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Telomere crisis occurs during tumorigenesis when depletion of the telomere reserve leads to frequent telomere fusions. The resulting dicentric chromosomes have been proposed to drive genome instability. Here, we examine the fate of dicentric human chromosomes in telomere crisis. We observed that dicentric chromosomes invariably persisted through mitosis and developed into 50-200 µm chromatin bridges connecting the daughter cells. Before their resolution at 3-20 hr after anaphase, the chromatin bridges induced nuclear envelope rupture in interphase, accumulated the cytoplasmic 3' nuclease TREX1, and developed RPA-coated single stranded (ss) DNA. CRISPR knockouts showed that TREX1 contributed to the generation of the ssDNA and the resolution of the chromatin bridges. Post-crisis clones showed chromothripsis and kataegis, presumably resulting from DNA repair and APOBEC editing of the fragmented chromatin bridge DNA. We propose that chromothripsis in human cancer may arise through TREX1-mediated fragmentation of dicentric chromosomes formed in telomere crisis.
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Instabilidade Cromossômica , Cromossomos Humanos , Instabilidade Genômica , Neoplasias/genética , Telômero , Aberrações Cromossômicas , Citocinese , DNA de Cadeia Simples/metabolismo , Exodesoxirribonucleases/metabolismo , Humanos , Mitose , Membrana Nuclear/metabolismo , Fosfoproteínas/metabolismoRESUMO
A key mutational process in cancer is structural variation, in which rearrangements delete, amplify or reorder genomic segments that range in size from kilobases to whole chromosomes1-7. Here we develop methods to group, classify and describe somatic structural variants, using data from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA), which aggregated whole-genome sequencing data from 2,658 cancers across 38 tumour types8. Sixteen signatures of structural variation emerged. Deletions have a multimodal size distribution, assort unevenly across tumour types and patients, are enriched in late-replicating regions and correlate with inversions. Tandem duplications also have a multimodal size distribution, but are enriched in early-replicating regions-as are unbalanced translocations. Replication-based mechanisms of rearrangement generate varied chromosomal structures with low-level copy-number gains and frequent inverted rearrangements. One prominent structure consists of 2-7 templates copied from distinct regions of the genome strung together within one locus. Such cycles of templated insertions correlate with tandem duplications, and-in liver cancer-frequently activate the telomerase gene TERT. A wide variety of rearrangement processes are active in cancer, which generate complex configurations of the genome upon which selection can act.
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Variação Genética , Genoma Humano/genética , Neoplasias/genética , Rearranjo Gênico/genética , Genômica , Humanos , Mutagênese Insercional , Telomerase/genéticaRESUMO
The discovery of drivers of cancer has traditionally focused on protein-coding genes1-4. Here we present analyses of driver point mutations and structural variants in non-coding regions across 2,658 genomes from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium5 of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). For point mutations, we developed a statistically rigorous strategy for combining significance levels from multiple methods of driver discovery that overcomes the limitations of individual methods. For structural variants, we present two methods of driver discovery, and identify regions that are significantly affected by recurrent breakpoints and recurrent somatic juxtapositions. Our analyses confirm previously reported drivers6,7, raise doubts about others and identify novel candidates, including point mutations in the 5' region of TP53, in the 3' untranslated regions of NFKBIZ and TOB1, focal deletions in BRD4 and rearrangements in the loci of AKR1C genes. We show that although point mutations and structural variants that drive cancer are less frequent in non-coding genes and regulatory sequences than in protein-coding genes, additional examples of these drivers will be found as more cancer genomes become available.
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Genoma Humano/genética , Mutação/genética , Neoplasias/genética , Quebras de DNA , Bases de Dados Genéticas , Regulação Neoplásica da Expressão Gênica , Estudo de Associação Genômica Ampla , Humanos , Mutação INDELRESUMO
In the Methods section of this Article, 'greater than' should have been 'less than' in the sentence 'Putative regions of clustered rearrangements were identified as having an average inter-rearrangement distance that was at least 10 times greater than the whole-genome average for the individual sample.â'. The Article has not been corrected.
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Pancreatic cancer is a highly fatal disease, and existing treatment methods are ineffective, so it is urgent to develop new effective treatment strategies. The high dependence of pancreatic cancer cells on glucose and glutamine suggests that disrupting this dependency could serve as an alternative strategy for pancreatic cancer therapy. We identified the vital genes glucose transporter 1 (GLUT1) and alanine-serine-cysteine transporter 2 (ASCT2) through bioinformatics analysis, which regulate glucose and glutamine metabolism in pancreatic cancer, respectively. Human serum albumin nanoparticles (HSA NPs) for delivery of GLUT1 and ASCT2 inhibitors, BAY-876/V-9302@HSA NPs, were prepared by a self-assembly process. This nanodrug inhibits glucose and glutamine uptake of pancreatic cancer cells through the released BAY-876 and V-9302, leading to nutrition deprivation and oxidative stress. The inhibition of glutamine leads to the inhibition of the synthesis of the glutathione, which further aggravates oxidative stress. Both of them lead to a significant increase in reactive oxygen species, activating caspase 1 and GSDMD and finally inducing pyroptosis. This study provides a new effective strategy for orthotopic pancreatic cancer treatment by dual starvation-induced pyroptosis. The study for screening metabolic targets using bioinformatics analysis followed by constructing nanodrugs loaded with inhibitors will inspire future targeted metabolic therapy for pancreatic cancer.
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Glucose , Glutamina , Neoplasias Pancreáticas , Piroptose , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Humanos , Glutamina/química , Glutamina/metabolismo , Glucose/metabolismo , Piroptose/efeitos dos fármacos , Sistema ASC de Transporte de Aminoácidos/metabolismo , Sistema ASC de Transporte de Aminoácidos/antagonistas & inibidores , Nanopartículas/química , Transportador de Glucose Tipo 1/metabolismo , Transportador de Glucose Tipo 1/antagonistas & inibidores , Linhagem Celular Tumoral , Antineoplásicos/farmacologia , Antineoplásicos/química , Antígenos de Histocompatibilidade Menor/metabolismo , Sistema y+ de Transporte de AminoácidosRESUMO
OBJECTIVE: To evaluate the effect of perioperative dexamethasone on postoperative complications after pancreaticoduodenectomy. BACKGROUND: The glucocorticoid dexamethasone has been shown to improve postoperative outcomes in surgical patients, but its effects on postoperative complications after pancreaticoduodenectomy are unclear. METHODS: This multicenter, double-blind, randomized controlled trial was conducted in four Chinese high-volume pancreatic centers. Adults undergoing elective pancreaticoduodenectomy were randomized to receive either 0.2 mg/kg dexamethasone or a saline placebo as an intravenous bolus within 5 minutes after anesthesia induction. The primary outcome was the Comprehensive Complication Index (CCI) score within 30 days after the operation, analyzed using the modified intention-to-treat principle. RESULTS: Among 428 patients for eligibility, 300 participants were randomized and 265 were included in the modified intention-to-treat analyses. One hundred thirty-four patients received dexamethasone and 131 patients received a placebo. The mean (SD) CCI score was 14.0 (17.5) in the dexamethasone group and 17.9 (20.3) in the placebo group (mean difference: -3.8; 95% CI: -8.4 to 0.7; P = 0.100). The incidence of major complications (Clavien-Dindo grade ≥III; 12.7% vs 16.0%, risk ratio: 0.79; 95% CI: 0.44 to 1.43; P = 0.439) and postoperative pancreatic fistula (25.4% vs 31.3%, risk ratio: 0.81; 95% CI: 0.55 to 1.19; P = 0.286) were not significantly different between the two groups. In the stratum of participants with a main pancreatic duct ≤3 mm (n = 202), the CCI score was significantly lower in the dexamethasone group (mean difference: -6.4; 95% CI: -11.2 to -1.6; P = 0.009). CONCLUSIONS: Perioperative dexamethasone did not significantly reduce postoperative complications within 30 days after pancreaticoduodenectomy.
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Dexametasona , Pancreaticoduodenectomia , Complicações Pós-Operatórias , Humanos , Pancreaticoduodenectomia/efeitos adversos , Dexametasona/uso terapêutico , Dexametasona/administração & dosagem , Masculino , Método Duplo-Cego , Feminino , Complicações Pós-Operatórias/prevenção & controle , Pessoa de Meia-Idade , Idoso , Glucocorticoides/administração & dosagem , Glucocorticoides/uso terapêutico , Assistência Perioperatória/métodos , Resultado do Tratamento , AdultoRESUMO
BACKGROUND: Obstructive Sleep Apnea (OSA) is a widespread sleep disturbance linked to metabolic and cardiovascular conditions. The Non-High-Density Lipoprotein Cholesterol to High-Density Lipoprotein Cholesterol Ratios (NHHR) has been proposed as being a potential biomarker to gauge cardiovascular risk. However, its relationship with OSA remains unclear. METHODS: This survey investigated the link NHHR to OSA in American citizens aged 20 and older using information collected via the National Health and Nutrition Examination Survey (NHANES) during the years 2017 to 2020. Logistic regression models with multivariable adjustments were employed to assess this relationship. Nonlinear associations were explored using smooth curve fitting, with a two-part linear regression model identifying a threshold effect. Subgroup analyses were conducted to evaluate population-specific differences. RESULTS: The survey encompassed 6763 participants, with an average age of 50.75 ± 17.32. The average NHHR stood at 2.74, accompanied by a standard deviation of 1.34, while the average frequency of OSA was 49.93%. Upon adjusting for covariates, each unit increase in NHHR may be associated with a 9% rise in OSA incidence. (95% confidence intervals 1.04-1.14; P < 0.0001). Notably, a U-shaped curve depicted the NHHR-OSA relationship, with an inflection point at 4.12. Subgroup analyses revealed consistent associations, with educational attainment and diabetes status modifying the NHHR-OSA relationship. CONCLUSION: The study highlights NHHR as a potential tool for OSA prediction, presenting avenues for advanced risk evaluation, tailored interventions, personalized treatment approaches, and preventive healthcare.
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HDL-Colesterol , Inquéritos Nutricionais , Apneia Obstrutiva do Sono , Humanos , Apneia Obstrutiva do Sono/sangue , Apneia Obstrutiva do Sono/epidemiologia , Pessoa de Meia-Idade , Masculino , Feminino , Estudos Transversais , Adulto , HDL-Colesterol/sangue , Idoso , Fatores de Risco , Biomarcadores/sangue , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/epidemiologiaRESUMO
Screen-printed carbon electrodes (SPCE) functionalized with MXene-based three-dimensional nanomaterials are reported for rapid determination of creatinine. Ti3C2TX MXene with in situ reduced AuNPs (MXene@AuNP) were used as a coreactant accelerator for efficient immobilization of enzymes. Creatinine could be oxidized by chitosan-embedded creatinine amidohydrolase, creatine amidinohydrolase, or sarcosine oxidase to generate H2O2, which could be electrochemically detected enhanced by Prussian blue (PB). The enzyme@CS/PB/MXene@AuNP/SPCE detected creatinine within the range 0.03-4.0 mM, with a limit of detection of 0.01 mM, with an average recovery of 96.8-103.7%. This indicates that the proposed biosensor is capable of detecting creatinine in a short amount of time (4 min) within a ± 5% percentage error, in contrast with the standard clinical colorimetric method. With this approach, reproducible and stable electrochemical responses could be achieved for determination of creatinine in serum, urine, or saliva. These results demonstrated its potential for deployment in resource-limited settings for early diagnosis and tracking the progression of chronic kidney disease (CKD).
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Técnicas Biossensoriais , Carbono , Creatinina , Técnicas Eletroquímicas , Eletrodos , Ferrocianetos , Ouro , Peróxido de Hidrogênio , Limite de Detecção , Nanopartículas Metálicas , Sarcosina Oxidase , Ureo-Hidrolases , Creatinina/sangue , Creatinina/urina , Carbono/química , Humanos , Sarcosina Oxidase/química , Ouro/química , Técnicas Biossensoriais/métodos , Técnicas Biossensoriais/instrumentação , Ferrocianetos/química , Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/instrumentação , Peróxido de Hidrogênio/química , Nanopartículas Metálicas/química , Ureo-Hidrolases/química , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Quitosana/química , Testes Imediatos , Amidoidrolases , TitânioRESUMO
Wearable sensors, specifically microneedle sensors based on electrochemical methods, have expanded extensively with recent technological advances. Today's wearable electrochemical sensors present specific challenges: they show significant modulus disparities with skin tissue, implying possible discomfort in vivo, especially over extended wear periods or on sensitive skin areas. The sensors, primarily based on polyethylene terephthalate (PET) or polyimide (PI) substrates, might also cause pressure or unease during insertion due to the skin's irregular deformation. To address these constraints, we developed an innovative, wearable, all-fiber-structured electrochemical sensor. Our composite sensor incorporates polyurethane (PU) fibers prepared via electrospinning as electrode substrates to achieve excellent adaptability. Electrospun PU nanofiber films with gold layers shaped via thermal evaporation are used as base electrodes with exemplary conductivity and electrochemical catalytic attributes. To achieve glucose monitoring, gold nanofibers functionalized by gold nanoflakes (AuNFs) and glucose oxidase (GOx) serve as the working electrode, while Pt nanofibers and Ag/AgCl nanofibers serve as the counter and reference electrode. The acrylamide-sodium alginate double-network hydrogel synthesized on electrospun PU fibers serves as the adhesive and substance-transferring layer between the electrodes. The all-fiber electrochemical sensor is assembled layer-by-layer to form a robust structure. Given the stretchability of PU nanofibers coupled with a high specific surface area, the manufactured porous microneedle glucose sensor exhibits enhanced stretchability, superior sensitivity at 31.94 µA (lg(mM))-1 cm-2, a broad detection range (1-30 mM), and a significantly low detection limit (1 mM, S/N = 3), as well as satisfactory biocompatibility. Therefore, the novel electrochemical microneedle design is well-suited for wearable or even implantable continuous monitoring applications, thereby showing promising significant potential within the global arena of wearable medical technology.
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Técnicas Biossensoriais , Nanofibras , Poliuretanos , Dispositivos Eletrônicos Vestíveis , Humanos , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Poliuretanos/química , Nanofibras/química , Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Glucose Oxidase/química , Glucose/análiseRESUMO
Due to the acceleration of urbanization and industrialization, air pollutants has been increasing, posing a major threat to human health and the ecological environment. During the past period of rapid growth, with the booming development of real estate, the air pollutants brought about by the construction of housing buildings have become more and more serious, especially sulfur dioxide, nitrogen dioxide, and dust, which cast a great threat to human life and seriously jeopardize human health. Compared with the traditional construction of houses, prefabricated buildings construction procedures are reduced, to some extent, can reduce air pollutants. Therefore, this paper takes an empirical perspective to include prefabricated buildings and air pollutants into the same research framework and analyze the inherent logical relationship. We found that prefabricated buildings have a substantial role in mitigating urban air pollution. This conclusion remained solid after various robustness tests including constructing instrumental variables. The effect is observed to be greater in cities above the non-sub-provincial level and those positioned within central regions. The conclusions explore new areas for the green and sustainable development of the construction industry, which in the future will have to fill the requirements of green development in order to survive. Else, perspectives from the construction industry, it provides a realistic solution to economic development and ecological protection, helping to alleviate or resolve the conflict between development and survival.
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Poluentes Atmosféricos , Poluição do Ar , Humanos , Poluição do Ar/prevenção & controle , Poeira , China , CidadesRESUMO
Emerging evidence has indicated that long noncoding RNAs (lncRNAs) are potential biomarkers and play crucial roles in cancer development. However, the functions and underlying mechanisms of lncRNA TPT1-AS1 in pancreatic ductal adenocarcinoma (PDAC) remain elusive. RNAseq data of PDAC tissues and normal tissues were analyzed, and lncRNAs which were associated with PDAC prognosis were identified. The clinical relevance of TPT1-AS1 for PDAC patients was explored, and the effects of TPT1-AS1 in PDAC progression were investigated in vitro and in vivo. LncRNA TPT1-AS1 was highly expressed in PDAC, and high TPT1-AS1 levels predicted a poor prognosis. Moreover, functional experiments revealed that TPT1-AS1 promoted pancreatic cancer cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT) process in vitro and in vivo. Mechanistically, TPT1-AS1 functioned as an endogenous sponge for miR-30a-5p, which increased integrin ß3 (ITGB3) level in pancreatic cancer cells. Conversely, our data revealed that ITGB3 could activate the transcription factor signal transducer and activator of transcription 3 (STAT3), which in turn bound directly to the TPT1-AS1 promoter and affected the expression of TPT1-AS1, thus forming a positive feedback loop with TPT1-AS1. Taken together, our results uncovered a reciprocal loop of TPT1-AS1 and ITGB3 which contributed to pancreatic cancer growth and development, and indicated that TPT1-AS1 might serve as a novel potential diagnostic biomarker and therapeutic target for PDAC patients.
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Carcinoma Ductal Pancreático , MicroRNAs , Neoplasias Pancreáticas , RNA Longo não Codificante , Carcinoma Ductal Pancreático/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Retroalimentação , Regulação Neoplásica da Expressão Gênica , Humanos , Integrina beta3/genética , Integrina beta3/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Neoplasias PancreáticasRESUMO
In this paper, a method of color holographic display with speckle noise suppression is proposed. Firstly, the intensity information of the object is extracted according to the red, green and blue (RGB) channels. The band-limited phase is calculated and used as the initial phase for each color channel. Secondly, the double-step Fresnel diffraction algorithm is used to calculate the computer-generated holograms (CGHs), and a filter plane that dynamically adjusts the position of the filter in the optical path is designed. Then, a divergent spherical phase factor is added to the CGHs. Finally, the time average method is used to further reduce the speckle noise. When the CGHs of the RGB channels are loaded on the digital micromirror device and illuminated by the RGB lights emitting in a temporal sequence, the color reconstructed images with speckle noise suppression can be displayed. The validity of the proposed method is verified.
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In this paper, a liquid crystal axicon based holographic near-eye display system with large viewing area is proposed. The viewing area of the system is extended by implementing the liquid crystal axicon. The error diffusion algorithm is used to calculate the computer-generated hologram (CGH). When incident on the liquid crystal axicon placed at the back focal plane of Fourier lens, the reconstruction light modulated by the CGH is deflected into two directions resulting in a viewing area extension. Meanwhile, to illustrate the potential of the proposed system, two-dimensional viewing area extension is demonstrated. It combines the frequency spectrum shift with the proposed system and achieves a double expansion of the horizontal viewing area and three-times expansion of the vertical viewing area. Feasibility of the proposed system is verified by optical experiments. The proposed system has potential applications in holographic augmented reality (AR) display.
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We analysed whole-genome sequences of 560 breast cancers to advance understanding of the driver mutations conferring clonal advantage and the mutational processes generating somatic mutations. We found that 93 protein-coding cancer genes carried probable driver mutations. Some non-coding regions exhibited high mutation frequencies, but most have distinctive structural features probably causing elevated mutation rates and do not contain driver mutations. Mutational signature analysis was extended to genome rearrangements and revealed twelve base substitution and six rearrangement signatures. Three rearrangement signatures, characterized by tandem duplications or deletions, appear associated with defective homologous-recombination-based DNA repair: one with deficient BRCA1 function, another with deficient BRCA1 or BRCA2 function, the cause of the third is unknown. This analysis of all classes of somatic mutation across exons, introns and intergenic regions highlights the repertoire of cancer genes and mutational processes operating, and progresses towards a comprehensive account of the somatic genetic basis of breast cancer.
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Neoplasias da Mama/genética , Genoma Humano/genética , Mutação/genética , Estudos de Coortes , Análise Mutacional de DNA , Replicação do DNA/genética , DNA de Neoplasias/genética , Feminino , Genes BRCA1 , Genes BRCA2 , Genômica , Humanos , Masculino , Mutagênese , Taxa de Mutação , Oncogenes/genética , Reparo de DNA por Recombinação/genéticaRESUMO
Pancreatic cancer, a highly aggressive tumour type with uniformly poor prognosis, exemplifies the classically held view of stepwise cancer development. The current model of tumorigenesis, based on analyses of precursor lesions, termed pancreatic intraepithelial neoplasm (PanINs) lesions, makes two predictions: first, that pancreatic cancer develops through a particular sequence of genetic alterations (KRAS, followed by CDKN2A, then TP53 and SMAD4); and second, that the evolutionary trajectory of pancreatic cancer progression is gradual because each alteration is acquired independently. A shortcoming of this model is that clonally expanded precursor lesions do not always belong to the tumour lineage, indicating that the evolutionary trajectory of the tumour lineage and precursor lesions can be divergent. This prevailing model of tumorigenesis has contributed to the clinical notion that pancreatic cancer evolves slowly and presents at a late stage. However, the propensity for this disease to rapidly metastasize and the inability to improve patient outcomes, despite efforts aimed at early detection, suggest that pancreatic cancer progression is not gradual. Here, using newly developed informatics tools, we tracked changes in DNA copy number and their associated rearrangements in tumour-enriched genomes and found that pancreatic cancer tumorigenesis is neither gradual nor follows the accepted mutation order. Two-thirds of tumours harbour complex rearrangement patterns associated with mitotic errors, consistent with punctuated equilibrium as the principal evolutionary trajectory. In a subset of cases, the consequence of such errors is the simultaneous, rather than sequential, knockout of canonical preneoplastic genetic drivers that are likely to set-off invasive cancer growth. These findings challenge the current progression model of pancreatic cancer and provide insights into the mutational processes that give rise to these aggressive tumours.
Assuntos
Carcinogênese/genética , Carcinogênese/patologia , Rearranjo Gênico/genética , Genoma Humano/genética , Modelos Biológicos , Mutagênese/genética , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Carcinoma in Situ/genética , Cromotripsia , Variações do Número de Cópias de DNA/genética , Progressão da Doença , Evolução Molecular , Feminino , Genes Neoplásicos/genética , Humanos , Masculino , Mitose/genética , Mutação/genética , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Metástase Neoplásica/genética , Metástase Neoplásica/patologia , Poliploidia , Lesões Pré-Cancerosas/genéticaRESUMO
Structural variants (SVs), including small insertion and deletion variants (indels), are challenging to detect through standard alignment-based variant calling methods. Sequence assembly offers a powerful approach to identifying SVs, but is difficult to apply at scale genome-wide for SV detection due to its computational complexity and the difficulty of extracting SVs from assembly contigs. We describe SvABA, an efficient and accurate method for detecting SVs from short-read sequencing data using genome-wide local assembly with low memory and computing requirements. We evaluated SvABA's performance on the NA12878 human genome and in simulated and real cancer genomes. SvABA demonstrates superior sensitivity and specificity across a large spectrum of SVs and substantially improves detection performance for variants in the 20-300 bp range, compared with existing methods. SvABA also identifies complex somatic rearrangements with chains of short (<1000 bp) templated-sequence insertions copied from distant genomic regions. We applied SvABA to 344 cancer genomes from 11 cancer types and found that short templated-sequence insertions occur in â¼4% of all somatic rearrangements. Finally, we demonstrate that SvABA can identify sites of viral integration and cancer driver alterations containing medium-sized (50-300 bp) SVs.
Assuntos
Genoma Humano/genética , Variação Estrutural do Genoma/genética , Genômica , Mutação INDEL/genética , Bases de Dados Genéticas , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Análise de Sequência de DNA , Deleção de Sequência/genética , Software , Integração Viral/genéticaRESUMO
In this paper, a curved composite hologram (CCH) generation method with suppressed speckle noise is proposed. The recorded 3D object is considered as many layers with different depths and the planar hologram (PH) for each layer is generated accordingly. Then the PH is transformed to curved hologram (CH). The CH of the recorded 3D object can be generated by superposing the CHs for all the layers. Also, the linear phase factor is superposed to the CH of the object. For different objects, the bending angle and linear phase factor of the hologram are different. The CCH is generated by superimposing the CHs of different objects. Finally, the CCH is encoded by using the error diffusion method and optimized by superposing of the digital lens. When the CCH is reproduced from different angles, the reconstructed images with suppressed speckle noise can be displayed. The experimental results verify the feasibility of the proposed method.
RESUMO
In this paper, a fast hologram generation method is proposed based on the optimal segmentation of a sub-computer-generated-hologram (sub-CGH). The relationship between the pixels on the hologram and the corresponding reconstructed image is calculated firstly. Secondly, the sub-CGH corresponding to the object point from the recorded object is optimized and divided into the optimized diffraction area and the invalid diffraction area. Then, the optimized diffraction area of the sub-CGH for each object point is pre-calculated and saved. Finally, the final hologram can be generated by superimposing all the sub-CGHs. With the proposed method, the calculation time for the final hologram can be significantly reduced and the quality of the reconstructed image is not affected. Moreover, the proposed method has the advantages of perspective enlargement compared with the traditional method, and the experiment results verify its feasibility.