A credit-based approach to scalable video transmission over a peer-to-peer social network

PhDThe objective of the research work presented in this thesis is to study scalable video transmission over peer-to-peer networks. In particular, we analyse how a credit-based approach and exploitation of social networking features can play a significant role in the design of such systems. Peer-to-peer systems are nowadays a valid alternative to the traditional client-server architecture for the distribution of multimedia content, as they transfer the workload from the service provider to the final user, with a subsequent reduction of management costs for the former. On the other hand, scalable video coding helps in dealing with network heterogeneity, since the content can be tailored to the characteristics or resources of the peers. First of all, we present a study that evaluates subjective video quality perceived by the final user under different transmission scenarios. We also propose a video chunk selection algorithm that maximises received video quality under different network conditions. Furthermore, challenges in building reliable peer-to-peer systems for multimedia streaming include optimisation of resource allocation and design mechanisms based on rewards and punishments that provide incentives for users to share their own resources. Our solution relies on a credit-based architecture, where peers do not interact with users that have proven to be malicious in the past. Finally, if peers are allowed to build a social network of trusted users, they can share the local information they have about the network and have a more complete understanding of the type of users they are interacting with. Therefore, in addition to a local credit, a social credit or social reputation is introduced. This thesis concludes with an overview of future developments of this research work

Intron 4-5 hTERT DNA Hypermethylation in Merkel Cell Carcinoma: Frequency, Association with Other Clinico-pathological Features and Prognostic Relevance

Merkel cell carcinoma (MCC) is an aggressive skin tumor with neuroendocrine differentiation, mainly affecting elderly population or immunocompromised individuals. As methylation of the human telomerase reverse transcriptase (mhTERT) has been shown to be a prognostic factor in different tumors, we investigated its role in MCC, in particular in intron 4-5 where rs10069690 has been mapped and recognized as a cancer susceptibility locus. DNA methylation analysis of hTERT gene was assessed retrospectively in a cohort of 69 MCC patients from the University of Bologna, University of Turin and University of Insubria. Overall mortality was evaluated with Kaplan-Meier curves and multivariable Royston-Parmar models. High levels of mhTERT (mhTERThigh) (HR\u2009=\u20092.500, p\u2009=\u20090.015) and p63 (HR\u2009=\u20092.659, p\u2009=\u20090.016) were the only two clinico-pathological features significantly associated with a higher overall mortality at the multivariate analysis. We did not find different levels of mhTERT between MCPyV (+) and (-) cases (21 vs 14, p\u2009=\u20090.554); furthermore, mhTERThigh was strongly associated with older age (80.5 vs 72 years, p\u2009=\u20090.026), no angioinvasion (40.7% vs 71.0%, p\u2009=\u20090.015), lower Ki67 (50 vs 70%, p\u2009=\u20090.005), and PD-L1 expressions in both tumor (0 vs 3%, p\u2009=\u20090.021) and immune cells (0 vs 10%, p\u2009=\u20090.002). mhTERT is a frequently involved epigenetic mechanism and a relevant prognostic factor in MCC. In addition, it belongs to the shared oncogenic pathways of MCC (MCPyV and UV-radiations) and it could be crucial, together with other epigenetic and genetic mechanisms as gene amplification, in determining the final levels of hTERT mRNA and telomerase activity in these patients

Impact of phospholipase C beta 1 in glioblastoma: a study on the main mechanisms of tumor aggressiveness

Glioblastoma represents the most lethal brain tumor in adults. Several studies have shown the key role of phospholipase C beta 1 (PLC beta 1) in the regulation of many mechanisms within the central nervous system suggesting PLC beta 1 as a novel signature gene in the molecular classification of high-grade gliomas. This study aims to determine the pathological impact of PLC beta 1 in glioblastoma, confirming that PLC beta 1 gene expression correlates with glioma's grade, and it is lower in 50 glioblastoma samples compared to 20 healthy individuals. PLC beta 1 silencing in cell lines and primary astrocytes, leads to increased cell migration and invasion, with the increment of mesenchymal transcription factors and markers, as Slug and N-Cadherin and metalloproteinases. Cell proliferation, through increased Ki-67 expression, and the main survival pathways, as beta-catenin, ERK1/2 and Stat3 pathways, are also affected by PLC beta 1 silencing. These data suggest a potential role of PLC beta 1 in maintaining a normal or less aggressive glioma phenotype

LYMPHOMAS OF ORAL CAVITY. CLINICALPATHOLOGICAL STUDY OF 46 CASES AND REVIEW OF LITERATURE.

Introduction: Although several clinico-pathologic studies on extra-nodal oral cavity lymphomas have been reported, our understanding of these tumours is incomplete. This is mainly because oral lymphomas are quite rare and the opportunity to apply modern techniques to their classification is limited. Propose: The aim of this study was to determinate both the histotype and phenotype of lymphomas presenting in the oral cavity. Materials and methods: Cases were classified according to the World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues 2001. Immunohistochemical stains were performed on tissue microarrays (TMA). Results: Forty-four cases of non-Hodgkin\u2019s lymphoma (NHL) and 2 cases of primitive Hodgkin\u2019s lymphoma (HL) were observed, with a slight female predominance (21M; 25F). Forty cases of NHL were primitive of the oral cavity, while six cases were secondary lesions. NHL were divided into five groups: 1) diffuse large B-cell lymphoma (DLBCL: 33 cases); 2) follicular lymphoma (FL: 5 cases); 3) extranodal marginal zone B-cell lymphoma (MZL: 3 cases); 4) mantle cell lymphoma (MCL: 1 case); 5) peripheral T-cell lymphomas, not otherwise specified (PTCL, NOS: 2 cases). HL occurred in two males, aged 25 and 65 years respectively. Both cases were diagnosed as nodular sclerosing HL. The lesions were variably located in different sites of the oral cavity, commonly affected sites being the soft and hard palate and tongue. The most frequent clinical appearance was a submucosal mass (34 cases). Dental waving was present in 5 cases and actinomycotic infection in one. Six cases appeared as slightly raised whitish lesions. Two cases (1 NHL and 1 HL) appeared in HIV infected patients. Conclusion: The present series shows that malignant lymphomas of the oral cavity more often represent de novo primary growths. The most frequent event is DLBCL affecting elderly patients in the palate or tongue. Although rare, HL should be considered among primary oral cavity lymphomas

Transglutaminase 2 May Be Associated with Peri-implant Gingival Overgrowth: Preliminary Assessments

Tissue transglutaminase 2 (TG2) is ubiquitously expressed in normal tissues and plays an important role in the pathophysiology of wound healing. An increase in periodontal tissues has been previously reported in cyclosporine-induced gingival overgrowth. PURPOSE: The aim of this study was to explore associations between TG2 expression and the vascularization and maturation processes of peri-implant soft tissues over time. MATERIALS AND METHODS: Edentulous patients proposed for mandibular implant-retained overdentures were included in the study. Biopsies of the peri-implant mucosa were performed at the first surgical stage and at 4, 8, and 12 months after prosthetic load. A follow-up program was directed to record plaque indexes, bleeding on probing data, and pocket probing depth around implants. An evaluation of the vessels' density was carried out by digital virtual microscopy and using an immunohistochemistry approach (antibodies anti-CD31, anti-TG2). A robust multivariable regression model was implemented. RESULTS: According to model results, blood vessel count and probing (as a marker of gingival overgrowth in absence of plaque) significantly decrease over time and are associated with TG2, particularly for values above the median. CONCLUSION: The association of an increased TG2 expression in the extracellular matrix might have a significant impact in the development of gingival overgrowth around a loaded implant

Transglutaminase 2 expression is significantly increased in cyclosporine-induced gingival overgrowth

Cyclosporine A is a potent immunosuppressant used to prevent organ transplant rejection and treat various autoimmune diseases. However, cyclosporine A can also induce gingival overgrowth, which is characterized by increased extracellular matrix due to an altered balance between collagen synthesis and degradation. This study proposed to verify whether trans-glutaminase 2, an enzyme thought to be responsible for the assembly and remodelling of extracellular matrix, plays any role in the pathogenesis of cyclosporine A-induced gingival overgrowth. Cyclosporine A-induced gingival overgrowths were collected from 21 liver transplant patients and case-controlled with 20 non-hyperplastic gingival biopsies from healthy patients who had previous periodontal treatment. In both groups, the presence and tissue distribution of transglutaminase 2 were determined by immunohistochemistry and analyzed in comparison with the tissue morphology and expression of lymphocyte-related antigens (CD3 and CD20) and a vessel-related marker (CD34). Transglutaminase 2 expression showed a significant increase (2.6-fold) in the stromal component of cyclosporine A-treated patients compared with controls (p<0.001), which suggested that transglutaminase 2 had a role in the pathogenesis of the disease. Further studies should investigate the therapeutic effect of anti-transglutaminase 2 drugs (putrescine or 1,4-diamino-butane) in these patients