Transparency effect in the emergence of monopolies in social networks

Power law degree distribution was shown in many complex networks. However, in most real systems, deviation from power-law behavior is observed in social and economical networks and emergence of giant hubs is obvious in real network structures far from the tail of power law. We propose a model based on the information transparency (transparency means how much the information is obvious to others). This model can explain power structure in societies with non-transparency in information delivery. The emergence of ultra powerful nodes is explained as a direct result of censorship. Based on these assumptions, we define four distinct transparency regions: perfect non-transparent, low transparent, perfect transparent and exaggerated regions. We observe the emergence of some ultra powerful (very high degree) nodes in low transparent networks, in accordance with the economical and social systems. We show that the low transparent networks are more vulnerable to attacks and the controllability of low transparent networks is harder than the others. Also, the ultra powerful nodes in the low transparent networks have a smaller mean length and higher clustering coefficients than the other regions.Comment: 14 Pages, 3 figure

The Effect of Dietary Constituents on Regulation of Epigenetic Changes in Cancer

BACKGROUND AND OBJECTIVE: The term “epigenetic” refers to all non-heritable and reversible changes in the expression of a gene that does not cause a change in the DNA sequence. The most important epigenetic mechanisms associated with gene expression include DNA methylation, histone modifications, and suppression of gene expression with RNA. Considering the reversibility of epigenetic changes, it seems that this feature can be influenced by dietary constituents and thus, we can prevent the spread of certain cancers by controlling the diet. The purpose of this study is to investigate the effects of food on the prevention of common cancers and the mechanisms involved in cellular activities based on recent studies and the compilation of their results. METHODS: In this review article, we searched Pubmed and Elsevier databases using certain keywords such as “epigenetics”, “cancer” and “nutrition” and articles related to the effects of epigenetics on cancer and dietary constituents were evaluated. FINDINGS: Of 439 studies found in the search engines between 1997 and 2016, 64 articles were selected and their results indicated that many of the active components in the diet will inhibit the incidence of cancer through DNA methylation mechanisms, histone modifications, and miRNA. CONCLUSION: The anticancer effect of the active compounds in the diet on specific epigenetic changes can be used as a special and unidentified mechanism for preventing cance

Impact of Pegylated Interferon-alfa-2a on Perforin Level in Patients With Chronic Hepatitis B; Preliminary Study

Background: Chronic hepatitis B is one of the most common causes of cirrhosis and hepatocellular toxicity in many countries, including Iran. Cytotoxic T lymphocyte (CTL) and Natural killer (NK) cells are the two of main cell populations considered as cytotoxic cells. One of the distinct pathways CTL and NK cells exert cytotoxicity is perforin/granzyme. After the cytotoxic cell/target cell junction, perforin is released from granules by exocytosis. Once it is anchored, perforin forms cylindrical pores through which granzymes and granulysin enter and induce apoptosis. Objectives: Large controlled trials have demonstrated the efficacy of PEG-IFN-alpha-2a in treatment of chronic hepatitis B. This study was aimed to examine whether the enhancement of cytotoxicity by PEG-IFN-alpha-2a is mainly due to the perforin pathway. Patients and Methods: This research work was performed on 50 patients and five healthy people. Patients with chronic hepatitis B were further subdivided into two groups: patients with inactive chronic hepatitis B (carriers, n = 30), and those with active chronic hepatitis B who were under treatment with PEG-IFN-alfa-2a (n = 20) for minimum six and maximum 12 months. Serum perforin level was measured using ELISA method (CUSABIO Company), HBV viral load was assessed using COBAS Taq-man, and we used Elecsys hepatitis B surface antigen (HBs Ag) II quantitative assay method for HBs Ag determination. HBeAg was evaluated by ELISA method, and AST and ALT were measured by routine laboratorymethods. Results: Based on the results obtained serum perforin level in healthy group was 0.64 ng/mL, the mean of serum perforin level in inactive HBs Ag carriers was 2.63ng/mL, and 4.63 ng/mL in patients with active chronic hepatitis B under treatment with PEG-IFN-alpha-2a. The mean of serum perforin level in patients with and without virologic response to treatment were 5.45 ng/mL, and 3.4 ng/mL respectively. Finally in patients with virologic response and seroconverted serum perforin level was 7.23 ng/mL. Conclusions: Based on our results higher perforin level in patients under treatment with PEG-IFN-alpha-2a, could be an indication of elevated cytotoxicity via perforin/granzyme pathway