Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 32
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Neurochirurgie ; 68(2): 183-187, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34481864

RESUMO

INTRODUCTION: Deformity associating coronal and sagittal malalignment can severely impair quality of life in Parkinson's disease (PD). Realignment using patient-specific rods (PSRs) is useful for achieving alignment goals. METHODS: This was a retrospective single-center analysis of a prospectively maintained database of all PD patients who underwent surgery between January 2013 and January 2017. Clinical evaluation, preoperatively and at 1 year's follow-up, used the Oswestry Disability Index (ODI). Radiological evaluation used systematic preoperative and 1-year postoperative full-spine radiographs. RESULTS: Twelve patients were included: 6 female, 6 male; mean age, 68.4 years. Mean follow-up was 40.8 months [range 12-70]. On average, 14 levels were fused [range 10-18]. Unplanned revision surgery was necessary for 8 patients at a mean 15.625 months after index surgery. Mean preoperative ODI score was 64% preoperatively [range 56-70] versus 52% [range 28-64] at 1 year's follow-up (P=0.004). Lumbar lordosis improved significantly, from -16.7° preoperatively to -41.4° at 1 year (P=0.006). Pelvic tilt was the least effectively corrected parameter, with a mean preoperative value of 31.6° vs. 27.8° at 1 year (P=0.19). Mean preoperative sagittal vertical axis was 149.7mm versus 73.6mm at 1 year (P=0.013). Mean preoperative coronal tilt was 68.2mm versus 22.9mm at 1 year (P=0.007). CONCLUSION: Parkinson's disease is a degenerative disease frequently associated with major spine malalignment. The severity of the postural disorders in these patients needs special precautions to avoid complications.


Assuntos
Doença de Parkinson , Fusão Vertebral , Idoso , Feminino , Seguimentos , Humanos , Masculino , Doença de Parkinson/complicações , Doença de Parkinson/cirurgia , Qualidade de Vida , Estudos Retrospectivos , Resultado do Tratamento
3.
Adv Orthop ; 2021: 5572181, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34040810

RESUMO

PURPOSE: The aim of this study is to analyze results according to postoperative pelvic incidence-lumbar lordosis (PI-LL) mismatch in the management of adult spine deformity (ASD) patients. Recently, it has been reported that in addition to lumbar lordosis amount, lordosis repartition between its proximal and distal parts was crucial. METHODS: We enrolled 77 consecutive ASD patients who underwent posterior spinal fusion and deformity correction between 2015 and 2018. On preoperative and 1-year follow-up radiographs, we analyzed different parameters such as L1-S1 lumbar lordosis, L1-L4 proximal lordosis (PLL), L4-S1 distal lordosis (DLL), pelvic tilt (PT), sagittal vertical axis (SVA), and PI-LL mismatch. Comparisons were performed according to postoperative PI-LL mismatch (defined as "aligned" when PI-LL was <10°). The relationship between lordosis distribution and postoperative alignment status was investigated. RESULTS: On the whole series, average lumbar lordosis, SVA, and PI-LL improved (28.2° vs.43.5°, 82 vs. 51 mm, and 26°vs. 14°, all p < 0.001, respectively). On the other hand, PT remained unchanged (30° vs. 28°, p > 0.05). 35 patients were classified as "aligned" and 42 as "not aligned." Patients from the "aligned" group had a significantly lower PI than patients from the "not aligned" group (52° vs. 61°, p=0.009). Postoperative PLL was not different between groups (18° vs. 16° p > 0.05), whereas DLL was significantly higher in the "aligned" group (31° vs. 22°, p=0.003). PI-LL was significantly correlated to DLL (rho = 0.407, p < 0.001) but not with PLL (rho = 0.110, p=0.342). CONCLUSIONS: Our results revealed that in ASD patients, postoperative malalignment was associated with a lack of DLL restoration. "Not aligned" patients had also a significantly higher pelvic incidence. Specific attention must be paid to restore optimal distal lumbar lordosis in order to set the amount and the distribution of optimal postoperative lumbar lordosis.

4.
Neurochirurgie ; 67(2): 152-156, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33157123

RESUMO

INTRODUCTION: Complex spinal surgery is known to be at risk of complications. Surgical site infection is a serious complication in spine surgery and its frequency is significantly increased in adult spinal deformity correction. The aim of this study is to identify patients' characteristics and risk factors of surgical site infection (SSI) following an osteotomy. METHODS: This is a single-center retrospective study of patients who underwent an osteotomy between January 2015 and December 2017. Surgical site infection diagnosis was based upon patient's clinical evidence of infection, biologic parameters, microbiological criteria and/or image findings. RESULTS: In total, 102 patients were eligible and 70 were women (68.6%). Mean age was 65 years old (27-83 years) and mean body mass index (BMI) was 26.14kg.m-2 (18.4-44.1). Eleven patients were in the SSI group and 91 in the No-SSI group. The mean Schwab grade was 1.5 (1-4) in the SSI group vs. 1.4 (1-5) in the No-SSI group (P=0.435). The mean operative time was on 201.9 minutes (67-377). Mean length of stay was 20.6 days (10-73) in the SSI group vs. 15 days (5-44) in the No-SSI group (P=0.041). Favorable outcome was found in 10 patients (90.9%) in the SSI group. CONCLUSION: Correction surgery for adult spinal deformity with osteotomies carries a high risk of complications specially SSI. Identification of risk factors, prevention and medical management of SSI should be well assessed.


Assuntos
Procedimentos Neurocirúrgicos/efeitos adversos , Osteotomia/efeitos adversos , Doenças da Coluna Vertebral/cirurgia , Infecção da Ferida Cirúrgica/etiologia , Adulto , Idoso , Antibacterianos/administração & dosagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Procedimentos Neurocirúrgicos/tendências , Osteotomia/tendências , Estudos Retrospectivos , Fatores de Risco , Doenças da Coluna Vertebral/diagnóstico , Infecção da Ferida Cirúrgica/diagnóstico , Infecção da Ferida Cirúrgica/prevenção & controle
5.
Adv Orthop ; 2020: 6120580, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32695518

RESUMO

Surgical management of adult spinal deformities remains challenging, and one of the major goals is to restore sagittal alignment. Spinal rods used for posterior fixation are usually delivered straight and bended manually during surgery. This manual bending can be responsible for undercorrection of the deformity. In the last years, prebended patient-specific rods have been developed and might be a valuable tool in order to optimize surgical results. The objective is therefore to use the time between surgical decision and operative room in order to realize a precise surgical planning and obtain patient-specific rods. We describe here the planning process and our preliminary experience with patient-specific rods in the management of adult deformity about 77 cases. On the 77 cases, PSR were used without further modifications of the shape. Based on 3-month postoperative evaluation, a significant decrease of sagittal vertical axis (-41%, p < 0.0001) and pelvic incidence-lumbar lordosis (-62%, p < 0.0001) was reported. Pelvic tilt was not significantly corrected, except in patients with Parkinson's disease. In this subgroup of patients, measurements revealed a significant correction of SVA and PI-LL (-53%, p=0.005, and -81%, p < 0.0001, respectively) but also of PT (-23%, p < 0.001). The use of PSR, in our experience, was feasible and provided satisfactory short-term results. It can be a valuable tool in the management of adult spinal deformities. Further studies will be needed in order to confirm these preliminary results.

6.
Support Care Cancer ; 28(5): 2127-2135, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31396747

RESUMO

BACKGROUND: Owing to recent advances in cancer therapy, updated data are required for clinicians counselling patients on treatment of spinal metastases. OBJECTIVE: To analyse the outcomes of surgical treatments of spinal metastases. METHODS: Prospective and multicentric study that included consecutively patients operated on for spinal metastases between January 2016 and January 2017. Overall survival was calculated with the Kaplan-Meier method. Cox proportional hazard model was used to calculate hazard ratio (HR) analysing mortality risk according to preoperative Karnofsky performance status (KPS), mobility level and neurological status. RESULTS: A total of 252 patients were included (145 males, 107 females) aged a mean 63.3 years. Median survival was 450 days. Primary cancer sites were lung (21%) and breast (19%). Multiple spinal metastases involved 122 patients (48%). Concomitant skeletal and visceral metastases were noted in 90 patients (36%). Main procedure was laminectomy and posterior fixation (57%). Overall, pain and mobility level were improved postoperatively. Most patients had normal preoperative motor function (50%) and remained so postoperatively. Patients "bedbound" on admission were the less likely to recover. In-hospital death rate was 2.4% (three disease progression, one septic shock, one pneumonia, one pulmonary embolism). Complication rate was 33%, deep wound infection was the most frequent aetiology. Higher mortality was observed in patients with poorest preoperative KPS (KPS 0-40%, HR = 3.1, p < 0.001) and mobility level ("bedbound", HR = 2.16, p < 0.001). Survival seemed also to be linked to preoperative neurological function. CONCLUSION: Surgical treatments helped maintain reasonable condition for patients with spinal metastases. Intervention should be offered before patients' condition worsen to ensure better outcomes.


Assuntos
Manejo da Dor/métodos , Neoplasias da Coluna Vertebral/secundário , Neoplasias da Coluna Vertebral/cirurgia , Idoso , Neoplasias da Mama/patologia , Progressão da Doença , Feminino , Humanos , Avaliação de Estado de Karnofsky , Neoplasias Pulmonares/patologia , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/patologia , Dor/complicações , Modelos de Riscos Proporcionais , Estudos Prospectivos , Estudos Retrospectivos , Neoplasias da Coluna Vertebral/mortalidade , Coluna Vertebral/patologia , Taxa de Sobrevida , Resultado do Tratamento
8.
Neurochirurgie ; 66(1): 24-28, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31836488

RESUMO

INTRODUCTION: Pyogenic spondylodiscitis is a rare disease, but incidence is increasing. Reported failure rates following conservative management range from 12% to 18%. The purpose of this study was to determine the safety and efficacy of posterior percutaneous pedicle screw fixation combined with anterior debridement and fusion (ADF) for infective spondylodiscitis in the thoracic and/or lumbar spine. METHODS: The retrospective study cohort comprised all patients without neurological deficit who underwent minimally invasive posterior and anterior surgery between April 2008 and April 2016 for thoracic and/or lumbar spondylodiscitis. RESULTS: Forty patients were eligible (16 female: 40%). The lumbar region was affected in 31 cases (77.5%). Source of infection was identified in only 22 cases (55%) and bacteriological identification was obtained in 32 cases (80%). Mean hospital stay was 14.8 days (range, 6-39 days). Complete recovery was achieved in 39 patients (97.5%) at 3 months' follow-up. Mean preoperative local kyphosis angle was 16.1o, versus 14o at 1-year (P>0.05). 36 patients (90%) had at least 1 year's follow-up, and fusion was obtained for all these cases. CONCLUSION: Two-stage minimally invasive surgery is effective and safe for the treatment of single or two-level thoracolumbar spondylodiscitis. It could be an alternative to conventional open surgery or conservative treatment.


Assuntos
Infecções Bacterianas/cirurgia , Desbridamento/métodos , Discite/cirurgia , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Procedimentos Neurocirúrgicos/métodos , Doenças da Medula Espinal/cirurgia , Fusão Vertebral/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Infecções Bacterianas/complicações , Discite/etiologia , Feminino , Seguimentos , Humanos , Fixadores Internos , Tempo de Internação , Região Lombossacral/cirurgia , Masculino , Pessoa de Meia-Idade , Parafusos Pediculares , Estudos Retrospectivos , Doenças da Medula Espinal/complicações , Resultado do Tratamento , Adulto Jovem
9.
PLoS One ; 13(1): e0190169, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29320542

RESUMO

The Phoenicians emerged in the Northern Levant around 1800 BCE and by the 9th century BCE had spread their culture across the Mediterranean Basin, establishing trading posts, and settlements in various European Mediterranean and North African locations. Despite their widespread influence, what is known of the Phoenicians comes from what was written about them by the Greeks and Egyptians. In this study, we investigate the extent of Phoenician integration with the Sardinian communities they settled. We present 14 new ancient mitogenome sequences from pre-Phoenician (~1800 BCE) and Phoenician (~700-400 BCE) samples from Lebanon (n = 4) and Sardinia (n = 10) and compare these with 87 new complete mitogenomes from modern Lebanese and 21 recently published pre-Phoenician ancient mitogenomes from Sardinia to investigate the population dynamics of the Phoenician (Punic) site of Monte Sirai, in southern Sardinia. Our results indicate evidence of continuity of some lineages from pre-Phoenician populations suggesting integration of indigenous Sardinians in the Monte Sirai Phoenician community. We also find evidence of the arrival of new, unique mitochondrial lineages, indicating the movement of women from sites in the Near East or North Africa to Sardinia, but also possibly from non-Mediterranean populations and the likely movement of women from Europe to Phoenician sites in Lebanon. Combined, this evidence suggests female mobility and genetic diversity in Phoenician communities, reflecting the inclusive and multicultural nature of Phoenician society.


Assuntos
Demografia , Etnicidade/história , Genoma Mitocondrial , Migração Humana/história , Mulheres , Adolescente , Adulto , Criança , Cultura , DNA Mitocondrial/análise , DNA Mitocondrial/isolamento & purificação , Etnicidade/genética , Feminino , Variação Genética , Haplótipos , História Antiga , Humanos , Itália , Líbano/etnologia , Região do Mediterrâneo , Filogenia , Dinâmica Populacional , Dente
10.
Am J Transplant ; 16(6): 1653-80, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26848550

RESUMO

The liver is an immunoregulatory organ in which a tolerogenic microenvironment mitigates the relative "strength" of local immune responses. Paradoxically, necro-inflammatory diseases create the need for most liver transplants. Treatment of hepatitis B virus, hepatitis C virus, and acute T cell-mediated rejection have redirected focus on long-term allograft structural integrity. Understanding of insults should enable decades of morbidity-free survival after liver replacement because of these tolerogenic properties. Studies of long-term survivors show low-grade chronic inflammatory, fibrotic, and microvascular lesions, likely related to some combination of environment insults (i.e. abnormal physiology), donor-specific antibodies, and T cell-mediated immunity. The resultant conundrum is familiar in transplantation: adequate immunosuppression produces chronic toxicities, while lightened immunosuppression leads to sensitization, immunological injury, and structural deterioration. The "balance" is more favorable for liver than other solid organ allografts. This occurs because of unique hepatic immune physiology and provides unintended benefits for allografts by modulating various afferent and efferent limbs of allogenic immune responses. This review is intended to provide a better understanding of liver immune microanatomy and physiology and thereby (a) the potential structural consequences of low-level, including allo-antibody-mediated injury; and (b) how liver allografts modulate immune reactions. Special attention is given to the microvasculature and hepatic mononuclear phagocytic system.


Assuntos
Imunidade Celular/imunologia , Transplante de Fígado , Aloenxertos , Animais , Humanos
11.
Rev Sci Instrum ; 86(9): 094102, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26429459

RESUMO

An Adaptable Multiple Power Source (AMPS) system has been designed and constructed. The AMPS system can provide up to 16 direct current (DC) (±400 V; 5 mA), 4 radio frequency (RF) (two 500 VPP sinusoidal signals each, 0.5-5 MHz) channels, 2 high voltage sources (±6 kV), and one ∼40 W, 250 °C temperature-regulated heater. The system is controlled by a microcontroller, capable of communicating with its front panel or a computer. It can assign not only pre-saved fixed DC and RF signals but also profiled DC voltages. The AMPS system is capable of driving many mass spectrometry components and ancillary devices and can be adapted to other instrumentation/engineering projects.


Assuntos
Fontes de Energia Elétrica , Espectrometria de Massas/instrumentação , Desenho de Equipamento , Análise de Fourier , Ondas de Rádio
12.
J Pediatr Urol ; 9(1): e94-7, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23141002

RESUMO

Conventional and robotic-assisted laparoscopy is being used for more and more complex urological procedures in children. There have recently been reports of laparoscopic or laparoscopic-assisted appendicovesicostomies in children. We report a case of combined laparoscopic-assisted nephrectomy, augmentation ureterocystoplasty and Mitrofanoff appendicovesicostomy in a 5-year-old boy with valve bladder syndrome.


Assuntos
Cistostomia/métodos , Laparoscopia/métodos , Nefrectomia/métodos , Doenças Ureterais/cirurgia , Doenças da Bexiga Urinária/cirurgia , Derivação Urinária/métodos , Apêndice/cirurgia , Pré-Escolar , Humanos , Masculino , Robótica/métodos
13.
J Evol Biol ; 23(9): 2022-9, 2010 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-20695962

RESUMO

The Pleistocene to Holocene transition was accompanied by a worldwide extinction event affecting numerous mammalian species. Several species such as the woolly mammoth and the giant deer survived this extinction wave, only to go extinct a few thousand years later during the Holocene. Another example for such a Holocene extinction is the Don-hare, Lepus tanaiticus, which inhabited the Russian plains during the late glacial. After being slowly replaced by the extant mountain hare (Lepus timidus), it eventually went extinct during the middle Holocene. Here, we report the phylogenetic relationship of L. tanaiticus and L. timidus based on a 339-basepair (bp) fragment of the mitochondrial D-loop. Phylogenetic tree- and network reconstructions do not support L. tanaiticus and L. timidus being different species. Rather, we suggest that the two taxa represent different morphotypes of a single species and the extinction of 'L. tanaiticus' represents the disappearance of a local morphotype rather than the extinction of a species.


Assuntos
Extinção Biológica , Lebres/classificação , Filogenia , Animais , DNA Mitocondrial/genética , Lebres/genética
14.
Oncogene ; 26(24): 3572-81, 2007 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-17173070

RESUMO

DDB2, a gene mutated in XPE patients, is involved in global genomic repair especially the repair of cyclobutane pyrimidine dimers (CPDs), and is regulated by p53 in human cells. We show that DDB2 is expressed in mouse tissues and demonstrate, using primary mouse epithelial cells, that mouse DDB2 is regulated by E2F transcription factors. Retinoblastoma (Rb), a tumor suppressor critical for the control of cell cycle progression, regulates E2F activity. Using Cre-Lox technology to delete Rb in primary mouse hepatocytes, we show that DDB2 gene expression increases, leading to elevated DDB2 protein levels. Furthermore, we show that endogenous E2F1 and E2F3 bind to DDB2 promoter and that treatment with E2F1-antisense or E2F1-small interfering RNA (siRNA) decreases DDB2 transcription, demonstrating that E2F1 is a transcriptional regulator for DDB2. This has consequences for global genomic repair: in Rb-null cells, where E2F activity is elevated, global DNA repair is increased and removal of CPDs is more efficient than in wild-type cells. Treatment with DDB2-siRNA decreases DDB2 expression and abolishes the repair phenotype of Rb-null cells. In summary, these results identify a new regulatory pathway for DDB2 by E2F, which does not require but is potentiated by p53, and demonstrate that DDB2 is involved in global repair in mouse epithelial cells.


Assuntos
Reparo do DNA/fisiologia , Proteínas de Ligação a DNA/metabolismo , Fator de Transcrição E2F1/metabolismo , Fator de Transcrição E2F3/metabolismo , Proteína do Retinoblastoma/genética , Animais , Células Cultivadas , Proteínas de Ligação a DNA/genética , Fator de Transcrição E2F1/genética , Fator de Transcrição E2F3/genética , Regulação da Expressão Gênica , Hepatócitos/metabolismo , Camundongos , Camundongos Mutantes , Proteína do Retinoblastoma/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
15.
Nucleic Acids Res ; 29(16): E80, 2001 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-11504888

RESUMO

This study evaluates the utility of Cre-expressing adenovirus for deletion of floxed genes in primary cells using primary murine hepatocytes. Adenovirus infection was very efficient, even at very low MOI (>95% infection at a MOI of 6) and did not reduce viability. High level LacZ expression was cytotoxic to hepatocytes but Cre expression had no effect on viability. Cre-mediated recombination was completed within a timespan that permits experimentation during primary culture (>95% recombination after 24 h), independently of the number of floxed alleles per cell. Recombination did not induce p53 or produce cytological nuclear abnormalities (even in polyploid cells). Contrary to expectation, deletion of DNA ligase 1 did not alter cell cycle progression, although Cre expression hastens entry to S phase from G(1), independently of the presence of floxed sequences. We conclude that adenovirus-mediated deletion of floxed alleles in primary cells is a straightforward and highly efficient tool for conducting preliminary studies of conditional gene targeting. Primary cells have advantages of differentiation, relative purity and ease of experimentation within controlled conditions, while avoiding confounding problems encountered in vivo (i.e. target cell specificity, kinetics and level of recombination, and elicitation of inflammatory and immune responses). This system could help identify important phenotypic effects and design and interpret in vivo studies.


Assuntos
Adenoviridae/genética , Sítios de Ligação Microbiológicos/genética , Integrases/metabolismo , Deleção de Sequência/genética , Proteínas Virais/metabolismo , Adenoviridae/fisiologia , Alelos , Animais , Apoptose , Western Blotting , Divisão Celular , Núcleo Celular/metabolismo , Sobrevivência Celular , Células Cultivadas , DNA/biossíntese , DNA Ligases/genética , DNA Ligases/metabolismo , Indução Enzimática , Formazans , Genes Reporter/genética , Hepatócitos/citologia , Hepatócitos/metabolismo , Hepatócitos/virologia , Integrases/biossíntese , Integrases/genética , Camundongos , Especificidade de Órgãos , Poliploidia , Recombinação Genética/genética , Fase S , Sais de Tetrazólio , Proteína Supressora de Tumor p53/metabolismo , Proteínas Virais/biossíntese , Proteínas Virais/genética , beta-Galactosidase/genética , beta-Galactosidase/metabolismo
16.
Br J Haematol ; 107(2): 247-53, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10583209

RESUMO

Receptor tyrosine kinases (RTKs) mediate cellular responses to the extracellular signals involved in the regulation of cell differentiation and proliferation. Ligand binding initiates a cascade of events, such as receptor dimerization and tyrosine phosphorylation. The c-kit gene encodes an RTK for stem cell factor (SCF), (c-kit ligand, KL), both of which play a critical role in the differentiation and growth of haemopoietic stem cells (HSCs). We investigated the expression of the c-kit and SCF genes and the presence of the corresponding proteins in haemopoietic tissues during human embryogenesis. We have examined c-kit and SCF transcripts levels in human embryonic yolk sac, the AGM region, and liver at different stages of gestation (days 25 to 63), using RT-PCR amplification combined with PhosphorImager quantitative analysis and RNase Protection Assay (RPA). Weak levels of SCF gene expression were observed in the AGM region (days 25 to 34) and high levels were found in the early-stage liver (day 34). The expression of c-kit transcript was observed in all studied tissues, but at various levels. The restricted presence of SCF protein following mRNA expression was demonstrated in embryonic liver CD38+ haemopoietic cells by immunocytochemistry. These observations suggest that the biological function of the c-kit receptor plays an important role in the early stages of human haemopoiesis, and that c-kit/SCF signalling is particularly involved in early human definitive haemopoiesis.


Assuntos
Hematopoese/fisiologia , Proteínas Proto-Oncogênicas c-kit/biossíntese , Fator de Células-Tronco/biossíntese , Embrião de Mamíferos/metabolismo , Sangue Fetal/metabolismo , Humanos , Imuno-Histoquímica , Fígado/embriologia , Fígado/metabolismo , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Saco Vitelino/metabolismo
18.
J Biol Chem ; 273(50): 33327-32, 1998 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-9837906

RESUMO

The mechanisms by which the hepatitis B x protein (HBx) contributes to hepatocarcinogenesis remain unclear. However, interaction with the tumor suppressor gene p53 and inhibition of p53-dependent cellular functions, including nucleotide excision repair, could be central to this process. We studied the levels of global repair (removal of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts) and transcription-coupled repair (removal of CPDs in both strands of the dihydrofolate reductase gene) in primary wild-type and p53-null mouse hepatocytes. We show that global repair of CPDs appears to be more efficient in mouse hepatocytes than in other commonly studied rodent cells and approaches the levels of human cells and that p53 is required for global genomic DNA repair of CPDs but not for transcription-coupled repair. We then investigated the effect of HBx expression on hepatocyte nucleotide excision repair. We demonstrate that HBx expression affects DNA repair in a p53-dependent manner. Transient HBx expression reduces global DNA repair in wild-type cells to the level of p53-null hepatocytes and has no effect on the repair of a transfected damaged plasmid. Therefore, in viral hepatitis, the hepatitis B virus could inhibit the p53-dependent component of global repair leading, over time, to accumulation of genetic defects and fostering carcinogenesis.


Assuntos
Reparo do DNA , Fígado/metabolismo , Transativadores/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Animais , Células Cultivadas , Dano ao DNA , Fígado/citologia , Masculino , Camundongos , Camundongos Knockout , Transativadores/genética , Proteína Supressora de Tumor p53/genética , Proteínas Virais Reguladoras e Acessórias
19.
FEBS Lett ; 425(3): 499-504, 1998 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-9563521

RESUMO

The role of p53 in DNA repair and cell cycle checkpoint after ultraviolet irradiation was investigated in an embryonic stem cell line homozygous for a targeted deletion of p53. Results indicate that loss of p53 does not alter the capacity of ES cells to respond to DNA damage. Wild-type and p53-deficient cells showed similar cessation of DNA synthesis after UV damage and similar ultimate capacity to repair a transiently transfected reporter plasmid. Interestingly, in the absence of DNA damaging treatment, the transit of p53-deficient cells through S phase was slower than wild-type cells. We suggest that this may result from the absence of a p53-dependent response to endogenous DNA damage: without p53 sensing endogenous damage leading to immediate repair, such damage may persist and thus delay DNA synthesis.


Assuntos
Ciclo Celular/fisiologia , Reparo do DNA/fisiologia , Células-Tronco/fisiologia , Proteína Supressora de Tumor p53/fisiologia , Animais , Cloranfenicol O-Acetiltransferase/genética , Cloranfenicol O-Acetiltransferase/metabolismo , Dano ao DNA/genética , Replicação do DNA/genética , Citometria de Fluxo , Deleção de Genes , Genes Reporter/genética , Interfase/fisiologia , Camundongos , Fase S/fisiologia , Ativação Transcricional/genética , Proteína Supressora de Tumor p53/genética , Raios Ultravioleta/efeitos adversos
20.
FASEB J ; 12(2): 181-8, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9472983

RESUMO

The tumor suppressor proteins IRF-1 and p53 are involved in response pathways after DNA damage. In different cell types, IRF-1 and p53 can cooperate to produce cell cycle arrest (embryo fibroblasts) or can independently trigger apoptosis (lymphoid cells). p53 may also regulate DNA repair, but there is no information on IRF-1 and repair. The cell lineage dependency of these effects precludes extrapolation of findings to other tissues of relevance to human cancer. Here, we report the consequences of IRF-1 deficiency for apoptosis, cell cycle arrest, and DNA repair in primary hepatocytes after DNA damage and extend previous work on the role of p53 in hepatocytes. IRF-1-deficient hepatocytes showed reduced DNA repair activity compared with wild-type, as assessed by unscheduled DNA synthesis after UV irradiation (10J/m2) and by host reactivation of a UV-damaged reporter construct. p53-deficient hepatocytes also showed reduced unscheduled DNA synthesis after UV, but there was no impairment of specific repair in host reactivation assays. IRF-1 deficiency did not affect the p53-dependent G1/S arrest after UV irradiation. Hepatocyte apoptosis after UV treatment, previously reported to be independent of p53, was also independent of IRF-1. However, IRF-1 deficiency produced dysregulation of p53, manifested as increased transactivation of a p53-reporter plasmid in undamaged hepatocytes, and accelerated p53 stabilization after DNA damage. Hence, in hepatocytes, IRF-1 is not required for growth arrest or apoptosis after DNA damage, but the results suggest for the first time a role in DNA repair regulation.


Assuntos
Reparo do DNA , Proteínas de Ligação a DNA/genética , Fígado/citologia , Fígado/fisiologia , Fosfoproteínas/genética , Proteína Supressora de Tumor p53/deficiência , Animais , Apoptose , Ciclo Celular , Células Cultivadas , Dano ao DNA , Replicação do DNA , Proteínas de Ligação a DNA/fisiologia , Genótipo , Humanos , Fator Regulador 1 de Interferon , Masculino , Camundongos , Camundongos Knockout , Fosfoproteínas/fisiologia , Plasmídeos/efeitos da radiação , Proteínas Recombinantes/metabolismo , Fatores de Transcrição/deficiência , Transfecção , Proteína Supressora de Tumor p53/fisiologia , Raios Ultravioleta
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...