric microlensing data has revealed the existence of the sub-Neptune-mass planet OGLE 2005-BLG-390Lb. We specifically aim to study potential Jovian companions and compare our findings with predictions from core-accretion and disc-instability models of planet formation. We also obtain an estimate of the detection probability for sub-Neptune mass planets similar to OGLE 2005-BLG-390Lb using a simplified simulation of a microlensing experiment. Methods: We compute the efficiency of our photometric data for detecting additional planets around OGLE 2005-BLG-390L, as a function of the microlensing model parameters and convert it into a function of the orbital axis and planet mass by means of an adopted model of the Milky Way. Results: We find that more than 50% of potential planets with a mass in excess of 1 MJ between 1.1 and 2.3 AU around OGLE 2005-BLG-390L would have revealed their existence, whereas for gas giants above 3 MJ in orbits between 1.5 and 2.2 AU, the detection efficiency reaches 70%; however, no such companion was observed. Our photometric microlensing data therefore do not contradict the existence of gas giant planets at any separation orbiting OGLE 2005-BLG-390L. Furthermore we find a detection probability for an OGLE 2005-BLG-390Lb-like planet of around 2{-}5%. In agreement with current planet formation theories, this quantitatively supports the prediction that sub-Neptune mass planets are common around low-mass stars.

Nonhomogeneous Boundary Value Problem for One-Dimensional Compressible Viscous Micropolar Fluid Model: Regularity of the Solution

Abstract: An initial-boundary value problem for 1D flow of a compressible viscous heat-conducting micropolar fluid is considered; the fluid is thermodynamically perfect and polytropic. Assuming that the initial data are Holder continuous on and transforming the original problem into homogeneous one, we prove that the state function is Holder continuous on , for each . The proof is based on a global-in-time existence theorem obtained in the previous research paper and on a theory of parabolic equations.

α′2-corrections to extremal dyonic black holes in heterotic string theory

Abstract: We calculate α'2-corrections to the entropy of the 5-dimensional 3-charge and the 4-dimensional 4-charge large extremal black holes using the low energy effective action of the heterotic string theory. In the 4-dimensional case, our results are in agreement with the microscopic statistical entropy both for the BPS and the non-BPS black holes. In the more interesting 5-dimensional case, where the direct microscopic stringy description is still unknown, our results for the BPS black holes are in agreement with the results obtained from the action supplemented with R2-correction obtained by supersymmetric completion of the gravitational Chern-Simons term. This agreement does not extend to the non-BPS black holes, for which we propose a different expression for the entropy. We show that the new expression is supported by certain α'3-order calculations, and by the arguments based on the AdS/CFT correspondence.

Oxidative stress parameters in different rat brain structures after electroconvulsive shock-induced seizures

Abstract: Electroconvulsive therapy has been used in the treatment of psychiatric disorders since the 1930s, but little progress has been made in understanding the cellular mechanisms underlying its therapeutic and adverse effects. Electroconvulsive shock (ECS) in animals provides a common experimental model for studying the effects of electroconvulsive therapy in humans. In order to examine the changes of the brain oxidative stress parameters in several brain structures in the early time period after ECS-induced seizures, the levels of lipid peroxidation as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in the rat hippocampus, cerebellum, frontal cortex and the pons/medulla region were determined at different time points during the first 24 h after single ECS-induced seizures. In the hippocampus and cerebellum the levels of lipid peroxidation were unchanged, while the SOD and GSH-Px activities were significantly increased. Levels of lipid peroxidation and the activities of SOD and GSH-Px were not statistically changed in the pons/medulla region. Levels of lipid peroxidation in the frontal cortex were significantly higher in comparison to the control group at all time points examined while the SOD and GSH-Px activities were not statistically changed. In conclusion, the results of the present study indicate that single ECS causes the rat brain structure-specific alterations in the levels of lipid peroxidation as well as in the SOD and GSH-Px activities at different time points within the first 24 h after the seizures induction. Oxidative lipid damage was evident only in the frontal cortex, while the hippocampus, cerebellum and the pons/medulla region remained oxidatively unaffected in our experimental conditions.

Genetic Predisposition to Idiopathic Recurrent Spontaneous Abortion: Contribution of Genetic Variations in IGF-2 and H19 Imprinted Genes

Abstract: Problem Recurrent spontaneous abortion (RSA) is a common clinical problem with a complex etiology of genetic and non-genetic causes, which remains to be fully determined. IGF-2 stimulates trophoblast invasion, proliferation and maturation of placenta, while H19 RNA suppresses growth. As genomic imprinting plays a critical role in the development of placenta and embryo, our aim was to evaluate the possible role of variations in IGF-2 and H19 imprinted genes as factors of predisposition for RSA. Method of study A case–control study was conducted to determine the association between IGF-2 and H19 gene polymorphisms and the susceptibility to RSA in 113 couples with RSA and 226 controls. PCR/RFLP were performed to analyze IGF-2 ApaI and H19 HhaI polymorphisms. Results We found a statistically significant difference in the genotype frequency distribution of IGF-2 ApaI polymorphism between males from couples with RSA and healthy males (χ2(2) = 45.12; P < 0.0001). There were no differences in the genotype and allele distribution of H19 polymorphism frequencies, or for the IGF-2 ApaI polymorphism between female groups. Conclusion The presence of IGF-2 ApaI polymorphism in partners of RSA women could affect IGF-2 level of expression in placenta and embryo and represent a risk factor for RSA susceptibility.

A feedback model of figure-ground assignment.

Abstract: A computational model is proposed in order to explain how bottom-up and top-down signals are combined into a unified perception of figure and background. The model is based on the interaction between the ventral and the dorsal stream. The dorsal stream computes saliency based on boundary signals provided by the simple and the complex cortical cells. Output from the dorsal stream is projected to the surface network which serves as a blackboard on which the surface representation is formed. The surface network is a recurrent network which segregates different surfaces by assigning different firing rates to them. The figure is labeled by the maximal firing rate. Computer simulations showed that the model correctly assigns figural status to the surface with a smaller size, a greater contrast, convexity, surroundedness, horizontal-vertical orientation and a higher spatial frequency content. The simple gradient of activity in the dorsal stream enables the simulation of the new principles of the lower region and the top-bottom polarity. The model also explains how the exogenous attention and the endogenous attention may reverse the figural assignment. Due to the local excitation in the surface network, neural activity at the cued region will spread over the whole surface representation. Therefore, the model implements the object-based attentional selection.