RESUMO
AIMS: There is little evidence about the survival of patients with colorectal cancer (CRC) also diagnosed with dementia. We quantified dementia severity and estimated how it is associated with 2-year overall survival. MATERIALS AND METHODS: Records of patients aged 65 years or older diagnosed with CRC in England and Wales were identified. A novel proxy for dementia severity combined dementia diagnosis in administrative hospital data with Eastern Cooperative Oncology Group performance status. Cox regression was used to estimate hazard ratios with and without risk adjustment. RESULTS: In total, 4033 of 105 250 CRC patients (3.8%) had dementia recorded. Two-year survival decreased with increasing dementia severity from 65.4% without dementia, 53.5% with mild dementia, 33.0% with moderate dementia to 16.5% with severe dementia (hazard ratio comparing severe with no dementia: 2.97; 95% confidence interval 2.79, 3.16). Risk adjustment for comorbidity and cancer stage reduced this association slightly (hazard ratio 2.52; 95% confidence interval 2.37, 2.68) and additional adjustment for treatment factors reduced it further (hazard ratio 1.60; 95% confidence interval 1.50, 1.70). CONCLUSIONS: Survival of CRC patients varied strongly according to dementia severity, suggesting that a 'one-size-fits-all' policy for the care of CRC patients with dementia is not appropriate. Comprehensive assessment of cancer patients with dementia that considers dementia severity is essential in a shared decision-making process that ensures patients receive the most appropriate treatment for their individual needs and preferences.
Assuntos
Neoplasias Colorretais , Demência , Humanos , Estudos de Coortes , País de Gales/epidemiologia , Prognóstico , Demência/epidemiologia , Neoplasias Colorretais/epidemiologia , Inglaterra/epidemiologiaRESUMO
BACKGROUND: Older adults undergoing emergency abdominal surgery have significantly poorer outcomes than younger adults. For those who survive, the level of care required on discharge from hospital is unknown and such information could guide decision-making. The ELF (Emergency Laparotomy and Frailty) study aimed to determine whether preoperative frailty in older adults was associated with increased dependence at the time of discharge. METHODS: The ELF study was a UK-wide multicentre prospective cohort study of older patients (65 years or more) undergoing emergency laparotomy during March and June 2017. The objective was to establish whether preoperative frailty was associated with increased care level at discharge compared with preoperative care level. The analysis used a multilevel logistic regression adjusted for preadmission frailty, patient age, sex and care level. RESULTS: A total of 934 patients were included from 49 hospitals. Mean(s.d.) age was 76·2(6·8) years, with 57·6 per cent women; 20·2 per cent were frail. Some 37·4 per cent of older adults had an increased care level at discharge. Increasing frailty was associated with increased discharge care level, with greater predictive power than age. The adjusted odds ratio for an increase in care level was 4·48 (95 per cent c.i. 2·03 to 9·91) for apparently vulnerable patients (Clinical Frailty Score (CFS) 4), 5·94 (2·54 to 13·90) for those mildly frail (CFS 5) and 7·88 (2·97 to 20·79) for those moderately or severely frail (CFS 6 or 7), compared with patients who were fit. CONCLUSION: Over 37 per cent of older adults undergoing emergency laparotomy required increased care at discharge. Frailty scoring was a significant predictor, and should be integrated into all acute surgical units to aid shared decision-making and discharge planning.
ANTECEDENTES: Los adultos mayores sometidos a cirugía abdominal de urgencia tienen resultados significativamente peores que los adultos jóvenes. Para aquellos pacientes que sobreviven, el nivel de atención que requieren tras el alta hospitalaria se desconoce y esta información podría servir de guía en la toma de decisiones. El estudio ELF (Emergency Laparotomy and Frailty) tenía como objetivo determinar si la fragilidad preoperatoria en adultos mayores se asociaba con un aumento de la dependencia en el momento del alta. MÉTODOS: El estudio ELF era un estudio multicéntrico extenso efectuado en el Reino Unido (n = 49) que incluyó una cohorte prospectiva de 934 pacientes mayores (> 65 años) sometidos a laparotomía de urgencia durante marzo-junio de 2017. El objetivo fue establecer si la fragilidad preoperatoria aumentaba el nivel de asistencia en el momento del alta en comparación con el nivel de asistencia preoperatorio. Para el análisis se utilizó una regresión logística multinivel ajustada a características previas al ingreso: fragilidad, edad del paciente, género, y nivel de asistencia. RESULTADOS: La edad media de los pacientes fue 76,2 años (DE = 6,83), con un 57% de mujeres, un 20,2% de pacientes frágiles y un 37,4% de adultos mayores que presentaron un aumento en el nivel de asistencia en el momento del alta. Un aumento de la fragilidad se asoció con un incremento en el nivel de asistencia en el momento del alta (y mayor poder predictivo que la edad). La razón de oportunidades (odds ratio, OR) ajustada por el aumento del nivel de asistencia fue 4,48 (i.c. del 95% 2,03-9,91) para pacientes aparentemente vulnerables (Clinical Frailty Scale, CFS 4); 5,94 (i.c. del 95% 2,54-13,90) para aquellos ligeramente frágiles (CFS 5); y 7,88 (i.c. del 95% 2,97-20,79) para aquellos con fragilidad moderada o grave (CFS 6 and 7) en comparación con pacientes en buenas condiciones. CONCLUSIÓN: Este es el primer estudio que documenta que más del 37% de adultos mayores sometidos a laparotomía de urgencia precisaron un aumento en el nivel de asistencia en el momento del alta. La evaluación de la fragilidad debería integrarse en todas las unidades quirúrgicas de agudos para ayudar a compartir la toma de decisiones y los planes de tratamiento.
Assuntos
Emergências , Fragilidade/epidemiologia , Avaliação Geriátrica/métodos , Laparotomia/métodos , Admissão do Paciente/tendências , Alta do Paciente , Medição de Risco/métodos , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Tomada de Decisões , Feminino , Seguimentos , Idoso Fragilizado , Humanos , Tempo de Internação , Masculino , Estudos Prospectivos , Fatores de RiscoRESUMO
AIMS: Adjuvant chemotherapy (ACT) for stage III colon cancer is well-established. This study aimed to explore the determinants of ACT use and between-hospital variation within the English National Health Service (NHS). MATERIALS AND METHODS: In total, 11 932 patients (diagnosed 2014-2017) with pathological stage III colon cancer in the English NHS were identified from the National Bowel Cancer Audit. Records were linked to Systemic Anti-Cancer Therapy and Hospital Episode Statistics databases. Multi-level logistic regression analyses were carried out to estimate independent factors for ACT use, including age, sex, deprivation, comorbidities, performance status, American Society of Anaesthesiologists (ASA) grade, surgical urgency, surgical access, TNM staging, readmission and hospital-level factors (university teaching hospital, on-site chemotherapy and high-volume centre). A random intercept was modelled for each English NHS hospital (n = 142). Between-hospital variation was explored using funnel plot methodology. Fully adjusted random-intercept models were fitted separately in young (<70 years) and elderly (≥70 years) patients and intra-class correlation coefficients estimated. RESULTS: 60.7% of patients received ACT. Age was the strongest determinant. Compared with patients aged <60 years, those aged 60-64 (adjusted odds ratio [aOR] 0.76, 95% confidence interval 0.63-0.93), 65-69 (aOR 0.63, 95% confidence interval 0.54-0.74), 70-74 (aOR 0.53, 95% confidence interval 0.44-0.62), 75-79 (aOR 0.23, 95% confidence interval 0.19-0.27) and ≥80 years (aOR 0.05, 95% confidence interval 0.04-0.06) were significantly less likely to receive ACT. With adjustment for other factors, ACT use was more likely in patients with higher socioeconomic status, fewer comorbidities, better performance status, lower ASA grade, advanced disease, elective resections, laparoscopic procedures and no unplanned readmissions. Hospital-level factors were non-significant. The observed proportions of ACT administration in the young and elderly were 46-100% (80% of hospitals 74-90%) and 10-81% (80% of hospitals 33-65%), respectively. Risk adjustment did not reduce between-hospital variation. Despite adjustment, age accounted for 9.9% (7.2-13.4%) of between-hospital variation in the elderly compared with 2.7% (1.2-5.7%) in the young. CONCLUSIONS: There is significant between-hospital variation in ACT use for stage III colon cancer, especially for older patients. Advanced age alone seems to be a greater barrier to ACT use in some hospitals.
Assuntos
Quimioterapia Adjuvante/estatística & dados numéricos , Neoplasias do Colo/tratamento farmacológico , Hospitais/estatística & dados numéricos , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Quimioterapia Adjuvante/métodos , Neoplasias do Colo/epidemiologia , Neoplasias do Colo/patologia , Comorbidade , Inglaterra/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Fatores Socioeconômicos , Medicina EstatalRESUMO
Knockout mice with only one Trp53 allele (+/- genotype) are highly susceptible to radiation-induced cancers, possibly through numerical chromosome changes. Patients with the Li-Fraumeni syndrome, having heterozygous TP53 germline mutations (+/mut genotype), are also susceptible to spontaneous and radiogenic cancers. We have investigated the susceptibility of six Li-Fraumeni syndrome +/mut and six normal fibroblast strains to induced numerical and unstable structural aberrations at six population doublings after exposure to 3 or 6 Gy gamma rays. Four of the irradiated Li-Fraumeni syndrome strains showed small increases in both aberration types, similar to those seen in the normal strains. In two irradiated Li-Fraumeni syndrome strains, there were high levels of induced structural changes, and one of these showed a modest increase in hyperploidy. We suggest that enhanced sensitivity to delayed radiation-induced chromosome changes in Li-Fraumeni syndrome cells requires other genetic alterations in addition to TP53 heterozygosity, apparently in contrast to the situation in Trp53 heterozygous null mice. If such additional alterations occur in vivo in Li-Fraumeni syndrome patients, they may predispose them to radiogenic cancers, mainly through enhanced structural rather than numerical chromosome changes. Our findings raise questions about the validity of quantitative extrapolation of cytogenetic data from Trp53-defective mice to radiogenic cancer risk in humans.
Assuntos
Quebra Cromossômica , Cromossomos Humanos/efeitos da radiação , Fibroblastos/efeitos da radiação , Raios gama/efeitos adversos , Síndrome de Li-Fraumeni/genética , Aneuploidia , Animais , Células Cultivadas/efeitos da radiação , Aberrações Cromossômicas , Cromossomos Humanos/ultraestrutura , Relação Dose-Resposta à Radiação , Fibroblastos/ultraestrutura , Genes p53 , Predisposição Genética para Doença , Genótipo , Humanos , Síndrome de Li-Fraumeni/patologia , Perda de Heterozigosidade , Camundongos , Camundongos Knockout , Tolerância a Radiação/genética , Especificidade da Espécie , Fatores de TempoRESUMO
We previously showed that cultured fibroblasts from patients with the cancer-prone Li-Fraumeni (LF) syndrome, having heterozygous germline TP53 mutations, sustain less ionizing radiation-induced permanent G(1)arrest than normal fibroblasts. In contrast, fibroblast strains from LF patients without TP53 mutations showed normal G(1)arrest. We have now investigated the relationship between the extent of G(1)arrest and the level of structural chromosome damage (mainly dicentrics, rings and acentric fragments) in cells at their first mitosis after G(1)irradiation, in 9 LF strains with TP53 mutations, 6 without TP53 mutations and 7 normal strains. Average levels of damage in the mutant strains were 50% higher than in normals, whereas in non-mutant LF strains they were 100% higher. DNA double strand breaks (dsb) are known to act as a signal for p53-dependent G(1)arrest and to be the lesions from which chromosome aberrations arise. These results suggest that a minimal level of dsb is required before the signal for arrest is activated and that p53-defective cells have a higher signal threshold than p53-proficient cells. Dsb that do not cause G(1)blockage can progress to mitosis and appear as simple deletions or interact to form exchange aberrations. The elevated levels in the non-mutant strains may arise from defects in the extent or accuracy of dsb repair. In LF cells with or without TP53 mutations, the reduced capacity to eliminate or repair chromosomal damage of the type induced by ionising radiation, may contribute to cancer predisposition in this syndrome.
Assuntos
Aberrações Cromossômicas , Fase G1/efeitos da radiação , Genes p53 , Mutação em Linhagem Germinativa , Síndrome de Li-Fraumeni/genética , Humanos , Síndrome de Li-Fraumeni/patologiaRESUMO
The mean in vitro lifespan of dermal fibroblast strains derived from cancer-affected individuals belonging to families conforming to the classical Li-Fraumeni-syndrome or the Li-Fraumeni-like syndrome (LF strains), but in whom no TP53 mutation has been found, was not significantly different to that of normal strains. This was in contrast to LF strains that carry TP53 mutations. Cytogenetic observations of numerical and structural chromosome abnormalities were made on Giemsa stained metaphases prepared at different times during the lifespan of strains. Five strains from different LF families showed significantly increased frequencies of abnormal cells during the last 10% of their lifetime compared with seven normal strains and three other LF strains fell outside the normal range but did not reach significance. Two LF strains fell within the normal range indicating heterogeneity of the phenotype in this subset of LF fibroblasts. Numerical aberrations were the major aberration type observed. These observations of genetic instability are similar, but generally less strongly expressed, to those seen in LF strains with TP53 mutations. The basis for genetic instability in LF strains without TP53 mutations is not known, but appears not to involve defects in either the G(1)checkpoint or the checkpoint kinase hChk2.
Assuntos
Aberrações Cromossômicas , Fibroblastos/metabolismo , Síndrome de Li-Fraumeni/genética , Proteína Supressora de Tumor p53/genética , Adolescente , Adulto , Idoso , Aneuploidia , Saúde da Família , Feminino , Fibroblastos/citologia , Humanos , Cariotipagem , Síndrome de Li-Fraumeni/patologia , Masculino , Pessoa de Meia-Idade , MutaçãoRESUMO
In a retrospective analysis, five cases of Zollinger-Ellison syndrome were found in a typical urban inner-city teaching hospital. Chronic alcohol abuse and heavy smoking characterized these patients, and four of them also had pancreatitis, suggesting an association of gastrin-producing tumors and pancreatic inflammation. Ductal obstruction by neuroendocrine tumors has been reported to cause pancreatitis in a few cases. In this analysis, however, a nonobstructive gastrinoma was the surgical diagnosis in three patients, and it was suggested by imaging studies in the two other cases. The potential other pathomechanisms for a dual cause-effect relationship of gastrinoma and pancreatitis are discussed.
Assuntos
Pancreatite/etiologia , Síndrome de Zollinger-Ellison/complicações , Adulto , Idoso , Feminino , Gastrinoma/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/complicações , Estudos RetrospectivosRESUMO
Studies of Li-Fraumeni syndrome fibroblasts heterozygous for germline TP53 mutations have shown that loss of heterozygosity (LOH) occurs during passaging and is associated with genomic instability, such as chromosomal aberrations and aneuploidy to investigate the genomic changes associated with LOH in Li-Fraumeni (LF) fibroblasts, we have analysed cell strains at increasing population doublings (PD) using Comparative Genomic Hybridization (CGH). We have looked at three groups of cell strains: LF mutation-carrying strains which showed LOH for TP53, LF mutation-carrying strains which did not show LOH, and strains from normal individuals. Using CGH, we have detected loss of distinct chromosomal regions associated with LOH in 4 out of 5 mutation-carrying strains. In particular we have found loss of chromosomal regions containing genes involved in cell cycle control or senescence, including loss of 9p and 17p in these strains. Other recurrent changes included loss of chromosomes 4q and 6q, regions shown to contain one or more tumour suppressor genes. No genomic alterations were detected at cumulative PD in the normal strains or in the LF mutation-carrying strains which did not show LOH for TP53. We have also analysed the three groups of strains for microsatellite instability and somatic TP53 mutations, and have found genetic alterations in only one strain.
Assuntos
Genes p53/genética , Síndrome de Li-Fraumeni/genética , Perda de Heterozigosidade/genética , Células Cultivadas , Deleção Cromossômica , Fibroblastos/diagnóstico por imagem , Fibroblastos/fisiologia , Mutação em Linhagem Germinativa/genética , Humanos , Síndrome de Li-Fraumeni/patologia , Repetições de Microssatélites/genética , Hibridização de Ácido Nucleico , UltrassonografiaRESUMO
Radiation-induced G1 arrest was studied in four classes of early passage skin fibroblasts comprising 12 normals, 12 heterozygous (mut/wt) TP53 mutation-carriers, two homozygous (mut/-) TP53 mutation-carriers and 16 strains from nine Li-Fraumeni syndrome or Li-Fraumeni-like families in which no TP53 mutation has been found, despite sequencing of all exons, exon-intron boundaries, 3' and 5' untranslated regions and promoter regions. In an assay of p53 allelic expression in yeast, cDNAs from these non-mutation strains behaved as wild-type p53. Using two different assays, we found G1 arrest was reduced in heterozygous strains with mis-sense mutations and one truncation mutation, when compared to the range established for the normal cells. Heterozygous strains with mutations at splice sites behaved like normal cells, whilst homozygous (mut/-) strains showed either extremely reduced, or no, arrest. Strains from all nine non-mutation families gave responses within the normal range. Exceptions to the previously reported inverse correlation between G1 arrest and clonogenic radiation resistance were observed, indicating that these phenotypes are not strictly interdependent.
Assuntos
Fibroblastos/efeitos da radiação , Fase G1/efeitos da radiação , Síndrome de Li-Fraumeni/genética , Alelos , Ensaio de Unidades Formadoras de Colônias , Fibroblastos/citologia , Triagem de Portadores Genéticos , Humanos , Síndrome de Li-Fraumeni/patologia , Mutação , Saccharomyces cerevisiae/genéticaRESUMO
Previous work has indicated a role for p53 in cell cycle control, genomic stability and cellular responses to DNA-damaging agents. However, few data are available for human fibroblasts heterozygous for defined germline mutations in TP53. We report studies on 25 strains derived from 12 families with Li-Fraumeni syndrome (LFS) and 18 strains from normal volunteers. The families include three that are classical LFS families, but in whom no TP53 mutation has been found. In the families with mutations, increased longevity and resistance to low-dose-rate ionizing radiation showed a statistically significant association with the presence of TP53 mutations. However, not all heterozygotes had increased longevity or were radioresistant, and fibroblasts from cancer-affected members of LFS families without TP53 mutations showed no significant increase in either of these end points. In contrast, all mutation-carrying strains showed evidence of genomic instability, expressed as aneuploidy, and accumulated structural chromosome aberrations in up to 100% of cells, usually accompanied by loss of the wild-type TP53 allele, immediately before senescence. Levels of aneuploidy higher than in normal cells were also observed in fibroblasts from families without TP53 mutations, suggesting that chromosome instability is a major factor in determining the cancer proneness of these families.
Assuntos
Aberrações Cromossômicas , Fibroblastos/ultraestrutura , Síndrome de Li-Fraumeni/genética , Adolescente , Adulto , Idoso , Criança , Feminino , Fibroblastos/efeitos da radiação , Genes p53 , Mutação em Linhagem Germinativa , Heterozigoto , Humanos , Síndrome de Li-Fraumeni/patologia , Masculino , Pessoa de Meia-Idade , FenótipoRESUMO
We report an extensive Li-Fraumeni-like family in which there is an unusual spectrum of tumours at relatively late onset. A germline TP53 splice donor mutation in exon 4 is present in all affected family members available for testing. The mutation abolishes correct splicing of intron 4 and techniques of RT-PCR have identified three different aberrant transcripts from the mutant TP53 allele. Using the yeast functional assay to analyse transcripts in cells from a number of family members with the mutant allele, TP53 appears wild-type. Functional studies have been carried out on cells from patients with and without cancer who carry the germline mutation, and on cells from unaffected individuals from the same family who do not carry the mutation. Using a number of functional endpoints known to distinguish between cells carrying mutant or wild-type TP53 alleles, we were unable to discriminate normal (wt/wt) from heterozygous (wt/mut) cells by lymphocyte apoptosis and fibroblast survival following low dose rate ionising radiation exposure. However germline mutation carriers show increased sensitivity to radiation-induced chromosome damage in the G2 phase of the cell cycle, and decreased transient and permanent G1 arrest. These studies demonstrate the importance of fully characterising the effects of TP53 germline mutations, and may explain some of the phenotypic features of this family.
Assuntos
Processamento Alternativo , Mutação em Linhagem Germinativa/genética , Síndrome de Li-Fraumeni/genética , Proteína Supressora de Tumor p53/genética , Adulto , Apoptose/genética , Apoptose/fisiologia , Saúde da Família , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Mutação em Linhagem Germinativa/fisiologia , Humanos , Síndrome de Li-Fraumeni/fisiopatologia , Linfócitos/citologia , Linfócitos/metabolismo , Masculino , Linhagem , Mutação Puntual/genética , Mutação Puntual/fisiologia , Proteína Supressora de Tumor p53/fisiologia , Leveduras/genéticaRESUMO
A 4-Mb region containing a senescence gene was defined at 6q21 by fluorescence in situ hybridization and deletion mapping after transfer of a normal human chromosome 6 to a BK virus-transformed mouse cell line. By screening three different yeast artificial chromosome (YAC) libraries, a YAC contig was constructed that covers the deleted region at 6q21. The contig is composed of 18 overlapping YACs with a size of 250-1800 kb and contains 3 CpG islands and 10 expressed sequence tags. By sequencing YACs and P1 artificial chromosomes, nine new sequence tagged sites and three new expressed sequence tags were detected that enrich the genetic resources of the region. The contig may also contain a fragile site, FRA6F, located close to a CpG island, which could be a landmark to localize the senescence gene. This YAC contig will be used to detect expressed sequences to clone and characterize the senescence gene at 6q21.
Assuntos
Senescência Celular/genética , Cromossomos Humanos Par 6/genética , Replicação do DNA/genética , Genes , Animais , Bacteriófago P1/genética , Sítios Frágeis do Cromossomo , Fragilidade Cromossômica , Passeio de Cromossomo , Cromossomos Artificiais de Levedura , Ilhas de CpG/genética , Biblioteca Gênica , Marcadores Genéticos , Humanos , Camundongos , TransfecçãoRESUMO
Fluorescence in situ hybridization has been used to define deletion breakpoints within chromosome bands 6q16-21 in cases of lymphoid malignancy. Previous evidence suggested that the region might contain a tumour-suppressor gene. Six yeast artificial chromosome probes, each selected using a single marker, were localized to 6q16-21 and the following order was confirmed; D6S330-D6S283-D6S301-D6S447-D6S246-FYN+ ++. Of 32 cases of lymphoid malignancy, 30 showed deletion of D6S246 and, in the two cases in which D6S246 was retained, the adjacent marker, D6S447, was deleted. These observations imply that a region of minimal deletion is located within a 2-megabase segment of 6q21, between D6S447 and D6S246, providing a candidate region for the location of a tumour-suppressor gene.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 6/genética , Linfoma não Hodgkin/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Biomarcadores Tumorais , Mapeamento Cromossômico , Cromossomos Artificiais de Levedura , Sondas de DNA , Genes Supressores de Tumor/genética , Humanos , Hibridização in Situ Fluorescente/métodos , Cariotipagem , Sitios de Sequências RotuladasRESUMO
Cancer predisposition in approximately 60% of Li-Fraumeni Syndrome (LFS) families is associated with germline mutation of the TP53 gene. The p53 protein has been shown to mediate G1 arrest following DNA damage. We have investigated gamma-irradiation-induced transient and permanent G1 arrest in normal and LFS fibroblasts. The duration of transient G1 arrest varied between strains, but there was no difference in the range between normal (2-12 h) and LFS (1-13 h) cells. However, the extent of permanent G1 arrest was greatly reduced in LFS fibroblasts (mean 33+/-8% of the cell population) compared with normals (mean 67+/-9%) and correlated with their increased radiation survival (r=0.97, P<0.001). This phenotype was observed in LFS fibroblasts both with (seven cases) and without (two cases) TP53 mutation. Parallel studies with fibroblasts derived from cancer-prone, p53-deficient mice revealed no radiation-induced G1 cell cycle arrest in p53 null (-/-) cells. The p53 +/- cells were comparable to the wt p53 cells in transient G1 arrest capacity, but showed a diminished permanent G1 arrest. These data clearly implicate p53 function in permanent G1 arrest. The reduced capacity for DNA damage-induced, permanent G1 arrest in LFS may contribute significantly to cancer predisposition in this familial syndrome.
Assuntos
Fase G1/efeitos da radiação , Genes p53/genética , Síndrome de Li-Fraumeni/genética , Animais , DNA de Neoplasias/biossíntese , Suscetibilidade a Doenças , Fibroblastos/efeitos da radiação , Fase G1/genética , Humanos , Síndrome de Li-Fraumeni/patologia , Camundongos , Camundongos Knockout , Mutação , Ensaio Tumoral de Célula-TroncoRESUMO
Twenty two expressed sequence tags (ESTs) have been mapped at the border of 6q16-->q21 and at the proximal end of 6q21, a candidate for two tumor suppressor genes and a senescence gene. Use of a translocation and deletion hybrid panel together with a 4-Mb YAC contig allowed us to precisely define the position of the ESTs. Thirteen ESTs were placed within the 4-Mb interval at the proximal portion of 6q21 using a restriction map of the YAC contig, seven ESTs span a 2-Mb region on the 6q16-->q21 border, and two are distal to the contig. Refinement of the localization of these ESTs will provide substantial assistance in identifying new genes within the region 6q16-->q21.
Assuntos
Envelhecimento/genética , Mapeamento Cromossômico , Cromossomos Humanos Par 6 , Genes Supressores de Tumor/genética , Translocação Genética , Cromossomos Artificiais de Levedura , Primers do DNA , Deleção de Genes , Marcadores Genéticos , HumanosAssuntos
Atitude , Testes Genéticos , Hispânico ou Latino , Coleta de Dados , Aconselhamento Genético , Humanos , Neoplasias , Estados UnidosRESUMO
A group of adult skin fibroblast cultures from four individuals representing Li-Fraumeni families with different mutations in the p53 gene were found to be resistant to low dose-rate (0.011 Gy per min) 60Co radiation when compared with a control group of four cultures from normal individuals. The Li-Fraumeni fibroblasts, which could not be distinguished from controls after high dose rate (1.07 Gy per min) irradiation, were shown to be heterozygous (+/mut) at the p53 locus at the time of irradiation.
Assuntos
Síndrome de Li-Fraumeni/genética , Tolerância a Radiação , Adolescente , Adulto , Células Cultivadas , Pré-Escolar , Feminino , Fibroblastos/efeitos da radiação , Genes p53 , Humanos , Masculino , Pessoa de Meia-Idade , MutaçãoAssuntos
Senescência Celular/genética , Cromossomos Humanos Par 6/genética , Genes Supressores de Tumor/genética , Mapeamento Cromossômico , Cromossomos Artificiais de Levedura , Clonagem Molecular , Ilhas de CpG , DNA Complementar , Regulação da Expressão Gênica no Desenvolvimento/genética , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Repetições de MicrossatélitesRESUMO
A panel of 63 radiation-reduced hybrids has been derived from a mouse cell line containing a neo-marked human Chromosome (Chr) 6, primarily to provide a resource for higher resolution localization of new markers. Hybrids were generated with radiation doses of 40-400 Gy, selected in G418, and were shown by PCR to contain the neo gene. PCR was also used to score the retention of 15 loci that map from 6q13 to q25.2 of the current consensus map, plus six other loci assigned to 6q26-q27. An average retention frequency of 27.8% was observed, with the highest frequencies at D6S313 and D6S280 (63.5%) located near the centromere at 6q13, and at D6S283 (68.5%) at 6q16.3-q21, presumably close to the neo integration site. Lowest frequencies (4.8%) were observed for telomeric markers. All markers segregated independently except D6S297 and D6S193. Agreement and some improvement to the current consensus map of 6q was made by mapping 12 loci by the non-parametric statistical method of Falk. In addition, deletion mapping with informative hybrids allowed the ordering of six loci from 6q26 to q27 and permitted some integration of maps of this region.
Assuntos
Cromossomos Humanos Par 6 , Quimera por Radiação , Animais , Sequência de Bases , Linhagem Celular , Mapeamento Cromossômico , Marcadores Genéticos , Humanos , Hibridização in Situ Fluorescente , Canamicina Quinase , Camundongos , Dados de Sequência Molecular , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Reação em Cadeia da PolimeraseRESUMO
Previous work has implicated putative tumour-suppressor (ts) genes at 6q27 and a broad region at 6p12-q23. Here we report the results of a coded, randomised study of allelic imbalance at 12 loci on 6q on 40 pairs of coded tumour-blood pairs from patients with ovarian tumours. Our results provide clear evidence for the involvement of different regions of 6q in tumours of different histological subtypes. The involvement in serous tumours of a ts gene at the distal site is confirmed. However, proximal 6q presents a complex picture, with possibly three further ts genes: one at 6q21-23.3 involved at high frequency in benign and endometrioid tumours, another at 6q14-q15, also involved in endometrioid tumours, and a third suggested by a smallest region of deletion at 6q16.3-q21, between D6S275 and D6S300, that appears to be involved in early stage tumours. These observations point the way to a statistical study of the involvement of 6q in tumours of different histological type and staging performed on larger cohorts of samples.