RESUMEN
BACKGROUND: Evidence supporting the effectiveness of aerobic training, specific for fatigue, in severely fatigued patients with multiple sclerosis (MS) is lacking. OBJECTIVE: To estimate the effectiveness of aerobic training on MS-related fatigue and societal participation in ambulant patients with severe MS-related fatigue. METHODS: Patients ( N = 90) with severe MS-related fatigue were allocated to 16-week aerobic training or control intervention. Primary outcomes were perceived fatigue (Checklist Individual Strength (CIS20r) fatigue subscale) and societal participation. An improvement of ⩾8 points on the CIS20r fatigue subscale was considered clinically relevant. Outcomes were assessed by a blinded observer at baseline, 2, 4, 6 and 12 months. RESULTS: Of the 89 patients that started treatment (median Expanded Disability Status Scale (interquartile range), 3.0 (2.0-3.6); mean CIS20r fatigue subscale (standard deviation (SD)), 42.6 (8.0)), 43 received aerobic training and 46 received the control intervention. A significant post-intervention between-group mean difference (MD) on the CIS20r fatigue subscale of 4.708 (95% confidence interval (CI) = 1.003-8.412; p = 0.014) points was found in favour of aerobic training that, however, was not sustained during follow-up. No effect was found on societal participation. CONCLUSION: Aerobic training in MS patients with severe fatigue does not lead to a clinically meaningful reduction in fatigue or societal participation when compared to a low-intensity control intervention.
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Terapia por Ejercicio/métodos , Fatiga/rehabilitación , Esclerosis Múltiple/rehabilitación , Evaluación de Resultado en la Atención de Salud , Participación Social , Adulto , Ejercicio Físico/fisiología , Fatiga/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/complicaciones , Método Simple CiegoRESUMEN
OBJECTIVE: This study evaluated the effect of relapse phenotype on disability accumulation in multiple sclerosis. METHODS: Analysis of prospectively collected data was conducted in 19,504 patients with relapse-onset multiple sclerosis and minimum 1-year prospective follow-up from the MSBase cohort study. Multivariable linear regression models assessed associations between relapse incidence, phenotype and changes in disability (quantified with Expanded Disability Status Scale and its Functional System scores). Sensitivity analyses were conducted. RESULTS: In 34,858 relapses recorded during 136,462 patient-years (median follow-up 5.9 years), higher relapse incidence was associated with greater disability accumulation (ß = 0.16, p < 0.001). Relapses of all phenotypes promoted disability accumulation, with the most pronounced increase associated with pyramidal (ß = 0.27 (0.25-0.29)), cerebellar (ß = 0.35 (0.30-0.39)) and bowel/bladder (ß = 0.42 (0.35-0.49)) phenotypes (mean (95% confidence interval)). Higher incidence of each relapse phenotype was associated with an increase in disability in the corresponding neurological domain, as well as anatomically related domains. CONCLUSION: Relapses are associated with accumulation of neurological disability. Relapses in pyramidal, cerebellar and bowel/bladder systems have the greatest association with disability change. Therefore, prevention of these relapses is an important objective of disease-modifying therapy. The differential impact of relapse phenotypes on disability outcomes could influence management of treatment failure in multiple sclerosis.
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Personas con Discapacidad/estadística & datos numéricos , Interferón beta/uso terapéutico , Esclerosis Múltiple/tratamiento farmacológico , Recurrencia , Adulto , Enfermedad Crónica , Evaluación de la Discapacidad , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/fisiopatología , Estudios ProspectivosRESUMEN
In a prospective multi-center observational study, we evaluated the frequency, severity, and impact on activities of daily living (ADL) of adverse effects (AEs) of high-dose intravenous methylprednisolone (IVMP) in relapsing remitting multiple sclerosis (MS) patients with a relapse. Online self-report questionnaires stating IVMP's most common AEs were completed at baseline, the 2nd day of treatment, and 1 day and 1 week after treatment. Eighty-five patients were included, 66 completed the baseline questionnaire, and 59 completed at least one post-baseline questionnaire. Patients reported on average 4 (median) AEs; two (3.4 %) reported no AE. Most frequent was change in taste (61 %), facial flushing (61 %), sick/stomach pain (53 %), sleep disturbance (44 %), appetite change (37 %), agitation (36 %), and behavioral changes (36 %). Of all AEs, 34.3 % were severe and 37.9 % impacted on ADL. A 3-day course resulted in 4 (median) AEs and a 5-day course in 7. All patients with high disease impact had two or more AEs, compared with 79 % of those with low impact (p < 0.01). Of patients with high disability, 45 % had severe AEs, compared with 16 % of those with low disability. Severe central nervous system (CNS)-related AEs occurred two times more frequently in patients with high disease impact, and two-and-a-half times more frequently in patients with high disability. Therefore, in virtually all patients, high-dose IVMP leads to AEs, with about one of three AEs being severe with impact on ADL. Patients with high disease impact or high disability may experience more (severe) AEs, due to a higher occurrence of severe CNS-related AEs.
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Antiinflamatorios/efectos adversos , Personas con Discapacidad , Metilprednisolona/efectos adversos , Esclerosis Múltiple Recurrente-Remitente/tratamiento farmacológico , Esclerosis Múltiple Recurrente-Remitente/psicología , Autoinforme , Actividades Cotidianas , Administración Intravenosa , Adulto , Anciano , Antiinflamatorios/administración & dosificación , Personas con Discapacidad/psicología , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Masculino , Metilprednisolona/administración & dosificación , Persona de Mediana Edad , Sistemas en Línea/estadística & datos numéricos , Estudios Prospectivos , Encuestas y CuestionariosRESUMEN
OBJECTIVES: (1) To assess real-time patterns of fatigue; (2) to assess the association between a real-time fatigue score and 3 commonly used questionnaires (Checklist Individual Strength [CIS] fatigue subscale, Modified Fatigue Impact Scale (MFIS), and Fatigue Severity Scale [FSS]); and (3) to establish factors that confound the association between the real-time fatigue score and the conventional fatigue questionnaires in patients with multiple sclerosis (MS). DESIGN: Cross-sectional study. SETTING: MS-specialized outpatient facility. PARTICIPANTS: Ambulant patients with MS (N=165) experiencing severe self-reported fatigue. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: A real-time fatigue score was assessed by sending participants 4 text messages on a particular day (How fatigued do you feel at this moment?; score range, 0-10). Latent class growth mixed modeling was used to determine diurnal patterns of fatigue. Regression analyses were used to assess the association between the mean real-time fatigue score and the CIS fatigue subscale, MFIS, and FSS. Significant associations were tested for candidate confounders (eg, disease severity, work status, sleepiness). RESULTS: Four significantly different fatigue profiles were identified by the real-time fatigue score, namely a stable high (n=79), increasing (n=57), stable low (n=16), and decreasing (n=13). The conventional questionnaires correlated poorly (r<.300) with the real-time fatigue score. The Epworth Sleepiness Scale significantly reduced the regression coefficient between the real-time fatigue score and conventional questionnaires, ranging from 15.4% to 35%. CONCLUSIONS: Perceived fatigue showed 4 different diurnal patterns in patients with MS. Severity of sleepiness is an important confounder to take into account in the assessment of fatigue.
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Fatiga/epidemiología , Fatiga/fisiopatología , Esclerosis Múltiple/epidemiología , Modalidades de Fisioterapia , Encuestas y Cuestionarios/normas , Adulto , Ritmo Circadiano , Estudios Transversales , Evaluación de la Discapacidad , Fatiga/psicología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/psicología , Percepción , Análisis de Regresión , Reproducibilidad de los Resultados , Autoinforme , Índice de Severidad de la EnfermedadRESUMEN
BACKGROUND: Multiple Sclerosis is more common in women than men and females have more relapses than men. In a large international cohort we have evaluated the effect of gender on disability accumulation and disease progression to determine if male MS patients have a worse clinical outcome than females. METHODS: Using the MSBase Registry, data from 15,826 MS patients from 25 countries was analysed. Changes in the severity of MS (EDSS) were compared between sexes using a repeated measures analysis in generalised linear mixed models. Kaplan-Meier analysis was used to test for sex difference in the time to reach EDSS milestones 3 and 6 and the secondary progressive MS. RESULTS: In relapse onset MS patients (n = 14,453), males progressed significantly faster in their EDSS than females (0.133 vs 0.112 per year, P<0.001,). Females had a reduced risk of secondary progressive MS (HR (95% CI) = 0.77 (0.67 to 0.90) P = 0.001). In primary progressive MS (n = 1,373), there was a significant increase in EDSS over time in males and females (P<0.001) but there was no significant sex effect on the annualized rate of EDSS change. CONCLUSION: Among registrants of MSBase, male relapse-onset patients accumulate disability faster than female patients. In contrast, the rate of disability accumulation between male and female patients with primary progressive MS is similar.
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Esclerosis Múltiple/patología , Adulto , Anciano , Estudios de Cohortes , Bases de Datos Factuales , Evaluación de la Discapacidad , Progresión de la Enfermedad , Femenino , Humanos , Factores Inmunológicos/uso terapéutico , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/tratamiento farmacológico , Esclerosis Múltiple/mortalidad , Modelos de Riesgos Proporcionales , Recurrencia , Sistema de Registros , Índice de Severidad de la Enfermedad , Factores SexualesRESUMEN
OBJECTIVES: The aim was to analyse risk of relapse phenotype recurrence in multiple sclerosis and to characterise the effect of demographic and clinical features on this phenotype. METHODS: Information about relapses was collected using MSBase, an international observational registry. Associations between relapse phenotypes and history of similar relapses or patient characteristics were tested with multivariable logistic regression models. Tendency of relapse phenotypes to recur sequentially was assessed with principal component analysis. RESULTS: Among 14,969 eligible patients (89,949 patient-years), 49,279 phenotypically characterised relapses were recorded. Visual and brainstem relapses occurred more frequently in early disease and in younger patients. Sensory relapses were more frequent in early or non-progressive disease. Pyramidal, sphincter and cerebellar relapses were more common in older patients and in progressive disease. Women presented more often with sensory or visual symptoms. Men were more prone to pyramidal, brainstem and cerebellar relapses. Importantly, relapse phenotype was predicted by the phenotypes of previous relapses. (OR = 1.8-5, p = 10(-14)). Sensory, visual and brainstem relapses showed better recovery than other relapse phenotypes. Relapse severity increased and the ability to recover decreased with age or more advanced disease. CONCLUSION: Relapse phenotype was associated with demographic and clinical characteristics, with phenotypic recurrence significantly more common than expected by chance.
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Esclerosis Múltiple Recurrente-Remitente/diagnóstico , Esclerosis Múltiple Recurrente-Remitente/fisiopatología , Adulto , Factores de Edad , Anciano , Evaluación de la Discapacidad , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Fenotipo , Pronóstico , Recurrencia , RiesgoRESUMEN
BACKGROUND: Multiple sclerosis (MS) is an important, highly disabling neurological disease, common among young adults in The Netherlands. Nevertheless, only a few studies to date have measured the burden imposed by MS on society in The Netherlands. OBJECTIVES: To estimate the cost and quality-of-life associated with MS in The Netherlands, while focusing on the burden of relapses and increasing disease severity. METHODS: MS patients in The Netherlands (n = 263) completed a web-based questionnaire which captured information on demographics, disease characteristics and severity (Expanded Disability Status Scale [EDSS]), co-morbidities, relapses, resource consumption, utilities, fatigue and activities of daily living (ADL). RESULTS: Most patients included in the study were receiving treatment for MS (76% of the sample). The mean cost per patient per year increased with worsening disability and was estimated at 30,938, 51,056, and 100,469 for patients with mild (EDSS 0-3), moderate (EDSS 4-6.5), and severe (EDSS 7-9) disability, respectively. The excess cost of relapses was estimated at 8195 among relapsing-remitting patients with EDSS score ≤5. The quality-of-life of patients decreased with disease progression and existence of relapses. CONCLUSIONS: The cost of MS in The Netherlands was higher compared to the results of previous studies. The TRIBUNE study provides an important update on the economic burden of MS in The Netherlands in an era of more widespread use of disease-modifying therapies. It explores the cost of MS linked to relapses and disease severity and examines the impact of MS on additional health outcomes beyond utilities such as ADL and fatigue. STUDY LIMITATIONS: Patients were selected from specialized treatment centers, therefore this sample may not be representative of the entire MS population in The Netherlands, i.e., few patients not receiving MS therapies were included. In addition, only a few patients with severe disability were included in the study sample; therefore, results for this disease severity sub-group should be interpreted with caution.
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Actividades Cotidianas , Costo de Enfermedad , Servicios de Salud/economía , Esclerosis Múltiple/economía , Calidad de Vida , Adulto , Comorbilidad , Progresión de la Enfermedad , Empleo/estadística & datos numéricos , Fatiga , Femenino , Servicios de Salud/estadística & datos numéricos , Humanos , Internet , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/clasificación , Esclerosis Múltiple/complicaciones , Países Bajos , Recurrencia , Índice de Severidad de la Enfermedad , Ausencia por Enfermedad/economía , Ausencia por Enfermedad/estadística & datos numéricos , Encuestas y CuestionariosAsunto(s)
Anticuerpos Monoclonales Humanizados/efectos adversos , Síndrome Inflamatorio de Reconstitución Inmune/inducido químicamente , Síndrome Inflamatorio de Reconstitución Inmune/diagnóstico , Leucoencefalopatía Multifocal Progresiva/inducido químicamente , Leucoencefalopatía Multifocal Progresiva/diagnóstico , Imagen por Resonancia Magnética , Esclerosis Múltiple Recurrente-Remitente/tratamiento farmacológico , Antiinflamatorios/uso terapéutico , Anticuerpos Monoclonales Humanizados/uso terapéutico , Encéfalo/irrigación sanguínea , Encéfalo/patología , Arterias Cerebrales/patología , Terapia Combinada , Diagnóstico Diferencial , Femenino , Humanos , Aumento de la Imagen , Interpretación de Imagen Asistida por Computador , Síndrome Inflamatorio de Reconstitución Inmune/tratamiento farmacológico , Infusiones Intravenosas , Metilprednisolona/uso terapéutico , Persona de Mediana Edad , Esclerosis Múltiple Recurrente-Remitente/diagnóstico , Natalizumab , Examen Neurológico/efectos de los fármacos , Intercambio PlasmáticoRESUMEN
OBJECTIVES: To compare treatment persistence between two dosages of interferon ß-1a in a large observational multiple sclerosis registry and assess disease outcomes of first line MS treatment at these dosages using propensity scoring to adjust for baseline imbalance in disease characteristics. METHODS: Treatment discontinuations were evaluated in all patients within the MSBase registry who commenced interferon ß-1a SC thrice weekly (nâ=â4678). Furthermore, we assessed 2-year clinical outcomes in 1220 patients treated with interferon ß-1a in either dosage (22 µg or 44 µg) as their first disease modifying agent, matched on propensity score calculated from pre-treatment demographic and clinical variables. A subgroup analysis was performed on 456 matched patients who also had baseline MRI variables recorded. RESULTS: Overall, 4054 treatment discontinuations were recorded in 3059 patients. The patients receiving the lower interferon dosage were more likely to discontinue treatment than those with the higher dosage (25% vs. 20% annual probability of discontinuation, respectively). This was seen in discontinuations with reasons recorded as "lack of efficacy" (3.3% vs. 1.7%), "scheduled stop" (2.2% vs. 1.3%) or without the reason recorded (16.7% vs. 13.3% annual discontinuation rate, 22 µg vs. 44 µg dosage, respectively). Propensity score was determined by treating centre and disability (score without MRI parameters) or centre, sex and number of contrast-enhancing lesions (score including MRI parameters). No differences in clinical outcomes at two years (relapse rate, time relapse-free and disability) were observed between the matched patients treated with either of the interferon dosages. CONCLUSIONS: Treatment discontinuations were more common in interferon ß-1a 22 µg SC thrice weekly. However, 2-year clinical outcomes did not differ between patients receiving the different dosages, thus replicating in a registry dataset derived from "real-world" database the results of the pivotal randomised trial. Propensity score matching effectively minimised baseline covariate imbalance between two directly compared sub-populations from a large observational registry.
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Interferón beta/administración & dosificación , Interferón beta/uso terapéutico , Cumplimiento de la Medicación , Esclerosis Múltiple/tratamiento farmacológico , Puntaje de Propensión , Adulto , Demografía , Relación Dosis-Respuesta a Droga , Esquema de Medicación , Femenino , Humanos , Inyecciones Subcutáneas , Interferón beta-1a , Interferón beta/farmacología , Estimación de Kaplan-Meier , Funciones de Verosimilitud , Imagen por Resonancia Magnética , Masculino , Reproducibilidad de los Resultados , Resultado del Tratamiento , Privación de TratamientoRESUMEN
BACKGROUND: Due to methodological shortcomings the available post-registration data on the adverse events (AEs) occurring in interferon beta-1a (INFb-1a)-treated patients fail to adequately validate phase III data and only partially inform on safety in daily practice. We assessed AEs in relapsing remitting multiple sclerosis (RRMS) patients treated with intramuscular (IM) INFb-1a in daily practice using data quality assurance measures similar to those in phase III trials. METHODS: A prospective, International Conference on Harmonization (ICH) - Good Clinical Practice (GCP)-based, clinical research organization (CRO)-supported study in 36 practices in the Netherlands, Belgium, the United Kingdom and Luxembourg. During 24 months after start of IM INFb-1a treatment 275 RRMS patients were assessed for AEs' severity (mild, moderate, severe) and relationship to treatment (not, unlikely, likely, definite). Data were compared with those reported in the pivotal phase III trial. FINDINGS: 75.3% of the patients experienced one or more AEs that were likely or definitely related to INFb-1a. Of all AEs 40.5% were likely or definitely treatment-related; 68.5% of these were mild, and 3% severe. 6.6% of the patients discontinued treatment because of an AE. Compared to the pivotal phase III trial, we found statistically significantly lower incidences for most of the common AEs: headache, muscle ache, fatigue, fever, chills, nausea. One patient died following two cerebral vascular events in study month 22, both AEs were assessed as not related to INFb-1a. CONCLUSION: Three out of four RRMS patients treated with IM INFb-1a in daily practice experience treatment-related AEs, most of these being mild. Our data externally validate the favorable phase III safety profile of IM INFb-1a and suggest that the real-life incidence of treatment-related AEs is less than reported in the pivotal phase III trial. Larger studies are needed to detect rare, potentially hazardous AEs of IM INFb-1a.
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Interferón beta/efectos adversos , Esclerosis Múltiple Recurrente-Remitente/tratamiento farmacológico , Adyuvantes Inmunológicos , Adulto , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Europa (Continente) , Humanos , Incidencia , Inyecciones Intramusculares , Interferón beta-1a , Interferón beta/administración & dosificación , Esclerosis Múltiple Recurrente-Remitente/complicaciones , Resultado del TratamientoRESUMEN
Fluorescence lifetime imaging microscopy (FLIM) is a quantitative microscopy technique for imaging nanosecond decay times of fluorophores. In the case of frequency-domain FLIM, several methods have been described to resolve the relative abundance of two fluorescent species with different fluorescence decay times. Thus far, single-frequency FLIM methods generally have been limited to quantifying two species with monoexponential decay. However, multiexponential decays are the norm rather than the exception, especially for fluorescent proteins and biological samples. Here, we describe a novel method for determining the fractional contribution in each pixel of an image of a sample containing two (multiexponentially) decaying species using single-frequency FLIM. We demonstrate that this technique allows the unmixing of binary mixtures of two spectrally identical cyan or green fluorescent proteins, each with multiexponential decay. Furthermore, because of their spectral identity, quantitative images of the relative molecular abundance of these fluorescent proteins can be generated that are independent of the microscope light path. The method is rigorously tested using samples of known composition and applied to live cell microscopy using cells expressing multiple (multiexponentially decaying) fluorescent proteins.
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Algoritmos , Biopolímeros/metabolismo , Transferencia Resonante de Energía de Fluorescencia/métodos , Microscopía de Fluorescencia por Excitación Multifotónica/métodosRESUMEN
Enhanced cyan and yellow fluorescent proteins are widely used for dual color imaging and protein-protein interaction studies based on fluorescence resonance energy transfer. Use of these fluorescent proteins can be limited by their thermosensitivity, dim fluorescence, and tendency for aggregation. Here we report the results of a site-directed mutagenesis approach to improve these fluorescent proteins. We created monomeric optimized variants of ECFP and EYFP, which fold faster and more efficiently at 37 degrees C and have superior solubility and brightness. Bacteria expressing SCFP3A were 9-fold brighter than those expressing ECFP and 1.2-fold brighter than bacteria expressing Cerulean. SCFP3A has an increased quantum yield (0.56) and fluorescence lifetime. Bacteria expressing SYFP2 were 12 times brighter than those expressing EYFP(Q69K) and almost 2-fold brighter than bacteria expressing Venus. In HeLa cells, the improvements were less pronounced; nonetheless, cells expressing SCFP3A and SYFP2 were both 1.5-fold brighter than cells expressing ECFP and EYFP(Q69K), respectively. The enhancements of SCFP3A and SYFP2 are most probably due to an increased intrinsic brightness (1.7-fold and 1.3-fold for purified recombinant proteins, compared to ECFP & EYFP(Q69K), respectively) and due to enhanced protein folding and maturation. The latter enhancements most significantly contribute to the increased fluorescent yield in bacteria whereas they appear less significant for mammalian cell systems. SCFP3A and SYFP2 make a superior donor-acceptor pair for fluorescence resonance energy transfer, because of the high quantum yield and increased lifetime of SCFP3A and the high extinction coefficient of SYFP2. Furthermore, SCFP1, a CFP variant with a short fluorescence lifetime but identical spectra compared to ECFP and SCFP3A, was characterized. Using the large lifetime difference between SCFP1 and SCFP3A enabled us to perform for the first time dual-lifetime imaging of spectrally identical fluorescent species in living cells.
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Proteínas Bacterianas/química , Proteínas Fluorescentes Verdes/química , Proteínas Luminiscentes/química , Secuencia de Bases , Cartilla de ADN , Transferencia Resonante de Energía de Fluorescencia , Células HeLa , Humanos , Datos de Secuencia Molecular , Pliegue de Proteína , Espectrometría de FluorescenciaRESUMEN
Fluorescence lifetime imaging microscopy (FLIM) is a technique to map the spatial distribution of nanosecond excited state lifetimes within microscopic images. FLIM systems have been implemented both in the frequency domain, using sinusoidally intensity-modulated excitation light and modulated detectors, and in the time domain, using pulsed excitation sources and time-correlated or time-gated detection. In this review we describe the different modes in which both frequency-domain and time-domain FLIM instruments have been constructed in wide-field and in point-scanning (confocal) microscopes. Also, novel additional strategies for constructing FLIM-instruments are discussed. In addition to technical implementation, this chapter gives an overview of the application of FLIM in cell biological en biomedical studies. Especially for in situ protein-protein interaction studies using fluorescence resonance energy transfer (FRET), FLIM has proven to be a robust and established technique in modern cell biology. Other application areas, including usage of lifetime contrast for ion-imaging, quantitative imaging, tissue characterization and medical applications, are discussed.
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Transferencia Resonante de Energía de Fluorescencia/instrumentación , Transferencia Resonante de Energía de Fluorescencia/métodos , Microscopía Fluorescente/instrumentación , Microscopía Fluorescente/métodos , Mapeo de Interacción de Proteínas/instrumentación , Mapeo de Interacción de Proteínas/métodos , Proteínas/metabolismo , Diseño de Equipo , Análisis de Falla de Equipo , Proteínas/análisisRESUMEN
Although the distribution of DNA-binding proteins inside the cell nucleus can be analyzed by immunolabeling or by tagging proteins with GFP, we cannot establish whether the protein is bound to DNA or not. Here, we describe a novel approach that allows imaging of the in situ interaction between a GFP-fusion protein and DNA in the cell nucleus, using fluorescence resonance energy transfer (FRET). We used fluorescence lifetime imaging microscopy (FLIM) as a reliable tool to detect protein in contact with DNA. The method was successfully applied to the DNA-binding proteins histone H2B and the glucocorticoid receptor and to the heterochromatin-associated proteins HP1alpha and HP1beta.
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Núcleo Celular/metabolismo , ADN/metabolismo , Transferencia Resonante de Energía de Fluorescencia/métodos , Proteínas Nucleares/metabolismo , Línea Celular Tumoral , Homólogo de la Proteína Chromobox 5 , Proteínas Fluorescentes Verdes/metabolismo , Células HeLa , Histonas/metabolismo , Humanos , Microscopía Fluorescente/métodos , Protaminas/metabolismo , Unión Proteica/fisiologíaRESUMEN
Cytoplasmic linker protein (CLIP)-170, CLIP-115, and the dynactin subunit p150(Glued) are structurally related proteins, which associate specifically with the ends of growing microtubules (MTs). Here, we show that down-regulation of CLIP-170 by RNA interference results in a strongly reduced accumulation of dynactin at the MT tips. The NH(2) terminus of p150(Glued) binds directly to the COOH terminus of CLIP-170 through its second metal-binding motif. p150(Glued) and LIS1, a dynein-associating protein, compete for the interaction with the CLIP-170 COOH terminus, suggesting that LIS1 can act to release dynactin from the MT tips. We also show that the NH(2)-terminal part of CLIP-170 itself associates with the CLIP-170 COOH terminus through its first metal-binding motif. By using scanning force microscopy and fluorescence resonance energy transfer-based experiments we provide evidence for an intramolecular interaction between the NH(2) and COOH termini of CLIP-170. This interaction interferes with the binding of the CLIP-170 to MTs. We propose that conformational changes in CLIP-170 are important for binding to dynactin, LIS1, and the MT tips.
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Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Microtúbulos/metabolismo , Secuencias de Aminoácidos/genética , Animales , Sitios de Unión/genética , Células COS , Regulación hacia Abajo/genética , Complejo Dinactina , Microtúbulos/genética , Microtúbulos/ultraestructura , Proteínas de Neoplasias , Unión Proteica/genética , Conformación Proteica , Estructura Terciaria de Proteína/genética , Subunidades de Proteína/genética , Subunidades de Proteína/metabolismo , Interferencia de ARNRESUMEN
BACKGROUND: Photobleaching can lead to significant errors in frequency-domain fluorescence lifetime imaging microscopy (FLIM). Existing correction methods for photobleaching require additional recordings and processing time and can result in additional noise. A method is introduced that suppresses the effects of photobleaching without the need for extra recordings or processing. METHODS: Existing bleach correction methods and the method introduced in this report whereby the recording order of the phases is permuted were compared using numerical simulations. RESULTS: Certain orders were found to make measurements virtually insensitive to photobleaching. At 12 recordings, errors in measured phase and modulation depth decreased by a factor 512 and 393, respectively, compared to recordings using sequential recording order. The optimal order is independent of modulation depth, phase, and extent of photobleaching. Thus, the same order can be used for practically all situations. Application of the method in FLIM measurements of EYFP-transfected HeLa cells was found effectively to suppress photobleaching induced artifacts. CONCLUSIONS: In view of the ease of implementation, its inherent robustness, and the possibility to still apply existing correction methods afterward, there is no good reason not to use the permuted recording order presented in this report instead of a sequential order.
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Artefactos , Microscopía Fluorescente/métodos , Microscopía Fluorescente/normas , Microscopía por Video/métodos , Fotoblanqueo , Células HeLa , Humanos , Microscopía por Video/normas , Factores de Tiempo , TransfecciónRESUMEN
BACKGROUND: It was found earlier that the difference in volume between unstained X- and Y-chromosome-bearing sperm heads could be detected using interference microscopy in visible light. This could be the basis for an alternative to the conventional method to sort X and Y sperm, which uses DNA staining and ultraviolet (UV)-excitation that may be harmful to sperm cells. A novel technique is introduced combining interferometry with flow cytometry. MATERIALS AND METHODS: Interference optics were built into an existing flow cytometer/cell sorter and used to sort fresh unstained bull sperm cells on the basis of their head volume. Sorted fractions were stained with a DNA stain, and reanalyzed using the conventional method. RESULTS: Purities between 60-66% were found in both X- and Y-enriched fractions. It was possible to sort up to 300 cells per second. The system was found to be less sensitive to the orientation of sperm cells than the conventional method. CONCLUSIONS: Interferometry can be combined with flow cytometry and used to obtain significantly enriched fractions of X- and Y-bearing sperm without staining and UV light. Sorting speeds and purities at this point, however, are much lower than with the conventional method.