3,553 research outputs found
Caracterització i identificació de les formes hereditàries de càncer colorectal
No full text[cat] El càncer colorectal (CCR) és una de les neoplàsies més prevalents en els països occidentals, i un dels tumors en el que els factors genètics juguen un paper fonamental en el seu desenvolupament. Així, l'anomenat CCR hereditari, entès com aquelles formes degudes a l'alteració de gens d'alta penetrança, suposa entre el 3-5% de tots els casos. Tot i que suposen un percentatge baix de forma global, l'elevada prevalença del CCR, i les conseqüències catastròfiques de les síndromes hereditàries, converteixen el diagnòstic d'aquestes malalties en un objectiu fonamental a la pràctica clínica, justificant la creació d'unitats específiques. El diagnòstic d'una síndrome hereditària té conseqüències potencialment beneficioses, no només pel pacient, sinó també pels familiars, podent realitzar un diagnòstic presimptomàtic. Per tant, el primer pas consisteix en identificar als individus o pacients que potencialment poden tenir una malaltia hereditària, per tal de poder realitzar en ells els estudis moleculars necessaris pel diagnòstic. Les síndromes hereditàries associades al CCR es divideixen des d'un punt de vista fenotípic en síndromes polipòsiques, com la poliposi adenomatosa familiar, i en síndromes no polipòsiques, encapçalades per la síndrome de Lynch, algunes formes de CCR associat al gen MYH i l'anomenat CCR hereditari tipus X. Mentre que a la pràctica clínica el diagnòstic de les síndromes polipòsiques és senzill donada la seva expressivitat clínica, el diagnòstic de les formes no polipòsiques representa un repte constant pel clínic, donat que en moltes ocasions el fenotip pot ser indistingible del CCR esporàdic. La síndrome de Lynch constitueix la forma més freqüent de CCR hereditari. L'estratègia diagnostica es basa en els criteris revisats de Bethesda, que tenen com objectiu identificar aquells pacients amb una major probabilitat de ser portadors d'una mutació germinal als gens reparadors de l'ADN, en els que estaria indicat avaluar la presència d'alteració del sistema de reparació de l'ADN en el tumor mitjançant l'estudi d'inestabilitat de microsatèl.lits o tinció per immunohistoquímica de les proteïnes reparadores de l'ADN. Encara que aquests criteris han demostrat ser una estratègia efectiva, han estat àmpliament criticats degut a la seva complexitat, i la necessitat d'avaluar el tumor, que en ocasions no és possible. Recentment, han aparegut diferents models predictius de mutació germinal en els gens reparadors de l'ADN, basats en la història personal, familiar i molecular. Aquests models, entre els que es troba l'anomenat PREMM1,2, ofereixen una aproximació quantitativa de la probabilitat de ser portador de mutacions, de forma que en funció de la magnitud d'aquesta, l'actitud preventiva i l'estratègia molecular podria ser diferent. No obstant, l'avaluació d'aquests models en una sèrie de pacients amb CCR de base poblacional no s'ha realitzat fins el moment. Per altra banda, el CCR associat al gen MYH és una síndrome de recent descripció, en el que a diferència de la síndrome de Lynch, la informació de les manifestacions fenotípiques i el risc de CCR associat a la presència de mutacions és molt reduïda. Així, tot i que els pacients amb mutacions bial.lèliques solen presentar una forma de poliposi adenomatosa, fins en un 30% no presenten adenomes associats al CCR. A més, el risc de CCR associat a mutacions monoal.lèliques és controvertit. Basant-se en el projecte EPICOLON, un estudi multicèntric de base poblacional que va recollir tots els pacients amb CCR incidents a Espanya durant els anys 2000-2001, la present tesi doctoral aprofundeix en la caracterització i identificació de la síndrome de Lynch i el CCR associat al gen MYH, aportant informació rellevant i novedosa al respecte.[eng] Colorectal cancer (CRC) is the second most common cancer in most developed countries. AColorectal cancer (CRC) is the second most common cancer in most developed countries. Although it is assumed that up to 20-25% of cases develop as a result of inherited genetic factors, known genes predisposing to this malignancy account for less than 5%. Hereditary CRC is traditionally divided into polyposic syndromes, such as familial adenomatous polyposis, and non polyposic syndromes, such as Lynch syndrome. Early diagnosis of these hereditary forms is crucial since intensive cancer screening and prophylactic surgery have been shown to reduce the incidence and mortality of CRC. Moreover, appropriate presymptomatic testing can be offered to reduce mortality among at-risk family members, and relatives not at risk can avoid unnecessary intensive surveillance. However, heterogeneity of non polyposic syndromes complicates early recognition, which is critical and often difficult. In parallel with this difficulty, diagnostic criteria continue to evolve as understanding and characterization of these syndromes improve. Indeed, identification of Lynch syndrome can be done by molecular pre-screening using microsatellite instability analysis and/or immunostaining in combination or not with clinical criteria. Nevertheless, Lynch syndrome identification is moving toward more refined algorithms and multivariable models which combine personal and familial data in order to obtain a quantitative estimation of the risk. Following this direction, the PREMM1,2 model provides a new and easy-to-use model to predict mutations in the MLH1/MSH2 genes. Whereas the model accurately discriminates gene mutation carriers in the subset of individuals at moderate to high risk for Lynch syndrome, its usefulness in an unselected CRC population is unknown. Furthermore, efficacy of the PREMM1,2 model in combination with tumor MMR testing has not yet been assessed. On the other hand, whereas it has conclusively demonstrated that biallelic MYH mutations confer a significant risk for colorectal cancer (CRC), the influence of monoallelic mutations remains controversial. In this sense, characterization of MYH-associated CRC is critical to identify individuals who may benefit from preventive strategies.Using data from the EPICOLON study, a prospective, multicenter, population-based cohort of CRC patients in Spain, the present Doctoral Thesis study in depth the characterization and identification of non polyposic hereditary colorectal syndromes.lthough it is assumed that up to 20-25% of cases develop as a result of inherited genetic factors, known genes predisposing to this malignancy account for less than 5%. Hereditary CRC is traditionally divided into polyposic syndromes, such as familial adenomatous polyposis, and non polyposic syndromes, such as Lynch syndrome. Early diagnosis of these hereditary forms is crucial since intensive cancer screening and prophylactic surgery have been shown to reduce the incidence and mortality of CRC. Moreover, appropriate presymptomatic testing can be offered to reduce mortality among at-risk family members, and relatives not at risk can avoid unnecessary intensive surveillance. However, heterogeneity of non polyposic syndromes complicates early recognition, which is critical and often difficult. In parallel with this difficulty, diagnostic criteria continue to evolve as understanding and characterization of these syndromes improve. Indeed, identification of Lynch syndrome can be done by molecular pre-screening using microsatellite instability analysis and/or immunostaining in combination or not with clinical criteria. Nevertheless, Lynch syndrome identification is moving toward more refined algorithms and multivariable models which combine personal and familial data in order to obtain a quantitative estimation of the risk. Following this direction, the PREMM1,2 model provides a new and easy-to-use model to predict mutations in the MLH1/MSH2 genes. Whereas the model accurately discriminates gene mutation carriers in the subset of individuals at moderate to high risk for Lynch syndrome, its usefulness in an unselected CRC population is unknown. Furthermore, efficacy of the PREMM1,2 model in combination with tumor MMR testing has not yet been assessed. On the other hand, whereas it has conclusively demonstrated that biallelic MYH mutations confer a significant risk for colorectal cancer (CRC), the influence of monoallelic mutations remains controversial. In this sense, characterization of MYH-associated CRC is critical to identify individuals who may benefit from preventive strategies.Using data from the EPICOLON study, a prospective, multicenter, population-based cohort of CRC patients in Spain, the present Doctoral Thesis study in depth the characterization and identification of non polyposic hereditary colorectal syndromes
Ordering of organic molecules on templated surfaces
No full textThis thesis describes the controlled growth of molecular nanostructures using modified metallic and semiconductor surfaces. The Ag/Si(lll)-(root3 x root3),the Sn/Cu(100) surface alloy system and the Bi/Si(100) nanolines and (2xn) surfaces were all investigated as suitable substrates for the controlled growth of pentacene, (C22H14) or trimesic acid, (C6H3(COOH)3) organic molecules. The following techniques were used in this study; Scanning Tunnelling Microscopy (STM), Low Energy Electron Diffraction (LEED), Normal Incident X-Ray Standing Waves (NIXSW) and Temperature Programmed Desorption (TPD).
The room temperature growth and ordering of trimesic acid on the AgfSi(ll1)-(root3 x root3) surface was investigated. An oblique unit cell was determined and a model proposed for the highly ordered close-packed domains.
The discovery of a new submonolayer phase on Sn/Cu(100) and the re-examined known phase are discussed. New models for these reconstructions are proposed. Adsorption of trimesic acid at room temperature on the clean substrate the lowest Sn coverage phase were studied. Two new Sn coverage dependent structures were discovered and bonding schemes in upright and flat orientations are discussed.
BifSi(100)-(2xn) surface was exploited as a template for the ordered growth of pentacene, which exhibited orientation specific adsorption. The Bi/Si(100)-(2xn) single domain surface created on vicinal silicon was used to test the suitable of Daresbury 4.2 beamline for NIXSW Imaging experiments and the quality of the results are discussed
A trio of gamma-ray burst supernovae : GRB 120729A, GRB 130215A/SN 2013ez, and GRB 130831A/SN 2013fu
No full textWe present optical and near-infrared (NIR) photometry for three gamma-ray burst supernovae (GRB-SNe): GRB 120729A, GRB 130215A/SN 2013ez, and GRB 130831A/SN 2013fu. For GRB 130215A/SN 2013ez, we also present optical spectroscopy at t − t0 = 16.1 d, which covers rest-frame 3000–6250 Å. Based on Fe ii λ5169 and Si ii λ6355, our spectrum indicates an unusually low expansion velocity of ~4000–6350 km s-1, the lowest ever measured for a GRB-SN. Additionally, we determined the brightness and shape of each accompanying SN relative to a template supernova (SN 1998bw), which were used to estimate the amount of nickel produced via nucleosynthesis during each explosion. We find that our derived nickel masses are typical of other GRB-SNe, and greater than those of SNe Ibc that are not associated with GRBs. For GRB 130831A/SN 2013fu, we used our well-sampled R-band light curve (LC) to estimate the amount of ejecta mass and the kinetic energy of the SN, finding that these too are similar to other GRB-SNe. For GRB 130215A, we took advantage of contemporaneous optical/NIR observations to construct an optical/NIR bolometric LC of the afterglow. We fit the bolometric LC with the millisecond magnetar model of Zhang & Mészáros (2001, ApJ, 552, L35), which considers dipole radiation as a source of energy injection to the forward shock powering the optical/NIR afterglow. Using this model we derive an initial spin period of P = 12 ms and a magnetic field of B = 1.1 × 1015 G, which are commensurate with those found for proposed magnetar central engines of other long-duration GRBs
Childhood cancers in families with and without Lynch syndrome
No full textInheritance of a germline mutation in one of the DNA mismatch repair (MMR) genes or the EPCAM gene is associated with an increased risk of colorectal cancer, endometrial cancer, and other adult malignancies (Lynch syndrome). The risk of childhood cancers in Lynch syndrome families, however, is not well studied. Using data from the Colon Cancer Family Registry, we compared the proportion of childhood cancers (diagnosed before 18 years of age) in the first-, second-, and third-degree relatives of 781 probands with a pathogenic mutation in one of the MMR genes; MLH1 (n = 275), MSH2 (n = 342), MSH6 (n = 99), or PMS2 (n = 55) or in EPCAM (n = 10) (Lynch syndrome families), with that of 5073 probands with MMR-deficient colorectal cancer (non-Lynch syndrome families). There was no evidence of a difference in the proportion of relatives with a childhood cancer between Lynch syndrome families (41/17,230; 0.24%) and non-Lynch syndrome families (179/94,302; 0.19%; p = 0.19). Incidence rate of all childhood cancers was estimated to be 147 (95% CI 107-206) per million population per year in Lynch syndrome families and 115 (95% CI 99.1-134) per million population per year in non-Lynch syndrome families. There was no evidence for a significant increase in the risk of all childhood cancers, hematologic cancers, brain and central nervous system cancers, Lynch syndrome-associated cancers, or other cancers in Lynch syndrome families compared with non-Lynch syndrome families. Larger studies, however, are required to more accurately define the risk of specific individual childhood cancers in Lynch syndrome families
Càncer colorectal hereditari: Aplicacions diagnòstiques de l'estudi de la dosi dels gens APC, MLH1 i MSH2
No full text[cat] Les síndromes de càncer colorectal (CCR) hereditari representen entre un 3% i un 5% de tots els casos de CCR i inclouen tots aquells individus amb un elevat grau d'agregació familiar. La més freqüent és la síndrome de Lynch, causada per la presència de mutacions en els gens reparadors del DNA, majoritàriament MLH1 i MSH2. La poliposi adenomatosa familiar (FAP) és la segona en incidència, es caracteritza per l'aparició de pòlips precursors a la neoplàsia colorectal i la seva causa principal és la presència de mutacions en el gen supressor tumoral APC. En els últims anys s'ha descobert que els grans reordenaments d'aquests gens són responsables de la malaltia en una part de les famílies que pateixen aquestes síndromes. A més, estudis d'expressió d'aquests gens en línia germinal han demostrat l'existència de desequilibris al·lèlics tant en famílies portadores de mutacions com en famílies on no es detecten mutacions en el DNA. L'objectiu d'aquesta tesi és l'estudi de la dosi en la dels gens MLH1, MSH2 i APC, implicats en la síndrome de Lynch i la FAP. D'aquesta forma, hem analitzat la dosi tant a nivell de DNA (grans reordenaments) com a nivell d'RNA (expressió específica d'al·lel), sempre treballant amb línia germinal de pacients. Els resultats aquí recollits permeten millorar l'estratègia de diagnòstic molecular de les famílies amb síndrome de Lynch i FAP que són ateses al nostre centre, al mateix temps que la comprensió del procés tumorogènic.[eng] Hereditary colorectal cancer (CRC) syndromes represent about 3% to 5% of all cases of CRC and include all those individuals with high familiar aggregation. The most frequent syndrome is Lynch syndrome, caused by the presence of mutations in the mismatch repair (MMR) genes, mostly MLH1 and MSH2. Familiar adenomatous polyposis (FAP) is the second in incidence, is characterized by precursor polyps and its mainly caused by mutations in the tumoral suppressor gene APC. Recently, it has been discovered that gross rearrangements of these genes are responsible of these two syndromes. Also, expression analyses of these genes in the germline have demonstrated the existence of allelic imbalances in both families carrying pathogenic mutations and families without detected mutations. Our aim was to study de dose of MLH1, MSH2 and APC genes in the germline of Lynch syndrome and polyposis families, respectively. To that end, we analyzed the dose at DNA level (gross rearrangements) and at RNA level (allele-specific expression) of these patients. The results summarized in this thesis permit improving the molecular diagnostic strategy in Lynch syndrome and FAP families, and also improve the knowledge of the tumorogenic process
Assessing Advance Care Planning in Individuals with Lynch Syndrome.
No full textLynch syndrome (LS) is a hereditary cancer syndrome characterized by an increased risk of multiple cancers, predominantly endometrial and colorectal, at a younger age (typically < 50). In prior research, high death anxiety and a lack of provider-initiated communication about advance care planning (ACP) have been shown to decrease a patient's likelihood of having advance directives. Providers often have gaps in knowledge and are uncomfortable with these conversations. We used a mixed methods approach (quantitative survey with a follow-up telephone interview) to assess knowledge, preferences, and attitudes regarding ACP in individuals with LS ( = 20). This study also assessed which ACP documents individuals already had in place and which persons (providers, family, or friends) an individual made aware of the documentation and/or preferences. These data were analyzed to determine patient preferences for who is responsible for initiating these conversations, identify motivating factors and barriers to these conversations, and determine whether the current conversations are adequate to meet the needs of this patient population. Participants recognized the importance of ACP and expressed interest in creating these documents. However, knowledge and confidence about these topics were lacking, with many participants attributing this to their young age and lack of experience. Although uncomfortable, many patients want to have ACP discussions with their providers, but frequently patients were only asked if these documents are completed with no further discussion. These findings can inform educational efforts to improve knowledge of ACP and interventional research to increase use of ACP by individuals with LS.https://doi.org/10.1007/s42399-021-00729-2http://www.ncbi.nlm.nih.gov/pmc/articles/pmc7808734
Identification of Lynch syndrome among patients with colorectal cancer.
No full textCONTEXT:
Lynch syndrome is the most common form of hereditary colorectal cancer (CRC) and is caused by germline mutations in DNA mismatch repair (MMR) genes. Identification of gene carriers currently relies on germline analysis in patients with MMR-deficient tumors, but criteria to select individuals in whom tumor MMR testing should be performed are unclear.
OBJECTIVE:
To establish a highly sensitive and efficient strategy for the identification of MMR gene mutation carriers among CRC probands.
DESIGN, SETTING, AND PATIENTS:
Pooled-data analysis of 4 large cohorts of newly diagnosed CRC probands recruited between 1994 and 2010 (n = 10,206) from the Colon Cancer Family Registry, the EPICOLON project, the Ohio State University, and the University of Helsinki examining personal, tumor-related, and family characteristics, as well as microsatellite instability, tumor MMR immunostaining, and germline MMR mutational status data.
MAIN OUTCOME:
Performance characteristics of selected strategies (Bethesda guidelines, Jerusalem recommendations, and those derived from a bivariate/multivariate analysis of variables associated with Lynch syndrome) were compared with tumor MMR testing of all CRC patients (universal screening).
RESULTS:
Of 10,206 informative, unrelated CRC probands, 312 (3.1%) were MMR gene mutation carriers. In the population-based cohorts (n = 3671 probands), the universal screening approach (sensitivity, 100%; 95% CI, 99.3%-100%; specificity, 93.0%; 95% CI, 92.0%-93.7%; diagnostic yield, 2.2%; 95% CI, 1.7%-2.7%) was superior to the use of Bethesda guidelines (sensitivity, 87.8%; 95% CI, 78.9%-93.2%; specificity, 97.5%; 95% CI, 96.9%-98.0%; diagnostic yield, 2.0%; 95% CI, 1.5%-2.4%; P < .001), Jerusalem recommendations (sensitivity, 85.4%; 95% CI, 77.1%-93.6%; specificity, 96.7%; 95% CI, 96.0%-97.2%; diagnostic yield, 1.9%; 95% CI, 1.4%-2.3%; P < .001), and a selective strategy based on tumor MMR testing of cases with CRC diagnosed at age 70 years or younger and in older patients fulfilling the Bethesda guidelines (sensitivity, 95.1%; 95% CI, 89.8%-99.0%; specificity, 95.5%; 95% CI, 94.7%-96.1%; diagnostic yield, 2.1%; 95% CI, 1.6%-2.6%; P < .001). This selective strategy missed 4.9% of Lynch syndrome cases but resulted in 34.8% fewer cases requiring tumor MMR testing and 28.6% fewer cases undergoing germline mutational analysis than the universal approach.
CONCLUSION:
Universal tumor MMR testing among CRC probands had a greater sensitivity for the identification of Lynch syndrome compared with multiple alternative strategies, although the increase in the diagnostic yield was modest
Silica supported Sn catalysts with tetrahedral Sn sites for selective isomerization of glucose to fructose
No full textLewis acid catalyzed isomerization of glucose to fructose is an important reaction for production of renewable chemicals. Here, we show the synthesis of an active and selective Lewis acid catalyst for this reaction by controlling Sn dispersion on SBA15. Sn loading of 1 wt. % over SBA15 (Sn/SBA15) maximized the formation of tetrahedral Sn species on the catalyst surface. Increasing the loading or changing support caused formation of SnO2 clusters which reduced fructose selectivity. A mechanism based on condensation of Sn with silanol group of SBA15 is proposed. The catalyst showed high selectivity of 93 % after 2 h with 57 % fructose yield. The Lewis acid catalyzed isomerization of glucose was proven by isotopic tracer study using D-glucose-2-d. The catalyst deactivated in the third cycle owing to byproduct deposition, but the activity was restored by recalcining the catalyst
Sn-Based Electrocatalyst Stability: A Crucial Piece to the Puzzle for the Electrochemical CO<sub>2</sub>Reduction toward Formic Acid
No full textNowadays, Sn-based electrocatalysts for the electrochemical CO2 reduction reaction (eCO2RR) toward formic acid have been reported to reach industrially relevant current densities and Faradaic efficiencies approaching 100%. However, electrocatalyst stability remains inadequate and appears to be a crucial piece to the puzzle, as lifetimes in the range of several thousands of hours should be reached for practical application and economic viability. Here, we provide insights into stability issues related to Sn-based electrocatalysts and electrolyzers for formic acid production. By determining the chemical and physical phenomena that occur during the electrochemical reduction reaction on the surface and bulk of Sn-based catalysts, we intend to elucidate the most common degradation mechanisms that impair long-term electrocatalytic activity of these catalysts. Moreover, highlighting the importance of correctly selected process conditions and an optimized reactor design allows us to unveil all necessary aspects for a stable Sn-based eCO2RR toward formic acid.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Large Scale Energy Storag
Influences of Nanostructures of Sn and Ir for the Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolysis
No full textThe influence of nanostructures and interaction of Sn and Ir in oxygen evolution catalysts in a polymer electrolyte membrane electrolyzer were investigated. For this aim, two synthesis methods, namely, the one-step solution combustion method and the precipitation-deposition method with sodium borohydride reduction, were evaluated to prepare distinct nanostructures. Sn addition to Ir-based oxygen evolution reaction catalysts has been reported to yield materials with higher activity; however, in our case, this was observed only for Sn/Ir catalysts prepared by the precipitation-deposition method. The nanolayer of Sn/SnO2 deposited over metallic Ir particles was identified to enhance the interfacial contacts, resulting in synergistic interactions. By deconvolution of the polarization curves into constituting contributions, the performance improvement was attributed to the higher exchange current density of the Sn/Ir powder as a consequence of a higher number of surface reaction sites created by the Sn-Ir interactions.ChemE/Catalysis Engineerin
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