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1.
RMD Open ; 10(1)2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38479751

RESUMO

OBJECTIVE: This post hoc analysis of the FINCH 1-3 (NCT02889796, NCT02873936 and NCT02886728) studies assessed specific effects of filgotinib on pain control and their relationship with other aspects of efficacy in patients with rheumatoid arthritis (RA). METHODS: Assessments included: residual pain responses of ≤10 and ≤20 mm on a 100 mm visual analogue scale (VAS); the proportion of patients who achieved VAS pain responses in addition to remission or low disease activity by Disease Activity Score-28 with C-reactive protein (DAS28-CRP) or Clinical Disease Activity Index (CDAI) criteria. RESULTS: Across studies, filgotinib reduced pain from week 2, with responses sustained throughout the studies. In FINCH 1, at week 24, 35.8%, 25.0%, 24.6% and 11.6% of patients in the filgotinib 200 mg, filgotinib 100 mg, adalimumab and placebo arms (each plus methotrexate) achieved VAS pain ≤20 mm in addition to DAS28-CRP remission; 26.3%, 17.9%, 17.2% and 7.6% achieved VAS pain ≤10 mm in addition to DAS28-CRP remission. A similar pattern was seen for CDAI remission. Time during which VAS pain was ≤10 or ≤20 mm was longest with filgotinib 200 mg and comparable between adalimumab and filgotinib 100 mg. Similar findings were reported for filgotinib in FINCH 2 and 3. CONCLUSION: In all RA populations studied, pain improvements occurred from week 2 and were sustained over time. In FINCH 1, filgotinib 100 mg provided similar pain amelioration to adalimumab, whereas filgotinib 200 mg resulted in greater pain improvement and higher proportion of patients with residual pain ≤10 or ≤20 mm and meeting DAS28-CRP remission criteria.


Assuntos
Antirreumáticos , Artrite Reumatoide , Tentilhões , Piridinas , Triazóis , Humanos , Animais , Antirreumáticos/efeitos adversos , Adalimumab/uso terapêutico , Tentilhões/metabolismo , Método Duplo-Cego , Artrite Reumatoide/complicações , Artrite Reumatoide/tratamento farmacológico , Proteína C-Reativa/metabolismo , Dor/tratamento farmacológico , Dor/etiologia
2.
Am J Manag Care ; 26(2): e41-e49, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-32059099

RESUMO

OBJECTIVES: To evaluate the cost-effectiveness of brentuximab vedotin (Adcetris) in combination with cyclophosphamide, doxorubicin, and prednisone (A+CHP) in the first-line setting for CD30-expressing peripheral T-cell lymphoma (PTCL). STUDY DESIGN: An economic model was developed using clinical and quality-of-life (QOL) data from the ECHELON-2 trial, in which A+CHP demonstrated significant improvement in progression-free survival (PFS) and overall survival (OS) versus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP). METHODS: A partitioned survival model, consisting of 3 health states (PFS, postprogression survival, and death), was constructed from a US payer perspective over a lifetime time horizon. PFS and OS observed from ECHELON-2 were extrapolated using standard parametric distributions. The best-fitting distributions (log-normal for both arms) were selected based on statistical goodness of fit and clinical plausibility of the long-term projections. Utilities were based on the European Quality of Life 5-Dimensional data collected in ECHELON-2. Medical resource use and costs were from literature and standard sources. RESULTS: The model predicted that A+CHP extended PFS and OS by 2.92 and 3.38 years, respectively, over CHOP. After incorporating QOL and discounting, A+CHP was associated with 1.79 quality-adjusted life-years gained at a total incremental cost of $159,388, resulting in an incremental cost-effectiveness ratio (ICER) of $89,217. Sensitivity analyses provided ICERs ranging approximately from $57,000 to $138,000. The estimated probability that A+CHP is cost-effective compared with CHOP was 82% at a willingness-to-pay threshold of $150,000. CONCLUSIONS: Based on the ECHELON-2 trial data, this analysis found A+CHP to be cost-effective for patients with previously untreated CD30-expressing PTCL.


Assuntos
Ensaios Clínicos como Assunto/economia , Análise Custo-Benefício/métodos , Modelos Econômicos , Análise de Sobrevida , Antineoplásicos Imunológicos/economia , Antineoplásicos Imunológicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/economia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Brentuximab Vedotin/economia , Brentuximab Vedotin/uso terapêutico , Ciclofosfamida/economia , Ciclofosfamida/uso terapêutico , Doxorrubicina/economia , Doxorrubicina/uso terapêutico , Humanos , Linfoma de Células T Periférico/tratamento farmacológico , Linfoma de Células T Periférico/economia , Prednisona/economia , Prednisona/uso terapêutico , Qualidade de Vida , Anos de Vida Ajustados por Qualidade de Vida , Vincristina/economia , Vincristina/uso terapêutico
3.
Lancet ; 393(10168): 229-240, 2019 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-30522922

RESUMO

BACKGROUND: Based on the encouraging activity and manageable safety profile observed in a phase 1 study, the ECHELON-2 trial was initiated to compare the efficacy and safety of brentuximab vedotin, cyclophosphamide, doxorubicin, and prednisone (A+CHP) versus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) for the treatment of CD30-positive peripheral T-cell lymphomas. METHODS: ECHELON-2 is a double-blind, double-dummy, randomised, placebo-controlled, active-comparator phase 3 study. Eligible adults from 132 sites in 17 countries with previously untreated CD30-positive peripheral T-cell lymphomas (targeting 75% with systemic anaplastic large cell lymphoma) were randomly assigned 1:1 to receive either A+CHP or CHOP for six or eight 21-day cycles. Randomisation was stratified by histological subtype according to local pathology assessment and by international prognostic index score. All patients received cyclophosphamide 750 mg/m2 and doxorubicin 50 mg/m2 on day 1 of each cycle intravenously and prednisone 100 mg once daily on days 1 to 5 of each cycle orally, followed by either brentuximab vedotin 1·8 mg/kg and a placebo form of vincristine intravenously (A+CHP group) or vincristine 1·4 mg/m2 and a placebo form of brentuximab vedotin intravenously (CHOP group) on day 1 of each cycle. The primary endpoint, progression-free survival according to blinded independent central review, was analysed by intent-to-treat. This trial is registered with ClinicalTrials.gov, number NCT01777152. FINDINGS: Between Jan 24, 2013, and Nov 7, 2016, 601 patients assessed for eligibility, of whom 452 patients were enrolled and 226 were randomly assigned to both the A+CHP group and the CHOP group. Median progression-free survival was 48·2 months (95% CI 35·2-not evaluable) in the A+CHP group and 20·8 months (12·7-47·6) in the CHOP group (hazard ratio 0·71 [95% CI 0·54-0·93], p=0·0110). Adverse events, including incidence and severity of febrile neutropenia (41 [18%] patients in the A+CHP group and 33 [15%] in the CHOP group) and peripheral neuropathy (117 [52%] in the A+CHP group and 124 [55%] in the CHOP group), were similar between groups. Fatal adverse events occurred in seven (3%) patients in the A+CHP group and nine (4%) in the CHOP group. INTERPRETATION: Front-line treatment with A+CHP is superior to CHOP for patients with CD30-positive peripheral T-cell lymphomas as shown by a significant improvement in progression-free survival and overall survival with a manageable safety profile. FUNDING: Seattle Genetics Inc, Millennium Pharmaceuticals Inc, a wholly owned subsidiary of Takeda Pharmacuetical Company Limited, and National Institutes of Health National Cancer Institute Cancer Center.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Imunoconjugados/administração & dosagem , Fatores Imunológicos/administração & dosagem , Linfoma Anaplásico de Células Grandes/tratamento farmacológico , Adulto , Idoso , Antineoplásicos/administração & dosagem , Brentuximab Vedotin , Ciclofosfamida/administração & dosagem , Intervalo Livre de Doença , Método Duplo-Cego , Doxorrubicina/administração & dosagem , Feminino , Humanos , Imunoconjugados/efeitos adversos , Fatores Imunológicos/efeitos adversos , Análise de Intenção de Tratamento , Masculino , Pessoa de Meia-Idade , Prednisona/administração & dosagem , Vincristina/administração & dosagem
4.
J Comput Graph Stat ; 25(4): 1195-1211, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27974868

RESUMO

High angular resolution diffusion imaging (HARDI) has recently been of great interest in mapping the orientation of intra-voxel crossing fibers, and such orientation information allows one to infer the connectivity patterns prevalent among different brain regions and possible changes in such connectivity over time for various neurodegenerative and neuropsychiatric diseases. The aim of this paper is to propose a penalized multi-scale adaptive regression model (PMARM) framework to spatially and adaptively infer the orientation distribution function (ODF) of water diffusion in regions with complex fiber configurations. In PMARM, we reformulate the HARDI imaging reconstruction as a weighted regularized least-squares regression (WRLSR) problem. Similarity and distance weights are introduced to account for spatial smoothness of HARDI, while preserving the unknown discontinuities (e.g., edges between white matter and grey matter) of HARDI. The L1 penalty function is introduced to ensure the sparse solutions of ODFs, while a scaled L1 weighted estimator is calculated to correct the bias introduced by the L1 penalty at each voxel. In PMARM, we integrate the multiscale adaptive regression models (Li et al., 2011), the propagation-separation method (Polzehl and Spokoiny, 2000), and Lasso (least absolute shrinkage and selection operator) (Tibshirani, 1996) to adaptively estimate ODFs across voxels. Experimental results indicate that PMARM can reduce the angle detection errors on fiber crossing area and provide more accurate reconstruction than standard voxel-wise methods.

5.
N C Med J ; 77(1): 52-8, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26763244

RESUMO

BACKGROUND: Clinical trials provide access to innovative, high-quality cancer treatment. Simultaneously, broad access helps to ensure that trials include heterogeneous patient populations, which improves the generalizability of findings and the development of interventions that are effective for diverse populations. We provide updated data describing enrollment into cancer treatment trials in North Carolina. METHODS: For the period 1996-2009, person-level data regarding cancer clinical trial enrollment and cancer incidence were obtained from the North Carolina Central Cancer Registry and the National Cancer Institute (NCI). Enrollment rates were estimated as the ratio of trial enrollment to cancer incidence for race, sex, and year for each county, Area Health Education Center region, and the state overall. Enrollment rates for common cancers are presented. RESULTS: From 1996 to 2009, North Carolina NCI treatment trial enrollment rates were 2.4% and 2.2% for white patients and minority patients, respectively. From 2007 to 2009, rates were 3.8% for white women, 3.5% for minority women, 1.3% for white men, and 1.0% for minority men; there was greater enrollment among more urban populations (2.4%) than among the most rural populations (1.5%). LIMITATIONS: This study is limited to NCI-sponsored treatment trials in North Carolina. Policies governing collection of original data necessitate a delay in data availability. CONCLUSIONS: Effort is needed to ensure trial access and enrollment among all North Carolina populations. Specifically, we identified racial and sex disparities, particularly for certain cancers (eg, breast cancer). Programs in North Carolina and across the nation can use the methods we employed to assess their success in broadening clinical trial enrollment to include diverse populations.


Assuntos
Ensaios Clínicos como Assunto , Etnicidade/estatística & dados numéricos , Grupos Minoritários/estatística & dados numéricos , Neoplasias/tratamento farmacológico , Seleção de Pacientes , Racismo , Adulto , Idoso , Feminino , Disparidades em Assistência à Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/etnologia , North Carolina , Fatores Socioeconômicos
6.
Pigment Cell Melanoma Res ; 29(1): 68-80, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26437005

RESUMO

The objective of this study was to assess potential functional attenuation or inactivation of the intra-S checkpoint during melanoma development. Proliferating cultures of skin melanocytes, fibroblasts, and melanoma cell lines were exposed to increasing fluences of UVC and intra-S checkpoint responses were quantified. Melanocytes displayed stereotypic intra-S checkpoint responses to UVC qualitatively and quantitatively equivalent to those previously demonstrated in skin fibroblasts. In comparison with fibroblasts, primary melanocytes displayed reduced UVC-induced inhibition of DNA strand growth and enhanced degradation of p21Waf1 after UVC, suggestive of enhanced bypass of UVC-induced DNA photoproducts. All nine melanoma cell lines examined, including those with activating mutations in BRAF or NRAS oncogenes, also displayed proficiency in activation of the intra-S checkpoint in response to UVC irradiation. The results indicate that bypass of oncogene-induced senescence during melanoma development was not associated with inactivation of the intra-S checkpoint response to UVC-induced DNA replication stress.


Assuntos
Melanócitos/citologia , Melanócitos/efeitos da radiação , Melanoma/patologia , Pontos de Checagem da Fase S do Ciclo Celular/efeitos da radiação , Raios Ultravioleta , Biomarcadores/metabolismo , Linhagem Celular , Quinase 1 do Ponto de Checagem , Dano ao DNA , Reparo do DNA/efeitos da radiação , Replicação do DNA/efeitos da radiação , DNA Polimerase Dirigida por DNA/metabolismo , Diploide , Relação Dose-Resposta à Radiação , Fibroblastos/efeitos da radiação , Humanos , Melaninas/metabolismo , Fosforilação/efeitos da radiação , Proteínas Quinases/metabolismo , Dímeros de Pirimidina/metabolismo
7.
Photochem Photobiol ; 91(1): 109-16, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25316620

RESUMO

We investigated the hypothesis that the strength of the activation of the intra-S DNA damage checkpoint varies within the S phase. Synchronized diploid human fibroblasts were exposed to either 0 or 2.5 J m(-2) UVC in early, mid- and late-S phase. The endpoints measured were the following: (1) radio-resistant DNA synthesis (RDS), (2) induction of Chk1 phosphorylation, (3) initiation of new replicons and (4) length of replication tracks synthesized after irradiation. RDS analysis showed that global DNA synthesis was inhibited by approximately the same extent (30 ± 12%), regardless of when during S phase the fibroblasts were exposed to UVC. Western blot analysis revealed that the UVC-induced phosphorylation of checkpoint kinase 1 (Chk1) on serine 345 was high in early and mid S but 10-fold lower in late S. DNA fiber immunostaining studies indicated that the replication fork displacement rate decreased in irradiated cells at the three time points examined; however, replicon initiation was inhibited strongly in early and mid S, but this response was attenuated in late S. These results suggest that the intra-S checkpoint activated by UVC-induced DNA damage is not as robust toward the end of S phase in its inhibition of the latest firing origins in human fibroblasts.


Assuntos
Dano ao DNA , Diploide , Fase S , Replicação do DNA , Fibroblastos/citologia , Humanos
8.
Photochem Photobiol ; 90(1): 145-54, 2014 01.
Artigo em Inglês | MEDLINE | ID: mdl-24148148

RESUMO

This study compared biological responses of normal human fibroblasts (NHF1) to three sources of ultraviolet radiation (UVR), emitting UVC wavelengths, UVB wavelengths, or a combination of UVA and UVB (solar simulator; emission spectrum, 94.3% UVA and 5.7% UVB). The endpoints measured were cytotoxicity, intra-S checkpoint activation, inhibition of DNA replication and mutagenicity. Results show that the magnitude of each response to the indicated radiation sources was best predicted by the density of DNA cyclobutane pyrimidine dimers (CPD). The density of 6-4 pyrimidine-pyrimidone photoproducts was highest in DNA from UVC-irradiated cells (14% of CPD) as compared to those exposed to UVB (11%) or UVA-UVB (7%). The solar simulator source, under the experimental conditions described here, did not induce the formation of 8-oxo-7,8-dihydroguanine in NHF1 above background levels. Taken together, these results suggest that CPD play a dominant role in DNA damage responses and highlight the importance of using endogenous biomarkers to compare and report biological effects induced by different sources of UVR.


Assuntos
Biomarcadores/análise , Fibroblastos/efeitos da radiação , Dímeros de Pirimidina/análise , Raios Ultravioleta , Humanos , Immunoblotting , Dímeros de Pirimidina/efeitos da radiação , Efeitos da Radiação
9.
Cell Cycle ; 12(22): 3555-63, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-24091629

RESUMO

The ATR/CHK1-dependent intra-S checkpoint inhibits replicon initiation and replication fork progression in response to DNA damage caused by UV (UV) radiation. It has been proposed that this signaling cascade protects against UV-induced mutations by reducing the probability that damaged DNA will be replicated before it can be repaired. Normal human fibroblasts (NHF) were depleted of ATR or CHK1, or treated with the CHK1 kinase inhibitor TCS2312, and the UV-induced mutation frequency at the HPRT locus was measured. Despite clear evidence of S-phase checkpoint abrogation, neither ATR/CHK1 depletion nor CHK1 inhibition caused an increase in the UV-induced HPRT mutation frequency. These results question the premise that the UV-induced intra-S checkpoint plays a prominent role in protecting against UV-induced mutagenesis.


Assuntos
Fibroblastos/metabolismo , Mutagênese/efeitos da radiação , Pontos de Checagem da Fase S do Ciclo Celular/fisiologia , Raios Ultravioleta/efeitos adversos , Linhagem Celular , Quinase 1 do Ponto de Checagem , Dano ao DNA/efeitos da radiação , Replicação do DNA/efeitos da radiação , Fibroblastos/citologia , Loci Gênicos , Humanos , Hipoxantina Fosforribosiltransferase/genética , Hipoxantina Fosforribosiltransferase/metabolismo , Mutação , Proteínas Quinases/genética , Proteínas Quinases/metabolismo
10.
Cell Cycle ; 12(2): 332-45, 2013 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-23255133

RESUMO

The ATR-dependent intra-S checkpoint protects DNA replication forks undergoing replication stress. The checkpoint is enforced by ATR-dependent phosphorylation of CHK1, which are mediated by the TIMELESS-TIPIN complex and CLASPIN. Although loss of checkpoint proteins is associated with spontaneous chromosomal instability, few studies have examined the contribution of these proteins to unchallenged DNA metabolism in human cells that have not undergone carcinogenesis or crisis. Furthermore, the TIMELESS-TIPIN complex and CLASPIN may promote replication fork protection independently of CHK1 activation. Normal human fibroblasts (NHF) were depleted of ATR, CHK1, TIMELESS, TIPIN or CLASPIN and chromosomal aberrations, DNA synthesis, activation of the DNA damage response (DDR) and clonogenic survival were evaluated. This work demonstrates in NHF lines from two individuals that ATR and CHK1 promote chromosomal stability by different mechanisms that depletion of CHK1 produces phenotypes that resemble more closely the depletion of TIPIN or CLASPIN than the depletion of ATR, and that TIMELESS has a distinct contribution to suppression of chromosomal instability that is independent of its heterodimeric partner, TIPIN. Therefore, ATR, CHK1, TIMELESS-TIPIN and CLASPIN have functions for preservation of intrinsic chromosomal stability that is separate from their cooperation for activation of the intra-S checkpoint response to experimentally induced replication stress. These data reveal a complex and coordinated program of genome maintenance enforced by proteins known for their intra-S checkpoint function.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Aberrações Cromossômicas , Replicação do DNA/fisiologia , Instabilidade Genômica/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Pontos de Checagem da Fase S do Ciclo Celular/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/deficiência , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Mutadas de Ataxia Telangiectasia , Western Blotting , Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/deficiência , Quinase 1 do Ponto de Checagem , Proteínas de Ligação a DNA , Fibroblastos , Citometria de Fluxo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/deficiência , Funções Verossimilhança , Proteínas Nucleares/deficiência , Proteínas Nucleares/metabolismo , Proteínas Quinases/deficiência , Proteínas Serina-Treonina Quinases/deficiência
11.
Cell Cycle ; 10(10): 1618-24, 2011 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-21508667

RESUMO

The Timeless-Tipin complex and Claspin are mediators of the ATR-dependent activation of Chk1 in the intra-S checkpoint response to stalled DNA replication forks. Tim-Tipin and Claspin also contribute to sister chromatid cohesion (SCC) in various organisms, likely through a replication-coupled process. Some models of the establishment of SCC posit that interactions between cohesin rings and replisomes could result in physiological replication stress requiring fork stabilization. The contributions of Timeless, Tipin, Claspin, Chk1 and ATR to SCC were investigated in genetically stable, human diploid fibroblast cell lines. Whereas Timeless, Tipin and Claspin showed similar contributions to UVC-induced activation of Chk1, siRNA-mediated knockdown of Timeless induced a 100-fold increase in sister chromatid discohesion, whereas the inductive effects of knocking down Tipin, Claspin and ATR were 4-20-fold. Knockdown of Chk1 did not significantly affect SCC. Consistent findings were obtained in two independently derived human diploid fibroblast lines and support a conclusion that SCC in human cells is strongly dependent on Timeless but independent of Chk1. Furthermore, the 10-fold difference in discohesion observed when depleting Timeless versus Tipin indicates that Timeless has a function in SCC that is independent of the Tim-Tipin complex, even though the abundance of Timeless is reduced when Tipin is targeted for depletion. A better understanding of how Timeless, Tipin and Claspin promote SCC will elucidate non-checkpoint functions of these proteins at DNA replication forks and inform models of the establishment of SCC.


Assuntos
Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/metabolismo , Cromátides/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Fibroblastos/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/antagonistas & inibidores , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Mutadas de Ataxia Telangiectasia , Proteínas de Transporte/antagonistas & inibidores , Proteínas de Transporte/genética , Proteínas de Ciclo Celular/antagonistas & inibidores , Proteínas de Ciclo Celular/genética , Quinase 1 do Ponto de Checagem , Replicação do DNA , Proteínas de Ligação a DNA , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Peptídeos e Proteínas de Sinalização Intracelular/genética , Metáfase , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/genética , Proteínas Quinases/química , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Raios Ultravioleta , Coesinas
12.
FASEB J ; 24(10): 3674-80, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20511393

RESUMO

We investigated whether apurinic/apyrimidinic (AP/abasic) sites were more frequent in regions of DNA replication in cells and whether their number increased during oxidative stress. DNA fiber spreading and fluorescent immunostaining were used to detect areas of DNA replication and sites of AP lesions in extended DNA fibers. The distribution of AP sites was determined in DNA fibers from vertebrate cells maintained under normal culture conditions or stressed with exogenous H(2)O(2). AP lesions per unit length were enumerated in bulk DNA or at replication sites. The background density of AP sites in DNA fibers was 5.4 AP sites/10(6) nt, while newly replicated DNA contained 12.9 AP sites/10(6) nt. In cells exposed to 20 µM H(2)O(2), AP sites in newly replicated DNA increased to 20.8/10(6) nt. Determinations of AP site density in bulk DNA by fiber analysis or standard slot blot assays agreed to within 10%. Our findings show that the fiber assay not only accurately determines the frequency of AP sites but also shows their distribution. They also reveal that there is increased susceptibility to oxidative damage in DNA regions undergoing replication, which may explain the previously observed clustering of AP sites.


Assuntos
Replicação do DNA , Animais , Linhagem Celular , Galinhas , Dano ao DNA , Microscopia de Fluorescência , Espécies Reativas de Oxigênio/metabolismo
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