Review: Biological and Pharmacological Basis of Cytolytic Viral Activation in EBV-Associated Nasopharyngeal Carcinoma

Epstein-Barr virus (EBV) infection contributes to the development of different types of human malignancies, especially nasopharyngeal carcinoma. As a herpesvirus, EBV can establish two major modes of virus-cell interactions: a latent or a lytic infection. Latent infection is prevalent in the vast majority of malignant cells in EBV-related malignancies. Inducing a switch from latent to lytic infection in a substantial fraction of malignant cells has long been considered as a potentially interesting therapeutic approach. Therapeutic benefits are expected from (1) the cytotoxic or cytostatic effects of viral products expressed in the context of the lytic cycle; (2) expression of viral enzymes capable of metabolizing pro-drugs selectively inside these cells and (3) broadening the expression spectrum of antigenic viral proteins. In this chapter, addressing non EBV-specialized readers, we first summarize the main aspects of EBV biology with emphasis on the cellular mechanisms known to control latent and lytic infections. Then, we outline the basic principles and requirements of cytolytic EBV activation performed with a therapeutic intent. Finally, we review the main categories of pharmacological agents reported to be active in the switch from latent to lytic infection, including drugs used for conventional anti-tumour chemotherapy, histone-deacetylase inhibitors and various miscellaneous compounds

Rapid obtention of stable, bioluminescent tumor cell lines using a tCD2-luciferase chimeric construct

<p>Abstract</p> <p>Background</p> <p>Bioluminescent tumor cell lines are experimental tools of major importance for cancer investigation, especially imaging of tumors in xenografted animals. Stable expression of exogenous luciferase in tumor cells combined to systemic injection of luciferin provides an excellent signal/background ratio for external optical imaging. Therefore, there is a need to rationalize and speed up the production of luciferase-positive tumor cell lines representative of multiple tumor phenotypes. For this aim we have designed a fusion gene linking the luciferase 2 protein to the c-terminus of a truncated form of the rat CD2 protein (<it>tCD2-luc2</it>). To allow simultaneous assessment of the wild-type luciferase 2 in a context of tCD2 co-expression, we have made a bicistronic construct for concomitant but separate expression of these two proteins (<it>luc2-IRES-tCD2</it>). Both the mono- and bi-cistronic constructs were transduced in lymphoid and epithelial cells using lentiviral vectors.</p> <p>Results</p> <p>The tCD2-luc2 chimera behaves as a type I membrane protein with surface presentation of CD2 epitopes. One of these epitopes reacts with the OX34, a widely spread, high affinity monoclonal antibody. Stably transfected cells are sorted by flow cytometry on the basis of OX34 staining. <it>In vitro</it> and, moreover, in xenografted tumors, the tCD2-luc2 chimera retains a substantial and stable luciferase activity, although not as high as the wild-type luciferase expressed from the <it>luc2-IRES-tCD2</it> construct. Expression of the tCD2-luc2 chimera does not harm cell and tumor growth.</p> <p>Conclusion</p> <p>Lentiviral transduction of the chimeric <it>tCD2-luc2 </it>fusion gene allows selection of cell clones with stable luciferase expression in less than seven days without antibiotic selection. We believe that it will be helpful to increase the number of tumor cell lines available for <it>in vivo </it>imaging and assessment of novel therapeutic modalities. On a longer term, the tCD2-luc2 chimera has the potential to be expressed from multi-cassette vectors in combination with various inserts of interest.</p

Multicast and Broadcast in wireless OFDM systems

Le système OFDM (Orthogonal Frequency Division Multiplexing) utilise plusieurs sous-porteuses pour transmettre de l information. Comparé à un schéma mono-porteuse, la modulation multi-porteuses OFDM permet d obtenir facilement des réglages optimaux (au sens de la capacité de Shannon) pour une transmission à haut débit sur un canal sélectif en fréquence. En ce sens, on peut alors garantir une transmission fiable et une meilleure gestion de l'énergie utilisée. Lors de la transmission avec une modulation OFDM, les sous-porteuses utilisent des canaux différents qui n ont pas forcement la même atténuation. Allouer le même niveau de puissance à chaque sous-porteuse ne garantit pas une capacité optimale dans une liaison point à point. Une allocation dynamique de la puissance (c est-à-dire attribuer différents niveaux de puissance aux sous-porteuses en fonction du canal) donne de meilleures performances. Par contre, dans une situation de diffusion (broadcast), l émetteur ne connaît pas les canaux vers tous les utilisateurs, et la meilleure stratégie consiste à émettre avec la même puissance sur toutes les sous-porteuses. Cette thèse a pour objectif d explorer les situations intermédiaires, et de proposer les outils d allocation de puissance appropriés. Cette situation intermédiaire est appelée multicast , ou multidiffusion : l émetteur envoie les signaux vers un nombre fini (pas trop grand) d utilisateurs, dont il connaît les paramètres de canaux, et il peut adapter son émission à cette connaissance des canaux. On est donc dans une situation intermédiaire entre le point à point et la diffusion . L objectif final de ce travail est d évaluer le gain apporté par la connaissance des canaux en situation de multicast par rapport à la même communication effectuée comme si on était en diffusion. Bien évidemment, quand le nombre de destinataires est très grand, les gains seront négligeables, car le signal rencontre un nombre très élevé de canaux, et une allocation de puissance uniforme sera quasi optimale. Quand le nombre est très faible, on sera proche du point à point et les gains devraient être sensibles. Nous proposons des outils pour quantifier ces améliorations dans les cas de systèmes ayant une antenne à l'émission et une antenne à la réception, dit SISO (Single Input Single Output) et de systèmes avec plusieurs antennes, dits MIMO (Multiple Input Multiple Output). Les étapes nécessaires pour réaliser ce travail sont : 1) En supposant une connaissance préalable de l état des canaux (entre station de base et terminaux), mettre en œuvre les outils de la théorie de l'information pour effectuer l allocation de puissance et évaluer les capacités des systèmes étudiés. 2) Pour le système multi-utilisateur SISO-OFDM, nous proposons un algorithme d'allocation de puissance sur chaque sous porteuse dans une situation de multicast. 3) Pour le système multi-utilisateur MIMO-OFDM, nous proposons un algorithme qui exploite les caractéristiques du précodage "zero forcing". L'objectif est alors de partager la puissance disponible entre toutes les sous-porteuses et toutes les antennes. 4) Enfin, dans une dernière étape nous nous intéressons à une conception efficace de la situation de diffusion, afin de déterminer à l aide d outils de géométrie stochastique quelle zone peut être couverte afin qu un pourcentage donné d utilisateurs reçoivent une quantité d information déterminée à l avance. Ceci permet de déterminer la zone de couverture sans mettre en œuvre des simulations intensives. La combinaison de ces outils permet un choix efficace des situations qui relèvent de la diffusion , du multicast et du point à point .The OFDM (Orthogonal Frequency Division Multiplexing) system uses multiple sub-carriers for data transmission. Compared to the single-carrier scheme, the OFDM technique allows optimal settings for high data rate transmission over a frequency selective channel (from the Shannon s capacity point of view). We can, by this way, ensure reliable communication and efficient energy use. When we use OFDM, the sub-carriers use different channels with different attenuations as well. The equal power allocation on each sub-carrier does not ensure an optimal capacity in a peer to peer link. Dynamic power allocation (i.e., assign different amount of power to subcarriers according to the channel) gives better results, assuming that the channel state information is available at the transmitter. Nevertheless, the transmitter does not know the channels to all users when broadcast transmission are used, and the best strategy is to transmit with the same power on all subcarriers. This thesis aims to explore the intermediate situations, and propose appropriate power allocation tools. This intermediate situation is called "multicast": the transmitter, which knows the channel parameters, sends signals to a finite number of users, and it can adapt the transmission using this knowledge. It is an intermediate position between the "peer to peer" and the "broadcast. The goal of this work is to evaluate the gain brought by the knowledge of the channel state information in multicast situation beside the broadcast situation. Obviously, when the number of receivers is very large, the gain will not be appreciable because the signal found on its path a very large number of channels, and a uniform power allocation is near optimal. When the number of users is very low, we will be close to the peer to peer transmission and gains should be more appreciable. We propose some tools to quantify these improvements in the case where the systems have one antenna at the transmitter and the receiver, this case named SISO (Single Input Single Output). We also propose those tools on systems with multiple antennas, called MIMO (Multiple Input Multiple Output). The steps required to do this work are: 1) Assuming that the channel state information of the users are known at the base station, we implement tools, using information theory, to perform power allocation and evaluate the capacities of the systems under study. 2) For multi-user SISO-OFDM scheme, we propose a power allocation algorithm on each subcarrier on multicast situation. 3) For multi-user MIMO-OFDM, we propose an algorithm that exploits the characteristics of the "zero forcing" precoding. The objective is to share the available power among all subcarriers and all antennas. 4) Finally, in a last step we focus on an efficient design of the broadcast situation. We use tools from stochastic geometry to determine which area can be covered, with the aim that a percentage of users can receive a predetermined amount of information. This determines the coverage area without implementing long period simulations. The combination of these tools allows an effective choice between the situations that fall under the "broadcast", "multicast" and "peer to peer" transmissions.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

EBV latent membrane protein 1 abundance correlates with patient age but not with metastatic behavior in north African nasopharyngeal carcinomas

BACKGROUND: Undifferentiated nasopharyngeal carcinomas are rare in a majority of countries but they occur at a high incidence in South China and to a lesser extent in North Africa. They are constantly associated with the Epstein-Barr virus (EBV) regardless of patient geographic origin. In North Africa, the distribution of NPC cases according to patient age is bi-modal with a large group of patients being around 50 years old (80%) and a smaller group below 25 years old. We and others have previously shown that the juvenile form of NPC has distinct biological characteristics including a low amount of p53 and Bcl2 in the tumor tissue and a low level of anti-EBV IgG and IgA in the peripheral blood. RESULTS: To get more insight on potential oncogenic mechanisms specific of these two forms, LMP1 abundance was assessed in 82 NPC patients of both groups, using immuno-histochemistry and semi-quantitative evaluation of tissue staining. Serum levels of anti-EBV antibodies were simultaneously assessed. For LMP1 staining, we used the S12 antibody which has proven to be more sensitive than the common anti-LMP1 CS1-4 for analysis of tissue sections. In all NPC biopsies, at least a small fraction of cells was positively stained by S12. LMP1 abundance was strongly correlated to patient age, with higher amounts of the viral protein detected in specimens of the juvenile form. In contrast, LMP1 abundance was not correlated to the presence of lymph node or visceral metastases, nor to the risk of metastatic recurrence. It was also independent of the level of circulating anti-EBV antibodies. CONCLUSION: The high amount of LMP1 recorded in tumors from young patients confirms that the juvenile form of NPC has specific features regarding not only cellular but also viral gene expression

Reduced frequency of cytotoxic CD56dim CD16+ NK cells leads to impaired antibody-dependent degranulation in EBV-positive classical Hodgkin lymphoma

Around 30–50% of classical Hodgkin lymphoma (cHL) cases in immunocompetent individuals from industrialized countries are associated with the B-lymphotropic Epstein-Barr virus (EBV). Although natural killer (NK) cells exhibit anti-viral and anti-tumoral functions, virtually nothing is known about quantitative and qualitative differences in NK cells in patients with EBV+ cHL vs. EBV- cHL. Here, we prospectively investigated 36 cHL patients without known immune suppression or overt immunodeficiency at diagnosis. All 10 EBV+ cHL patients and 25 out 26 EBV- cHL were seropositive for EBV antibodies, and EBV+ cHL patients presented with higher plasma EBV DNA levels compared to EBV- cHL patients. We show that the CD56dim CD16+ NK cell subset was decreased in frequency in EBV+ cHL patients compared to EBV- cHL patients. This quantitative deficiency translates into an impaired CD56dim NK cell mediated degranulation toward rituximab-coated HLA class 1 negative lymphoblastoid cells in EBV+ compared to EBV- cHL patients. We finally observed a trend to a decrease in the rituximab-associated degranulation and ADCC of in vitro expanded NK cells of EBV+ cHL compared to healthy controls. Our findings may impact on the design of adjunctive treatment targeting antibody-dependent cellular cytotoxicity in EBV+ cHL

The reduction of 4-nitrobenzene diazonium electrografted layer: An electrochemical study coupled to in situ sum-frequency generation spectroscopy

This work describes an electrochemical study of 4-nitrobenzene diazonium (4-NBD) reduction onto glassy carbon (GC) electrode coupled to in situ sum-frequency generation (SFG) spectroscopy. After 4-NBD grafting at 0.3 V vs. saturated calomel electrode (SCE) onto GC, SFG allowed a clear signal assigned to the symmetrical vibration mode of the nitro (NO2) groups to be observed at 1349 cm-1 or 1353 cm-1 depending on whether the spectrum was recorded in air or inside the solution. This result proved that 4-NBD grafting actually occurs at a potential as high as 0.3 V vs. SCE. The combination of SFG data and cyclic voltammetry (CV) also indicated that at such a potential, NO2 groups did not experience reduction process into hydroxylamine (NHOH) or amine (NH2) groups. The electrolysis of grafted NO2 moieties at -0.1 V was followed by CV and in situ by SFG. The exponential decay of the NO2 signal located at 1353 cm-1 vs. electrolysis time was in accordance with a charge transfer-limited reaction rate for a species immobilized at the electrode surface, and allowed a first order kinetic rate constant for NO2 reduction to be estimated k = 0.006 s-1. The integration of the peaks observed on the corresponding cyclic voltammograms (CVs) which were attributed to the NO/NHOH reversible system showed that the NO2 reduction produced both hydroxylamine and amine groups and was not quantitative. The fact that SFG spectroscopy was silent for long electrolysis time values suggested the remaining nitro groups to be located far from the electrode surface, as a consequence of an electron tunneling efficiency which decreased throughout the film thickness. Further electrolysis at -0.8 V allowed the remaining nitro groups to be reduced into NH2 with almost quantitative yields. All these results suggest the existence of a stratified layer during the electrolysis process, in which there is no limitation due to H+ diffusion in the organic film

Beam tests of the trigger and digital processing electronics for the electromagnetic calorimeter of the CMS experiment

A prototype of the trigger and digital processing electronics for the electromagnetic calorimeter of the CMS experiment, coupled to a prototype of the PbWO4 crystal calorimeter, was tested during summer 96 in the H4 beamline at the CERN SPS. A very successful operation was achieved for this system, which runs in synchronous and pipelined mode at the LHC clock frequency, and performs the basic trigger and data acquisition functions needed in the CMS electromagnetic calorimeter. The performance of the trigger front-end electronics is well within the established requirements: a highly efficient bunch crossing identification ( &gt; 99.9%), a good trigger energy resolution ( s/E ~9%/sq( E)+2%) and a highly efficient electron cluster shape identification ( ~99%) have been achieved. The FERMI digitizing system based on a dynamic analog compressor and a sampling ADC showed a very good perform ance, in particular the energy resolution for 150 GeV electrons was 0.54%, equal to the resolution obtained with a conventional charge integration ADC system