Directed integration of new insulated lentiviral vectors to heterochromatin towards safer gene transfer to stem cells

The need for better gene transfer systems towards improved risk=benefit balance for patients remains a major challenge in the clinical translation of gene therapy (GT). We have investigated the improvement of integrating vectors safety in combining (i) new short synthetic genetic insulator elements (GIE) and (ii) directing genetic integration to heterochromatin. We have designed SIN-insulated retrovectors with two candidate GIEs and could identify a specific combination of insulator 2 repeats which translates into best functional activity, high titers and boundary effect in both gammaretro (p20) and lentivectors (DCaro4) (see Duros et al, abstract ibid). Since GIEs are believed to shield the transgenic cassette from inhibitory effects and silencing, DCaro4 has been further tested with chimeric HIV-1 derived integrases which comprise C-ter chromodomains targeting heterochromatin through either histone H3 (ML6chimera) or methylatedCpGislands (ML10). With DCaro4 only and both chimeras, a homogeneous expression is evidenced in over 20% of the cells which is sustained over time. With control lentivectors, less than 2% of cells express GFP as compared to background using a control double-mutant in both catalytic and ledgf binding-sites; in addition, a two-times increase of expression can be induced with histone deacetylase inhibitors. Our approach could significantly reduce integration into open chromatin sensitive sites in stem cells at the time of transduction, a feature which might significantly decrease subsequent genotoxicity, according to X-SCIDs patients data.Work performed with the support of EC-DG research within the FP6-Network of Excellence, CLINIGENE: LSHB-CT-2006-018933

Impact of a cis-associated gene expression SNP on chromosome 20q11.22 on bipolar disorder susceptibility, hippocampal structure and cognitive performance.

BackgroundBipolar disorder is a highly heritable polygenic disorder. Recent enrichment analyses suggest that there may be true risk variants for bipolar disorder in the expression quantitative trait loci (eQTL) in the brain.AimsWe sought to assess the impact of eQTL variants on bipolar disorder risk by combining data from both bipolar disorder genome-wide association studies (GWAS) and brain eQTL.MethodTo detect single nucleotide polymorphisms (SNPs) that influence expression levels of genes associated with bipolar disorder, we jointly analysed data from a bipolar disorder GWAS (7481 cases and 9250 controls) and a genome-wide brain (cortical) eQTL (193 healthy controls) using a Bayesian statistical method, with independent follow-up replications. The identified risk SNP was then further tested for association with hippocampal volume (n = 5775) and cognitive performance (n = 342) among healthy individuals.ResultsIntegrative analysis revealed a significant association between a brain eQTL rs6088662 on chromosome 20q11.22 and bipolar disorder (log Bayes factor = 5.48; bipolar disorder P = 5.85×10(-5)). Follow-up studies across multiple independent samples confirmed the association of the risk SNP (rs6088662) with gene expression and bipolar disorder susceptibility (P = 3.54×10(-8)). Further exploratory analysis revealed that rs6088662 is also associated with hippocampal volume and cognitive performance in healthy individuals.ConclusionsOur findings suggest that 20q11.22 is likely a risk region for bipolar disorder; they also highlight the informative value of integrating functional annotation of genetic variants for gene expression in advancing our understanding of the biological basis underlying complex disorders, such as bipolar disorder.

I must walk through the gate : an ontological necessity

This research is a self-study into my life as an athlete, elementary school teacher, leamer, and as a teacher educator/academic. Throughout the inquiry, I explore how my beliefs and values infused my lived experiences and ultimately influenced my constructivist, humanist, and ultimately my holistic teaching and learning practice which at times disrupted the status quo. I have written a collection of narratives (data generation) which embodied my identity as an unintelligent student/leamer, a teacher/learner, an experiential learner, a tenacious participant, and a change agent to name a few. As I unpack my stories and hermeneutically reconstruct their intent, I question their meaning as I explore how I can improve my teaching and learning practice and potentially effect positive change when instructing beginning teacher candidates at a Faculty of Education. At the outset I situate my story and provide the necessary political, social, and cultural background information to ground my research. I follow this with an in depth look at the elements that interconnect the theoretical framework of this self-study by presenting the notion of writing at the boundaries through auto ethnography (Ellis, 2000; Ellis & Bochner, 2004) and writing as a method of inquiry (Richardson, 2000). The emergent themes of experiential learning, identity, and embodied knowing surfaced during the data generation phase. I use the Probyn' s (1990) .. metaphor of locatedness to unpack these themes and ponder the question, Where is experience located? I deepen the exploration by layering Drake's (2007) KnowlDo/Be framework alongside locatedness and offer descriptions of learning moments grounded in pedagogical theories. In the final phase, I introduce thirdspace theory (Bhabha, 1994; Soja, 1996) as a space that allowed me to puzzle educational dilemmas and begin to reconcile the binaries that existed in my life both personally, and professionally. I end where I began by revisiting the questions that drove this study. In addition, Ireflect upon the writing process and the challenges that I encountered while immersed in this approach and contemplate the relevance of conducting a self-study. I leave the reader with what is waiting for me on the other side of the gate, for as Henry James suggested, "Experience is never limited, and it is never complete."

La responsabilidad civil extracontractual hacia un sistema bipolar.

Tesis (Doctor en Derecho) UANL, 2012.

Amorphous Oxide Transparent Thin Films: Growth, Characterisation and Application to Thin Film Transistors

This work mainly concentrate to understand the optical and electrical properties of amorphous zinc tin oxide and amorphous zinc indium tin oxide thin films for TFT applications. Amorphous materials are promising in achieving better device performance on temperature sensitive substrates compared to polycrystalline materials. Most of these amorphous oxides are multicomponent and as such there exists the need for an optimized chemical composition. For this we have to make individual targets with required chemical composition to use it in conventional thin film deposition techniques like PLD and sputtering. Instead, if we use separate targets for each of the cationic element and if separately control the power during the simultaneous sputtering process, then we can change the chemical composition by simply adjusting the sputtering power. This is what is done in co-sputtering technique. Eventhough there had some reports about thin film deposition using this technique, there was no reports about the use of this technique in TFT fabrication until very recent time. Hence in this work, co-sputtering has performed as a major technique for thin film deposition and TFT fabrication. PLD were also performed as it is a relatively new technique and allows the use high oxygen pressure during deposition. This helps to control the carrier density in the channel and also favours the smooth film surface. Both these properties are crucial in TFT.Zinc tin oxide material is interesting in the sense that it does not contain costly indium. Eventhough some works were already reported in ZTO based TFTs, there was no systematic study about ZTO thin film's various optoelectronic properties from a TFT manufacturing perspective. Attempts have made to analyse the ZTO films prepared by PLD and co-sputtering. As more type of cations present in the film, chances are high to form an amorphous phase. Zinc indium tin oxide is studied as a multicomponent oxide material suitable for TFT fabrication.

Preparation and Characterization ofHigh-k Aluminum Oxide Thin Films by Atomic Layer Deposition for Gate Dielectric Applications

Present work deals with the Preparation and characterization of high-k aluminum oxide thin films by atomic layer deposition for gate dielectric applications.The ever-increasing demand for functionality and speed for semiconductor applications requires enhanced performance, which is achieved by the continuous miniaturization of CMOS dimensions. Because of this miniaturization, several parameters, such as the dielectric thickness, come within reach of their physical limit. As the required oxide thickness approaches the sub- l nm range, SiO 2 become unsuitable as a gate dielectric because its limited physical thickness results in excessive leakage current through the gate stack, affecting the long-term reliability of the device. This leakage issue is solved in the 45 mn technology node by the integration of high-k based gate dielectrics, as their higher k-value allows a physically thicker layer while targeting the same capacitance and Equivalent Oxide Thickness (EOT). Moreover, Intel announced that Atomic Layer Deposition (ALD) would be applied to grow these materials on the Si substrate. ALD is based on the sequential use of self-limiting surface reactions of a metallic and oxidizing precursor. This self-limiting feature allows control of material growth and properties at the atomic level, which makes ALD well-suited for the deposition of highly uniform and conformal layers in CMOS devices, even if these have challenging 3D topologies with high aspect-ratios. ALD has currently acquired the status of state-of-the-art and most preferred deposition technique, for producing nano layers of various materials of technological importance. This technique can be adapted to different situations where precision in thickness and perfection in structures are required, especially in the microelectronic scenario.

Organic field-effect transistors and phototransistors based on amorphous materials

A comparison between the charge transport properties in low molecular amorphous thin films of spiro-linked compound and their corresponding parent compound has been demonstrated. The field-effect transistor method is used for extracting physical parameters such as field-effect mobility of charge carriers, ON/OFF ratios, and stability. In addition, phototransistors have been fabricated and demonstrated for the first time by using organic materials. In this case, asymmetrically spiro-linked compounds are used as active materials. The active materials used in this study can be divided into three classes, namely Spiro-linked compounds (symmetrically spiro-linked compounds), the corresponding parent-compounds, and photosensitive spiro-linked compounds (asymmetrically spiro-linked com-pounds). Some of symmetrically spiro-linked compounds used in this study were 2,2',7,7'-Tetrakis-(di-phenylamino)-9,9'-spirobifluorene (Spiro-TAD),2,2',7,7'-Tetrakis-(N,N'-di-p-methylphenylamino)-9,9'-spirobifluorene (Spiro-TTB), 2,2',7,7'-Tetra-(m-tolyl-phenylamino)-9,9'-spirobifluorene (Spiro-TPD), and 2,2Ž,7,7Ž-Tetra-(N-phenyl-1-naphtylamine)-9,9Ž-spirobifluorene (Spiro alpha-NPB). Related parent compounds of the symmetrically spiro-linked compound used in this study were N,N,N',N'-Tetraphenylbenzidine (TAD), N,N,N',N'-Tetrakis(4-methylphenyl)benzidine (TTB), N,N'-Bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), and N,N'-Diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (alpha-NPB). The photosensitive asymmetrically spiro-linked compounds used in this study were 2,7-bis-(N,N'-diphenylamino)-2',7'-bis(biphenyl-4-yl)-9,9'-spirobifluorene (Spiro-DPSP), and 2,7-bis-(N,N'-diphenylamino)-2',7'-bis(spirobifluorene-2-yl)-9,9'-spirobifluorene (Spiro-DPSP^2). It was found that the field-effect mobilities of charge carriers in thin films of symmetrically spiro-linked compounds and their corresponding parent compounds are in the same order of magnitude (~10^-5 cm^2/Vs). However, the thin films of the parent compounds were easily crystallized after the samples have been exposed in ambient atmosphere and at room temperature for three days. In contrast, the thin films and the transistor characteristics of symmetrically spiro-linked compound did not change significantly after the samples have been stored in ambient atmosphere and at room temperature for several months. Furthermore, temperature dependence of the mobility was analyzed in two models, namely the Arrhenius model and the Gaussian Disorder model. The Arrhenius model tends to give a high value of the prefactor mobility. However, it is difficult to distinguish whether the temperature behaviors of the material under consideration follows the Arrhenius model or the Gaussian Disorder model due to the narrow accessible range of the temperatures. For the first time, phototransistors have been fabricated and demonstrated by using organic materials. In this case, asymmetrically spiro-linked compounds are used as active materials. Intramolecular charge transfer between a bis(diphenylamino)biphenyl unit and a sexiphenyl unit leads to an increase in charge carrier density, providing the amplification effect. The operational responsivity of better than 1 A/W can be obtained for ultraviolet light at 370 nm, making the device interesting for sensor applications. This result offers a new potential application of organic thin film phototransistors as low-light level and low-cost visible blind ultraviolet photodetectors.