RESUMO
The CRISPR-Cas9 system has revolutionized our ability to precisely modify the genome and has led to gene editing in clinical applications. Comprehensive analysis of gene editing products at the targeted cut-site has revealed a complex spectrum of outcomes. ON-target genotoxicity is underestimated with standard PCR-based methods and necessitates appropriate and more sensitive detection methods. Here, we present two complementary Fluorescence-Assisted Megabase-scale Rearrangements Detection (FAMReD) systems that enable the detection, quantification, and cell sorting of edited cells with megabase-scale loss of heterozygosity (LOH). These tools reveal rare complex chromosomal rearrangements caused by Cas9-nuclease and show that LOH frequency depends on cell division rate during editing and p53 status. Cell cycle arrest during editing suppresses the occurrence of LOH without compromising editing. These data are confirmed in human stem/progenitor cells, suggesting that clinical trials should consider p53 status and cell proliferation rate during editing to limit this risk by designing safer protocols.
Assuntos
Sistemas CRISPR-Cas , Proteína Supressora de Tumor p53 , Humanos , Sistemas CRISPR-Cas/genética , Proteína Supressora de Tumor p53/genética , Pontos de Checagem do Ciclo Celular/genética , Divisão Celular , Separação Celular , RNARESUMO
CRISPR-Cas9 is a promising technology for gene therapy. However, the ON-target genotoxicity of CRISPR-Cas9 nuclease due to DNA double-strand breaks has received little attention and is probably underestimated. Here we report that genome editing targeting globin genes induces megabase-scale losses of heterozygosity (LOH) from the globin CRISPR-Cas9 cut-site to the telomere (5.2 Mb). In established lines, CRISPR-Cas9 nuclease induces frequent terminal chromosome 11p truncations and rare copy-neutral LOH. In primary hematopoietic progenitor/stem cells, we detect 1.1% of clones (7/648) with acquired megabase LOH induced by CRISPR-Cas9. In-depth analysis by SNP-array reveals the presence of copy-neutral LOH. This leads to 11p15.5 partial uniparental disomy, comprising two Chr11p15.5 imprinting centers (H19/IGF2:IG-DMR/IC1 and KCNQ1OT1:TSS-DMR/IC2) and impacting H19 and IGF2 expression. While this genotoxicity is a safety concern for CRISPR clinical trials, it is also an opportunity to model copy-neutral-LOH for genetic diseases and cancers.
Assuntos
Sistemas CRISPR-Cas , Edição de Genes/métodos , Globinas/genética , Células-Tronco Hematopoéticas/metabolismo , Perda de Heterozigosidade/genética , Deleção de Sequência , Células Cultivadas , Deleção Cromossômica , Cromossomos Humanos Par 11/genética , Metilação de DNA , Expressão Gênica , Células HEK293 , Células-Tronco Hematopoéticas/citologia , Humanos , Fator de Crescimento Insulin-Like II/genética , Polimorfismo de Nucleotídeo Único , RNA Longo não Codificante/genéticaRESUMO
A liquid chromatographic method was developed to analyse a tablet containing three anti-human immunodeficiency virus (HIV) compounds: lamivudine, zidovudine and a compound with the code name TMC278.HCl. Due to the presence of UV absorbing chromophores in the three active components, a single LC method with UV detection was developed. A Hypersil BDS C(18) column was used as stationary phase and the assay was performed with gradient elution using mobile phases containing acetonitrile, 0.2M potassium dihydrogen phosphate and water. The sample pretreatment is performed by treating the formulation with dimethyl sulfoxide-water (1:1) followed by filtration. After method development, the influence of the different chromatographic parameters on the separation, the interference of other active compounds and excipients, the repeatability and the linearity were investigated. The method was shown to be robust, selective, linear and repeatable. Finally, the content of the compounds in the tablet was determined.
Assuntos
Fármacos Anti-HIV/química , Lamivudina/química , Nitrilas/química , Pirimidinas/química , Zidovudina/química , Bioensaio , Calibragem , Química Farmacêutica , Cromatografia Líquida/métodos , HIV/efeitos dos fármacos , Humanos , Luz , Estrutura Molecular , Padrões de Referência , Rilpivirina , Espalhamento de Radiação , Sensibilidade e Especificidade , Solventes/química , Espectrofotometria Ultravioleta/métodos , ComprimidosRESUMO
2-Chloro-2'-deoxyadenosine (CdA) is a deoxyadenosine analogue which targets enzymes involved in DNA synthesis, and hence might interfere with the resynthesis step of DNA repair. We tested this hypothesis in resting B cell chronic lymphocytic leukemia (B-CLL) lymphocytes, after firstly characterizing unscheduled DNA synthesis occurring in these cells. We observed that the spontaneous incorporation of [methyl-3H]thymidine (dThd) into DNA of B-CLL cells was not completely inhibitable by hydroxyurea (HU) which blocks DNA replication. In addition, in the presence of HU, dThd incorporation could be upregulated by UVC radiation or DNA alkylation, without re-entry of the cells into S phase. CdA was found to inhibit both spontaneous and upregulated DNA synthesis in B-CLL cells. Phosphorylation of CdA was essential to exert this effect. We finally observed a strong synergistic cytotoxicity between UV light and CdA, which was correlated with activation of caspase-3 and high molecular weight DNA fragmentation, two markers of apoptosis. Taken together, these observations indicate that in B-CLL cells CdA inhibits unscheduled DNA synthesis which represents the polymerizing step of a repair process responsive to DNA aggression. Inhibition of this process by CdA, together with a combined activation of the apoptotic proteolytic cascade by CdA and UV, may explain their synergistic cytotoxicity.
Assuntos
Antimetabólitos Antineoplásicos/farmacologia , Linfócitos B/efeitos dos fármacos , Cladribina/farmacologia , Reparo do DNA/efeitos dos fármacos , Replicação do DNA/efeitos dos fármacos , Leucemia Linfocítica Crônica de Células B/patologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Pró-Fármacos/farmacologia , Radiossensibilizantes/farmacologia , Alquilantes/farmacologia , Alquilação , Antimetabólitos Antineoplásicos/metabolismo , Apoptose/efeitos dos fármacos , Apoptose/efeitos da radiação , Linfócitos B/metabolismo , Linfócitos B/efeitos da radiação , Caspase 3 , Caspases/análise , Cladribina/metabolismo , Dano ao DNA , DNA de Neoplasias/biossíntese , DNA de Neoplasias/efeitos dos fármacos , DNA de Neoplasias/efeitos da radiação , Depressão Química , Humanos , Hidroxiureia/farmacologia , Proteínas de Neoplasias/análise , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/efeitos da radiação , Fosforilação , Pró-Fármacos/metabolismo , Tolerância a Radiação , Timidina/metabolismo , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/metabolismo , Células Tumorais Cultivadas/efeitos da radiação , Raios UltravioletaRESUMO
The effects of 2-chloro-2'-deoxyadenosine (CdA, cladribine), an adenosine deaminase-resistant analogue toxic for both proliferating and resting lymphoid cells, were investigated in the human leukemia cell line EHEB, which was derived from a patient with B-cell chronic lymphocytic leukemia. These cells were found to be less sensitive to CdA than B-cell chronic lymphocytic leukemia lymphocytes (approximately 25-fold) and other human lymphoblastic cell lines (10-1000-fold). Phosphorylation of CdA by deoxycytidine kinase and intracellular accumulation of 2-chloro-2'-deoxyadenosine triphosphate (CdATP) were similar in EHEB cells and in other CdA-sensitive cell lines. In contrast, the inhibitory effect of CdA on ribonucleotide reductase activity, which was investigated in situ by the conversion of cytidine into deoxyribonucleotides and its incorporation into DNA, was much less pronounced in EHEB cells than in other human lymphoblastic cells. Accordingly, concentrations of deoxynucleoside triphosphates did not decrease and even tended to rise. Unexpectedly, incorporation of thymidine and deoxycytidine into DNA was increased severalfold after a 24-h incubation with CdA. CdA also increased the activities of deoxycytidine kinase and thymidine kinase approximately 4-fold. Analysis of the cell cycle by flow cytometry showed that after 24 h, CdA provoked an increase in the proportion of cells in S phase, synthesizing DNA. We conclude that the EHEB cell line is resistant to the cytotoxic action of CdA not only because of a lack of inhibition of ribonucleotide reduction but also because CdA, in contrast with its known effects, provokes in this cell line an increase in the proportion of cells replicating their DNA. Unraveling of the mechanism of this effect may shed light on clinical resistance to CdA.
Assuntos
Antineoplásicos/farmacologia , Cladribina/farmacologia , Leucemia de Células B/patologia , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/fisiologia , Sobrevivência Celular/efeitos dos fármacos , Cladribina/metabolismo , Citidina/metabolismo , DNA de Neoplasias/efeitos dos fármacos , DNA de Neoplasias/metabolismo , Desoxicitidina/metabolismo , Desoxicitidina Quinase/efeitos dos fármacos , Desoxicitidina Quinase/metabolismo , Relação Dose-Resposta a Droga , Resistencia a Medicamentos Antineoplásicos , Humanos , Concentração Inibidora 50 , Leucemia de Células B/tratamento farmacológico , Leucemia de Células B/metabolismo , Nucleotídeos/metabolismo , Fosforilação , Ribonucleotídeo Redutases/efeitos dos fármacos , Ribonucleotídeo Redutases/metabolismo , Timidina Quinase/efeitos dos fármacos , Timidina Quinase/metabolismo , Células Tumorais CultivadasRESUMO
BACKGROUND AND PURPOSE: A cost minimization analysis of radiotherapy (RT), laser microsurgery (L) or partial laryngectomy (PL), which are equally effective options for T1N0 glottic SCC was carried out from the perspective of the National Health Care System. METHODS: For each modality, the various events associated with the diagnostic procedure, the primary treatment, the complications, and the salvage treatment were individualized. The charges of each of these events weighted for the frequency of occurrence were then determined using the 'fee for service' policy established by the National Health Insurance of Belgium. RESULTS: A total cost of 5172, 5847 and 11563 EURO were calculated for RT, L and PL, respectively. For L, cost included post-operative RT applied in case of positive margins (30%). For PL, the cost of the primary treatment accounted for 68% of the total cost whereas it only accounted for 50 and 43% for L and RT, respectively. For RT, L or PL, complications accounted for less than 10% of the total cost. The cost of salvage treatment reached 19, 14 and 8% of the total cost for RT, L and PL, respectively. A sensitivity analysis indicated that reduction of the duration of hospitalization decreases the costs without affecting the ranking between the three options. Also, the cost of L could be reduced even slightly below the cost of RT by decreasing the need for post-operative RT. CONCLUSIONS: RT and L have almost the same expected average cost for the treatment of T1N0 glottic SCC, whereas PL is twice as expensive.
Assuntos
Carcinoma de Células Escamosas/economia , Carcinoma de Células Escamosas/terapia , Neoplasias Laríngeas/economia , Neoplasias Laríngeas/terapia , Bélgica , Carcinoma de Células Escamosas/patologia , Terapia Combinada , Redução de Custos , Glote , Humanos , Neoplasias Laríngeas/patologia , Laringectomia/economia , Terapia a Laser/economia , Tempo de Internação/economia , Microcirurgia/economia , Radioterapia/economiaRESUMO
PURPOSE: The aim of this study was to retrospectively compare the efficacy and functional results of three treatment options for T1N0M0 glottic carcinomas applied in a single institution. MATERIALS AND METHODS: One hundred six charts of patients with biopsy-proven T1N0M0 glottic carcinomas treated between 1979 and 1995 were reviewed. There were 81 T1a and 25 T1b tumors. Forty-one patients were treated by radiotherapy (RT) (median dose of 64 Gy), 34 patients were treated by partial laryngectomy (PL) and 31 patients were treated by laser microsurgery (L) of which 10 received postoperative RT for positive margins. In 18 patients, a perceptual voice rating on a visual scale was performed by the patients themselves, three non-speech specialists and two speech therapists. RESULTS: With a median follow-up time of 63.5 months, the 5- and 10-year loco-regional control probabilities reached 91 and 87%, respectively, without any difference between the treatment groups. After salvage laryngectomy, the 5- and 10-year loco-regional control probabilities reached 97% without any difference between the treatment groups. For the whole population, overall survival reached 78 and 62.4% at 5 and 10 years, respectively. The actuarial incidence of second primary reached 19% at 10 years. Regarding the quality of voice, overall there was a trend towards a worse satisfaction index, more hoarseness and more breathiness after PL than after L or RT. CONCLUSIONS: Our data suggested that assuming proper selection of patients, RT and L yielded similar outcomes and functional results. Local recurrence can be adequately salvaged by surgery. On the other hand, PL appeared to yield similar loco-regional control probability but with a worse quality of voice.
Assuntos
Carcinoma/radioterapia , Glote/efeitos da radiação , Neoplasias Laríngeas/radioterapia , Laringectomia/métodos , Terapia a Laser/métodos , Microcirurgia , Análise Atuarial , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Carcinoma/patologia , Carcinoma/cirurgia , Feminino , Seguimentos , Glote/patologia , Glote/cirurgia , Rouquidão/etiologia , Humanos , Neoplasias Laríngeas/patologia , Neoplasias Laríngeas/cirurgia , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Segunda Neoplasia Primária/patologia , Satisfação do Paciente , Dosagem Radioterapêutica , Radioterapia Adjuvante , Estudos Retrospectivos , Terapia de Salvação , Taxa de Sobrevida , Resultado do Tratamento , Qualidade da VozRESUMO
BACKGROUND AND PURPOSE: To determine the influence of the number of fractions (or the dose per fraction) on the proton relative biological effectiveness (RBE). MATERIALS AND METHODS: Intestinal crypt regeneration in mice was used as the biological endpoint. RBE was determined relative to cobalt-60 gamma rays for irradiations in one, three and ten fractions separated by a time interval of 3.5h. Proton irradiations were performed at the middle of a 7-cm Spread Out Bragg Peak (SOBP). RESULTS: Proton RBEs (and corresponding gamma dose per fraction) at the level of 20 regenerated crypts per circumference were found equal to 1.15+/-0.04 (10.0 Gy), 1.15+/-0.05 (4.8 Gy) and 1.14+/-0.07 (1.7 Gy) for irradiations in one, three and ten fractions, respectively. Alpha/beta ratios as derived from direct analysis of the 'quantal radiation response data' were found to be 7.6 Gy for gamma rays and 8.2 Gy for protons. Additional proton irradiations in ten fractions at the end of the SOBP were found to be more effective than at the middle of the SOBP by a factor of 1.14 (1.05-1.23). CONCLUSION: Proton RBE for crypt regeneration was found to be independent of fractionation up to ten fractions. One can expect that it remains unchanged for higher number of fractions as the lethalities for doses smaller than 3 Gy are exclusively due to direct lethal events. As a tendency for increased effectiveness at the end of the SOBP is reported in the majority of the studies, for clinical applications it would be advisable to allow for by arranging a sloping depth dose curve in the deeper part of the target volume. Finally, it must be noticed that most of in vitro and in vivo RBE values for protons are larger than the current clinical RBE (RBE=1.10).
Assuntos
Fracionamento da Dose de Radiação , Intestinos/efeitos da radiação , Tolerância a Radiação , Animais , Feminino , Raios gama , Intestinos/patologia , Intestinos/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Prótons , Radioterapia de Alta Energia , Distribuição Aleatória , Regeneração , Irradiação Corporal TotalRESUMO
In 76 patients with a renal allograft the plasma concentration of pyridoxal-5'-phosphate, the activity concentrations of aspartate aminotransferase and alanine aminotransferase and the percentage stimulation of both enzymes have been investigated. Generally, the concentration of the coenzyme was decreased in the patient group compared to normal individuals. The percentage increase of aspartate aminotransferase is the same for the patients as for the normal group. However, the stimulation of alanine aminotransferase is greatly increased for the patient group except for those patients who received cyclosporine A instead of azathioprine. The highly significant inverse correlation between the plasma pyridoxal-5'-phosphate concentration and the percentage stimulation of the enzymatic activity of aspartate aminotransferase and alanine aminotransferase observed before for a normal group, is not present in our patient group. The percentage increase is independent on the activity concentration of the enzymes. It is concluded that the high stimulation of alanine aminotransferase depends on the administration of azathioprine.
Assuntos
Alanina Transaminase/sangue , Aspartato Aminotransferases/sangue , Transplante de Rim , Fosfato de Piridoxal/sangue , Adulto , Apoenzimas/sangue , Catálise , Ciclosporinas/farmacologia , Ativação Enzimática/efeitos dos fármacos , Feminino , Antígenos de Superfície da Hepatite B/análise , Humanos , Masculino , Pessoa de Meia-Idade , Fosfato de Piridoxal/farmacologiaRESUMO
In 16 patients with a renal allograft the activity concentrations of aspartate aminotransferase and alanine aminotransferase and the percentage stimulation of both enzymes were investigated. After the transplantation the patients received prednisone and cyclosporine A as immunosuppressive therapy, while exactly 3 months after the date of transplantation prednisone and azathioprine were given as immunosuppressives. In the first period, the percentage increase of the activity concentration of aspartate aminotransferase and alanine aminotransferase upon supplementation of pyridoxal-5'-phosphate in vitro were similar to that of healthy individuals. In the second period, however, the percentage increase of the activity concentration of alanine aminotransferase was much higher than that of aspartate aminotransferase. Cyclosporine A given during a period of about 400 days did not influence the percentage increase of both enzymes. It is concluded that the high stimulation of alanine aminotransferase in the second period depends on the presence of azathioprine or its metabolites in serum.
Assuntos
Apoenzimas/sangue , Apoproteínas/sangue , Azatioprina/efeitos adversos , Ciclosporinas/efeitos adversos , Transplante de Rim , Transaminases/sangue , Adulto , Alanina Transaminase/sangue , Aspartato Aminotransferases/sangue , Creatinina/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prednisona/efeitos adversosRESUMO
The available knowledge on potential radiosensitizing nucleoside analogues with special focus on fludarabine and gemcitabine is reviewed. These analogues are prodrugs whose active triphosphate forms inhibit various enzymes involved in DNA synthesis and repair. Several properties of these analogues support their use as radiosensitizers. As repair inhibitors, they have the potential to increase the amount of residual DNA and chromosome damage after irradiation, and as DNA synthesis inhibitors, they specifically target the S-phase cell component and could thus overcome the detrimental effect of tumor clonogen repopulation during fractionated irradiation. Also, through their cytotoxic effect, these analogues could increase tumor cell loss, facilitating tumor reoxygenation, and thus obviate tumor hypoxia's inhibitory effect on radioresponse. Induction of DNA damage in all phases of the cell cycle by irradiation could create DNA sites for drug incorporation, possibly inducing an apoptotic response in cells outside of S-phase. Experimental data addressing these hypotheses are reviewed and updates on ongoing clinical trials combining fludarabine or gemcitabine and irradiation are given.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias/tratamento farmacológico , Neoplasias/radioterapia , Nucleosídeos/uso terapêutico , Pró-Fármacos/uso terapêutico , Radiossensibilizantes/uso terapêutico , Desoxicitidina/análogos & derivados , Desoxicitidina/uso terapêutico , Humanos , Nucleosídeos/química , Vidarabina/análogos & derivados , Vidarabina/uso terapêutico , GencitabinaRESUMO
PURPOSE: The present study investigated in vitro radio-enhancement by gemcitabine (dFdC) in two head and neck squamous cell carcinomas with different intrinsic cellular radiosensitivity. MATERIALS AND METHODS: Radiosensitive (SCC61, SF2=0.16) and radioresistant (SQD9, SF2=0.49) human head and neck squamous cell carcinomas were used. Confluent cells were incubated with dFdC and irradiated in drug-free medium with a single dose of 250 kV X-rays (0-12Gy). Cell survival curves were corrected for the toxicity of the drug alone. RESULTS: In both cell lines, radio-enhancement was observed with 5 microM dFdC incubated for 3 h prior to irradiation. Dose modification factors (DMF) at a surviving fraction level of 0.5 reached 1.3 (95% CI 1.1-1.6) and 1.5 (95% CI 1.4-1.5) for SQD9 and SCC61 cells, respectively. Radio-enhancement was associated with a modest increase in the alpha term of the linear-quadratic model. In SQD9 cells, radio-enhancement increased with dFdC incubation time. At 24h, DMF reached a value of 1.5 (95% CI 0.9-3.2). In SCC61 cells at 24h, DMF reached a value of 1.1 (95% CI 0.9-1.2). In both cell lines, radio-enhancement increased with dFdC concentration up to 5-10 microM from which values it levelled off up to 100 microM. CONCLUSIONS: The data indicated that dFdC induced a modest radio-enhancement in both cell lines. For a short incubation time, dFdC did not radio-enhance preferentially the more radio-resistant cells, whereas the opposite was observed for a longer time. In both cell lines, radio-enhancement was saturated above a dFdC concentration of 5-10 microM.
Assuntos
Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/radioterapia , Desoxicitidina/análogos & derivados , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/radioterapia , Radiossensibilizantes/farmacologia , Carcinoma de Células Escamosas/patologia , Morte Celular/efeitos dos fármacos , Morte Celular/efeitos da radiação , Terapia Combinada , Desoxicitidina/farmacologia , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Tolerância a Radiação , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/efeitos da radiação , GencitabinaRESUMO
OBJECTIVE: To assess the risk of ischemic cord injury, we have retrospectively studied the 115 patients who underwent a replacement of the thoracic descending or thoraco-abdominal aorta between January 1980 and December 1994. METHODS: In 72 patients the aortic lesion was located above the diaphragm. The aortic replacement was performed with the aid of extracorporeal circulation in all but 2 patients (97.2%). Only two cases of postoperative paraplegia were observed (2.7%). In 43 patients (10 females and 33 males aged from 26 to 69 years), the occurrence of postoperative paraplegia was considered as a major risk, because of the extension of the aortic lesions (Crawford types I, II and III). Twenty-six patients (60.4%) suffered from chronic dissection and 17 patients had atheromatous aneurysms. Sixteen patients (37.2%) had Marfan syndrome. Twelve patients (27.9%) had already undergone aortic replacement. A preoperative study of the spinal cord vascularization was carried out in 36 patients (83.6%) and the Adamkiewicz artery was visualized in 28 patients (77.8%). In 17 patients (39.5%, group I), the surgical procedure was performed without the aid of extracorporeal circulation. In the remaining 26 patients (60.5%, group II), the surgical procedure was carried out with the aid of cardiopulmonary bypass and profound hypothermic circulatory arrest. Sequential unclamping of the aorta was used in all patients. The cord vascularization was surgically restored in 32 patients (74.4%). When the Adamkiewicz artery was identified, the critical intercostal artery was reimplanted together with the two pairs of adjacent intercostal arteries (25 patients). When the origin of the Adamkiewicz artery remained unknown, the two or three most important patent pairs of intercostal arteries were reimplanted (7 patients). In 8 patients (18.6%) there were no patent intercostal arteries. RESULTS: Hospital mortality accounted for 37.2% (16 patients, including 5 patients with paraplegia). On univariate analysis, extension of the aortic lesions, emergency and redo surgery were the only significant risk factors of mortality (P = 0.05). Cord ischemia was observed in 9 patients (21%): permanent paraplegia in 7 patients (16.2%) and transient medullar disturbance in 2 patients (4.6%). The occurrence of paraplegia was reduced, though not significantly, in group II (16%) vs group I (29%) and in patients with preoperative assessment of the cord vascularization (18% vs 38%). CONCLUSIONS: In our experience: 1) The risk of paraplegia is related to the extension and the type of the aortic lesions. 2) The preoperative study of the medullar vascularization and the use of extracorporeal circulation with deep hypothermia and sequential aortic unclamping, reduce the risk of severe cord ischemia, and 3) Occurrence of postoperative paraplegia depends on several factors and cannot be totally prevented by the surgical technique.
Assuntos
Aneurisma da Aorta Abdominal/cirurgia , Aneurisma da Aorta Torácica/cirurgia , Dissecção Aórtica/cirurgia , Complicações Intraoperatórias/prevenção & controle , Isquemia/prevenção & controle , Paraplegia/prevenção & controle , Complicações Pós-Operatórias/prevenção & controle , Medula Espinal/irrigação sanguínea , Adulto , Idoso , Anastomose Cirúrgica , Dissecção Aórtica/mortalidade , Aneurisma da Aorta Abdominal/mortalidade , Aneurisma da Aorta Torácica/mortalidade , Artérias/cirurgia , Arteriosclerose/mortalidade , Arteriosclerose/cirurgia , Prótese Vascular , Feminino , Mortalidade Hospitalar , Humanos , Complicações Intraoperatórias/mortalidade , Isquemia/mortalidade , Masculino , Síndrome de Marfan/mortalidade , Síndrome de Marfan/cirurgia , Pessoa de Meia-Idade , Paraplegia/mortalidade , Complicações Pós-Operatórias/mortalidade , Reoperação , Risco , Resultado do TratamentoRESUMO
To explain why 2-chloro-2'-deoxyadenosine (CdA) is unable to block DNA synthesis and cell cycle progression, and paradoxically enhances progression from G1 into S phase in the CdA-resistant leukemia EHEB cell line, we studied its metabolism and effects on proteins regulating the transition from G1 to S phase. A low deoxycytidine kinase activity and CdATP accumulation, and a lack of p21 induction despite p53 phosphorylation and accumulation may account for the inability of CdA to block the cell cycle. An alternative pathway involving pRb phosphorylation seems implicated in the CdA-induced increase in G1 to S phase progression.