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58 result(s) for "Vallée, Maxime"
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Modelling mutational landscapes of human cancers in vitro
Experimental models that recapitulate mutational landscapes of human cancers are needed to decipher the rapidly expanding data on human somatic mutations. We demonstrate that mutation patterns in immortalised cell lines derived from primary murine embryonic fibroblasts (MEFs) exposed in vitro to carcinogens recapitulate key features of mutational signatures observed in human cancers. In experiments with several cancer-causing agents we obtained high genome-wide concordance between human tumour mutation data and in vitro data with respect to predominant substitution types, strand bias and sequence context. Moreover, we found signature mutations in well-studied human cancer driver genes. To explore endogenous mutagenesis, we used MEFs ectopically expressing activation-induced cytidine deaminase (AID) and observed an excess of AID signature mutations in immortalised cell lines compared to their non-transgenic counterparts. MEF immortalisation is thus a simple and powerful strategy for modelling cancer mutation landscapes that facilitates the interpretation of human tumour genome-wide sequencing data.
Elucidating Genomic Characteristics of Lung Cancer Progression from In Situ to Invasive Adenocarcinoma
To examine the diversity of somatic alterations and clonal evolution according to aggressiveness of disease, nineteen tumor-blood pairs of ‘formerly bronchiolo-alveolar carcinoma (BAC)’ which had been reclassified into preinvasive lesion (adenocarcinoma in situ ; AIS), focal invasive lesion (minimally invasive adenocarcinoma; MIA) and invasive lesion (lepidic predominant adenocarcinoma; LPA and non-lepidic predominant adenocarcinoma; non-LPA) according to IASLC/ATS/ERS 2011 classification were explored by whole exome sequencing. Several distinct somatic alterations were observed compare to the lung adenocarcinoma study from the Cancer Genome Atlas (TCGA). There were higher numbers of tumors with significant APOBEC mutation fold enrichment (73% vs. 58% TCGA). The frequency of KRAS mutations was lower in our study (5% vs. 32% TCGA), while a higher number of mutations of RNA-splicing genes, RBM10 and U2AF1 , were found (37% vs. 11% TCGA). We found neither mutational pattern nor somatic copy number alterations that were specific to AIS/MIA. We demonstrated that clonal cell fraction was the only distinctive feature that discriminated LPA/non-LPA from AIS/MIA. The broad range of clonal frequency signified a more branched clonal evolution at the time of diagnosis. Assessment of tumor clonal cell fraction might provide critical information for individualized therapy as a prognostic factor, however this needs further study.
Epidemiology and risk factors for ureteral stent-associated urinary tract infections in non-transplanted renal patients: a systematic review of the literature
PurposePathophysiology and risk factors for Ureteral Stent-Associated Urinary Tract Infection (USAUTI) have been poorly investigated. This situation results in highly diverse practices regarding USAUTI prevention, diagnosis and treatment. The aim of the present study was to describe the epidemiology and risk factors for USAUTI in non-transplanted patients.MethodsWe conducted a systematic literature review based on a comprehensive PubMed® bibliographic strategy, between October 1998 and March 2020. The methodological quality of the studies included was analyzed according to dedicated grids. The main endpoints were the correlation between different potential risk factors and infection ureteral stent-associated urinary tract infection or colonization rate. Conclusions and their level of evidence were reported on the basis of a critical analysis of the best available scientific evidence. This work has been submitted to a national review, which enabled the potentially divergent opinions of experts to be collected, thereby ensuring adequate quality of data.Results and conclusionTwenty-six studies out of the 505 articles identified, were included in the final analysis. Staphylococcusspp, E.coli, Klebsiellaspp, Pseudomonaaeruginosa, Enterococcusspp. and Candidaspp. were the microorganisms most often responsible for asymptomatic bacteriuria (ABU) or USAUTI. Longer indwelling time, diabetes mellitus, female gender, chronic renal failure, diabetic nephropathy and cancer were identified as risk factors for ABU and ureteral stent colonization. No specific risk factor for UTI was identified in the literature studied. A causal relationship between ureteral stent colonization and USAUTI or urosepsis remains to be demonstrated.
RAD51 and Breast Cancer Susceptibility: No Evidence for Rare Variant Association in the Breast Cancer Family Registry Study
Although inherited breast cancer has been associated with germline mutations in genes that are functionally involved in the DNA homologous recombination repair (HRR) pathway, including BRCA1, BRCA2, TP53, ATM, BRIP1, CHEK2 and PALB2, about 70% of breast cancer heritability remains unexplained. Because of their critical functions in maintaining genome integrity and already well-established associations with breast cancer susceptibility, it is likely that additional genes involved in the HRR pathway harbor sequence variants associated with increased risk of breast cancer. RAD51 plays a central biological function in DNA repair and despite the fact that rare, likely dysfunctional variants in three of its five paralogs, RAD51C, RAD51D, and XRCC2, have been associated with breast and/or ovarian cancer risk, no population-based case-control mutation screening data are available for the RAD51 gene. We thus postulated that RAD51 could harbor rare germline mutations that confer increased risk of breast cancer. We screened the coding exons and proximal splice junction regions of the gene for germline sequence variation in 1,330 early-onset breast cancer cases and 1,123 controls from the Breast Cancer Family Registry, using the same population-based sampling and analytical strategy that we developed for assessment of rare sequence variants in ATM and CHEK2. In total, 12 distinct very rare or private variants were characterized in RAD51, with 10 cases (0.75%) and 9 controls (0.80%) carrying such a variant. Variants were either likely neutral missense substitutions (3), silent substitutions (4) or non-coding substitutions (5) that were predicted to have little effect on efficiency of the splicing machinery. Altogether, our data suggest that RAD51 tolerates so little dysfunctional sequence variation that rare variants in the gene contribute little, if anything, to breast cancer susceptibility.
Impact of hospital internships on success in university summative objective structured clinical examinations: Large-scale experience in a French medical school
Objective structured clinical examinations (OSCEs) are extensively used in many medical schools worldwide with the stated objective to assess students' clinical skills acquired during internships. The objective of the present study was to assess the factors associated with success in university summative OSCEs, especially the impact of previous hospital internships in corresponding disciplines and supervision during internships. This was a cross-sectional study assessing the results in the summative OSCEs of 4th year medical students during the 2021-2022 academic year in a French medical school. The summative OSCEs included five stations for each student. Each student answered a survey at the end of summative OSCEs about previous internships, the supervision they had and perceived difficulty levels for each station. The scores in each station were assessed according to previous hospital internships in the corresponding discipline. Analysis of predictive factors of success in OSCEs, defined by a score ≥ 10/20 at each station, were performed using univariate and multivariate logistic regression. Out of the 220 students participating in the summative OSCEs, 182 (83%) answered the survey. One hundred and forty-four (79%) of these students had carried out hospital internships in at least one of the disciplines evaluated during the OSCEs. Students having completed an internship in the corresponding discipline had significantly higher OSCEs scores for interrogation, communication, therapeutic education and procedure stations compared to those who had not. Previous internship in corresponding disciplines was independently associated with success in OSCEs in interrogation (OR 9.45 [1.34-66.8] p = 0.02), clinical examination (OR 6.93 [1.88-25.57] p = 0.004, and therapeutic education (OR 3.09 [1.22-7.82] p = 0.02) stations. Previous hospital internships in the discipline evaluated by the OSCEs are associated with success in summative OSCEs. This reinforces the importance of student involvement during their hospital internships.
Asymptomatic bacteriuria prior to partial and radical nephrectomy: To screen or not to screen? Results from the national and multicenter TOCUS database
Introduction In the era of increased bacterial resistance, the main strategy is to reduce the prescription of antibiotics when possible. Nowadays, it is highly recommended to screen for asymptomatic bacteriuria (ABU), prior to urological surgery with potential mucosal breach or urine exposure. Screening and treating urinary colonization is a strategy widely adopted before radical and partial nephrectomy but without any evidence. Our main end point in this study is to analyze the relationship between preoperative urine culture and the risk of postoperative febrile urinary tract infection (UTI) or surgical-site infection (SSI) in partial or radical nephrectomy patients. Methods We conducted a multicenter retrospective cohort study between January 2016 and January 2023 in 11 French tertiary referral hospitals (TOCUS database). We collected the data for 269 patients including several pre-, intra-, and post-operative variables that could potentially increase the risk of postoperative UTI and SSI including preoperative urinary culture results. Results The incidence rate of postoperative UTI and SSI was 8.9% in our study. After conducting a logistic multivariate analysis, a propensity score matching analysis, and a subgroup analysis, we found no significant correlation between the urine culture and the postoperative UTI risk [OR = 1.2 (0.5–2.7) ( p  = 0.7)]. Only the postoperative non-infectious complications were related to a higher risk of postoperative UTI [OR = 12 (4–37), p  < 0.001)]. Conclusion Our research shows that screening and treating for ABU prior to radical or partial nephrectomy seems to be unnecessary to prevent postoperative UTI and SSI.
Torsion of the spermatic cord in adults: a multicenter experience in adults with surgical exploration for acute scrotal pain with suspected testicular torsion
ABSTRACT Acute scrotal pain (ASP) requiring surgical exploration is common in the pediatric population, but little has been reported on this subject with regard to the adult population. The aim of this study was to investigate the demographic and clinical characteristics and outcomes of scrotal explorations performed on adult patients. Patients over 21 years of age who underwent surgical exploration for ASP with suspected testicular torsion (TT) at 14 French hospitals between January 2005 and December 2019 were included in this study. The main outcome measures were demographic characteristics, pathology found during scrotal exploration, and perioperative outcomes. Logistic regression was used to perform univariate and multivariate analyses to identify predictors of TT. Data for 1329 men were analyzed. The median age was 30 (interquartile range [IQR]: 25-35; range: 21-89) years. Regarding the clinical examination, 867 (65.2%) patients presented with an elevation of the testicle, 613 (46.1%) patients with scrotal edema or erythema, and 211 (15.9%) patients with nausea or vomiting. Operative findings identified TT in only 684 (51.5%) patients, epididymo-orchitis in 112 (8.4%) patients, a tumor in 16 (1.2%) patients, and no causes in 475 (35.7%) patients. Orchiectomy for nonviable testes was required in 101 (7.6%) patients. In multivariate analysis, an elevation of the testicle, erythema/swelling, and the presence of nausea/vomiting were found to be associated with the occurrence of TT. Testicular torsion is not exclusive to children and adolescents, so must be considered in males of any age with acute scrotal findings. However, one-third of scrotal explorations in adults did not lead to a diagnosis.
Revealing the Molecular Portrait of Triple Negative Breast Tumors in an Understudied Population through Omics Analysis of Formalin-Fixed and Paraffin-Embedded Tissues
Triple negative breast cancer (TNBC), defined by the lack of expression of the estrogen receptor, progesterone receptor and human epidermal receptor 2, is an aggressive form of breast cancer that is more prevalent in certain populations, in particular in low- and middle-income regions. The detailed molecular features of TNBC in these regions remain unexplored as samples are mostly accessible as formalin-fixed paraffin embedded (FFPE) archived tissues, a challenging material for advanced genomic and transcriptomic studies. Using dedicated reagents and analysis pipelines, we performed whole exome sequencing and miRNA and mRNA profiling of 12 FFPE tumor tissues collected from pathological archives in Mexico. Sequencing analyses of the tumor tissues and their blood pairs identified TP53 and RB1 genes as the most frequently mutated genes, with a somatic mutation load of 1.7 mutations/exome Mb on average. Transcriptional analyses revealed an overexpression of growth-promoting signals (EGFR, PDGFR, VEGF, PIK3CA, FOXM1), a repression of cell cycle control pathways (TP53, RB1), a deregulation of DNA-repair pathways, and alterations in epigenetic modifiers through miRNA:mRNA network de-regulation. The molecular programs identified were typical of those described in basal-like tumors in other populations. This work demonstrates the feasibility of using archived clinical samples for advanced integrated genomics analyses. It thus opens up opportunities for investigating molecular features of tumors from regions where only FFPE tissues are available, allowing retrospective studies on the search for treatment strategies or on the exploration of the geographic diversity of breast cancer.
ABRAXAS (FAM175A) and Breast Cancer Susceptibility: No Evidence of Association in the Breast Cancer Family Registry
Approximately half of the familial aggregation of breast cancer remains unexplained. This proportion is less for early-onset disease where familial aggregation is greater, suggesting that other susceptibility genes remain to be discovered. The majority of known breast cancer susceptibility genes are involved in the DNA double-strand break repair pathway. ABRAXAS is involved in this pathway and mutations in this gene impair BRCA1 recruitment to DNA damage foci and increase cell sensitivity to ionizing radiation. Moreover, a recurrent germline mutation was reported in Finnish high-risk breast cancer families. To determine if ABRAXAS could be a breast cancer susceptibility gene in other populations, we conducted a population-based case-control mutation screening study of the coding exons and exon/intron boundaries of ABRAXAS in the Breast Cancer Family Registry. In addition to the common variant p.Asp373Asn, sixteen distinct rare variants were identified. Although no significant difference in allele frequencies between cases and controls was observed for the identified variants, two variants, p.Gly39Val and p.Thr141Ile, were shown to diminish phosphorylation of gamma-H2AX in MCF7 human breast adenocarcinoma cells, an important biomarker of DNA double-strand breaks. Overall, likely damaging or neutral variants were evenly represented among cases and controls suggesting that rare variants in ABRAXAS may explain only a small proportion of hereditary breast cancer.