RESUMEN
Chromosome translocations are hallmark of cancer and of radiation-induced cell killing, reflecting joining of incongruent DNA-ends that alter the genome. Translocation-formation requires DNA end-joining mechanisms and incompletely characterized, permissive chromatin conditions. We show that chromatin destabilization by clusters of DNA double-strand-breaks (DSBs) generated by the I-SceI meganuclease at multiple, appropriately engineered genomic sites, compromises c-NHEJ and markedly increases cell killing and translocation-formation compared to single-DSBs. Translocation-formation from DSB-clusters utilizes Parp1 activity, implicating alt-EJ in their formation. Immunofluorescence experiments show that single-DSBs and DSB-clusters uniformly provoke the formation of single γ-H2AX foci, suggesting similar activation of early DNA damage response (DDR). Live-cell imaging also shows similar single-focus recruitment of the early-response protein MDC1, to single-DSBs and DSB-clusters. Notably, the late DDR protein, 53BP1 shows in live-cell imaging strikingly stronger recruitment to DSB-clusters as compared to single-DSBs. This is the first report that chromatin thripsis, in the form of engineered DSB-clusters, compromises first-line DSB-repair pathways, allowing alt-EJ to function as rescuing-backup. DSB-cluster-formation is indirectly linked to the increased biological effectiveness of high ionization-density radiations, such as the alpha-particles emitted by radon gas or the heavy-ions utilized in cancer therapy. Our observations provide the first direct mechanistic explanation for this long-known effect.
Asunto(s)
Cromosomas de los Mamíferos/metabolismo , Cromotripsis , Roturas del ADN de Doble Cadena , Translocación Genética , Proteína 1 de Unión al Supresor Tumoral P53/metabolismo , Animales , Células CHO , Muerte Celular , Células Clonales , Cricetinae , Cricetulus , Reparación del ADN , Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Genoma , Proteínas Fluorescentes Verdes/metabolismo , Metafase , Proteínas de Saccharomyces cerevisiae/metabolismo , Transducción de SeñalRESUMEN
Hemobilia is an extremely rare cause of upper gastrointestinal bleeding. It often has intermittent manifestation, which may lead to significant diagnostic delay. In 65% of the cases, the causes are iatrogenic, in 7% the cause is malignancy, in 5% - gallstones, in 8% it is inflammation (cholecystitis, parasites, reflux cholangitis), vascular abnormality is the cause in 7% (most commonly pseudoaneurysm of the hepatic artery), and pancreatic pseudocyst causes hemobilia in 1%. In almost all cases, the bleeding originates from intrahepatic or extrahepatic bile ducts, and rarely from the pancreas.
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Fístula , Hemobilia , Conducto Colédoco , Diagnóstico Tardío/efectos adversos , Fístula/complicaciones , Fístula/diagnóstico , Fístula/patología , Hemobilia/diagnóstico , Hemobilia/etiología , Hemobilia/terapia , Arteria Hepática/diagnóstico por imagen , Arteria Hepática/patología , Arteria Hepática/cirugía , HumanosRESUMEN
This study analyzed the effects of biliprotein C-phycocyanin (C-PC) on the enzymatic antioxidant defence system in lymphocytes of nuclear power-plant workers and non-exposed controls. Changes in the protein levels of manganese super oxide dismutase (MnSOD), catalase and glutathione-S-transferase (GST) were used as markers for early biological effects of a single in vitro exposure of cells to: (i) 2Gy gamma rays; (ii) 5muM C-PC; and (iii) a combination of C-PC plus irradiation with 2Gy. The results showed that C-PC selectively stimulated the lymphocyte antioxidant defence system of occupationally exposed subjects. The activation of the antioxidant protective mechanisms as part of the early radiation response was probably related to the chronic low-dose occupational exposure. The modulating capacity of C-PC at the molecular level may be of interest for the protection of occupationally exposed persons.
Asunto(s)
Antioxidantes/farmacología , Catalasa/metabolismo , Glutatión Transferasa/metabolismo , Linfocitos/efectos de los fármacos , Linfocitos/efectos de la radiación , Ficocianina/farmacología , Superóxido Dismutasa/metabolismo , Adulto , Estudios de Casos y Controles , Terapia Combinada , Femenino , Rayos gamma , Humanos , Masculino , Persona de Mediana Edad , Plantas de Energía Nuclear , Exposición Profesional , Proyectos Piloto , Dosis de RadiaciónRESUMEN
Detrimental effects of ionizing radiation (IR) are correlated to the varying efficiency of IR to induce complex DNA damage. A double strand break (DSB) can be considered the simpler form of complex DNA damage. These types of damage can consist of DSBs, single strand breaks (SSBs) and/or non-DSB lesions such as base damages and apurinic/apyrimidinic (AP; abasic) sites in different combinations. Enthralling theoretical (Monte Carlo simulations) and experimental evidence suggests an increase in the complexity of DNA damage and therefore repair resistance with linear energy transfer (LET). In this study, we have measured the induction and processing of DSB and non-DSB oxidative clusters using adaptations of immunofluorescence. Specifically, we applied foci colocalization approaches as the most current methodologies for the in situ detection of clustered DNA lesions in a variety of human normal (FEP18-11-T1) and cancerous cell lines of varying repair efficiency (MCF7, HepG2, A549, MO59K/J) and radiation qualities of increasing LET, that is γ-, X-rays 0.3-1 keV/µm, α-particles 116 keV/µm and 36Ar ions 270 keV/µm. Using γ-H2AX or 53BP1 foci staining as DSB probes, we calculated a DSB apparent rate of 5-16 DSBs/cell/Gy decreasing with LET. A similar trend was measured for non-DSB oxidized base lesions detected using antibodies against the human repair enzymes 8-oxoguanine-DNA glycosylase (OGG1) or AP endonuclease (APE1), that is damage foci as probes for oxidized purines or abasic sites, respectively. In addition, using colocalization parameters previously introduced by our groups, we detected an increasing clustering of damage for DSBs and non-DSBs. We also make correlations of damage complexity with the repair efficiency of each cell line and we discuss the biological importance of these new findings with regard to the severity of IR due to the complex nature of its DNA damage.
Asunto(s)
Daño del ADN/genética , Reparación del ADN/genética , Transferencia Lineal de Energía/genética , Radiación Ionizante , HumanosRESUMEN
Heat shock protein 90 (Hsp90) is a highly conserved molecular chaperone, involved in the folding, assembly, stabilization and activation of numerous proteins with unrelated amino acid sequences and functions. Geldanamycin (GA), a natural benzoquinone, can inhibit the chaperone activity of Hsp90. It has been shown that GA can produce superoxide anions and increase the intracellular oxidative stress, which, in addition to the direct inhibition of Hsp90, might also contribute to the modifying effects of the inhibitor on the early response in human mononuclear cells exposed to ionizing radiation. The present study shows that GA antagonizes the radiation-induced suppression on MnSOD and catalase, key enzymes of the radical scavenging systems. By significantly up-regulating catalase levels over the entire range of doses from 0.5 to 4 Gy, the inhibitor of Hsp90 exerted adaptive protection and modified the early radiation response of the human blood cells.
RESUMEN
The aim of this study was to compare findings from clinical examinations, MRI scans and arthroscopy in ACL injury of the knee in order to assess the diagnostic significance of both examination findings. This study was conducted to manage the reliability of clinical diagnosis in ACL tear injuries. All patients attending our clinic with knee pain from 2009 to 2013 underwent systematic and thorough clinical assessment. Of 103 patients with knee problems arthroscopy ACL tears was diagnosed in 73. All these patients underwent therapeutic arthroscopic knee surgery. The clinical diagnosis was evaluated and confirmed during this procedure. The accuracy, sensitivity and specificity were calculated based on these arthroscopic findings. The MRI accuracy of clinical diagnosis in our study was 82.5% for ACL tears. Accuracy for two of three clinical examination tests of clinical diagnosis in our study was 96% and 94% for ACL tears. According to our obtained correlation between clinical examinations, MRI scan and arthroscopy for ACL injuries, we concluded that carefully performed clinical examination can give equal or better diagnosis of ACL injuries in comparison with MRI scan. Our study revealed MRI scan high sensitivity and specificity and not so high accuracy for ACL injuries of the knee joint in comparison with arthroscopy. MRI is an appropriate screening tool for therapeutic arthroscopy, making diagnostic arthroscopy unnecessary in most patients. According to our findings we can conclude that a positive anterior drawer test and a positive Lachman clinical examination test is more accurate for predicting, i.e. diagnosis of ACL tear. On the ither hand, MRI scan findings showed less accuracy for predicting, i.e. diagnosis of ACL tear. According to many studies of clinical examination tests compared (correlated) with arthroscopy, the accuracy of predicting ACL tears depends on the level of the skilled orthopaedic or trauma surgeon's hands. Based on these findings, we feel that MRI, except in certain circumstances, is an expensive and unnecessary diagnostic test in patients with suspected meniscal and ACL pathology.
Asunto(s)
Lesiones del Ligamento Cruzado Anterior , Artroscopía/métodos , Traumatismos de la Rodilla/diagnóstico , Imagen por Resonancia Magnética/métodos , Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Rotura , Lesiones de Menisco Tibial , Adulto JovenRESUMEN
PURPOSE: The study aimed to analyze the impact of the proteasome inhibitors MG132 (N-carbobenzyoxyl-L-leucyl-L-leucyl-L-leucinal), lactacystin and celastrol on manganese superoxide dismutase (MnSOD), catalase and glutathione-S-transferase-π (GST-π), and on the heat shock protein 70 (Hsp70) in human peripheral blood mononuclear cells (PBMC), exposed to ionizing radiation. MATERIALS AND METHODS: Changes in protein levels were analyzed by Western blot. Cellular viability, proteasome activity, level of oxidative stress and apoptosis were determined by standard colorimetric and fluorescence assays. RESULTS: MG132 and lactacystin induced an increase in the intracellular levels of Hsp70. MnSOD was up-regulated by MG132 and celastrol, and GST-π was up-regulated by MG132 and lactacystin. Notably, the proteasome inhibitors significantly modified the protein levels in the irradiated cells and dramatically reduced the intracellular pool of oxidative species. The combined effect of radiation and proteasome inhibition was a dose-dependent up-regulation of the antioxidant enzymes and Hsp70. CONCLUSIONS: All three proteasome inhibitors showed antioxidant effects in PBMC and up-regulated the antioxidant enzymes MnSOD, catalase and GST-π and the stress protein Hsp70, modifying the early radiation response, and conferring protection against the effects of ionizing radiation.
Asunto(s)
Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/fisiología , Estrés Oxidativo/fisiología , Estrés Oxidativo/efectos de la radiación , Complejo de la Endopetidasa Proteasomal/metabolismo , Inhibidores de Proteasoma/farmacología , Células Cultivadas , Relación Dosis-Respuesta a Droga , Relación Dosis-Respuesta en la Radiación , Humanos , Leucocitos Mononucleares/efectos de la radiación , Dosis de Radiación , Protectores contra Radiación/farmacologíaRESUMEN
Cyclosporin A(CsA) - induced gingival overgrowth(GO) is a current problem of tissue-specific mechanism which is still incompletely explained. The apoptotic process has been of particular interest like a new concept in the etiology of this unwanted effect. The aim of our study was to detect the level of apoptosis, expression bcl-2 and p53, associated with the different doses of CsA. in gingival stroma. A cohort of 84 kidney transplant recipients was divided into four subgroups based on average daily dose of therapeutically applied CsA (Neoral®), (100 mg, 125 mg, 150 mg and 175 mg). The control group consisted of 21 patients, clinically diagnosed with periodontitis, who were not subjected to any medicamentous treatment causing gingival overgrowth. The following indexes were analyzed: plaque index (PI), index of gingival inflammation (GI) according to Loe-Silnes, and gingival overgrowth index (GOI) according to MacGaw et al. The tissue samples were subjected to a semiquantitative analysis to detect apoptotical cells and immunohistochemically stained to detect the expression of the bcl-2 and p53 proteins. The difference in percentage of apoptotic cells between the group taking 175 mg and other subgroups, as well as the control group was statistically significant (p<0.05). There was a significant difference in percentage of expression bcl-2 between the 175 mg group compared to the other three subgroups and the control (p=0.001). However, a statistically significant positive correlation between the medicament dose, p53, apoptosis, and bcl-2 was registered (p<0.05). Inflammation plays the most important role in the induction of apoptosis and proliferation in gingival tissues.
Asunto(s)
Apoptosis/efectos de los fármacos , Ciclosporina/efectos adversos , Sobrecrecimiento Gingival/inducido químicamente , Inmunosupresores/efectos adversos , Inflamación/complicaciones , Humanos , Proteínas Proto-Oncogénicas c-bcl-2/análisis , Proteína p53 Supresora de Tumor/análisisRESUMEN
The Oxford classification for the pathological classification of a glomerular disease in IgA nephropathy was established and published in 2009. Four of the pathological variables: 1) mesangial hypercellularity score, 2) segmental glomerulosclerosis, 3) endocapillary hypercellularity and 4) tubular atrophy/interstital fibrosis were presented as having value in predicting renal outcome in this glomerular disease. These features were recommended to be taken into account for predicting the outcome. In our study, we correlated these four variables with the outcome of the disease in 40 adult patients with IgA nephropathy. Standard histopathologic procedure was used to determine four variables as 0/1. The results were compared with renal outcome, clinical data were obtained from the out-patient files of the patients. The whole follow-up period was 3-27 years. The average survival of the whole group was 10.8±7.47 years (M±SD). Mesangial hypercellularity was confirmed to be associated with the renal outcome (p=0.047), as well as glomerular sclerosis (p=0.009), endocapillary hypercellularity (p=0.001) and tubular atrophy/interstitial fibrosis (p=0.045). When we analysed only patients with a severe form of the disease (nephrotic syndrome; patients treated with immunosuppression), the survival of the patients was associated only with the degree of tubulointerstitial changes (p=0.018). Analysing separately patients with mild clinical form, we found only a predictive value of segmental glomerulosclerosis on renal survival.