RESUMO
INTRODUCTION: Aortic stenosis is one of the most common valvular heart diseases in the ageing population. Patients with symptomatic severe aortic stenosis are at high risk of sudden death. Surgical aortic-valve replacement is the gold standard of treatment but many patients do not receive surgery because of advanced age or co-morbidities. Recently, transcatheter aortic valve implantation has been developed as an option for these patients. This study aimed to assess efficacy and safety of this procedure in the Hong Kong Chinese population. METHODS: Data for baseline patient characteristics, procedure parameters, and clinical outcomes up to 1-year post-implantation in a regional hospital in Hong Kong were collected and analysed. RESULTS: A total of 56 patients with severe aortic stenosis underwent the procedure from December 2010 to September 2015. Their mean (± standard deviation) age was 81.9 ± 4.8 years; 64.3% of them were male. Their mean logistic EuroSCORE was 22.6% ± 13.4%. After implantation, the mean aortic valve area improved from 0.70 cm2 ± 0.19 cm2 to 1.94 cm2 ± 0.37 cm2. Of the patients, 92% were improved by at least one New York Heart Association functional class. Stroke and major vascular complications occurred in one (1.8%) and five (8.9%) patients, respectively. A permanent pacemaker was implanted in seven (12.5%) patients. Both hospital and 30-day mortalities were 1.8%. The 1-year all-cause and cardiovascular mortality rates were 12.5% and 7.1%, respectively. CONCLUSIONS: Transcatheter aortic valve implantation has been developed as an alternative treatment for patients with symptomatic severe aortic stenosis who are deemed inoperable or high risk for surgery. Our results are very promising and comparable with those of major clinical trials.
Assuntos
Estenose da Valva Aórtica/cirurgia , Substituição da Valva Aórtica Transcateter/estatística & dados numéricos , Idoso , Idoso de 80 Anos ou mais , Feminino , Hong Kong , Humanos , Modelos Logísticos , Masculino , Substituição da Valva Aórtica Transcateter/métodos , Resultado do TratamentoRESUMO
Antiangiogenesis is an appealing anticancer approach but requires continued presence of the antiangiogenic agents, which can be remedied by gene therapy. Baculovirus is an emerging gene delivery vector but only mediates transient expression (<7 days); thus, this study primarily aimed to develop a hybrid baculovirus for sustained antiangiogenic gene expression and cancer therapy. We first constructed plasmids featuring adeno-associated virus inverted terminal repeats (AAV ITRs), oriP/Epstein-Barr virus-expressed nuclear antigen 1 (EBNA1) or Sleeping Beauty (SB) transposon and compared their efficacies in terms of persistent expression. In human embryonic kidney (HEK293) cells, AAV ITR failed to prolong the expression while oriP/EBNA1 moderately extended the expression to 35 days. In contrast, the SB system led to stable expression beyond 77 days even without antibiotic selection. Given this finding, we constructed a hybrid SB baculovirus expressing the SB transposase and harboring the transgene cassette flanked by inverted repeat/direct-repeat (IR/DR) elements recognizable by SB. The hybrid SB baculovirus efficiently transduced mammalian cells and mediated an expression duration longer than that by conventional baculoviruses, thanks to the transgene persistence and integration. The SB baculovirus (Bac-SB-T2hEA/w) expressing the antiangiogenic fusion protein comprising endostatin and angiostatin (hEA) also enabled prolonged hEA expression. With sustained hEA expression, Bac-SB-T2hEA/w repressed the angiogenesis in vivo, hindered the growth of two different tumors (prostate tumor allografts and human ovarian tumor xenografts) in mice and extended the life span of animals. These data altogether implicated the potential of the hybrid SB-baculovirus vector for prolonged hEA expression and for the treatment of multiple types of angiogenesis-dependent tumors.
Assuntos
Baculoviridae/genética , Terapia Genética , Vetores Genéticos , Animais , Dependovirus/genética , Feminino , Expressão Gênica , Células HEK293 , Humanos , Masculino , Camundongos , Neoplasias Ovarianas/terapia , Neoplasias da Próstata/terapia , Recombinação Genética , Sequências Repetidas Terminais , Transdução Genética , Transgenes , Transposases/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Activated macrophage/microglia may mediate tissue injury in a variety of CNS disorders. To examine this, transgenic mice were developed in which the expression of a macrophage/microglia activation cytokine, interleukin-3 (IL-3), was targeted to astrocytes using a murine glial fibrillary acidic protein fusion gene. Transgenic mice with low levels of IL-3 expression developed from 5 mo of age, a progressive motor disorder characterized at onset by impaired rota-rod performance. In symptomatic transgenic mice, multi-focal, plaque-like white matter lesions were present in cerebellum and brain stem. Lesions showed extensive primary demyelination and remyelination in association with the accumulation of large numbers of proliferating and activated foamy macrophage/microglial cells. Many of these cells also contained intracisternal crystalline pole-like inclusions similar to those seen in human patients with multiple sclerosis. Mast cells were also identified while lymphocytes were rarely, if at all present. Thus, chronic CNS production of low levels of IL-3 promotes the recruitment, proliferation and activation of macrophage/microglial cells in white matter regions with consequent primary demyelination and motor disease. This transgenic model exhibits many of the features of human inflammatory demyelinating diseases including multiple sclerosis and HIV leukoencephalopathy.
Assuntos
Encéfalo/patologia , Doenças Desmielinizantes/patologia , Interleucina-3/biossíntese , Macrófagos/patologia , Microglia/patologia , Animais , Encéfalo/metabolismo , Encéfalo/ultraestrutura , Divisão Celular , Doenças Desmielinizantes/etiologia , Doenças Desmielinizantes/metabolismo , Técnicas de Transferência de Genes , Interleucina-3/genética , Camundongos , Camundongos Transgênicos , Microscopia EletrônicaRESUMO
The aim of this study was to investigate means of increasing the efficiency with which cancer cell death following local radiation therapy (RT) is translated into the generation of tumor immunity since, if this were to be achieved, it would be expected to enhance the rates of disease-free recurrence and survival. Our investigations centered around the use of interleukin-3 (IL-3), expressed intratumorally using an inducible adenoviral vector, to alter the immunogenicity of established murine TRAMP-C1 prostate cancer receiving a course of fractionated local RT (7 Gy per fraction per day for 5 days). Because high systemic levels of IL-3 can be associated with toxicity, a tetracycline-regulated gene delivery system was employed. The results show that while intratumoral IL-3 expression or RT alone caused a modest delay in TRAMP-C1 tumor growth, the combination was synergistic with 50% of mice being cured and developing a long-term, tumor-specific state of immunity. Immunological analyses performed on splenic lymphocytes demonstrated that, compared to RT or IL-3 alone, combined treatment significantly increased the number of tumor-specific IFN-gamma-secreting and cytotoxic T cells. The study demonstrates that tetracycline-regulated IL-3 gene expression within tumors can enhance the immune response to prostate cancer and this can augment the efficacy of a course of RT without additional side effects.
Assuntos
Terapia Genética/métodos , Vetores Genéticos/farmacologia , Interleucina-3/genética , Neoplasias da Próstata/terapia , Tetraciclina/farmacologia , Adenoviridae/genética , Animais , Terapia Combinada , Vetores Genéticos/efeitos dos fármacos , Vetores Genéticos/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias da Próstata/imunologia , Neoplasias da Próstata/patologia , Neoplasias da Próstata/radioterapiaRESUMO
The nuclear suppressor allele NSM3 in strain FF1210-6C/170-E22 (E22), which suppresses a mutation of the yeast mitochondrial tRNA(Asp)gene in Saccharomyces cerevisiae, was cloned and identified. To isolate the NSM3 allele, a genomic DNA library using the vector YEp13 was constructed from strain E22. Nine YEp13 recombinant plasmids were isolated and shown to suppress the mutation in the mitochondrial tRNA(Asp)gene. These nine plasmids carry a common 4. 5-kb chromosomal DNA fragment which contains an open reading frame coding for yeast mitochondrial aspartyl-tRNA synthetase (AspRS) on the basis of its sequence identity to the MSD1 gene. The comparison of NSM3 DNA sequences between the suppressor and the wild-type version, cloned from the parental strain FF1210-6C/170, revealed a G to A transition that causes the replacement of amino acid serine (AGU) by an asparagine (AAU) at position 388. In experiments switching restriction fragments between the wild type and suppressor versions of the NSM3 gene, the rescue of respiratory deficiency was demonstrated only when the substitution was present in the construct. We conclude that the base substitution causes the respiratory rescue and discuss the possible mechanism as one which enhances interaction between the mutated tRNA(Asp)and the suppressor version of AspRS.
Assuntos
Aspartato-tRNA Ligase/genética , Genes Fúngicos , Mutação de Sentido Incorreto , RNA de Transferência de Ácido Aspártico/genética , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Alelos , Sequência de Aminoácidos , Núcleo Celular/genética , Clonagem Molecular , DNA Fúngico/genética , DNA Mitocondrial/genética , Escherichia coli/genética , Amplificação de Genes , Mitocôndrias/enzimologia , Dados de Sequência Molecular , Plasmídeos/genética , Homologia de Sequência de Aminoácidos , Supressão GenéticaRESUMO
Late effects after radiotherapy for brain tumors can be severe and tend to limit the efficacy of this treatment modality. The mechanisms governing the development of late radiation-induced lesions in the brain are not clear, but they are preceded by cycles of molecular and cellular events including production of cytokines, one of which is tumor necrosis factor (TNF)-alpha. There is literature to support possible roles for TNF-alpha as a contributor to edema, gliosis, and demyelination in the brain, all of which are histopathologically associated with radiation-induced brain damage. We have examined the role of TNF-alpha signaling in the response to brain irradiation using TNFRp55- or TNFRp75-deficient and control mice. Mice lacking TNFRp75 exhibited increased early radiation-induced apoptosis in putative stem cell regions of the brain. At 1 month, they had decreased proliferative responses in the same regions, and by 3 months they were demonstrating dose-dependent seizures and other severe neurological abnormalities that were not seen in control or TNFRp55-/- mice. Seizure activity correlated with the onset of extensive demyelination, and by 6 months, levels of myelin basic protein in irradiated TNFRp75-/- mice were approximately 40% of those seen in the other two strains; the animals were moribund and had to be euthanized. These observations indicate that radiation-induced TNF-alpha, acting through TNFRp75, protects against the development of late complications of brain irradiation.
Assuntos
Encéfalo/efeitos da radiação , Tolerância a Radiação/fisiologia , Transdução de Sinais/efeitos da radiação , Fator de Necrose Tumoral alfa/fisiologia , Animais , Antígenos CD/genética , Antígenos CD/fisiologia , Apoptose/efeitos da radiação , Encéfalo/metabolismo , Encéfalo/fisiologia , Divisão Celular/efeitos da radiação , Doenças Desmielinizantes/etiologia , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Bainha de Mielina/metabolismo , Lesões Experimentais por Radiação/etiologia , Lesões Experimentais por Radiação/metabolismo , Receptores do Fator de Necrose Tumoral/genética , Receptores do Fator de Necrose Tumoral/fisiologia , Receptores Tipo I de Fatores de Necrose Tumoral , Receptores Tipo II do Fator de Necrose Tumoral , Convulsões/etiologia , Transdução de Sinais/fisiologiaRESUMO
Expression of a murine interleukin 3 gene in murine fibrosarcoma cells (FSA-JmIL-3) did not alter their survival after in vitro irradiation. However, FSA-JmIL-3 tumors established in vivo were much more sensitive to irradiation than was the parental tumor. Following 25 Gy of irradiation, parental fibrosarcoma tumors regrew after a growth delay of 10 days, but FSA-JmIL-3 tumors continued to regress. Examination of the cellular composition of tumors following irradiation revealed that, instead of tumor cell repopulation, the FSA-JmIL-3 tumors became heavily infiltrated with lymphocytes, indicating that the effect of irradiation was to allow the IL-3-elicited cellular immune response to infiltrate the tumors and mediate rejection. This study indicates that combining gene immunotherapy approaches with radiotherapy might increase the effectiveness of both, and it seems logical to pursue such treatment options.
Assuntos
Fibrossarcoma/radioterapia , Interleucina-3/fisiologia , Sarcoma Experimental/radioterapia , Animais , Sobrevivência Celular/efeitos da radiação , Feminino , Fibrossarcoma/genética , Fibrossarcoma/imunologia , Fibrossarcoma/patologia , Expressão Gênica , Granulócitos/patologia , Antígenos H-2/metabolismo , Receptores de Hialuronatos/metabolismo , Molécula 1 de Adesão Intercelular/metabolismo , Linfócitos do Interstício Tumoral/patologia , Macrófagos/patologia , Camundongos , Camundongos Endogâmicos C3H , Sarcoma Experimental/genética , Sarcoma Experimental/imunologia , Sarcoma Experimental/patologia , Transdução GenéticaRESUMO
IL-3 gene expression within tumors leads to host-cell infiltration, particularly by macrophages, slower tumor growth, and enhanced immunogenicity. Surprisingly, tumor-associated macrophages (TAMs) from within FSAN-JmIL3 tumors had decreased expression of TNF-alpha and iNOS. On short-term culture, TAMs from FSAN-JmIL3 tumors regained their capacity to produce TNF-alpha and NO, indicating that they were primed in vivo. In vitro experiments were unable to demonstrate differences between FSAN-JmIL3 and FSAN tumor cells in their ability to stimulate TNF-alpha production by TAMs. In the absence of evidence that TAM activation was responsible for the slower growth of FSAN-JmIL3 tumors, the response of tumor cells to these effector molecules was studied. TNF-alpha and NO were cytotoxic for FSAN-JmIL3 cells but growth stimulatory for FSAN. These tumor-related phenotypic changes may contribute as much if not more than functional changes in host infiltrating cells to the slower growth of FSAN-JmIL3 tumors in vivo.
Assuntos
Fibrossarcoma/patologia , Regulação Neoplásica da Expressão Gênica , Interleucina-3/genética , Macrófagos/fisiologia , Proteínas de Neoplasias/genética , Óxido Nítrico Sintase/biossíntese , Fator de Necrose Tumoral alfa/biossíntese , Animais , Apoptose , Contagem de Células , Citotoxicidade Imunológica , DNA Complementar/genética , Progressão da Doença , Feminino , Fibrossarcoma/induzido quimicamente , Fibrossarcoma/metabolismo , Fibrossarcoma/secundário , Interleucina-3/biossíntese , Interleucina-3/fisiologia , Neoplasias Pulmonares/secundário , Camundongos , Camundongos Endogâmicos C3H , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/fisiologia , Transplante de Neoplasias , Óxido Nítrico/biossíntese , Óxido Nítrico/farmacologia , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase Tipo II , Fenótipo , RNA Mensageiro/biossíntese , RNA Neoplásico/biossíntese , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/fisiologia , Transfecção , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Transgenic mice overexpressing cytokines facilitate analysis of the effects of these immunomodulators on indigenous cells of the central nervous system. This study examines morphological aspects of demyelination and permeability changes, in a recently described transgenic model (termed GFAP-IL3). GFAP-IL3 mice develop progressive motor disease at approximately 5 months. Lesions identified after disease onset, showed activation of microglia, astroglial proliferation with phagocytosis of lipids, and immigration of macrophages and mast cells into neural parenchyma. Lymphocytes failed to appear until the later stages of the disease. Later, cerebellar and brain stem white matter contained focal demyelinating lesions with intense macrophage infiltration and a proliferative astrocytosis. Dystrophic axonal changes were noted, in addition to demyelination in heavily infiltrated lesions. Mast cells, variably present in the thalamus and meninges of wild type mice, were greatly increased at these sites in GFAP-IL3 mice. Blood-brain barrier (BBB) defects were documented with leakage of intravenously injected horseradish peroxidase. Mast cell infiltration into the CNS and their degranulation at the site of injury, may represent initial events in a spontaneous process of macrophage mediated demyelination in which glial cells and macrophages are both involved in the phagocytic process.
Assuntos
Astrócitos/patologia , Barreira Hematoencefálica , Encéfalo/patologia , Doenças Desmielinizantes/patologia , Interleucina-3/genética , Mastócitos/patologia , Neuroglia/patologia , Animais , Astrócitos/imunologia , Astrócitos/ultraestrutura , Transporte Axonal , Axônios/patologia , Axônios/ultraestrutura , Encéfalo/fisiopatologia , Divisão Celular , Cerebelo/patologia , Cerebelo/ultraestrutura , Doenças Desmielinizantes/genética , Doenças Desmielinizantes/fisiopatologia , Proteína Glial Fibrilar Ácida/análise , Proteína Glial Fibrilar Ácida/biossíntese , Peroxidase do Rábano Silvestre , Interleucina-3/análise , Interleucina-3/fisiologia , Mastócitos/fisiologia , Camundongos , Camundongos Transgênicos , Neuroglia/fisiologia , Neuroglia/ultraestrutura , Especificidade de Órgãos , FagocitoseRESUMO
The cDNA encoding the catalytic subunit of Drosophila melanogaster (Dm) DNA polymerase delta (Pol delta) was isolated by a combination of PCR amplification and cDNA library screening. The cDNA is 3457 nucleotides in length and contains an open reading frame (ORF) that encodes a protein of 1092 amino acids (124,799 Da). The ORF contains the sequence that was determined for a peptide from the purified catalytic subunit of Dm Pol delta. Polyclonal antibodies raised against Dm Pol delta specifically recognize a protein of the expected size when the cDNA is expressed in either Escherichia coli or insect cells. Comparison of the deduced aa sequence with other Pol delta sequences demonstrates that Pol delta is one of the most highly conserved of the DNA polymerases.
Assuntos
DNA Polimerase Dirigida por DNA/genética , Drosophila melanogaster/enzimologia , Drosophila melanogaster/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , DNA Polimerase III , DNA Complementar/genética , Expressão Gênica , Genes de Insetos , Dados de Sequência Molecular , RNA Mensageiro/genética , Alinhamento de Sequência , Homologia de Sequência de AminoácidosRESUMO
The goal of this study was to explore immunological strategies to increase local and systemic tumor control in patients receiving radiation therapy. In previous studies, interleukin-3 (IL-3) gene expression within murine tumors was shown to increase their response to irradiation through immune mechanisms. In this study, the efficacy of systemically administered IL-3 gene-transduced irradiated tumor cell vaccines was tested for their ability to augment radiation responses against established immunogenic (FSAR) and nonimmunogenic (FSAN) tumors. Vaccines of irradiated FSAR/FSAN or FSAN-JmIL-3/FSAR-JmIL-3 cells were given intraperitoneally just before and after local irradiation of parental tumors with diameters of 8 mm, as well as in two booster doses. The IL-3 gene-transduced tumor cell vaccines were more effective than the parental vaccines at delaying tumor growth after irradiation, although no complete cures resulted. Responses were largely specific to the tumor type, indicating that tumor-specific immunity was enhanced by IL-3 vaccine administration. When the experiment was repeated in the C3H/HeJ mice, which are deficient in tumor necrosis factor-alpha production, the vaccines were still effective, but less so than in C3H/HeN mice. Systemic IL-3 vaccine treatment increased intratumoral levels of intercellular adhesion molecule-1, Mac-1, EB22/5.3, tumor necrosis factor-alpha, and IL-1 mRNA in irradiated tumors, indicating that cellular infiltration was part of the response. The study demonstrates that local radiation therapy can enhance the efficacy of genetically altered vaccine-based immunotherapy for cancer by decreasing tumor burden. At the same time, tumor cell vaccines may improve the cure rate of local radiation therapy by eliminating residual cancer cells. Although less effective than intratumoral gene expression, administration of IL-3 gene-transduced tumor cell vaccines is clinically a more feasible strategy that may be useful in situations in which the tumor load is small.
Assuntos
Terapia Genética , Imunoterapia , Interleucina-3/genética , Neoplasias Experimentais/terapia , Animais , Vacinas Anticâncer/administração & dosagem , Divisão Celular , Feminino , Camundongos , Camundongos Endogâmicos C3H , Neoplasias Experimentais/patologia , Neoplasias Experimentais/radioterapiaRESUMO
PURPOSE: Using a guinea pig model of lumbar myelopathy, various factors affecting the tolerance of spinal cord to irradiation were assessed: (a) extent of initial injury (b) time interval between priming and test doses (c) animal age at the time of initial radiation treatment. METHODS AND MATERIALS: A 3 cm section of lumbar spinal cord of guinea pigs was irradiated with fractionated doses of 4.5 Gy gamma rays given as 9 fractions per week. Guinea pigs were primed with 9 x 4.5 Gy in 7 days which is 60% of the ED50 for a continuous course of treatment. After 28 or 40 weeks, animals were retreated with 6-14 fractions of 4.5 Gy. Animals were observed for 2 years following the priming dose and both the incidence and latency of myelopathy recorded. RESULTS: Young adult guinea pigs (8 wk old) showed both a decreased radiation tolerance and latency compared to old individuals (40 wk old). At 28 or 40 wk after 9 x 4.5 Gy, only about 8% of the initial injury was remembered in young adult guinea pigs. CONCLUSION: The amount of residual injury was dependent on the initial damage as a proportion of the tolerance dose. The spinal cord shows a greater capacity for long-term recovery than generally appreciated and re-treatment doses clinically prescribed may be lower than necessary.
Assuntos
Tolerância a Radiação , Medula Espinal/efeitos da radiação , Fatores Etários , Animais , Relação Dose-Resposta à Radiação , Feminino , Cobaias , Fatores de TempoRESUMO
The aim of this study was to investigate the pathological and cellular basis for radiation-induced myelopathy in guinea pigs by monitoring biochemical alterations in levels of myelin basic protein and 2',3'-cyclic nucleotide phosphohydrolase. Guinea pigs were irradiated to the lumbar region with various doses of neutrons or cobalt gamma irradiation. The ED50s for paralysis were 17.2 Gy and 67.5 Gy for neutron and cobalt irradiation, respectively, and was histologically associated with demyelination. In spinal cords taken from animals at the onset of paralysis myelin basic protein levels were decreased in direct relationship to the radiation dose. The lowest doses to cause paralysis led to a 25% decrease in MBP levels. In a separate experiment, alterations in MBP were measured in the spinal cords over the time period leading up to paralysis. Surprisingly, decreases in MBP were found immediately after the end of the 4 week irradiation period. These early changes in MBP were not markedly dose dependent and occurred with nonparalyzing doses. Dose-dependent decreases were found only just before the onset of paralysis. CNPase activity measured in the same specimens showed changes that were essentially similar to those for MBP. In the CSF, MBP levels were essentially constant until onset of paralysis. This study showed that demyelination, as assessed by the levels of the myelin-associated proteins MBP and CNPase, can occur soon after spinal cord irradiation but that profound dose-dependent changes are seen only immediately preceding the onset of paralysis. Although increases in MBP in the CSF were associated with the onset of radiation-induced myelopathy, its assay is unlikely to predict this complication of irradiation.
Assuntos
2',3'-Nucleotídeo Cíclico Fosfodiesterases/análise , Proteína Básica da Mielina/análise , Diester Fosfórico Hidrolases , Medula Espinal/efeitos da radiação , 2',3'-Nucleotídeo Cíclico 3'-Fosfodiesterase , Animais , Relação Dose-Resposta à Radiação , Feminino , Cobaias , Proteína Básica da Mielina/líquido cefalorraquidiano , Paralisia/etiologia , Paralisia/metabolismo , Medula Espinal/química , Medula Espinal/patologia , Fatores de TempoRESUMO
PURPOSE: To investigate the effects of short-term administration of dexamethasone (DEX) on radiation-induced responses in the mouse lung, focusing on expression of pro-inflammatory cytokine and related genes. METHODS AND MATERIALS: At indicated times after thoracic irradiation and/or drug treatment, mRNA expression levels of cytokines (mTNF-alpha, mIL-1 alpha, mIL-1 beta, mIL-2, mIL-3, mIL-4, mIL-5, mIL-6, mIFN-gamma) and related genes in the lungs of C3H/HeN mice were measured by RNase protection assay. RESULTS: Radiation-induced pro-inflammatory cytokine mRNA expression levels in lung peak at 6 h after thoracic irradiation. DEX (5 mg/kg) suppresses both basal cytokine mRNA levels and this early response when given immediately after irradiation. However, by 24 h, in mice treated with DEX alone or DEX plus radiation, there was a strong rebound effect that lasted up to 3 days. Modification of the early radiation-induced response by DEX did not change the second wave of cytokine gene expression in the lung that occurs at 1 to 2 weeks, suggesting that early cytokine gene induction might not determine subsequent molecular events. A single dose of DEX attenuated, but did not completely suppress, increases in cytokine mRNA levels induced by lipopolysaccharide (2.5 mg/kg) treatment, but, unlike with radiation, no significant rebound effect was seen. Five days of dexamethasone treatment in the pneumonitic phase also inhibited pro-inflammatory cytokine gene expression and, again, there was a rebound effect after withdrawal of the drug. CONCLUSIONS: Our findings suggest that short-term use of dexamethasone can temporarily suppress radiation-induced pro-inflammatory cytokine gene expression, but there may be a rebound after drug withdrawal and the drug does little to change the essence and course of the pneumonitic process.
Assuntos
Anti-Inflamatórios/farmacologia , Dexametasona/farmacologia , Interleucinas/metabolismo , Pulmão/efeitos dos fármacos , Pulmão/efeitos da radiação , Fator de Necrose Tumoral alfa/metabolismo , Animais , Anti-Inflamatórios/administração & dosagem , Dexametasona/administração & dosagem , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/efeitos da radiação , Molécula 1 de Adesão Intercelular/efeitos dos fármacos , Molécula 1 de Adesão Intercelular/metabolismo , Molécula 1 de Adesão Intercelular/efeitos da radiação , Interleucinas/efeitos da radiação , Pulmão/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C3H , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/metabolismo , RNA Mensageiro/efeitos da radiação , Fator de Necrose Tumoral alfa/efeitos dos fármacos , Fator de Necrose Tumoral alfa/efeitos da radiaçãoRESUMO
PURPOSE: To investigate the in vivo acute phase molecular response of the brain to ionizing radiation. METHODS AND MATERIALS: C3Hf/Sed/Kam mice were given midbrain or whole-body irradiation. Cerebral expression of interleukins (IL-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6), interferon (IFN-gamma), tumor necrosis factors (TNF-alpha and TNF-beta), intercellular adhesion molecule-1 (ICAM-1), inducible nitric oxide synthetase (iNOS), von Willebrand factor (vWF), alpha 1-antichymotrypsin (EB22/5.3), and glial fibrillary acidic protein (GFAP) was measured at various times after various radiation doses by ribonuclease (RNase) protection assay. The effects of dexamethasone or pentoxifylline treatment of mice on radiation-induced gene expression were also examined. RESULTS: Levels of TNF-alpha, IL-1 beta, ICAM-1, EB22/5.3 and to a lesser extent IL-1 alpha and GFAP, messenger RNA were increased in the brain after irradiation, whether the dose was delivered to the whole body or only to the midbrain. Responses were radiation dose dependent, but were not found below 7 Gy; the exception being ICAM-1, which was increased by doses as low as 2 Gy. Most responses were rapid, peaking within 4-8 h, but antichymotrypsin and GFAP responses were delayed and still elevated at 24 h, by which time the others had subsided. Pretreatment of mice with dexamethasone or pentoxifylline suppressed radiation-induced gene expression, either partially or completely. Dexamethasone was more inhibitory than pentoxifylline at the doses chosen. CONCLUSIONS: The initial response of the brain to irradiation involves expression of inflammatory gene products, which are probably responsible for clinically observed early symptoms of brain radiotherapy. This mechanism explains the beneficial effects of the clinical use of steroids in such circumstances.
Assuntos
Irradiação Craniana , Citocinas/efeitos da radiação , Regulação da Expressão Gênica/efeitos da radiação , RNA Mensageiro/efeitos da radiação , Animais , Anti-Inflamatórios/farmacologia , Citocinas/biossíntese , Citocinas/efeitos dos fármacos , Dexametasona/farmacologia , Relação Dose-Resposta à Radiação , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Molécula 1 de Adesão Intercelular/biossíntese , Molécula 1 de Adesão Intercelular/efeitos dos fármacos , Molécula 1 de Adesão Intercelular/efeitos da radiação , Interleucina-1/biossíntese , Interleucina-1/efeitos da radiação , Linfotoxina-alfa/biossíntese , Linfotoxina-alfa/efeitos da radiação , Camundongos , Camundongos Endogâmicos C3H , Pentoxifilina/farmacologia , RNA Mensageiro/biossíntese , RNA Mensageiro/efeitos dos fármacos , Dosagem Radioterapêutica , Fatores de Tempo , Transcrição Gênica/efeitos da radiação , Fator de Necrose Tumoral alfa/biossíntese , Fator de Necrose Tumoral alfa/efeitos dos fármacos , Fator de Necrose Tumoral alfa/efeitos da radiação , Vasodilatadores/farmacologiaRESUMO
The goals of this study were to quantify myelin-associated changes in the brain following single doses of radiation and to determine their relationship to the dose limits that this tissue can tolerate. Mice developed a transient loss of balance 1 month after 60 Gy doses 250 kVp X-rays to the brain and 3-4 months after 30-45 Gy radiation, but not after lower doses. The symptoms were transient and lasted approximately 1 month. The ED50/300 for radiation-induced brain death, which occurred large between 200 and 240 days, was 32.4 Gy (29.1, 35.5 Gy, 95% confidence limit of mean). At the time that animals developed neurological symptoms, 3-4 months after irradiation with doses of 30-45 Gy, biochemical assays of myelin-associated proteins showed decreases in 2',3'-cyclic nucleotide phosphohydrolase (CNPase) and myelin basic protein (MBP) levels that were not seen with lower radiation doses. By 120-180 days, further dose-dependent decreases in both CNPase and MBP levels were found after 20-45 Gy irradiation that preceded and correlated with death. The correlation of the decrease in CNPase and MBP levels with the incidence of transient neurological malfunction and animal death, together with histological evidence, suggests that demyelination is responsible for these phenomena.
Assuntos
2',3'-Nucleotídeo Cíclico Fosfodiesterases/efeitos da radiação , Encéfalo/efeitos da radiação , Doenças Desmielinizantes/etiologia , Proteína Básica da Mielina/efeitos da radiação , Animais , Masculino , Camundongos , Doses de Radiação , Organismos Livres de Patógenos Específicos , Taxa de SobrevidaRESUMO
The aim of this study was to investigate the responses of astrocytes and microglia to whole brain irradiation. Levels of glial fibrillary acidic protein (GFAP), which is a marker for astrocytes, were measured by ELISA in irradiated brains taken at varying time points after irradiation. GFAP levels were increased between 120 and 180 days after single doses of 20-45 Gy radiation, but not after lower doses (2 or 8 Gy). The increases in GFAP levels were confirmed by Western blot analysis and immunohistochemical staining which showed that the number of GFAP-positive astrocytes was increased, as was their staining intensity. Coincidently with the increase in astrocyte staining, there was an increase in the number and the intensity of microglial cell staining for Mac I antigen. Autoradiography of brain tissue following in vivo administration of [3H]thymidine showed an increased number of labelled cells during the same time period. The radiation-induced astrocytic and microglial responses that follows brain irradiation is indicative of reactive gliosis and inflammation occurring during the latent period up to the onset of late radiation-induced injury. This gliosis increases with radiation dose. The possibility that gliosis may participate in modifying postirradiation injury in the brain is discussed.
Assuntos
Astrócitos/efeitos da radiação , Encéfalo/efeitos da radiação , Microglia/efeitos da radiação , Animais , Astrócitos/imunologia , Química Encefálica , Ensaio de Imunoadsorção Enzimática , Proteína Glial Fibrilar Ácida/análise , Antígeno de Macrófago 1/análise , Masculino , Camundongos , Camundongos Endogâmicos C3H , Microglia/imunologia , Organismos Livres de Patógenos EspecíficosRESUMO
Although radiotherapy is a front line treatment for brain tumors, little is known about the in vivo molecular responses of brain to irradiation. In this study, expression of c-fos, c-jun and junB immediate-early genes were followed in mouse brain after irradiation. C-fos and junB, but not c-jun, mRNA was induced within 15 min in unanesthetized irradiated mice. Induction was transient and lasted < 4 h. The response was dose-dependent with increases in c-fos and junB mRNA levels after dose of > or = 2 and 7 Gy, respectively. Anesthesia of mice with pentobarbitol delayed the increases in mRNA expression and the response was attenuated. Pre-treatment of mice with dexamethasone, in a schedule which suppressed acute-phase gene expression after brain irradiation, did not significantly change c-fos and junB induction. Our results show that c-fos and junB responses occur in the brain in response to irradiation and that they can be modified by pentobarbital treatment but suggest that there is no direct correlation between the level of mRNA expression and later expression of cytokines or other acute-phase response genes.
Assuntos
Encéfalo/efeitos da radiação , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-jun/genética , RNA Mensageiro/biossíntese , Animais , Encéfalo/metabolismo , Dexametasona/farmacologia , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos da radiação , Camundongos , Camundongos Endogâmicos C3H , RNA Mensageiro/efeitos da radiaçãoRESUMO
Cells from patients with ataxia telangiectasia (AT) are abnormal in their response to irradiation as judged by clonogenic survival and accumulation in G2 phase. The relationship of the results of these two assays, however, is still a matter of controversy. Flow cytometry was used to measure the distribution of cells in the phases of the cell cycle after 2 Gy irradiation in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) and SV40-transformed fibroblasts. AT cells showed increased and prolonged accumulation in G2/M phase regardless of the cell type (lymphoblastoid or fibroblast) or complementation group (A, C or D). To test the hypothesis that prolonged accumulation of AT cells in G2 phase after irradiation was not simply a reflection of their radiosensitivity, we gave iso-survival radiation doses to SV40-transformed fibroblasts of two AT and one control cell lines. The two AT cell lines exited from the G2/M-phase block more slowly than control cells after each dose tested. This implies that prolonged accumulation in G2/M phase in AT cells is not directly related to radiosensitivity as measured by clonogenic survival, but that factors involved in the exit from G2 phase after irradiation may be abnormally regulated. We found that G2-phase arrest of AT cells did not necessarily result in a fatal consequence in the first cell cycle after irradiation. Furthermore, G2-phase arrest did not lead to detectable DNA fragmentation characteristic of apoptosis as judged by gel electrophoresis.
Assuntos
Ataxia Telangiectasia/patologia , Fase G2/efeitos da radiação , Mitose/efeitos da radiação , Linhagem Celular , Linhagem Celular Transformada , Sobrevivência Celular/efeitos da radiação , Herpesvirus Humano 4 , Humanos , Proteína Supressora de Tumor p53/análiseRESUMO
Astrocytes and microglial cells cultured from murine brain were stimulated to produce tumor necrosis factor alpha (TNF) by exposure to lipopolysaccharide (LPS). TNF alpha production began within 2 h with maximum production between 4 and 8 h after stimulation. Clinically relevant low (2 Gy), but not high (8 Gy), doses of radiation significantly increased TNF production by astrocytes and microglial cells in response to LPS. The radiation effect was even more marked with multiple 2 Gy doses. TNF is cytotoxic for oligodendrocytes and for certain tumor cells. It increases vascular permeability and enhances immune responses as well as having other biological effects. It is conceivable that production of TNF by astrocytes and microglial cells during clinical radiation therapy might influence the responses of tumor and/or normal CNS tissues.