Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 44
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
BMC Bioinformatics ; 21(1): 431, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-33008363

RESUMO

BACKGROUND: This paper describes a web based tool that uses a combination of sonification and an animated display to inquire into the SARS-CoV-2 genome. The audio data is generated in real time from a variety of RNA motifs that are known to be important in the functioning of RNA. Additionally, metadata relating to RNA translation and transcription has been used to shape the auditory and visual displays. Together these tools provide a unique approach to further understand the metabolism of the viral RNA genome. This audio provides a further means to represent the function of the RNA in addition to traditional written and visual approaches. RESULTS: Sonification of the SARS-CoV-2 genomic RNA sequence results in a complex auditory stream composed of up to 12 individual audio tracks. Each auditory motive is derived from the actual RNA sequence or from metadata. This approach has been used to represent transcription or translation of the viral RNA genome. The display highlights the real-time interaction of functional RNA elements. The sonification of codons derived from all three reading frames of the viral RNA sequence in combination with sonified metadata provide the framework for this display. Functional RNA motifs such as transcription regulatory sequences and stem loop regions have also been sonified. Using the tool, audio can be generated in real-time from either genomic or sub-genomic representations of the RNA. Given the large size of the viral genome, a collection of interactive buttons has been provided to navigate to regions of interest, such as cleavage regions in the polyprotein, untranslated regions or each gene. These tools are available through an internet browser and the user can interact with the data display in real time. CONCLUSION: The auditory display in combination with real-time animation of the process of translation and transcription provide a unique insight into the large body of evidence describing the metabolism of the RNA genome. Furthermore, the tool has been used as an algorithmic based audio generator. These audio tracks can be listened to by the general community without reference to the visual display to encourage further inquiry into the science.


Assuntos
Betacoronavirus/genética , Genoma Viral , Software , Betacoronavirus/isolamento & purificação , COVID-19 , Infecções por Coronavirus/patologia , Infecções por Coronavirus/virologia , Genômica , Humanos , Fases de Leitura Aberta/genética , Pandemias , Pneumonia Viral/patologia , Pneumonia Viral/virologia , RNA Viral/química , RNA Viral/genética , RNA Viral/metabolismo , SARS-CoV-2
2.
Trends Biochem Sci ; 40(6): 293-5, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25936978

RESUMO

Twenty years ago Trends in Biochemical Sciences published an innovative origami template for modeling the DNA double helix. Presented here are adaptations of this, including a chemical structure designed for transparent acetate, plus hybrid DNA/RNA, RNA hairpin, and single-stranded models. These models are useful teaching tools for understanding the 3D structure of DNA.


Assuntos
DNA/genética , Modelos Moleculares , Conformação de Ácido Nucleico , DNA/química , Relação Estrutura-Atividade
3.
BMC Bioinformatics ; 19(1): 179, 2018 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-29792161

RESUMO

BACKGROUND: The homozygous yeast deletion library includes approximately 4800 diploid strains each containing one deleted non-essential gene. Hundreds of publications have arisen through experimentation using this genome-wide biological resource. As part of this work over 677 genesets have been collated from these experiments representing the phenotypic responses of the library to a diverse set of chemical and physical challenges. DESCRIPTION: A website called the Saccharomyces cerevisiae Homozygous Deletion Library Tools (ScHo DeLiTo-96) has been developed with the primary goal of browsing and identifying genes shared between these responsive phenotypes (available at yeastdb.org ). Geneset comparisons have been performed for each phenotype against all others to identify common genes. Genesets and other curated information are stored in a relational database and a website interface allows users to query and browse the data in an intuitive way to reveal commonality between selected phenotypic responses. The most commonly occurring genes in all of the stored phenotypes are highly over-represented in the GO slim term "cellular ion homeostasis" indicating that genes shared between phenotypes may highlight a common cellular response. Additionally, user derived genesets can be uploaded and intersected against the stored data to reveal common responses which may otherwise have been obscure. CONCLUSION: These tools provide a simple method to perform niche enquiries between datasets derived from the yeast deletion library.


Assuntos
Deleção de Genes , Biblioteca Gênica , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Deleção de Sequência/genética
4.
BMC Cancer ; 18(1): 1284, 2018 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-30577821

RESUMO

BACKGROUND: Cisplatin has been widely used for the treatment of cancer and its antitumour activity is attributed to its capacity to form DNA adducts, predominantly at guanine residues, which impede cellular processes such as DNA replication and transcription. However, there are associated toxicity and drug resistance issues which plague its use. This has prompted the development and screening of a range of chemotherapeutic drug analogues towards improved efficacy. The biological properties of three novel platinum-based compounds consisting of varying cis-configured ligand groups, as well as a commercially supplied compound, were characterised in this study to determine their potential as anticancer agents. METHODS: The linear amplification reaction was employed, in conjunction with capillary electrophoresis, to quantify the sequence specificity of DNA adducts induced by these compounds using a DNA template containing telomeric repeat sequences. Additionally, the DNA interstrand cross-linking and unwinding efficiency of these compounds were assessed through the application of denaturing and native agarose gel electrophoresis techniques, respectively. Their cytotoxicity was determined in HeLa cells using a colorimetric cell viability assay. RESULTS: All three novel platinum-based compounds were found to induce DNA adduct formation at the tandem telomeric repeat sequences. The sequence specificity profile at these sites was characterised and these were distinct from that of cisplatin. Two of these compounds with the enantiomeric 1,2-diaminocyclopentane ligand (SS and RR-DACP) were found to induce a greater degree of DNA unwinding than cisplatin, but exhibited marginally lower DNA cross-linking efficiencies. Furthermore, the RR-isomer was more cytotoxic in HeLa cells than cisplatin. CONCLUSIONS: The biological characteristics of these compounds were assessed relative to cisplatin, and a variation in the sequence specificity and a greater capacity to induce DNA unwinding was observed. These compounds warrant further investigations towards developing more efficient chemotherapeutic drugs.


Assuntos
Adutos de DNA/efeitos dos fármacos , DNA/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Compostos Organoplatínicos/química , Cisplatino/análogos & derivados , Cisplatino/química , Cisplatino/uso terapêutico , Reagentes de Ligações Cruzadas , DNA/química , Dano ao DNA/efeitos dos fármacos , Células HeLa , Humanos , Conformação de Ácido Nucleico/efeitos dos fármacos , Compostos Organoplatínicos/uso terapêutico , Platina/química , Platina/uso terapêutico , Estereoisomerismo
5.
BMC Bioinformatics ; 18(1): 221, 2017 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-28438115

RESUMO

BACKGROUND: DNA Sonification refers to the use of an auditory display to convey the information content of DNA sequence data. Six sonification algorithms are presented that each produce an auditory display. These algorithms are logically designed from the simple through to the more complex. Three of these parse individual nucleotides, nucleotide pairs or codons into musical notes to give rise to 4, 16 or 64 notes, respectively. Codons may also be parsed degenerately into 20 notes with respect to the genetic code. Lastly nucleotide pairs can be parsed as two separate frames or codons can be parsed as three reading frames giving rise to multiple streams of audio. RESULTS: The most informative sonification algorithm reads the DNA sequence as codons in three reading frames to produce three concurrent streams of audio in an auditory display. This approach is advantageous since start and stop codons in either frame have a direct affect to start or stop the audio in that frame, leaving the other frames unaffected. Using these methods, DNA sequences such as open reading frames or repetitive DNA sequences can be distinguished from one another. These sonification tools are available through a webpage interface in which an input DNA sequence can be processed in real time to produce an auditory display playable directly within the browser. The potential of this approach as an analytical tool is discussed with reference to auditory displays derived from test sequences including simple nucleotide sequences, repetitive DNA sequences and coding or non-coding genes. CONCLUSION: This study presents a proof-of-concept that some properties of a DNA sequence can be identified through sonification alone and argues for their inclusion within the toolkit of DNA sequence browsers as an adjunct to existing visual and analytical tools.


Assuntos
Algoritmos , Recursos Audiovisuais , Código Genético , Análise de Sequência de DNA/métodos , Música , Fases de Leitura
6.
Lancet ; 388(10040): 178-86, 2016 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-27178476

RESUMO

BACKGROUND: Increased mortality rates associated with weekend hospital admission (the so-called weekend effect) have been attributed to suboptimum staffing levels of specialist consultants. However, evidence for a causal association is elusive, and the magnitude of the weekend specialist deficit remains unquantified. This uncertainty could hamper efforts by national health systems to introduce 7 day health services. We aimed to examine preliminary associations between specialist intensity and weekend admission mortality across the English National Health Service. METHODS: Eligible hospital trusts were those in England receiving unselected emergency admissions. On Sunday June 15 and Wednesday June 18, 2014, we undertook a point prevalence survey of hospital specialists (consultants) to obtain data relating to the care of patients admitted as emergencies. We defined specialist intensity at each trust as the self-reported estimated number of specialist hours per ten emergency admissions between 0800 h and 2000 h on Sunday and Wednesday. With use of data for all adult emergency admissions for financial year 2013-14, we compared weekend to weekday admission risk of mortality with the Sunday to Wednesday specialist intensity ratio within each trust. We stratified trusts by size quintile. FINDINGS: 127 of 141 eligible acute hospital trusts agreed to participate; 115 (91%) trusts contributed data to the point prevalence survey. Of 34,350 clinicians surveyed, 15,537 (45%) responded. Substantially fewer specialists were present providing care to emergency admissions on Sunday (1667 [11%]) than on Wednesday (6105 [42%]). Specialists present on Sunday spent 40% more time caring for emergency patients than did those present on Wednesday (mean 5·74 h [SD 3·39] vs 3·97 h [3·31]); however, the median specialist intensity on Sunday was only 48% (IQR 40-58) of that on Wednesday. The Sunday to Wednesday intensity ratio was less than 0·7 in 104 (90%) of the contributing trusts. Mortality risk among patients admitted at weekends was higher than among those admitted on weekdays (adjusted odds ratio 1·10, 95% CI 1·08-1·11; p<0·0001). There was no significant association between Sunday to Wednesday specialist intensity ratios and weekend to weekday mortality ratios (r -0·042; p=0·654). INTERPRETATION: This cross-sectional analysis did not detect a correlation between weekend staffing of hospital specialists and mortality risk for emergency admissions. Further investigation is needed to evaluate whole-system secular change during the implementation of 7 day services. Policy makers should exercise caution before attributing the weekend effect mainly to differences in specialist staffing. FUNDING: National Institute for Health Research Health Services and Delivery Research Programme.


Assuntos
Mortalidade Hospitalar , Hospitalização/estatística & dados numéricos , Admissão e Escalonamento de Pessoal/estatística & dados numéricos , Médicos/provisão & distribuição , Especialização/estatística & dados numéricos , Estudos Transversais , Emergências , Inglaterra , Política de Saúde , Hospitais , Humanos , Razão de Chances , Medicina Estatal , Inquéritos e Questionários , Fatores de Tempo
7.
BMC Cancer ; 16: 333, 2016 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-27225032

RESUMO

BACKGROUND: The anti-tumour activity of cisplatin is thought to be a result of its capacity to form DNA adducts which prevent cellular processes such as DNA replication and transcription. These DNA adducts can effectively induce cancer cell death, however, there are a range of clinical side effects and drug resistance issues associated with its use. In this study, the biological properties of three novel dinuclear platinum-based compounds (that contain alkane bridging linkers of eight, ten and twelve carbon atoms in length) were characterised to assess their potential as anticancer agents. METHODS: The properties of these compounds were determined using a DNA template containing seven tandem telomeric repeat sequences. A linear amplification reaction was used in combination with capillary electrophoresis to quantify the sequence specificity of DNA adducts formed by these compounds at base pair resolution. The DNA cross-linking ability of these compounds was assessed using denaturing agarose gel electrophoresis and cytotoxicity was determined in HeLa cells using a colorimetric cell viability assay. RESULTS: The dinuclear compounds were found to preferentially form DNA adducts at guanine bases and they exhibited different damage intensity profiles at the telomeric repeat sequences compared to that of cisplatin. The dinuclear compounds were found to exhibit a low level of cytotoxicity relative to cisplatin and their cytotoxicity increased as the linker length increased. Conversely, the interstrand cross-linking efficiency of the dinuclear compounds increased as the linker length decreased and the compound with the shortest alkane linker was six-fold more effective than cisplatin. CONCLUSIONS: Since the bifunctional compounds exhibit variation in sequence specificity of adduct formation and a greater ability to cross-link DNA relative to cisplatin they warrant further investigation towards the goal of developing new cancer chemotherapeutic agents.


Assuntos
Cisplatino/farmacologia , Reagentes de Ligações Cruzadas/farmacologia , DNA/efeitos dos fármacos , Compostos de Platina/farmacologia , Sequência de Bases , Sobrevivência Celular/efeitos dos fármacos , DNA/química , Adutos de DNA , Células HeLa , Humanos , Estrutura Molecular , Conformação de Ácido Nucleico , Compostos de Platina/química
8.
J Infect Dis ; 203(1): 18-24, 2011 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-21148492

RESUMO

We describe the first confirmed person-to-person transmission of oseltamivir-resistant pandemic influenza A(H1N1) 2009 virus that occurred in a hematology unit in the United Kingdom. Eleven cases of (H1N1) 2009 virus infection were identified, of which, ten were related as shown by sequence analysis of the hemagglutinin and neuraminidase genes. H275Y analysis demonstrated that 8 of 10 case patients had oseltamivir-resistant virus, with 4 of 8 case patients infected by direct transmission of resistant virus. Zanamivir should be considered as first-line therapy for influenza in patients with lymphopenic hematological conditions and uptake of influenza vaccination encouraged to further reduce the number of susceptible individuals.


Assuntos
Antivirais/farmacologia , Farmacorresistência Viral , Vírus da Influenza A Subtipo H1N1/efeitos dos fármacos , Influenza Humana/transmissão , Influenza Humana/virologia , Oseltamivir/farmacologia , Adulto , Idoso , Substituição de Aminoácidos/genética , Infecção Hospitalar/transmissão , Infecção Hospitalar/virologia , Hemaglutininas Virais/genética , Hospitais , Humanos , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Linfopenia/complicações , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Neuraminidase/genética , RNA Viral/genética , Análise de Sequência de DNA , Reino Unido , Proteínas Virais/genética
9.
BMJ Qual Saf ; 30(7): 536-546, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33115851

RESUMO

BACKGROUND: In 2013, the English National Health Service launched the policy of 7-day services to improve care quality and outcomes for weekend emergency admissions. AIMS: To determine whether the quality of care of emergency medical admissions is worse at weekends, and whether this has changed during implementation of 7-day services. METHODS: Using data from 20 acute hospital Trusts in England, we performed randomly selected structured case record reviews of patients admitted to hospital as emergencies at weekends and on weekdays between financial years 2012-2013 and 2016-2017. Senior doctor ('specialist') involvement was determined from annual point prevalence surveys. The primary outcome was the rate of clinical errors. Secondary outcomes included error-related adverse event rates, global quality of care and four indicators of good practice. RESULTS: Seventy-nine clinical reviewers reviewed 4000 admissions, 800 in duplicate. Errors, adverse events and care quality were not significantly different between weekend and weekday admissions, but all improved significantly between epochs, particularly errors most likely influenced by doctors (clinical assessment, diagnosis, treatment, prescribing and communication): error rate OR 0.78; 95% CI 0.70 to 0.87; adverse event OR 0.48, 95% CI 0.33 to 0.69; care quality OR 0.78, 95% CI 0.70 to 0.87; all adjusted for age, sex and ethnicity. Postadmission in-hospital care processes improved between epochs and were better for weekend admissions (vital signs with National Early Warning Score and timely specialist review). Preadmission processes in the community were suboptimal at weekends and deteriorated between epochs (fewer family doctor referrals, more patients with chronic disease or palliative care designation). CONCLUSIONS AND IMPLICATIONS: Hospital care quality of emergency medical admissions is not worse at weekends and has improved during implementation of the 7-day services policy. Causal pathways for the weekend effect may extend into the prehospital setting.


Assuntos
Admissão do Paciente , Medicina Estatal , Serviço Hospitalar de Emergência , Inglaterra , Política de Saúde , Mortalidade Hospitalar , Hospitais , Humanos , Qualidade da Assistência à Saúde , Fatores de Tempo
10.
Trends Cell Biol ; 15(6): 319-26, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15953550

RESUMO

Genome-wide analyses of yeast provide insight into cellular responses to reactive oxygen species (ROS). Many deletion mutants are sensitive to at least one ROS, but no one oxidant is representative of 'oxidative stress' despite the widespread use of a single compound such as H(2)O(2). This has major implications for studies of pathological situations. Cells have a range of mechanisms for maintaining resistance that involves either induction or repression of many genes and extensive remodeling of the transcriptome. Cells have constitutive defense systems that are largely unique to each oxidant, but overlapping, inducible repair systems. The pattern of the transcriptional response to a particular ROS depends on its concentration, and 'classical' antioxidant systems that are induced by high concentrations of ROS can be repressed when cells adapt to low concentrations of ROS.


Assuntos
Células/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Animais , Apoptose , Humanos , Oxirredução , Estresse Oxidativo , Fatores de Transcrição/metabolismo
11.
J Infect Prev ; 20(2): 91-98, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30944593

RESUMO

BACKGROUND: We sought to reduce healthcare-associated infections (HCAIs) through the application of complexity science. OBJECTIVE: To confirm incidental findings that altering the structure of microbiology reports with targeted education led to better utilisation of laboratory resources, while participating in efforts to reduce HCAI. METHODS: We adopted a different approach to laboratory result authorisation, using narrative to engage the clinicians and induce behavioural change. Subsequent educational opportunities emphasised key messages. FINDINGS/RESULTS: Positive urine means calculated by the analysis tool numbered 2179/month throughout the study period. Negative urines started at 5576/month, reduced to 5134/month in November 2014 and to 4602/month in April 2016, coinciding with our changes. Opportunity costs were saved. DISCUSSION: The changes in both policy and reporting were contemporaneous with a decline in negative samples. There were no significant changes in the number of positive specimens. The efficiency and effectiveness of the laboratory was improved and resources released: £145,000 ($182,000) for a resident population of 384,000. This suggests an annual release of about £25 million ($31 million) may be possible in the UK and £122 million ($155 million) in the USA.

12.
Tuberculosis (Edinb) ; 119: 101865, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31563810

RESUMO

This study describes the analysis of DNA from heat-killed (boilate) isolates of Mycobacterium tuberculosis from two UK outbreaks where DNA was of sub-optimal quality for the standard methodologies routinely used in microbial genomics. An Illumina library construction method developed for sequencing ancient DNA was successfully used to obtain whole genome sequences, allowing analysis of the outbreak by gene-by-gene MLST, SNP mapping and phylogenetic analysis. All cases were spoligotyped to the same Haarlem H1 sub-lineage. This is the first described application of ancient DNA library construction protocols to allow whole genome sequencing of a clinical tuberculosis outbreak. Using this method it is possible to obtain epidemiologically meaningful data even when DNA is of insufficient quality for standard methods.


Assuntos
DNA Bacteriano/genética , Genoma Bacteriano/genética , Mycobacterium tuberculosis/genética , Polimorfismo de Nucleotídeo Único , Tuberculose/microbiologia , Criança , Surtos de Doenças , Saúde Global , Humanos , Tipagem de Sequências Multilocus , Tuberculose/epidemiologia , Sequenciamento Completo do Genoma
13.
Future Healthc J ; 5(1): 5-6, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31098522

RESUMO

For the last 4 years, this part of the Future Healthcare Journal has been the place to find regular overview updates on progress made by the Future Hospital Programme of the Royal College of Physicians, together with its partners, in realising the vision of the Future Hospital Commission. As outlined in this article, the Future Hospital Programme has now concluded. However, much of its work is being carried on by the RCP Quality Improvement Programme, which can be contacted on RCPQI@rcplondon.ac.uk. Follow the Quality Improvement Programme on Twitter: @RCP_QI.

14.
Future Healthc J ; 4(2): 78-79, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31098439

RESUMO

This part of the Future Hospital Journal is where you will find regular overview updates on progress made by the Future Hospital Programme of the Royal College of Physicians, together with its partners, in realising the vision of the Future Hospital Commission. We very much welcome your feedback. If you have any comments, or would like to be involved in the work of the Programme, please contact futurehospital@rcplondon.ac.uk. Follow the Future Hospital Programme on Twitter: @RCPFutureHosp.

15.
Future Healthc J ; 4(3): 158-159, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31098463

RESUMO

This part of the Future Healthcare Journal is where you will find regular overview updates on progress made by the Future Hospital Programme of the Royal College of Physicians, together with its partners, in realising the vision of the Future Hospital Commission. We very much welcome your feedback. If you have any comments, or would like to be involved in the work of the Programme, please contact futurehospital@rcplondon.ac.uk. Follow the Future Hospital Programme on Twitter: @RCPFutureHosp.

16.
Future Hosp J ; 4(1): 9-10, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31098275

RESUMO

This part of the Future Hospital Journal is where you will find regular overview updates on -progress made by the Future Hospital Programme of the Royal -College of Physicians, together with its -partners, in realising the vision of the Future -Hospital -Commission. We very much welcome your feedback. If you have any comments, or would like to be involved in the work of the Programme, please contact futurehospital@rcplondon.ac.uk.

17.
Biochim Biophys Acta ; 1678(2-3): 126-34, 2004 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-15157738

RESUMO

Chromatin structure at the silencer region of the epsilon-globin promoter was investigated using novel nitrogen mustards as probes of protein--DNA interactions. Sites of protection and enhancement that corresponded to known transcription factor binding sites were detected in both K562 and HeLa cells at this gene region. Protection was observed at several sites including the GATA-1/YY1 motifs. Of particular interest was a large 155 bp footprint that was observed at the epsilon-globin gene silencer region of the promoter. This large footprint was consistent with the presence of a positioned nucleosome core in intact human cells at this silencer region. Additionally, the DNA sequence at the epsilon-globin silencer and promoter was compared for 11 mammalian species. Significant areas of conservation were found that correlated with known transcription factor binding motifs. This phylogenetic footprinting analysis was compared to the genomic footprinting data at the epsilon-globin silencer region.


Assuntos
Globinas/genética , Motivos de Aminoácidos , Animais , Sequência de Bases , Sítios de Ligação , Cromatina/metabolismo , DNA/metabolismo , Dano ao DNA , Globinas/metabolismo , Células HeLa , Humanos , Células K562 , Mecloretamina/farmacologia , Modelos Genéticos , Dados de Sequência Molecular , Família Multigênica , Nucleossomos/metabolismo , Filogenia , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , Análise de Sequência de DNA , Especificidade da Espécie
18.
Biochim Biophys Acta ; 1574(3): 223-30, 2002 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-11997087

RESUMO

As part of an ongoing drug development programme, this paper describes the sequence specificity and time course of DNA adduct formation for a series of novel DNA-targeted analogues of cis-diaminedichloroplatinum(II) (cisplatin) (9-aminoacridine-4-carboxamide Pt complexes) in intact HeLa cells. The sequence specificity of DNA damage caused by cisplatin and analogues in human (HeLa) cells was studied using Taq DNA polymerase and a linear amplification/polymerase stop assay. Primer extension is inhibited by a Pt-DNA adduct, and hence the sites of these lesions can be analysed on DNA sequencing gels. The repetitive alphoid DNA sequence was used as the target DNA in human cells. The 9-aminoacridine-4-carboxamide Pt complexes exhibited a markedly different sequence specificity relative to cisplatin and other analogues. The sequence specificity of the 9-aminoacridine-4-carboxamide Pt complexes is shifted away from a preference for runs of guanines. The 9-aminoacridine-4-carboxamide Pt complexes have an enhanced preference for GA dinucleotides. This is the first occasion that an altered DNA sequence specificity has been demonstrated for a cisplatin analogue in human cells. A time course of DNA damage revealed that the DNA-targeted Pt complexes, consisting of four 9-aminoacridine-4-carboxamide Pt complexes and one acridine-4-carboxamide Pt complex, damaged DNA more rapidly compared to cisplatin and non-targeted analogues. A comparison of the time taken to reach half the maximum relative intensity indicated that the DNA-targeted Pt complexes reacted approximately 4-fold faster than cisplatin and the non-targeted analogues.


Assuntos
Cisplatino/análogos & derivados , Adutos de DNA/química , Dano ao DNA , Substâncias Intercalantes/farmacologia , Compostos Organoplatínicos/farmacologia , Aminoacridinas/química , Sequência de Bases , Sítios de Ligação , Cisplatino/farmacologia , Células HeLa , Humanos , Substâncias Intercalantes/química , Compostos Organoplatínicos/química , Taq Polimerase , Fatores de Tempo
19.
Int J Biochem Cell Biol ; 37(3): 665-78, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15618023

RESUMO

The retinoblastoma tumour suppressor protein is a key cell cycle regulator. Protein-DNA interactions at the retinoblastoma (RB1) promoter, including the 'essential regulatory region', were investigated using novel DNA-targeted nitrogen mustards in intact human cells. The footprinting experiments were carried out in two different environments: in intact HeLa and K562 cells where the access of DNA-targeted probes to chromatin is affected by cellular protein-DNA interactions associated with gene regulation; and in purified DNA where their access is unencumbered by protein-DNA interactions. Using the ligation-mediated PCR (LMPCR) technique, the sites of damage were determined at base pair resolution on DNA sequencing gels. Our results demonstrate that, in intact cells, footprints were observed at the E2F, ATF and RBF1/Sp1 DNA binding motifs in the RB1 promoter. In addition, a novel footprint was observed at a previously unidentified cycle homology region (CHR) and at four uncharacterised protein-DNA binding sites. In further experiments, nitrogen mustard-treated cells were FACS sorted into G1, S and G2/M phases of the cell cycle prior to LMPCR analysis. Expression of the RB1 gene is cell cycle-regulated and footprinting studies of the promoter in FACS-sorted cells indicated that transcription factor binding at the GC box, CHR binding motif and the 'essential regulatory region' are cell cycle dependent.


Assuntos
Pegada de DNA , DNA , Genes do Retinoblastoma , Regiões Promotoras Genéticas , Sequências Reguladoras de Ácido Nucleico , Alquilantes/farmacologia , Ciclo Celular , Dano ao DNA/efeitos dos fármacos , Proteínas de Ligação a DNA , Citometria de Fluxo , Células HeLa , Humanos , Células K562 , Mecloretamina/farmacologia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA
20.
Free Radic Biol Med ; 37(1): 23-35, 2004 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-15183192

RESUMO

Free radicals can initiate the oxidation of polyunsaturated fatty acids in cells through the process of lipid peroxidation. The genome-wide transcriptional changes in Saccharomyces cerevisiae after treatment with the toxic lipid peroxidation product linoleic acid hydroperoxide (LoaOOH) were identified. High-dose treatment led to a switch in transcription from biosynthetic to protective functions. This response encompassed a set of genes stimulated predominantly by LoaOOH, and not by other oxidants or heat shock, which contained components of the pleiotropic drug resistance system. The dose dependence of the transcriptional response revealed that large and widespread changes occur only in response to higher doses. Pretreatment of cells with sublethal doses of LoaOOH induces resistance to an otherwise lethal dose through the process of adaptation. Adaptive doses elicited a more subtle transcriptional response affecting metabolic functions, including an increase in the capacity for detoxification and downregulation of the rate of protein synthesis. Surprisingly, the cellular response to adaptive doses did not include induction of oxidative-stress defense enzymes nor of transcripts involved in general cellular defense systems.


Assuntos
Genoma Fúngico , Peróxidos Lipídicos/farmacologia , Saccharomyces cerevisiae/genética , Transcrição Gênica/genética , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Peroxidação de Lipídeos , RNA Mensageiro/genética , Espécies Reativas de Oxigênio/metabolismo , Saccharomyces cerevisiae/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA