Networks and their traffic in multiplayer games

Computer games called multiplayer real-time, or (MCG) are at the forefront of the use of the possibilities of the network. Research on this subject have been made for military simulations, virtual reality systems, computer support teamwork, the solutions diverge on the problems posed by MCG. With this in mind, this document provides an overview of the four issues affecting networking at the MCG. First, network resources (bandwidth, latency and computing capacity), together with the technical limits within which the MCG must operate. Second, the distribution concepts include communication architectures (peer-to-peer, client / server, server / network), and data and control architectures (centralized, distributed and reproduced) .Thirdly, scalability allows the MCG to adapt to changes in parameterization resources. Finally, security is intended to fend off the traps and vandalism, which are common in online games; to check traffic, particularly these games we decided to take the massively multiplayer game League of Legends, a scene corresponding to a situation of real life in a network of ADSL access network is deployed has been simulated by using NS2Three variants of TCP, it means SACK TCP, New Reno TCP, and TCP Vegas, have been considered for the cross traffic. The results show that TCP Vegas is able to maintain a constant speed while racing against the game traffic, since it avoids the packet loss and the delays in the tail caused by high peaks, without increasing the size of the sender window. SACK TCP and TCP New Reno, on the other hand, tend to increase continuously the sender window size, which could allow a greater loss of packages and also to cause unwanted delays for the game traffic.Computer games called multiplayer real-time, or (MCG) are at the forefront of the use of the possibilities of the network. Research on this subject have been made for military simulations, virtual reality systems, computer support teamwork, the solutions diverge on the problems posed by MCG. With this in mind, this document provides an overview of the four issues affecting networking at the MCG. First, network resources (bandwidth, latency and computing capacity), together with the technical limits within which the MCG must operate. Second, the distribution concepts include communication architectures (peer-to-peer, client / server, server / network), and data and control architectures (centralized, distributed and reproduced) .Thirdly, scalability allows the MCG to adapt to changes in parameterization resources. Finally, security is intended to fend off the traps and vandalism, which are common in online games; to check traffic, particularly these games we decided to take the massively multiplayer game League of Legends, a scene corresponding to a situation of real life in a network of ADSL access network is deployed has been simulated by using NS2.Three variants of TCP, it means SACK TCP, New Reno TCP, and TCP Vegas, have been considered for the cross traffic. The results show that TCP Vegas is able to maintain a constant speed while racing against the game traffic, since it avoids the packet loss and the delays in the tail caused by high peaks, without increasing the size of the sender window. SACK TCP and TCP New Reno, on the other hand, tend to increase continuously the sender window size, which could allow a greater loss of packages and also to cause unwanted delays for the game traffic.Redes y su Tráfico en Juegos MultijugadorLos juegos de computador en tiempo real, o (MCG) están a la vanguardia de la utilización de las posibilidades de la red. Las investigaciones sobre esta materia se han hecho para las simulaciones militares, sistemas de realidad virtual, soporte informático del trabajo en equipo, las soluciones propuestas divergen sobre los problemas que plantea el MCG. Con esto en mente, este documento ofrece una visión general de los cuatro aspectos que afectan a la creación de redes en el MCG. En primer lugar, los recursos de redes (ancho de banda, latencia y capacidad de cálculo), junto con los límites técnicos dentro de la cual el MCG debe operar. En segundo lugar, los conceptos de distribución incluyen arquitecturas de comunicación (peer-to-peer, cliente / servidor, servidor / red), y los datos y arquitecturas de control (centralizado, distribuido y reproducido) .Thirdly, la escalabilidad permite que el MCG para adaptarse a los cambios en los recursos de parametrización. Por último, la seguridad está destinado para defenderse de las trampas y el vandalismo, que son comunes en los juegos en línea; para comprobar el tráfico, en particular de estos juegos que decidimos tomar el juego masivo multijugador Liga de Leyendas, se despliega una escena de red correspondiente a una situación de la vida real en una red de acceso ADSL se ha simulado mediante el uso de NS2.Tres variantes de TCP, que significa TCP SACK, Nueva Reno TCP y TCP Vegas, han sido consideradas para el tráfico transversal. Los resultados muestran que TCP Vegas es capaz de mantener una velocidad constante, mientras que una carrera contra el tráfico juego, ya que evita la pérdida de paquetes y los retrasos en la cola causado por los altos picos, sin aumentar el tamaño de la ventana de remitente. SACK TCP y TCP New Reno, por otro lado, tienden a aumentar continuamente el tamaño de la ventana remitente, lo que podría permitir una mayor pérdida de paquetes y también para causar retrasos no deseados para el tráfico de juego.Redes e seu tráfego nos jogos multijogadoresO multiplayer Jogos de computador em tempo real ou (MCG) estão na vanguarda da utilização das possibilidades da rede. As investigações sobre este assunto têm sido feitas para simulações militares, sistemas de realidade virtual, suporte informatizado de trabalho em equipe, as soluções propostas divergem sobre os problemas colocados pela MCG. Com isto em mente, este artigo fornece uma visão geral dos quatro aspectos que afetam a criação de redes no MCG. Em primeiro lugar, os recursos de redes (largura de banda, latência e capacidade de cálculo), juntamente com os limites técnicos dentro do qual o MCG deve operar. Em segundo lugar, os conceitos de distribuição incluem arquiteturas de comunicação (peer-to-peer, cliente / servidor, servidor / rede) e dados e arquiteturas de controle (centralizado, distribuído e replicado) .Thirdly, a escalabilidade permite que o MCG para se adaptar às mudanças em recursos de parametrização. Finalmente, a segurança destina-se a defendê-la contra as armadilhas e vandalismo, que são comuns em jogos on-line; para verificar o tráfego em particular destes jogos, decidimos tomar o enorme jogo multiplayer League of Legends, ele é implantado uma cena rede correspondendo a uma situação da vida real em uma rede de acesso ADSL foi simulada usando NS2. Três variantes do TCP, isso significa Sack TCP, New Reno TCP e TCP Vegas, foram considerados para o tráfego de cruz. Os resultados mostram que o TCP Vegas é capaz de manter uma velocidade constante durante a corrida contra o tráfego de jogo, uma vez que evita a perda de pacotes e os atrasos na cauda causada por picos elevados, sem aumentar o tamanho da janela do remetente. SACO TCP e TCP New Reno, por outro lado, tendem a aumentar continuamente o tamanho da janela de transmissão, o que poderia permitir uma maior perda de pacotes e também para causar atrasos indesejáveis para o tráfego de jogo

Networks and their traffic in multiplayer games

Computer games called multiplayer real-time, or (MCG) are at the forefront of the use of the possibilities of the network. Research on this subject have been made for military simulations, virtual reality systems, computer support teamwork, the solutions diverge on the problems posed by MCG. With this in mind, this document provides an overview of the four issues affecting networking at the MCG. First, network resources (bandwidth, latency and computing capacity), together with the technical limits within which the MCG must operate. Second, the distribution concepts include communication architectures (peer-to-peer, client / server, server / network), and data and control architectures (centralized, distributed and reproduced) .Thirdly, scalability allows the MCG to adapt to changes in parameterization resources. Finally, security is intended to fend off the traps and vandalism, which are common in online games; to check traffic, particularly these games we decided to take the massively multiplayer game League of Legends, a scene corresponding to a situation of real life in a network of ADSL access network is deployed has been simulated by using NS2Three variants of TCP, it means SACK TCP, New Reno TCP, and TCP Vegas, have been considered for the cross traffic. The results show that TCP Vegas is able to maintain a constant speed while racing against the game traffic, since it avoids the packet loss and the delays in the tail caused by high peaks, without increasing the size of the sender window. SACK TCP and TCP New Reno, on the other hand, tend to increase continuously the sender window size, which could allow a greater loss of packages and also to cause unwanted delays for the game traffic.Computer games called multiplayer real-time, or (MCG) are at the forefront of the use of the possibilities of the network. Research on this subject have been made for military simulations, virtual reality systems, computer support teamwork, the solutions diverge on the problems posed by MCG. With this in mind, this document provides an overview of the four issues affecting networking at the MCG. First, network resources (bandwidth, latency and computing capacity), together with the technical limits within which the MCG must operate. Second, the distribution concepts include communication architectures (peer-to-peer, client / server, server / network), and data and control architectures (centralized, distributed and reproduced) .Thirdly, scalability allows the MCG to adapt to changes in parameterization resources. Finally, security is intended to fend off the traps and vandalism, which are common in online games; to check traffic, particularly these games we decided to take the massively multiplayer game League of Legends, a scene corresponding to a situation of real life in a network of ADSL access network is deployed has been simulated by using NS2.Three variants of TCP, it means SACK TCP, New Reno TCP, and TCP Vegas, have been considered for the cross traffic. The results show that TCP Vegas is able to maintain a constant speed while racing against the game traffic, since it avoids the packet loss and the delays in the tail caused by high peaks, without increasing the size of the sender window. SACK TCP and TCP New Reno, on the other hand, tend to increase continuously the sender window size, which could allow a greater loss of packages and also to cause unwanted delays for the game traffic.Redes y su Tráfico en Juegos MultijugadorLos juegos de computador en tiempo real, o (MCG) están a la vanguardia de la utilización de las posibilidades de la red. Las investigaciones sobre esta materia se han hecho para las simulaciones militares, sistemas de realidad virtual, soporte informático del trabajo en equipo, las soluciones propuestas divergen sobre los problemas que plantea el MCG. Con esto en mente, este documento ofrece una visión general de los cuatro aspectos que afectan a la creación de redes en el MCG. En primer lugar, los recursos de redes (ancho de banda, latencia y capacidad de cálculo), junto con los límites técnicos dentro de la cual el MCG debe operar. En segundo lugar, los conceptos de distribución incluyen arquitecturas de comunicación (peer-to-peer, cliente / servidor, servidor / red), y los datos y arquitecturas de control (centralizado, distribuido y reproducido) .Thirdly, la escalabilidad permite que el MCG para adaptarse a los cambios en los recursos de parametrización. Por último, la seguridad está destinado para defenderse de las trampas y el vandalismo, que son comunes en los juegos en línea; para comprobar el tráfico, en particular de estos juegos que decidimos tomar el juego masivo multijugador Liga de Leyendas, se despliega una escena de red correspondiente a una situación de la vida real en una red de acceso ADSL se ha simulado mediante el uso de NS2.Tres variantes de TCP, que significa TCP SACK, Nueva Reno TCP y TCP Vegas, han sido consideradas para el tráfico transversal. Los resultados muestran que TCP Vegas es capaz de mantener una velocidad constante, mientras que una carrera contra el tráfico juego, ya que evita la pérdida de paquetes y los retrasos en la cola causado por los altos picos, sin aumentar el tamaño de la ventana de remitente. SACK TCP y TCP New Reno, por otro lado, tienden a aumentar continuamente el tamaño de la ventana remitente, lo que podría permitir una mayor pérdida de paquetes y también para causar retrasos no deseados para el tráfico de juego.Redes e seu tráfego nos jogos multijogadoresO multiplayer Jogos de computador em tempo real ou (MCG) estão na vanguarda da utilização das possibilidades da rede. As investigações sobre este assunto têm sido feitas para simulações militares, sistemas de realidade virtual, suporte informatizado de trabalho em equipe, as soluções propostas divergem sobre os problemas colocados pela MCG. Com isto em mente, este artigo fornece uma visão geral dos quatro aspectos que afetam a criação de redes no MCG. Em primeiro lugar, os recursos de redes (largura de banda, latência e capacidade de cálculo), juntamente com os limites técnicos dentro do qual o MCG deve operar. Em segundo lugar, os conceitos de distribuição incluem arquiteturas de comunicação (peer-to-peer, cliente / servidor, servidor / rede) e dados e arquiteturas de controle (centralizado, distribuído e replicado) .Thirdly, a escalabilidade permite que o MCG para se adaptar às mudanças em recursos de parametrização. Finalmente, a segurança destina-se a defendê-la contra as armadilhas e vandalismo, que são comuns em jogos on-line; para verificar o tráfego em particular destes jogos, decidimos tomar o enorme jogo multiplayer League of Legends, ele é implantado uma cena rede correspondendo a uma situação da vida real em uma rede de acesso ADSL foi simulada usando NS2. Três variantes do TCP, isso significa Sack TCP, New Reno TCP e TCP Vegas, foram considerados para o tráfego de cruz. Os resultados mostram que o TCP Vegas é capaz de manter uma velocidade constante durante a corrida contra o tráfego de jogo, uma vez que evita a perda de pacotes e os atrasos na cauda causada por picos elevados, sem aumentar o tamanho da janela do remetente. SACO TCP e TCP New Reno, por outro lado, tendem a aumentar continuamente o tamanho da janela de transmissão, o que poderia permitir uma maior perda de pacotes e também para causar atrasos indesejáveis para o tráfego de jogo

Decreased Equilibrative Nucleoside Transporter 1 (ENT1) Activity Contributes to the High Extracellular Adenosine Levels in Mesenchymal Glioblastoma Stem-Like Cells.

Glioblastoma multiforme is one of the most malignant types of cancer. This is mainly due to a cell subpopulation with an extremely aggressive potential, called glioblastoma stem-like cells (GSCs). These cells produce high levels of extracellular adenosine which has been associated with increased chemoresistance, migration, and invasion in glioblastoma. In this study, we attempted to elucidate the mechanisms that control extracellular adenosine levels in GSC subtypes. By using primary and U87MG-derived GSCs, we associated increased extracellular adenosine with the mesenchymal phenotype. [3H]-adenosine uptake occurred mainly through the equilibrative nucleoside transporters (ENTs) in GSCs, but mesenchymal GSCs have lower expression and ENT1-mediated uptake activity than proneural GSCs. By analyzing expression and enzymatic activity, we determined that ecto-5′-nucleotidase (CD73) is predominantly expressed in proneural GSCs, driving AMPase activity. While in mesenchymal GSCs, both CD73 and Prostatic Acid Phosphatase (PAP) contribute to the AMP (adenosine monophosphate) hydrolysis. We did not observe significant differences between the expression of proteins involved in the metabolization of adenosine among the GCSs subtypes. In conclusion, the lower expression and activity of the ENT1 transporter in mesenchymal GSCs contributes to the high level of extracellular adenosine that these GSCs present.post-print2,37 M

A afinação do violino : noções de temperamento para desenvolvimento da acuidade auditiva e melhoria da afinação no contexto musical

O presente Relatório Final expõe e concretiza os percursos realizados ao longo do meu estágio, traduzido através de uma Prática Profissional (PP) subordinado ao tema: A afinação do violino: Noções de temperamento no desenvolvimento da acuidade auditiva e na melhoria da afinação, em contextos académico. Procurando evidenciar os desenvolvimentos efectuados junto de um conjunto de alunos das classes de violino, do Conservatório de Música do Porto (CMP), divide-se em duas partes fundamentais e complementares: Da primeira parte fazem parte um conjunto de sessões e de orientações que compõem esta Prática Profissional (PP), nomeadamente planificações organizadas e orientadas, aulas assistidas, aulas leccionadas, e a elaboração de materiais didácticos. Da segunda parte fazem parte os procedimentos metodológicos que orientam, sob a forma de artigo científico, um Projecto de Intervenção Pedagógica (PIP), por mim concebido e realizado, cujas questões de investigação se situam no âmbito dos seguintes horizontes: A afinação é uma aprendizagem trabalhada através de audiação? Ou, trata-se simplesmente de treino, de imitação e de repetição? De que forma um enquadramento teórico sistemático, com recurso a conceitos da acústica (série dos harmónicos) e da teoria musical (tríade M/m e sensíveis) - em suma temperamento - podem ajudar o aluno de violino a melhor audiar e assim melhorar a afinação? No sentido de se obterem respostas para esta problemática, realizou-se uma investigação ação, cujos resultados evidenciam a pertinência deste estudo, confirmando e acentuando a necessidade da realização de outros projetos e programas, que conduzam os alunos a melhorias substantivas nas suas práticas instrumentais, quotidianas.This Final Report shows and materializes the path carried out during my internship, through the Professional Practice (PP), under the theme: Violin tuning: Notions of temperament in the development of auditory acuity and in the improvement of tuning, in academic contexts. Aiming to highlight the developments carried out with a group of students from the violin classes, from the Conservatory of Music of Oporto (CMP), it is divided into two fundamental and complementary parts: The first part includes a set of sessions and guidelines that make up this Professional Practice (PP), namely organized and guided planning, attended classes, taught classes, and the development of didactic materials. The second part includes the methodological procedures that guide, in the form of a scientific article, a Pedagogical Intervention Project (PIP), conceived and carried out by me, whose research questions are situated within the scope of the following horizons: Is tuning a learning process that can be worked through audiation? Or, is it simply training through rote and repetition? How can a systematic theoretical framework, using the concepts of acoustics (harmonics series) and musical theory (M/m and sensitive triads) - in short temperament - help the violin student to better audiar and thus improve the tuning? In order to obtain answers to this problem, an action-research was carried out, the results of which confirm the relevance of this research, confirming and emphasizing the need to carry out other projects and programs that lead students to substantial improvements in their instrumental practices, everyday

Networks and their traffic in multiplayer games

Computer games called multiplayer real-time, or (MCG) are at the forefront of the use of the possibilities of the network. Research on this subject have been made for military simulations, virtual reality systems, computer support teamwork, the solutions diverge on the problems posed by MCG. With this in mind, this document provides an overview of the four issues affecting networking at the MCG. First, network resources (bandwidth, latency and computing capacity), together with the technical limits within which the MCG must operate. Second, the distribution concepts include communication architectures (peer-to-peer, client / server, server / network), and data and control architectures (centralized, distributed and reproduced) .Thirdly, scalability allows the MCG to adapt to changes in parameterization resources. Finally, security is intended to fend off the traps and vandalism, which are common in online games; to check traffic, particularly these games we decided to take the massively multiplayer game League of Legends, a scene corresponding to a situation of real life in a network of ADSL access network is deployed has been simulated by using NS2.Three variants of TCP, it means SACK TCP, New Reno TCP, and TCP Vegas, have been considered for the cross traffic. The results show that TCP Vegas is able to maintain a constant speed while racing against the game traffic, since it avoids the packet loss and the delays in the tail caused by high peaks, without increasing the size of the sender window. SACK TCP and TCP New Reno, on the other hand, tend to increase continuously the sender window size, which could allow a greater loss of packages and also to cause unwanted delays for the game traffic.Redes y su Tráfico en Juegos MultijugadorLos juegos de computador en tiempo real, o (MCG) están a la vanguardia de la utilización de las posibilidades de la red. Las investigaciones sobre esta materia se han hecho para las simulaciones militares, sistemas de realidad virtual, soporte informático del trabajo en equipo, las soluciones propuestas divergen sobre los problemas que plantea el MCG. Con esto en mente, este documento ofrece una visión general de los cuatro aspectos que afectan a la creación de redes en el MCG. En primer lugar, los recursos de redes (ancho de banda, latencia y capacidad de cálculo), junto con los límites técnicos dentro de la cual el MCG debe operar. En segundo lugar, los conceptos de distribución incluyen arquitecturas de comunicación (peer-to-peer, cliente / servidor, servidor / red), y los datos y arquitecturas de control (centralizado, distribuido y reproducido) .Thirdly, la escalabilidad permite que el MCG para adaptarse a los cambios en los recursos de parametrización. Por último, la seguridad está destinado para defenderse de las trampas y el vandalismo, que son comunes en los juegos en línea; para comprobar el tráfico, en particular de estos juegos que decidimos tomar el juego masivo multijugador Liga de Leyendas, se despliega una escena de red correspondiente a una situación de la vida real en una red de acceso ADSL se ha simulado mediante el uso de NS2.Tres variantes de TCP, que significa TCP SACK, Nueva Reno TCP y TCP Vegas, han sido consideradas para el tráfico transversal. Los resultados muestran que TCP Vegas es capaz de mantener una velocidad constante, mientras que una carrera contra el tráfico juego, ya que evita la pérdida de paquetes y los retrasos en la cola causado por los altos picos, sin aumentar el tamaño de la ventana de remitente. SACK TCP y TCP New Reno, por otro lado, tienden a aumentar continuamente el tamaño de la ventana remitente, lo que podría permitir una mayor pérdida de paquetes y también para causar retrasos no deseados para el tráfico de juego.Redes e seu tráfego nos jogos multijogadoresO multiplayer Jogos de computador em tempo real ou (MCG) estão na vanguarda da utilização das possibilidades da rede. As investigações sobre este assunto têm sido feitas para simulações militares, sistemas de realidade virtual, suporte informatizado de trabalho em equipe, as soluções propostas divergem sobre os problemas colocados pela MCG. Com isto em mente, este artigo fornece uma visão geral dos quatro aspectos que afetam a criação de redes no MCG. Em primeiro lugar, os recursos de redes (largura de banda, latência e capacidade de cálculo), juntamente com os limites técnicos dentro do qual o MCG deve operar. Em segundo lugar, os conceitos de distribuição incluem arquiteturas de comunicação (peer-to-peer, cliente / servidor, servidor / rede) e dados e arquiteturas de controle (centralizado, distribuído e replicado) .Thirdly, a escalabilidade permite que o MCG para se adaptar às mudanças em recursos de parametrização. Finalmente, a segurança destina-se a defendê-la contra as armadilhas e vandalismo, que são comuns em jogos on-line; para verificar o tráfego em particular destes jogos, decidimos tomar o enorme jogo multiplayer League of Legends, ele é implantado uma cena rede correspondendo a uma situação da vida real em uma rede de acesso ADSL foi simulada usando NS2. Três variantes do TCP, isso significa Sack TCP, New Reno TCP e TCP Vegas, foram considerados para o tráfego de cruz. Os resultados mostram que o TCP Vegas é capaz de manter uma velocidade constante durante a corrida contra o tráfego de jogo, uma vez que evita a perda de pacotes e os atrasos na cauda causada por picos elevados, sem aumentar o tamanho da janela do remetente. SACO TCP e TCP New Reno, por outro lado, tendem a aumentar continuamente o tamanho da janela de transmissão, o que poderia permitir uma maior perda de pacotes e também para causar atrasos indesejáveis para o tráfego de jogo.Computer games called multiplayer real-time, or (MCG) are at the forefront of the use of the possibilities of the network. Research on this subject have been made for military simulations, virtual reality systems, computer support teamwork, the solutions diverge on the problems posed by MCG. With this in mind, this document provides an overview of the four issues affecting networking at the MCG. First, network resources (bandwidth, latency and computing capacity), together with the technical limits within which the MCG must operate. Second, the distribution concepts include communication architectures (peer-to-peer, client / server, server / network), and data and control architectures (centralized, distributed and reproduced) .Thirdly, scalability allows the MCG to adapt to changes in parameterization resources. Finally, security is intended to fend off the traps and vandalism, which are common in online games; to check traffic, particularly these games we decided to take the massively multiplayer game League of Legends, a scene corresponding to a situation of real life in a network of ADSL access network is deployed has been simulated by using NS2Three variants of TCP, it means SACK TCP, New Reno TCP, and TCP Vegas, have been considered for the cross traffic. The results show that TCP Vegas is able to maintain a constant speed while racing against the game traffic, since it avoids the packet loss and the delays in the tail caused by high peaks, without increasing the size of the sender window. SACK TCP and TCP New Reno, on the other hand, tend to increase continuously the sender window size, which could allow a greater loss of packages and also to cause unwanted delays for the game traffic

Novel therapeutic strategies for traumatic brain injury: Acute antioxidant reinforcement

Traumatic brain injury (TBI) is the most important cause of disability in individuals under the age of 45 years and thus represents a significant social and economic burden. Evidence strongly suggests that oxidative stress is a cornerstone event leading to and propagating secondary injury mechanisms such as excitotoxicity, mitochondrial dysfunction, apoptosis, autophagy, brain edema, and inflammation. TBI has defied conventional approaches to diagnosis and therapy development because of its heterogeneity and complexity. Therefore, it is necessary to explore alternative approaches to therapy development for TBI. The aim of this review is to present a therapeutic approach for TBI, taking into account the evidence supporting the role for oxidative stress in the pathophysiological processes of secondary brain injury. The role of agents such as mitochondria-targeted antioxidants (melatonin and new mitochondria-targeted antioxidants), nicotinamide adenine dinucleotide phosphate (NADPH) inhi

O6-methylguanine-DNA-methyltransferase (MGMT) expression in patients with glioblastoma multiforme Expresión de O6-metilguanina-ADNmetiltransferasa (MGMT) en pacientes chilenos con glioblastoma multiforme

© 2018, Sociedad Medica de Santiago. All rights reserved. Background: Patients with Glioblastoma multiforme (GBM) have a five years survival of less than 5%, but the response to chemotherapy with alkylating agents can vary depending on the methylation status of O6-methylguanine- DNA-methyltransferase (MGMT). Genetic testing has limitations for routine use, while immunohistochemistry (IHC) offers a fast and affordable technique but with heterogeneous results in the literature. Aim: To evaluate MGMT expression by IHC in tumor tissue of Chilean patients with GBM. Material and Methods: Tumor samples of 29 patients with a pathological diagnosis of GBM were studied. We performed IHC staining and manual analysis of positive and negative cells for MGMT expression. A cut-off of at least 10% of cells expressing MGMT was used. Demographic and clinical features of patients were obtained from clinical records. Results: The median number of cells counted per case was 692 (interquartile range [IQR]

O6 - methylguanine DNA methyltransferase immunostaining intensity in glioblastoma

Immunohistochemistry (IHC) for O6-methylguanine-DNA-methyltransferase (MGMT) has shown heterogeneous results. Cell staining intensity has not been included as a quantifiable variable in IHC analyses. We performed MGMT IHC in 29 patients diagnosed as glioblastoma classifying cells into three categories based on nuclear staining intensity compared with adjacent endothelium. The median proportions of strong-moderate, weak and no staining cells were 10%, 16% and 71%, respectively. The proportion of positive cases for MGMT expression varies from 38% to 52% depending on the classification of weakly stained cells. This letter challenges previous studies that have not included intensity as a variable for IHC analysis.(FIDECNO) from the Department of Neurological Sciences, Faculty of Medicine, University of Chile

O-6-methylguanine-DNA-methyltransferase (MGMT) expression in patients with glioblastoma multiforme

Background: Patients with Glioblastoma multiforme (GBM) have a five years survival of less than 5%, but the response to chemotherapy with alkylating agents can vary depending on the methylation status of O-6-methylguanine-DNA-methyltransferase (MGMT). Genetic testing has limitations for routine use, while immunohistochemistry (IHC) offers a fast and affordable technique but with heterogeneous results in the literature. Aim: To evaluate MGMT expression by IHC in tumor tissue of Chilean patients with GBM. Material and Methods: Tumor samples of 29 patients with a pathological diagnosis of GBM were studied. We performed IHC staining and manual analysis of positive and negative cells for MGMT expression. A cut-off of at least 10% of cells expressing MGMT was used. Demographic and clinical features of patients were obtained from clinical records. Results: The median number of cells counted per case was 692 (interquartile range [IQR] 492-928). Fifteen cases (52%) were positive for MGMT expression. Median overall survival was 5.3 months (IQR 3.4-12-8). The effect of MGMT expression on the therapeutic response was not studied since only 3 patients received chemotherapy. Conclusions: Our results are similar to international reports, but we were not able to determine the association between MGMT expression and therapeutic response

Adenosine A(3) receptor elicits chemoresistance mediated by multiple resistance-associated protein-1 in human glioblastoma stem-like cells

MRP1 transporter correlates positively with glioma malignancy and the Multiple Drug Resistance (MDR) phenotype in Glioblastoma Multiforme (GBM). Evidence shows that the MRP1 transporter is controlled by the adenosine signalling axis. The aim of this study was to identify the role of adenosine on the MDR phenotype in Glioblastoma Stem-like Cells (GSCs), the cell population responsible for the tumorigenic and chemoresistance capabilities of this tumour. We found that GSCs have increased intrinsic capacity to generate extracellular adenosine, thus controlling MRP1 transporter expression and activity via activation of the adenosine A(3) receptor (A(3)AR). We showed PI3K/Akt and MEK/ERK1/2 signaling pathways downstream A3AR to control MRP1 in GSCs. In vitro pharmacological blockade of A3AR had a chemosensitizing effect, enhancing the actions of antitumour drugs and decreasing cell viability and proliferation of GSCs. In addition, we produced an in vivo xenograft model by subcutaneous inoculation of human GSCs in NOD/SCID-IL2Rg null mice. Pharmacological blockade of A3AR generated a chemosensitizing effect, enhancing the effectiveness of the MRP1 transporter substrate, vincristine, reducing tumour size and the levels of CD44 and Nestin stem cell markers as well as the Ki-67 proliferation indicator. In conclusion, we demonstrated the chemosensitizing effect of A3AR blockade on GSCs.FONDECYT-Chile 1121121 1130414 1160777 3150626 CONICYT-Chile 2113100