142 research outputs found
The role of evolution in the genetic susceptibility of intracranial aneurysm
Les Inuits du Nunavik regroupent des peuples autochtones de l'Arctique qui au fil de lâhistoire ont formĂ© une petite population isolĂ©e dans la rĂ©gion du Nunavik (nord de la province de QuĂ©bec, Canada). Le profil gĂ©nĂ©tique unique des Inuits du Nunavik est le rĂ©sultat dâune adaptation Ă leur milieu de vie et il est considĂ©rĂ© comme liĂ© Ă certaines de leurs susceptibilitĂ©s pathologiques. Une Ă©volution neutre, ainsi quâune suite dâĂ©vĂ©nements adaptatifs, ont façonnĂ© le gĂ©nome de ces Inuits et indirectement engendrĂ© leur prĂ©disposition accrue Ă certains troubles cardio-vasculaires et cĂ©rĂ©bro-vasculaires (ex : hypertension et anĂ©vrismes intracrĂąniens (AI)).
Les AI sont des faiblesses cĂ©rĂ©bro-vasculaires localisĂ©es pouvant mener Ă des dilatations et renflements localisĂ©s de la paroi vasculaire. De telles distorsions sont susceptibles de perturber les vaisseaux et entrainer des hĂ©morragies sous-arachnoĂŻdiennes. Les AI sont un dĂ©sordre complexe dont la prĂ©valence est Ă©levĂ©e (4-8%) et diffĂ©rentes populations (non reliĂ©es aux Inuits) ont aussi un risque accru de dĂ©velopper des AI. Le dĂ©veloppement des AI est associĂ© Ă la fois Ă des facteurs environnementaux et gĂ©nĂ©tiques; plusieurs Ă©tudes gĂ©nomiques ont identifiĂ© des rĂ©gions associĂ©es aux AI. Une grande part de l'hĂ©ritabilitĂ© gĂ©nĂ©tique des AI demeure encore inexpliquĂ©e, en particulier dans des populations autres que les finnois et les japonais. Toutefois il est Ă noter que peu dâĂ©tudes gĂ©nĂ©tiques des AI ont tenu compte de la contribution de variations gĂ©nĂ©tiques spĂ©cifiques Ă la population Ă©tudiĂ©e.
Pour amĂ©liorer nos connaissances sur la part encore inexpliquĂ©e de l'hĂ©ritabilitĂ© des AI (qui implique une grande hĂ©tĂ©rogĂ©nĂ©itĂ© gĂ©nĂ©tique et des variations peu pĂ©nĂ©trantes), nous avons combinĂ© le sĂ©quençage Ă haut dĂ©bit au gĂ©notypage des polymorphismes sur puces afin dâĂ©tablir la signature gĂ©nĂ©tique des deux populations fondatrices du QuĂ©bec prĂ©disposĂ©es aux AI (Inuits du Nunavik et Canadiens français). Comme ces populations ont des caractĂ©ristiques distinctes, nous avons utilisĂ© des approches diffĂ©rentes pour tenter dâidentifier des facteurs de risque gĂ©nĂ©tiques. Les Inuits du Nunavik reprĂ©sentent une population autochtone et de nombreux aspects de leur signature gĂ©nĂ©tique diffĂšrent de celles des principales populations, nous avons choisi dâapprofondir leur histoire et profil gĂ©nomique avant de vĂ©rifier si des associations gĂ©nomiques pouvaient ĂȘtre Ă©tablies avec les IA. Nous avons tout d'abord examinĂ© les rĂ©gions codantes du gĂ©nome et observĂ© de nombreuses composantes gĂ©nĂ©tiques spĂ©cifiques aux Inuits du Nunavik qui reflĂštent que la population sâest adaptĂ©e Ă son environnement (ex: ascendance Inuit homogĂšne, augmentation du dĂ©sĂ©quilibre de liaison et signature gĂ©nĂ©tique). Des signes de sĂ©lection naturelle, jusquâalors non-identifiĂ©s, ont rĂ©vĂ©lĂ© une accumulation de variations gĂ©nĂ©tiques dans des gĂšnes impliquĂ©s dans le processus d'adhĂ©sion cellulaire et de la rĂ©ponse immunitaire (ex. CPNE7 et ICAM5). D'autres analyses ont rĂ©vĂ©lĂ© un variant dans le gĂšne CCM2 qui prĂ©sente une sĂ©lection positive et est significativement associĂ© aux AI chez les Inuits du Nunavik. En ce qui concerne l'Ă©tiologie gĂ©nĂ©tique des AI dans la population des Canadiens français, nous avons adoptĂ© une approche diffĂ©rente et utilisĂ© des variations spĂ©cifiques aux Canadiens français, qui ont Ă©tĂ© identifiĂ©es par le sĂ©quençage complet de l'exome. Ces variations ont permis de gĂ©nĂ©rer une liste de gĂšnes Ă risque potentiel, qui ont ensuite Ă©tĂ© priorisĂ©s en utilisant un test d'association par gĂšne de type « burden ». RNF213 est apparu comme le meilleur gĂšne candidat; il est vraisemblablement la consĂ©quence dâune dĂ©rive gĂ©nĂ©tique. Les mesures gĂ©nĂ©tiques et fonctionnelles subsĂ©quentes ont validĂ© la contribution possible de RNF213 au dĂ©veloppement des AI chez les Canadiens français. Les rĂ©sultats prĂ©sentĂ©s dans cette thĂšse soulignent l'importance de prendre en compte le contexte gĂ©nĂ©tique spĂ©cifique apportĂ© par l'Ă©volution lorsqu'une maladie complexe est Ă©tudiĂ©e. Il a Ă©galement Ă©tĂ© montrĂ© que les variations dâun gĂšne spĂ©cifique (ex. CCM2 et RNF213) peuvent contribuer au dĂ©veloppement de diffĂ©rentes pathologies lorsqu'ils sont observĂ©s dans des populations distinctes. D'une maniĂšre gĂ©nĂ©rale, nos dĂ©couvertes gĂ©nĂ©tiques ont permis dâidentifier de nouvelles « piĂšces » gĂ©nĂ©tiques et pour avancer le « casse-tĂȘte » incomplet de l'hĂ©ritabilitĂ© gĂ©nĂ©tique des AI ; la gĂ©nĂ©tique des populations a Ă©tĂ© un Ă©lĂ©ment clĂ© pour cette avancĂ©e.Nunavik Inuit is a group of Arctic indigenous people, who have historically presented as a small and isolated population across the Nunavik region of northern Quebec (Canada). The unique genetic profile of Nunavik Inuit is the result of years of adaptation to their living condition, and it is likely responsible for their increased susceptibility to certain pathological conditions. Prior studies have shown that as a consequence of neutral evolution or past adaptive events, todayâs Inuit are predisposed to cardio-cerebrovascular disorders, e.g. hypertension and intracranial aneurysm (IA).
IA is defined as localized cerebrovascular weakness which leads to vascular dilation or ballooning, and such distortions are susceptible to disrupt the affected vessels and lead to subarachnoid hemorrhage. It is a complex disorder with a high prevalence (4-8%) and certain populations have been observed to present an increased risk of developing IA. Both environmental and genetic factors are deemed to contribute to the development of IA and in regards to the latter, independent genome-wide association studies (GWAS) have identified multiple loci associated with IA. Nonetheless, there is still a large portion of the genetic heritability of IA, especially in different populations other than Finnish and Japanese that remains unexplained. However, fewer IA genetic studies have taken in consideration the contribution of population specific genetic variants.
To address some of the IA missing heritability that is deemed to be accountable to its genetic heterogeneity and low penetrance, we have combined high throughput sequencing (HTS) with SNP-chip genotyping to examine the genetic signatures of two founder populations from Quebec that are predisposed to IA, including Nunavik Inuit and French-Canadians (FC). Because these populations have distinct genetic characteristics, we used different approaches for the identification of genetic risk factors. Nunavik Inuit is an indigenous population and many aspects of its genetic signatures differ from those of separate world-wide major populations; therefore we chose to conduct extensive population genetic studies in regards to their genetic history and genomic profile before we undertook to test if any association could be established between genomic loci and disease susceptibility. We observed many genetic components that are specific to the Nunavik Inuit population, including its homogeneous Inuit ancestry, increased linkage disequilibrium (LD) and genetic signatures which reflect the population had a long history of adaptations to their environment. Previously unidentified signals of natural selection, which focused on coding regions of the genome revealed an accumulation of genetic variants in genes involved in the processes of cell adhesion and immune responses (e.g. CPNE7 and ICAM5). Further analyses revealed a variant in CCM2 to be under positive selection and significantly associated with IA in Nunavik Inuit. In regard to the genetic etiology of IA in the French-Canadian population, we took a different approach and used French-Canadian specific variants that were identified by whole exome sequencing to generate a list of potential risk genes; which were further prioritized using a gene based burden association test. RNF213 emerged as a prime candidate gene that had undergone possible genetic drift and the follow-up genetic and functional examinations further supported its potential contribution to the development of IA among French-Canadians. The results presented in this thesis highlighted the importance of taking into consideration the specific genetic background brought by natural selection or genetic drift, both are driving forces of evolution, when a complex disease is being studied. It also further confirmed that variants in a specific gene (e.g. RNF213 or CCM2) may contribute to the development of different pathogenesis when examined in distinct populations. Overall as our genetic findings identified new genetic âpiecesâ that further completed the missing heritability âpuzzleâ of IA genetics; evidence for these âpiecesâ were interestingly highlighted through population genetics
Numerical Security Analysis of Three-State Quantum Key Distribution Protocol with Realistic Devices
Quantum key distribution (QKD) is a secure communication method that utilizes
the principles of quantum mechanics to establish secret keys. The central task
in the study of QKD is to prove security in the presence of an eavesdropper
with unlimited computational power. In this work, we successfully solve a
long-standing open question of the security analysis for the three-state QKD
protocol with realistic devices, i,e, the weak coherent state source. We prove
the existence of the squashing model for the measurement settings in the
three-state protocol. This enables the reduction of measurement dimensionality,
allowing for key rate computations using the numerical approach. We conduct
numerical simulations to evaluate the key rate performance. The simulation
results show that we achieve a communication distance of up to 200 km.Comment: 14 pages, 5 figure
A hybrid algorithm for quadratically constrained quadratic optimization problems
Quadratically Constrained Quadratic Programs (QCQPs) are an important class
of optimization problems with diverse real-world applications. In this work, we
propose a variational quantum algorithm for general QCQPs. By encoding the
variables on the amplitude of a quantum state, the requirement of the qubit
number scales logarithmically with the dimension of the variables, which makes
our algorithm suitable for current quantum devices. Using the primal-dual
interior-point method in classical optimization, we can deal with general
quadratic constraints. Our numerical experiments on typical QCQP problems,
including Max-Cut and optimal power flow problems, demonstrate a better
performance of our hybrid algorithm over the classical counterparts.Comment: 8 pages, 3 figure
Association between -238 but not -308 polymorphism of Tumor necrosis factor alpha (TNF-alpha)v and unexplained recurrent spontaneous abortion (URSA) in Chinese population
<p>Abstract</p> <p>Objectives</p> <p>TNF-alpha is a critical cytokine produced by Th1 cells while altered T helper 1 (Th1)-Th2 balance is found crucial for a successful pregnancy.</p> <p>Study Design</p> <p>A cohort of 132 Southern Chinese Han RSA patients and 152 controls constituted the subjects of this study. Two functional polymorphisms -308 and -238 of TNF-alpha were studied by association analysis.</p> <p>Results</p> <p>lack of association was found in TNF-alpha -308 SNP yet a significant difference was discovered in -238 polymorphism.</p> <p>Conclusion</p> <p>This study suggested that TNF-alpha may be a risk factor in Chinese RSA patients. However the ethnic differences may also contribute to the results.</p
Mutation analysis of the WNT4 gene in Han Chinese women with premature ovarian failure
BACKGROUND: The WNT4 gene plays an important role in female sex determination and differentiation. It also contributes to maintaining of the ovaries and the survival of follicles. METHODS: We sequenced the coding region and splice sites of WNT4 in 145 Han Chinese women with premature ovarian failure (POF) and 200 healthy controls. RESULTS: Only one novel variation, in Exon 2 (195C > T), was detected among the women with POF. However, this synonymous variation did not result in a change in amino acid sequence (65 Asp > Asp). No further variants were found in any of the samples. CONCLUSION: Although we cannot provide any evidence that it is a possible disease-causing gene, this study is the first attempt to investigate the possible role of WNT4 in Han Chinese women with POF
ASSIST: Interactive Scene Nodes for Scalable and Realistic Indoor Simulation
We present ASSIST, an object-wise neural radiance field as a panoptic
representation for compositional and realistic simulation. Central to our
approach is a novel scene node data structure that stores the information of
each object in a unified fashion, allowing online interaction in both intra-
and cross-scene settings. By incorporating a differentiable neural network
along with the associated bounding box and semantic features, the proposed
structure guarantees user-friendly interaction on independent objects to scale
up novel view simulation. Objects in the scene can be queried, added,
duplicated, deleted, transformed, or swapped simply through mouse/keyboard
controls or language instructions. Experiments demonstrate the efficacy of the
proposed method, where scaled realistic simulation can be achieved through
interactive editing and compositional rendering, with color images, depth
images, and panoptic segmentation masks generated in a 3D consistent manner
Direct-Current Generator Based on Dynamic Water-Semiconductor Junction with Polarized Water as Moving Dielectric Medium
There is a rising prospective in harvesting energy from water droplets, as
microscale energy is required for the distributed sensors in the interconnected
human society. However, achieving a sustainable direct-current generating
device from water flow is rarely reported, and the quantum polarization
principle of the water molecular remains uncovered. Herein, we propose a
dynamic water-semiconductor junction with moving water sandwiched between two
semiconductors as a moving dielectric medium, which outputs a sustainable
direct-current voltage of 0.3 V and current of 0.64 uA with low internal
resistance of 390 kilohm. The sustainable direct-current electricity is
originating from the dynamic water polarization process in water-semiconductor
junction, in which water molecules are continuously polarized and depolarized
driven by the mechanical force and Fermi level difference, during the movement
of the water on silicon. We further demonstrated an encapsulated portable
power-generating device with simple structure and continuous direct-current
voltage, which exhibits its promising potential application in the field of
wearable electronic generators
A Novel CRYGD Mutation (p.Trp43Arg) Causing Autosomal Dominant Congenital Cataract in a Chinese Family
To identify the genetic defect associated with autosomal dominant congenital nuclear cataract in a Chinese family, molecular genetic investigation via haplotype analysis and direct sequencing were performed Sequencing of the CRYGD gene revealed a c.127T>C transition, which resulted in a substitution of a highly conserved tryptophan with arginine at codon 43 (p.Trp43Arg). This mutation co-segregated with all affected individuals and was not observed in either unaffected family members or in 200 normal unrelated individuals. Biophysical studies indicated that the p.Trp43Arg mutation resulted in significant tertiary structural changes. The mutant protein was much less stable than the wild-type protein, and was more prone to aggregate when subjected to environmental stresses such as heat and UV irradiation. © 2010 Wiley-Liss, Inc
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