RESUMO
AIM: To investigate the prevalence of gingivitis and periodontitis, and the oral hygiene status of adults with cystic fibrosis (CF) in the Republic of Ireland. MATERIALS AND METHODS: A case-control study in the form of a clinical examination of 92 adults with a diagnosis of CF was carried out in the adult CF unit in Cork University Hospital. A 40-item questionnaire was used to capture socio-demographic variables and medical and dental information. Two calibrated examiners carried out a periodontal assessment on participants, using the WHO-recommended CPI-modified index, and oral hygiene status was measured using the Greene-Vermillion index. The results were compared with a population-based control group of similar socio-demographic profile. RESULTS: Oral hygiene levels (plaque and calculus) were significantly worse in people with CF, with a median plaque index of 0.83 (interquartile range [IQR] 0.333-1.542) in the CF group compared with 0.5 (IQR 0.167-0.667) in the non-CF group. Calculus index in the CF group was 0.33 (IQR 0.17-0.83) compared with 0.33 (IQR 0.125-0.33) in the non-CF group. However, periodontal disease levels were significantly lower in the CF group. Gingivitis (bleeding on probing ≥ 10% sites) was seen in 67.4% of the CF group, compared with 83.7% of the non-CF group, OR 0.365 (95% confidence interval [CI] 0.181-0.736), relative risk (RR) 0.779 (95% CI 0.655-0.928). Mild periodontitis (periodontal probing depth [PPD] < 5 mm) was seen in 15.2% of the CF group, compared with 31.5% of the non-CF group, OR 0.390 (CI 0.190-0.800), RR 0.483 (95% CI 0.273-0.852). Severe periodontitis (PPD ≥ 6 mm) was seen in 0% of the CF group, compared with 9.8% of the non-CF group. There was a tendency, albeit non-significant, towards reduced periodontitis in PWCF who regularly took antibiotics, particularly azithromycin. CONCLUSIONS: In this study, adults with CF had poor oral hygiene practices, with high levels of plaque and calculus. Despite this finding, adults with CF had lower levels of clinical gingivitis and periodontitis than seen in a non-CF control group. Further study is required to examine the causes of this phenomenon.
Assuntos
Cálculos , Fibrose Cística , Placa Dentária , Gengivite , Doenças Periodontais , Periodontite , Adulto , Humanos , Higiene Bucal/métodos , Prevalência , Fibrose Cística/complicações , Fibrose Cística/epidemiologia , Estudos de Casos e Controles , Doenças Periodontais/epidemiologia , Gengivite/epidemiologiaRESUMO
Rationale: Clinical trials have shown that use of elexacaftor/tezacaftor/ivacaftor (ETI) is associated with improvements in sweat chloride, pulmonary function, nutrition, and quality of life in people with cystic fibrosis (CF). Little is known about the impact of ETI on ventilation inhomogeneity and lung structure. Objectives: RECOVER is a real-world study designed to measure the impact of ETI in people with CF. The primary endpoints were lung clearance (lung clearance index; LCI2.5) and FEV1. Secondary endpoints included spirometry-controlled chest computed tomography (CT) scores. Methods: The study was conducted in seven sites in Ireland and the United Kingdom. Participants ages 12 years and older who were homozygous for the F508del mutation (F508del/F508del) or heterozygous for F508del and a minimum-function mutation (F508del/MF) were recruited before starting ETI and were followed up over 12 months. LCI2.5 was measured using nitrogen multiple breath washout (MBW) at baseline and at 6 and 12 months. Spirometry was performed as per the criteria of the American Thoracic Society and the European Respiratory Society. Spirometry-controlled chest CT scans were performed at baseline and at 12 months. CT scans were scored using the Perth Rotterdam Annotated Grid Morphometric Analysis (PRAGMA) system. Other outcome measures include weight, height, Cystic Fibrosis Quality of Life Questionnaire-Revised (CFQ-R), and sweat chloride. Measurements and Main Results: One hundred seventeen people with CF ages 12 and older were recruited to the study. Significant improvements were seen in LCI scores (-2.5; 95% confidence interval [CI], -3.0, -2.0) and in the percents predicted for FEV1 (8.9; 95% CI, 7.0, 10.9), FVC (6.6; 95% CI, 4.9, 8.3), and forced expiratory flow between 25% and 75% of expired volume (12.4; 95% CI, 7.8, 17.0). Overall PRAGMA-CF scores reflecting airway disease improved significantly (-3.46; 95% CI, -5.23, -1.69). Scores for trapped air, mucus plugging, and bronchial wall thickening improved significantly, but bronchiectasis scores did not. Sweat chloride levels decreased in both F508del/F508del (-43.1; 95% CI, -47.4, -38.9) and F508del/MF (-42.8; 95% CI, -48.5, -37.2) groups. Scores on the Respiratory Domain of the CFQ-R improved by 14.2 points (95% CI, 11.3, 17.2). At 1 year, sweat chloride levels were significantly lower for the F508del/F508del group compared with scores for the F508del/MF group (33.93 vs. 53.36, P < 0.001). Conclusions: ETI is associated with substantial improvements in LCI2.5, spirometry, and PRAGMA-CF CT scores in people with CF ages 12 years and older. ETI led to improved nutrition and quality of life. People in the F508del/F508del group had significantly lower sweat chloride on ETI treatment compared with the F508del/MF group. Clinical trial registered with www.clinicaltrials.gov (NCT04602468).
Assuntos
Fibrose Cística , Humanos , Aminofenóis/uso terapêutico , Benzodioxóis/uso terapêutico , Agonistas dos Canais de Cloreto/uso terapêutico , Cloretos/análise , Fibrose Cística/diagnóstico por imagem , Fibrose Cística/tratamento farmacológico , Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/uso terapêutico , Pulmão , Mutação , Qualidade de Vida , Tomografia Computadorizada por Raios XRESUMO
Distributed optical fibre sensing (DOFS)-based strain measurement systems are now routinely deployed across infrastructure health monitoring applications. However, there are still practical performance and measurement issues associated with the fibre's attachment method, particularly with thermoplastic pipeline materials (e.g., high-density polyethylene, HDPE) and adhesive affixment methods. In this paper, we introduce a new optical fibre installation method that utilises a hot-weld encapsulation approach that fully embeds the fibre onto the pipeline's plastic surface. We describe the development, application and benefits of the new embedment approach (as compared to adhesive methods) and illustrate its practical performance via a full-scale, real-world, dynamic loading trial undertaken on a 1.8 m diameter, 6.4 m long stormwater pipeline structure constructed from composite spiral-wound, steel-reinforced, HDPE pipe. The optical frequency domain reflectometry (OFDR)-based strain results show how the new method improves strain transference and dynamic measurement performance and how the data can be easily interpreted, in a practical context, without the need for complex strain transfer functions. Through the different performance tests, based on UK rail-road network transport loading conditions, we also show how centimetre- to metre-scale strain variations can be clearly resolved at the frequencies and levels consistent with transport- and construction-based, buried infrastructure loading scenarios.
RESUMO
BACKGROUND: Molecular Tumour Boards (MTBs) were created with the purpose of supporting clinical decision-making within precision medicine. Though in use globally, reporting on these meetings often focuses on the small percentages of patients that receive treatment via this process and are less likely to report on, and assess, patients who do not receive treatment. METHODS: A literature review was performed to understand patient attrition within MTBs and barriers to patients receiving treatment. A total of 51 papers were reviewed spanning a 6-year period from 11 different countries. RESULTS: In total, 20% of patients received treatment through the MTB process. Of those that did not receive treatment, the main reasons were no mutations identified (27%), no actionable mutations (22%) and clinical deterioration (15%). However, data were often incomplete due to inconsistent reporting of MTBs with only 55% reporting on patients having no mutations, 55% reporting on the presence of actionable mutations with no treatment options and 59% reporting on clinical deterioration. DISCUSSION: As patient attrition in MTBs is an issue which is very rarely alluded to in reporting, more transparent reporting is needed to understand barriers to treatment and integration of new technologies is required to process increasing omic and treatment data.
Assuntos
Deterioração Clínica , Neoplasias , Tomada de Decisão Clínica , Humanos , Neoplasias/genética , Neoplasias/patologia , Neoplasias/terapia , Medicina de PrecisãoRESUMO
OBJECTIVES: Cystic Fibrosis is an autosomal recessive condition. It is a multisystem disease treated with a broad range of pharmacological therapies, diet and nutrition, and physiotherapy. Previous studies suggest that people with cystic fibrosis have a higher prevalence of developmental defects of enamel which may place this population at a greater risk of developing oral diseases such as caries. The aim of this study was to assess a cohort of people with cystic fibrosis (PwCF) for the presence of developmental defects of enamel and compare the results with a control group of people without cystic fibrosis. METHODS: A cross sectional study involving 92 participants with cystic fibrosis and 92 controls was conducted in Cork University Dental School & Hospital. All participants completed a detailed questionnaire prior to undergoing a full clinical examination. The Developmental Defect of Enamel Index was used as a measurement index. All data was statistically analysed with the help of statisticians from Cystic Fibrosis Registry of Ireland. RESULTS: 64 % (n = 59) of PwCF had enamel defects compared to just 30 % (n = 28) of people without cystic fibrosis. The median number of teeth affected by enamel defects in the study group was 1.5, compared to 0 in the control group. CONCLUSION: In this study the cohort of PwCF had more enamel defects than people without CF. Further research is required to investigate the aetiology of these findings. CLINICAL SIGNIFICANCE: Clinicians should be vigilant after teeth have erupted in PwCF as they may have an increased susceptibility to developmental defects of enamel.
Assuntos
Fibrose Cística , Esmalte Dentário , Humanos , Fibrose Cística/complicações , Estudos Transversais , Feminino , Masculino , Adulto , Prevalência , Esmalte Dentário/anormalidades , Adulto Jovem , Estudos de Coortes , Hipoplasia do Esmalte Dentário/epidemiologia , Hipoplasia do Esmalte Dentário/etiologia , Irlanda/epidemiologia , Estudos de Casos e Controles , Adolescente , Pessoa de Meia-Idade , Defeitos de Desenvolvimento do Esmalte DentárioRESUMO
The use of Digital Healthcare Products is leading to significant improvements in clinical practice. Herein, we discuss the development of PROACT 2.0 (Patient Reported Opinions About Clinical Tolerability v2.0), a novel open-source mobile and web application developed at Fondazione IRCCS Istituto Nazionale Tumori in Milan. It was developed in collaboration with The Christie, Manchester, in the context of work package 2 of the UpSMART Accelerator project, involving a consortium of referral cancer centers from the UK, Spain and Italy. PROACT 2.0 enhances communication between patients and healthcare providers in cancer clinical trials, allowing patients to report adverse events and side effects, and healthcare teams to collect valuable patient-reported outcome measures for treatment management. PROACT 2.0 supports text, audio, and video messaging, offering a secure, non-urgent communication channel that integrates with, or replaces, traditional methods. Its user-friendly and multilingual interface provides a new route for patient engagement and streamlines the handling of logistical information. Positive feedback from initial testing warrants future enhancements for broader applicability in cancer research and treatment.
RESUMO
The ongoing development and integration of telehealth within CF care has been accelerated in response to the Covid-19 pandemic, with many centres publishing their experiences. Now, as the restrictions of the pandemic ease, the use of telehealth appears to be waning, with many centres returning to routine traditional face-to-face services. For most, telehealth is not integrated into clinical care models, and there is a lack of guidance on how to integrate such a service into clinical care. The aims of this systematic review were to first identify manuscripts which may inform best CF telehealth practices, and second, to analyse these finding to determine how the CF community may use telehealth to improve care for patients, families, and Multidisciplinary Teams into the future. To achieve this, the PRISMA review methodology was utilised, in combination with a modified novel scoring system that consolidates expert weighting from key CF stakeholders, allowing for the manuscripts to be placed in a hierarchy in accordance with their scientific robustness. From the 39 found manuscripts, the top ten are presented and further analysed. The top ten manuscripts are exemplars of where telehealth is used effectively within CF care at this time, and demonstrate specific use cases of its potential best practices. However, there is a lack of guidance for implementation and clinical decision making, which remains an area for improvement. Thus, it is suggested that further work explores and provides guidance for standardised implementation into CF clinical practice.
Assuntos
COVID-19 , Fibrose Cística , Telemedicina , Humanos , Fibrose Cística/diagnóstico , Fibrose Cística/epidemiologia , Fibrose Cística/terapia , Pandemias , COVID-19/epidemiologiaRESUMO
PURPOSE: Matching patients with cancer to precision medicine clinical trials on the basis of their tumor genotype has the potential to improve outcomes for patients who have exhausted standard-of-care treatment options. However, the matching process presents a substantial challenge because of the number of clinical trials available. We describe a free, open source research tool designed to extract relevant trial information to support oncologists in the matching process, and we illustrate its utility with recent case studies of patients who were matched to trials using this tool. METHODS: Trial records are sourced from ClinicalTrials.gov and indexed using natural language processing techniques, including named entity recognition, term normalization, and relationship extraction. Relationships between trials and genetic alterations are assigned scores on the basis of a rule-based system. All data are updated daily. A user interface is provided via R Shiny app. RESULTS: An instance of the trial match tool, configured for UK clinical trials, is hosted by the digital Experimental Cancer Medicine Team (see link in Data Sharing Statement). Users select the relevant cancer type and genetic alteration(s). Matching studies are ranked according to the score assigned for the selected genetic alterations. Results may be downloaded and attached to the patient's health record if desired. The tool is currently being used to support the ongoing TARGET National study, which aims to match up to 6,000 patients to early phase clinical trials. We present three case studies that exemplify relationships between genetic alterations and studies. CONCLUSION: With increasing numbers of precision medicine treatments and as comprehensive molecular profiling of tumor samples becomes more common, decision support tools are likely to become increasingly important. This work represents an important step toward the development and wider implementation of such systems.
Assuntos
Neoplasias , Oncologistas , Humanos , Mutação , Neoplasias/diagnóstico , Neoplasias/genética , Neoplasias/terapia , Medicina de Precisão , Ensaios Clínicos como AssuntoRESUMO
OBJECTIVES: Dexamethasone has now been incorporated into the standard of care for COVID-19 hospital patients. However, larger intensive care unit studies have failed to show discernible improvements in mortality in the recent wave. We aimed to investigate the impacts of these factors on disease outcomes in a UK hospital study. METHODS: This retrospective observational study reports patient characteristics, interventions and outcomes in COVID-19 patients from a UK teaching hospital; cohort 1, pre 16th June-2020 (pre-dexamethasone); cohort 2, 17th June to 30th November-2020 (post-dexamethasone, pre-VOC 202,012/01 as dominant strain); cohort 3, 1st December-2020 to 3rd March-2021 (during establishment of VOC202012/01 as the dominant strain). RESULTS: Dexamethasone treatment was more common in cohorts 2 and 3 (42.7% and 51.6%) compared with cohort 1 (2.5%). After adjusting for risk, odds of death within 28 days were 2-fold lower in cohort 2 vs 1 (OR:0.47,[0.27,0.79],p = 0.006). Mortality was higher cohort 3 vs 2 (20% vs 14%); but not significantly different to cohort 1 (OR: 0.86,[0.64, 1.15],p = 0.308). CONCLUSIONS: The real world finding of lower mortality following dexamethasone supports the published trial evidence and highlights ongoing need for research with introduction of new treatments and ongoing concern over new COVID-19 variants.
Assuntos
Tratamento Farmacológico da COVID-19 , COVID-19 , COVID-19/epidemiologia , Dexametasona/uso terapêutico , Hospitalização/estatística & dados numéricos , Hospitais de Ensino , Humanos , Unidades de Terapia Intensiva , SARS-CoV-2 , Reino Unido/epidemiologiaRESUMO
OBJECTIVES: COVID-19 is a heterogeneous disease, and many reports have described variations in demographic, biochemical and clinical features at presentation influencing overall hospital mortality. However, there is little information regarding longitudinal changes in laboratory prognostic variables in relation to disease progression in hospitalised patients with COVID-19. DESIGN AND SETTING: This retrospective observational report describes disease progression from symptom onset, to admission to hospital, clinical response and discharge/death among patients with COVID-19 at a tertiary centre in South East England. PARTICIPANTS: Six hundred and fifty-one patients treated for SARS-CoV-2 between March and September 2020 were included in this analysis. Ethical approval was obtained from the HRA Specific Review Board (REC 20/HRA/2986) for waiver of informed consent. RESULTS: The majority of patients presented within 1 week of symptom onset. The lowest risk patients had low mortality (1/45, 2%), and most were discharged within 1 week after admission (30/45, 67%). The highest risk patients, as determined by the 4C mortality score predictor, had high mortality (27/29, 93%), with most dying within 1 week after admission (22/29, 76%). Consistent with previous reports, most patients presented with high levels of C reactive protein (CRP) (67% of patients >50 mg/L), D-dimer (98%>upper limit of normal (ULN)), ferritin (65%>ULN), lactate dehydrogenase (90%>ULN) and low lymphocyte counts (81%Assuntos
COVID-19
, Biomarcadores
, Estudos de Coortes
, Humanos
, Estudos Longitudinais
, Estudos Retrospectivos
, SARS-CoV-2
, Centros de Atenção Terciária
, Reino Unido
RESUMO
With the rise of digital transformation in the pharmaceutical industry, digital therapeutics are being integrated in drug development clinical trials. In the TWINKLE study, information about asthmatic patients' disease control and quality-of-life (QoL) was measured by daily video recording, in conjunction with daily electronic questionnaires and home-based spirometry. From the video messages, sentiment and emotion AI was applied to detect subtle QoL changes in asthmatic patients after receiving treatments. Sentiment scores, derived from patients' daily messages via natural language processing, correlated strongly with metrics of lung functions and outcomes of electronic questionnaires. However, video-derived emotional analysis exhibited strong interpersonal variations and systematic biases, yet still showed utility in detecting QoL changes after personalized calibration and signal aggregation. Compared to traditional patient-reported outcomes, all three categories of digital measurements were able to detect significantly improved asthma control from patients who responded to treatments. The result provides insights into developing novel digital outcomes through the application of connected digital devices and advanced AI tailored to clinical settings.Clinical relevance- Digital outcomes involving connected digital devices and AI for sentiment/emotion analysis could capture subtle QoL changes reliably and earlier than hospital visits, reducing burden and improving disease management. Integrating digital therapeutics in asthma drug development trials may prove to be feasible and valuable.
Assuntos
Asma , Qualidade de Vida , Asma/tratamento farmacológico , Atitude , Emoções , Humanos , Processamento de Linguagem NaturalRESUMO
DNA damage such as double-strand breaks presents severe difficulties for the cell to repair, especially if genetic stability is to be preserved. Recombination of the damaged DNA molecule with an undamaged homologous sequence provides a potential mechanism for the high-fidelity repair of such damage, and genes encoding homologous recombination (HR) proteins have been identified in mammalian cells. Xrcc2 is a protein with homology to Rad51, the core component of HR, but with a nonredundant role in damage repair. Here, we make the first study of the consequences of knocking out one or both copies of the Xrcc2 gene in mouse cells. In addition to growth arrest and sensitivity to agents causing severe DNA damage, we show that order-of-magnitude higher levels of chromosomal alterations are sustained in primary or immortal Xrcc2(-/-) embryonic fibroblasts. Using spectral karyotyping, we find that aneuploidy and complex chromosome exchanges, including an unexpectedly high frequency of homologue exchanges, are hallmarks of Xrcc2 deficiency. In addition, we find evidence for mild haploinsufficiency of Xrcc2. These responses are linked to several indicators of reduced HR in Xrcc2(-/-) cells, including a 30-fold reduction in gene conversion and reduced levels of Rad51-focus formation and of sister-chromatid exchange. Our data have similarities to recent studies of the disruption of breast cancer-predisposing (Brca) genes in mouse cells and are contrasted to analyses of cells carrying disruptions of genes in the other main pathway for double-strand break repair, nonhomologous end joining.
Assuntos
Instabilidade Cromossômica/fisiologia , Proteínas de Ligação a DNA/deficiência , Aneuploidia , Animais , Linhagem Celular , Centrossomo/patologia , Dano ao DNA , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Embrião de Mamíferos , Fibroblastos/citologia , Fibroblastos/fisiologia , Camundongos , Camundongos Knockout , Rad51 Recombinase , Troca de Cromátide IrmãRESUMO
Patients with overactive bladder often exhibit abnormal bladder contractions in response to intravesical cold saline (positive ice-water test). The molecular entity involved in cold sensation within the urinary bladder is unknown, but a potential candidate is the ion channel, transient receptor potential (melastatin)-8 (TRPM8). The objective of the present study was to investigate the role of TRPM8 in a bladder-cooling reflex evoked in anaesthetised guinea-pigs that is comparable to the positive ice-water test seen in patients. Guinea-pig TRPM8 was cloned from L6 dorsal root ganglia (DRG) and expressed in HEK293 cells. Functional agonist- and cold-induced Ca2+ influx and electrophysiology assays were performed in these cells, and for comparison in HEK293 cells expressing human TRPM8, using a novel TRPM8 antagonist, the S-enantiomer of 1-phenylethyl 4-(benzyloxy)-3-methoxybenzyl (2-aminoethyl) carbamate hydrochloride (PBMC). Potency data from these assays was used to calculate intravenous infusion protocols for targeted plasma concentrations of PBMC in studies on micturition reflexes evoked by intravesical infusion of menthol or cold saline in anaesthetised guinea-pigs. Tissue expression of TRPM8 in guinea-pig bladder, urethra and in dorsal root ganglia neurones traced from the bladder was also investigated. TRPM8 mRNA and protein were detected in L6 dorsal root ganglia, bladder urothelium and smooth muscle. PBMC antagonised in vitro activation of human and guinea-pig TRPM8 and reversed menthol and cold-induced facilitation of the micturition reflex at plasma concentrations consistent with in vitro potencies. The present data suggest that the bladder-cooling reflex in the guinea-pig involves TRPM8. The potential significance of TRPM8 in bladder disease states deserves future investigation.
Assuntos
Canais de Cátion TRPM/antagonistas & inibidores , Anilidas/farmacologia , Animais , Regulação da Temperatura Corporal , Carbamatos/farmacologia , Feminino , Gânglios Espinais/metabolismo , Cobaias , Células HEK293 , Humanos , Masculino , Mentol/análogos & derivados , Mentol/farmacologia , Músculo Liso/metabolismo , Neurônios/metabolismo , Canais de Cátion TRPM/agonistas , Canais de Cátion TRPM/genética , Canais de Cátion TRPM/fisiologia , Uretra/metabolismo , Bexiga Urinária/metabolismoRESUMO
In germ line cells, recombination is required for gene reassortment and proper chromosome segregation at meiosis, whereas in somatic cells it provides an important mechanism for the repair of DNA double-strand breaks. Five proteins (RAD51B, RAD51C, RAD51D, XRCC2, and XRCC3) that share homology with RAD51 recombinase and are known as the RAD51 paralogs are important for recombinational repair, as paralog-defective cell lines exhibit spontaneous chromosomal aberrations, defective DNA repair, and reduced gene targeting. The paralogs form two distinct protein complexes, RAD51B-RAD51C-RAD51D-XRCC2 and RAD51C-XRCC3, but their precise cellular roles remain unknown. Here, we show that, like MLH1, RAD51C localized to mouse meiotic chromosomes at pachytene/diplotene. Using immunoprecipitation and gel filtration analyses, we found that Holliday junction resolvase activity associated tightly and co-eluted with the 80-kDa RAD51C-XRCC3 complex. Taken together, these data indicate that the RAD51C-XRCC3-associated Holliday junction resolvase complex associates with crossovers and may play an essential role in the resolution of recombination intermediates prior to chromosome segregation.
Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Recombinação Genética , Animais , Movimento Celular , Imunoprecipitação da Cromatina , Cromatografia em Gel , Aberrações Cromossômicas , Quebras de DNA de Cadeia Dupla , Reparo do DNA , Proteínas de Ligação a DNA/metabolismo , Células HeLa , Humanos , Masculino , Camundongos , Ligação ProteicaRESUMO
During genetic recombination and the recombinational repair of chromosome breaks, DNA molecules become linked at points of strand exchange. Branch migration and resolution of these crossovers, or Holliday junctions (HJs), complete the recombination process. Here, we show that extracts from cells carrying mutations in the recombination/repair genes RAD51C or XRCC3 have reduced levels of HJ resolvase activity. Moreover, depletion of RAD51C from fractionated human extracts caused a loss of branch migration and resolution activity, but these functions were restored by complementation with a variety of RAD51 paralog complexes containing RAD51C. We conclude that the RAD51 paralogs are involved in HJ processing in human cells.
Assuntos
DNA Cruciforme/metabolismo , Proteínas de Ligação a DNA/metabolismo , Resolvases de Junção Holliday/metabolismo , Substituição de Aminoácidos , Animais , Células CHO , Linhagem Celular , Cricetinae , Reparo do DNA , DNA Cruciforme/química , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Feminino , Células HeLa , Humanos , Mutação , Estrutura Terciária de Proteína , Proteínas Recombinantes/metabolismo , Recombinação GenéticaRESUMO
The highly conserved RAD51 protein has a central role in homologous recombination. Five novel RAD51-like genes have been identified in mammalian cells, but little is known about their functions. A DNA damage-sensitive hamster cell line, irs3, was found to have a mutation in the RAD51L2 gene and an undetectable level of RAD51L2 protein. Resistance of irs3 to DNA-damaging agents was significantly increased by expression of the human RAD51L2 gene, but not by other RAD51-like genes or RAD51 itself. Consistent with a role for RAD51L2 in homologous recombination, irs3 cells show a reduction in sister chromatid exchange, an increase in isochromatid breaks, and a decrease in damage-dependent RAD51 focus formation compared with wild type cells. As recently demonstrated for human cells, we show that RAD51L2 forms part of two separate complexes of hamster RAD51-like proteins. Strikingly, neither complex of RAD51-like proteins is formed in irs3 cells. Our results demonstrate that RAD51L2 has a key role in mammalian RAD51-dependent processes, contingent on the formation of protein complexes involved in homologous recombination repair.
Assuntos
Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Recombinação Genética , Sequência de Aminoácidos , Animais , Western Blotting , Mapeamento Cromossômico , Clonagem Molecular , Cricetinae , Dano ao DNA , Reparo do DNA , DNA Complementar/metabolismo , Relação Dose-Resposta à Radiação , Vetores Genéticos , Humanos , Microscopia de Fluorescência , Mitomicina/farmacologia , Dados de Sequência Molecular , Mutação , Fenótipo , Testes de Precipitina , Ligação Proteica , Isoformas de Proteínas , Homologia de Sequência de Aminoácidos , Troca de Cromátide Irmã , Transfecção , Raios XRESUMO
An acquired genetic instability, resulting from the loss of some types of DNA repair, is an early event in the development of a subset of human cancers. The involvement of BRCA1 and BRCA2 in the homologous recombination repair (HRR) of double-strand breaks in DNA implicates this pathway in the suppression of breast cancer. A family of proteins related to human RAD51, including XRCC2, are essential components of this repair pathway. Using site-directed mutagenesis of XRCC2, we show that non-conservative substitution or deletion of amino acid 188 of XRCC2 can significantly affect cellular sensitivity to DNA damage, and that a polymorphic variant at this site (R188H ), present on 6% of chromosomes in the population, has a weak effect on damage sensitivity. We tested the hypothesis that the R188H polymorphism could be a low-penetrance susceptibility factor for breast cancer, by genotyping 521 women with breast cancer and a total of 895 control women. Carriage of the rare allele of XRCC2 R188H was associated with breast cancer overall [odds ratio 1.3; 95% confidence interval (CI)=(1.0, 1.8)] and when younger-onset cases with a positive family history were compared with older controls with no family history [odds ratio 1.9; 95% CI=(1.0, 3.8)]. These results support the hypothesis that subtle variation in DNA repair capacity may influence cancer susceptibility in the population.