Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 268
Filtrar
Más filtros

Bases de datos
Tipo del documento
Intervalo de año de publicación
1.
Neuropathol Appl Neurobiol ; 43(3): 227-241, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26785938

RESUMEN

AIMS: Understanding the causes of axonal pathology remains a key goal in the pursuit of new therapies to target disease progression in multiple sclerosis (MS). Anterograde axonal transport of many proteins vital for axonal viability is mediated by the motor protein KIF5A, which has been linked to several neurological diseases. This study aimed to investigate the expression of KIF5A protein and its associated cargoes: amyloid precursor protein (APP) and neurofilament (NF) in post mortem MS and control white matter (WM) and to determine if KIF5A expression is influenced by the presence of MS risk single nucleotide polymorphisms (SNPs) identified in the region of the KIF5A gene. METHODS: Using immunoblotting assays we analysed the expression of KIF5A, APP and NF phospho-isoforms in 23 MS cases and 12 controls. RESULTS: We found a significant reduction in KIF5A and associated cargoes in MS WM and an inverse correlation between KIF5A and APP/NF protein levels. Furthermore, homozygous carriers of MS risk gene SNPs show significantly lower levels of KIF5A protein compared to MS patients with no copies of the risk SNPs. CONCLUSIONS: We conclude that reduced expression of axonal motor KIF5A may have important implications in determining axonal transport deficits and ongoing neurodegeneration in MS.


Asunto(s)
Axones/metabolismo , Cinesinas/genética , Esclerosis Múltiple/genética , Esclerosis Múltiple/patología , Sustancia Blanca/patología , Adulto , Anciano , Axones/patología , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/metabolismo , Proteínas de Neurofilamentos/metabolismo , Polimorfismo de Nucleótido Simple , Transporte de Proteínas/genética , Sustancia Blanca/metabolismo
2.
Neuroimage ; 111: 379-84, 2015 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-25721427

RESUMEN

Individual differences in the temporal dynamics of the haemodynamic response can reflect cortical excitation and can reveal underlying cortical physiology. Here, we show differences in the shape of the haemodynamic response that are dependent on stimulus parameters. Two sets of visual stimuli were used varying in parameters that are known to manipulate the haemodynamic response in the visual cortex. We measured the oxyhaemoglobin response using near infrared spectroscopy. The first set of stimuli comprised chromatic square-wave gratings that varied with respect to the separation in the CIE UCS chromaticities of the alternating bars. The gratings with large separations in chromaticity evoked an oxyhaemoglobin response with greater amplitude, consistent with greater activation of the visual cortex. The second set of stimuli comprised horizontal achromatic gratings that (1) were static, (2) drifted at a constant velocity towards fixation, or (3) reversed direction every half spatial cycle to create a vertical vibrating motion. Although the three types of grating had a similar effect on the amplitude of the oxyhaemoglobin response, the moving gratings (2 and 3) evoked a steeper decrease in oxyhaemoglobin concentration after stimulus-offset. The steeper slope appears to reflect the post-stimulus undershoot and the slope may provide a correlate of cortical excitability when the amplitude of the haemodynamic response has saturated.


Asunto(s)
Hemodinámica/fisiología , Oxihemoglobinas , Reconocimiento Visual de Modelos/fisiología , Espectroscopía Infrarroja Corta/métodos , Corteza Visual/fisiología , Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven
3.
Mult Scler ; 20(7): 812-21, 2014 06.
Artículo en Inglés | MEDLINE | ID: mdl-24144874

RESUMEN

BACKGROUND: Multiple sclerosis (MS) is a neurological disease characterised by central nervous system inflammation, demyelination, axonal degeneration and neuronal injury. Preventing neuronal and axon damage is of paramount importance in attempts to prevent disease progression. Intact axonal transport mechanisms are crucial to axonal integrity and evidence suggests these mechanisms are disrupted in MS. Anterograde axonal transport is mediated to a large extent through the kinesin superfamily proteins. Recently, certain kinesin superfamily proteins (KIF5A, KIF1B and KIF21B) were implicated in MS pathology. OBJECTIVES: To investigate the expression of KIF5A, KIF21B and KIF1B in MS and control post-mortem grey matter. METHODS: Using both quantitative real-time polymerase chain reaction (PCR) and Immunodot-blots assays, we analysed the expression of kinesin superfamily proteins in 27 MS cases and 13 control cases not linked to neurological disease. RESULTS: We have shown significant reductions in KIF5A, KIF21B and KIF1B messenger ribonucleic acid (mRNA) expression and also KIF5A protein expression in MS grey matter, as compared to control grey matter. CONCLUSION: We have shown significant reductions in mRNA and protein levels of axonal motor proteins in the grey matter of MS cases, which may have important implications for the pathogenesis of neuronal/axonal injury in the disease.


Asunto(s)
Sustancia Gris/química , Cinesinas/análisis , Esclerosis Múltiple/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Progresión de la Enfermedad , Regulación hacia Abajo , Femenino , Sustancia Gris/diagnóstico por imagen , Humanos , Cinesinas/genética , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/diagnóstico por imagen , Esclerosis Múltiple/genética , Esclerosis Múltiple/mortalidad , ARN Mensajero/genética
4.
Eur J Neurosci ; 35(12): 1887-93, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22708600

RESUMEN

Given the significant socioeconomic impact of progressive multiple sclerosis (MS) and the paucity of treatment options, there is an urgent need to develop new and effective therapies for this disabling condition. The relatively recent appreciation that progressive disability is largely driven by neuronal loss has focused considerable research attention on neuroprotective strategies. This has coincided with the emergence of oxidative damage as a prominent effector mechanism of axonal damage in studies of MS pathogenesis, which has opened up a new range of putative targets for neuroprotective therapy in MS. Mitochondrial sirtuins are NAD(+)-dependent protein deacetylases associated with the control of metabolism, aging, and stem cell proliferation and differentiation. Their role in inflammatory demyelinating disease has not been fully characterized, and is the subject of ongoing research. Here, we expound the rationale behind selecting mitochondrial sirtuins as a therapeutic target in demyelinating disease, and report preliminary data that warrant further investigation.


Asunto(s)
Mitocondrias/enzimología , Esclerosis Múltiple/enzimología , Sirtuinas/metabolismo , Adulto , Humanos , Terapia Molecular Dirigida/métodos , Esclerosis Múltiple/tratamiento farmacológico , Estrés Oxidativo/fisiología , Sirtuinas/antagonistas & inhibidores
5.
Heliyon ; 8(3): e09095, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35846467

RESUMEN

Background: Environmental health and other researchers can benefit from automated or semi-automated summaries of data within published studies as summarizing study methods and results is time and resource intensive. Automated summaries can be designed to identify and extract details of interest pertaining to the study design, population, testing agent/intervention, or outcome (etc.). Much of the data reported across existing publications lack unified structure, standardization and machine-readable formats or may be presented in complex tables which serve as barriers that impede the development of automated data extraction methodologies.As full automation of data extraction seems unlikely soon, encouraging investigators to submit structured summaries of methods and results in standardized formats with meta-data tagging of content may be of value during the publication process. This would produce machine-readable content to facilitate automated data extraction, establish sharable data repositories, help make research data FAIR, and could improve reporting quality. Objectives: A pilot study was conducted to assess the feasibility of asking participants to summarize study methods and results using a structured, web-based data extraction model as a potential workflow that could be implemented during the manuscript submission process. Methods: Eight participants entered study details and data into the Health Assessment Workplace Collaborative (HAWC). Participants were surveyed after the extraction exercise to ascertain 1) whether this extraction exercise will impact their conducting and reporting of future research, 2) the ease of data extraction, including which fields were easiest and relatively more problematic to extract and 3) the amount of time taken to perform data extractions and other related tasks. Investigators then presented participants the potential benefits of providing structured data in the format they were extracting. After this, participants were surveyed about 1) their willingness to provide structured data during the publication process and 2) whether they felt the potential application of structured data entry approaches and their implementation during the journal submission process should continue to be further explored. Conclusions: Routine provision of structured data that summarizes key information from research studies could reduce the amount of effort required for reusing that data in the future, such as in systematic reviews or agency scientific assessments. Our pilot study suggests that directly asking authors to provide that data, via structured templates, may be a viable approach to achieving this: participants were willing to do so, and the overall process was not prohibitively arduous. We also found some support for the hypothesis that use of study templates may have halo benefits in improving the conduct and completeness of reporting of future research. While limitations in the generalizability of our findings mean that the conditions of success of templates cannot be assumed, further research into how such templates might be designed and implemented does seem to have enough chance of success that it ought to be undertaken.

6.
Oncoimmunology ; 11(1): 2066050, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35558159

RESUMEN

Systemic relapse after radiotherapy and surgery is the major cause of disease-related mortality in sarcoma patients. Combining radiotherapy and immunotherapy is under investigation as a means to improve response rates. However, the immune contexture of sarcoma is understudied. Here, we use a retrospective cohort of sarcoma patients, treated with neoadjuvant radiotherapy, and TCGA data. We explore therapeutic targets of relevance to sarcoma, using genomics and multispectral immunohistochemistry to provide insights into the tumor immune microenvironment across sarcoma subtypes. Differential gene expression between radioresponsive myxoid liposarcoma (MLPS) and more radioresistant undifferentiated pleomorphic sarcoma (UPS) indicated UPS contained higher transcript levels of a number of immunotherapy targets (CD73/NT5E, CD39/ENTPD1, CD25/IL2RA, and 4-1BB/TNFRSF9). We focused on 4-1BB/TNFRSF9 and other costimulatory molecules. In TCGA data, 4-1BB correlated to an inflamed and exhausted phenotype. OX40/TNFRSF4 and 4-1BB/TNFRSF9 were highly expressed in sarcoma subtypes versus other cancers. Despite OX40 and 4-1BB being described as Treg markers, we identified that they delineate distinct tumor immune profiles. This was true for sarcoma and other cancers. While only a limited number of samples could be analyzed, spatial analysis of OX40 expression identified two diverse phenotypes of OX40+ Tregs, one associated with and one independent of tertiary lymphoid structures (TLSs). Patient stratification is of intense interest for immunotherapies. We provide data supporting the viewpoint that a cohort of sarcoma patients, appropriately selected, are promising candidates for immunotherapies. Spatial profiling of OX40+ Tregs, in relation to TLSs, could be an additional metric to improve future patient stratification.


Asunto(s)
Sarcoma , Neoplasias de los Tejidos Blandos , Adulto , Humanos , Recurrencia Local de Neoplasia , Estudios Retrospectivos , Sarcoma/genética , Sarcoma/terapia , Linfocitos T Reguladores , Microambiente Tumoral
7.
Neuropathol Appl Neurobiol ; 37(2): 166-78, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20819172

RESUMEN

AIMS: we explored whether cellular fusion and heterokaryon formation between human and rodent cells in the cerebellum of mice occurs after intravenous injection of human bone marrow-derived mesenchymal stem cells (MSCs). The influence of central nervous system inflammation on this process was also assessed. In addition, we examined whether tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma, factors associated with inflammation, increase cellular fusion between human MSCs and rodent cerebellar neurons in vitro. METHODS AND RESULTS: human MSCs were intravenously injected into mice with experimental autoimmune encephalomyelitis (EAE) and control mice. After 22 days, mouse Purkinje cells expressing human Golgi Zone were found within the Purkinje cell layer of the cerebellum, indicating that fusion and heterokaryon formation had occurred. The numbers of heterokaryons in the cerebellum were markedly increased in mice with EAE compared with control mice. Rodent cerebellar neuronal cells labelled with enhanced green fluorescent proteinin vitro were co-cultured with human bone marrow-derived MSCs in the presence of TNF-alpha and/or IFN-gamma to determine their influence on fusion events. We found that fusion between MSCs and cerebellar neurons did occur in vitro and that the frequency of cellular fusion increased in the presence of TNF-alpha and/or IFN-gamma. CONCLUSIONS: we believe that this is the first paper to define fusion and heterokaryon formation between human MSCs and rodent cerebellar neurons in vivo. We have also demonstrated that fusion between these cell populations occurs in vitro. These findings indicate that MSCs may be potential therapeutic agents for cerebellar diseases, and other neuroinflammatory and neurodegenerative disorders.


Asunto(s)
Fusión Celular/métodos , Encefalomielitis Autoinmune Experimental , Trasplante de Células Madre Mesenquimatosas/métodos , Células Madre Mesenquimatosas/citología , Células de Purkinje/citología , Animales , Humanos , Ratones , Ratones Endogámicos C57BL
8.
Clin Oncol (R Coll Radiol) ; 33(6): 407-414, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33726945

RESUMEN

Immune checkpoint inhibitors have transformed the management of patients with metastatic urothelial cancer, by leading to long-term response and prolongation of survival in a subset of patients. Unfortunately, only one in five patients with metastatic urothelial cancer responds to anti-programmed death ligand-1 ([AQ1]anti-PD-1) monotherapy. Preclinical and early clinical evidence indicates that radiotherapy not only acts locally, but also exerts systemic anti-tumour effects by modulating the immune system. It is hypothesised that combining checkpoint inhibitors with radiotherapy might enhance an anti-tumour immune response and increase response rates. So far, a handful of early phase clinical trials have been performed seeking to answer this question in urothelial cancer patients. The current review summarises the available preclinical and clinical evidence on radiotherapy/immunotherapy combinations in locally advanced and metastatic bladder cancer and suggests future avenues worthy of exploration.


Asunto(s)
Inmunoterapia , Neoplasias de la Vejiga Urinaria , Antígeno B7-H1 , Terapia Combinada , Humanos , Receptor de Muerte Celular Programada 1 , Neoplasias de la Vejiga Urinaria/tratamiento farmacológico , Neoplasias de la Vejiga Urinaria/radioterapia
9.
J Neurol ; 268(6): 2175-2184, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33484325

RESUMEN

There is increasing interest in the development of multiple sclerosis (MS) biomarkers that reflect central nervous system tissue injury to determine prognosis. We aimed to assess the prognostic value of kinesin superfamily motor protein KIF5A in MS by measuring levels of KIF5A in cerebrospinal fluid (CSF) combined with analysis of single nucleotide polymorphisms (SNPs; rs12368653 and rs703842) located within a MS susceptibility gene locus at chromosome 12q13-14 region. Enzyme-linked immunosorbent assay was used to measure KIF5A in CSF obtained from two independent biobanks comprising non-inflammatory neurological disease controls (NINDC), clinically isolated syndrome (CIS) and MS cases. CSF KIF5A expression was significantly elevated in progressive MS cases compared with NINDCs, CIS and relapsing-remitting MS (RRMS). In addition, levels of KIF5A positively correlated with change in MS disease severity scores (EDSS, MSSS and ARMSSS), in RRMS patients who had documented disease progression at 2-year clinical follow-up. Copies of adenine risk alleles (AG/AA; rs12368653 and rs703842) corresponded with a higher proportion of individuals in relapse at the time of lumbar puncture (LP), higher use of disease-modifying therapies post LP and shorter MS duration. Our study suggests that CSF KIF5A has potential as a predictive biomarker in MS and further studies into the potential prognostic value of analysing MS susceptibility SNPs should be considered.


Asunto(s)
Cinesinas , Esclerosis Múltiple Crónica Progresiva , Esclerosis Múltiple Recurrente-Remitente , Esclerosis Múltiple , Biomarcadores , Progresión de la Enfermedad , Genotipo , Humanos , Cinesinas/genética , Esclerosis Múltiple/diagnóstico , Esclerosis Múltiple/genética , Esclerosis Múltiple Recurrente-Remitente/genética
10.
Child Care Health Dev ; 36(5): 709-18, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20533915

RESUMEN

INTRODUCTION: Government early intervention services for children with intellectual disability (ID) in Western Australia have adopted the model of family-centred care. The aim of this study was to evaluate how well it was being practised, to describe the pattern of service utilization and to identify factors influencing parental perceptions of family-centred care. METHODS: The study included children aged 0-6 years with ID, who were registered clients of Disability Services Commission, Western Australia. Parents completed a postal survey questionnaire about the frequency and type of services received and their perceptions of services using the Measure of Processes of Care (MPOC-56) questionnaire. Mean scores for the five MPOC domains were compared using anova against the independent variables of child age group, child diagnostic group, service type and frequency, place of residence, family and demographic variables. Significant variables in each domain were then entered into multivariate analyses. RESULTS: Of 292 eligible families, 165 (59%) returned a completed questionnaire. While over 50% of children had contact with occupational, speech and physical therapists at least once per month, less than 20% of children had at least annual contact with either psychology or dental services. Families rated their satisfaction highest for 'respectful and supportive care' and lowest for 'providing general information'. Individual item analyses indicated less satisfaction with 'co-ordinated and comprehensive care'. Higher means were associated with more frequent contact with occupational therapy. CONCLUSION: Overall respondents reported early intervention services for young children with ID in Western Australia provided satisfactory family-centred care by means of the 56-item MPOC. The frequency of contact with allied health professionals was positively associated with parental ratings of family-centred care. The study indicates under-servicing in dental care and psychology services.


Asunto(s)
Servicios de Salud del Niño/normas , Intervención Educativa Precoz/métodos , Discapacidad Intelectual/rehabilitación , Terapia Ocupacional/métodos , Padres/psicología , Niño , Preescolar , Atención a la Salud , Salud de la Familia , Humanos , Lactante , Análisis Multivariante , Encuestas y Cuestionarios , Australia Occidental
11.
Vision Res ; 170: 53-59, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32259647

RESUMEN

A masked randomised control design compared the effectiveness of precision ophthalmic tints in improving the recognition of emotion in Autism Spectrum Disorders (ASD). Fourteen children aged 10-14 with ASD and 14 control children matched on verbal and non-verbal IQ, wore spectacles with coloured lenses to complete two tasks that involved the observation of coloured video sequences in which social interactions were depicted. On one occasion (randomly first or second) the coloured lenses provided light of a colour that the child had one month previously selected as optimal for the clarity of text. On the other occasion the lenses differed in CIE UCS chromaticity by 0.077. Performance in the ASD group was superior in both social interaction tasks with the lenses that provided the optimal colour of light.


Asunto(s)
Trastorno del Espectro Autista , Reconocimiento en Psicología , Cognición Social , Trastorno del Espectro Autista/fisiopatología , Estudios de Casos y Controles , Niño , Emociones , Anteojos , Humanos , Lectura
12.
Artículo en Inglés | MEDLINE | ID: mdl-31236523

RESUMEN

Despite known associations of insomnia disorder with alterations in cytokine and glucocorticoid (GC) production, neither the sensitivity of immune cells to a GC signal nor the reactivity of the hypothalamus-pituitary-adrenal (HPA) axis and inflammatory system to stress, or adaptation of these systems to repeated stress have been assessed in patients with insomnia. To investigate potential dysregulation in stress reactivity and adaptation to repeated exposure, a physiological stressor (the cold pressor test; CPT) was repeatedly administered to N = 20 participants with insomnia disorder (based on DSM-V, 18 females, age 30 ±â€¯2.5 years) and N = 20 sex-matched healthy controls following an at-home actigraphy and in-laboratory PSG. HPA and inflammatory markers (serum cortisol, plasma interleukin [IL]-6) were measured at baseline/resting levels and following each of the three CPTs. In addition, sensitivity of monocytes to the synthetic GC dexamethasone was assessed in-vitro at baseline levels in order to examine the cortisol-IL-6 interplay at the cell level. Compared to healthy controls, individuals with insomnia disorder exhibited shorter sleep duration as assessed by actigraphy and PSG (p ≤ 0.05). HPA, but not inflammatory reactivity to the repeated CPT challenge was greater in insomnia disorder (p ≤ 0.05 for group effect), due to greater cortisol responses to the initial CPT (p ≤ 0.05). There were no between-group differences in the ability of the HPA to adapt to stress repetition nor in basal/resting levels of cortisol, IL-6, and GC sensitivity. These findings suggest that insomnia disorder potentiates HPA axis reactivity to initial/novel stressors, which may constitute a pathway underlying adverse health consequences in the long term.

13.
PLoS Comput Biol ; 3(12): e242, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18085817

RESUMEN

Processes that repeat in time, such as the cell cycle, the circadian rhythm, and seasonal variations, are prevalent in biology. Mathematical models can represent our knowledge of the underlying mechanisms, and numerical methods can then facilitate analysis, which forms the foundation for a more integrated understanding as well as for design and intervention. Here, the intracellular molecular network responsible for the mammalian circadian clock system was studied. A new formulation of detailed sensitivity analysis is introduced and applied to elucidate the influence of individual rate processes, represented through their parameters, on network functional characteristics. One of four negative feedback loops in the model, the Per2 loop, was uniquely identified as most responsible for setting the period of oscillation; none of the other feedback loops were found to play as substantial a role. The analysis further suggested that the activity of the kinases CK1delta and CK1varepsilon were well placed within the network such that they could be instrumental in implementing short-term adjustments to the period in the circadian clock system. The numerical results reported here are supported by previously published experimental data.


Asunto(s)
Relojes Biológicos/fisiología , Retroalimentación/fisiología , Modelos Biológicos , Proteínas Nucleares/metabolismo , Oscilometría/métodos , Periodicidad , Transducción de Señal/fisiología , Factores de Transcripción/metabolismo , Animales , Simulación por Computador , Humanos , Proteínas Circadianas Period
14.
Vaccine ; 36(36): 5470-5476, 2018 08 28.
Artículo en Inglés | MEDLINE | ID: mdl-28778616

RESUMEN

The prevention of paediatric bacterial meningitis and septicaemia has recently entered a new era with the availability of two vaccines against capsular group B meningococcus (MenB). Both of these vaccines are based on sub-capsular proteins of the meningococcus, an approach that overcomes the challenges set by the poorly immunogenic MenB polysaccharide capsule but adds complexity to predicting and measuring the impact of their use. This review describes the development and use of MenB vaccines to date, from the use of outer membrane vesicle (OMV) vaccines in MenB outbreaks around the world, to emerging evidence on the effectiveness of the newly available vaccines. While recent data from the United Kingdom supports the potential for protein-based vaccines to provide direct protection against MenB disease in immunised children, further research is required to understand the breadth and duration of this protection. A more detailed understanding of the impact of immunisation with these vaccines on nasopharyngeal carriage of the meningococcus is also required, to inform both their potential to induce herd immunity and to preferentially select for carriage of strains not susceptible to vaccine-induced antibodies. Although a full understanding of the potential impact of these vaccines will only be possible with this additional information, the availability of new tools to prevent the devastating effect of invasive MenB disease is a significant breakthrough in the fight against childhood sepsis and meningitis.


Asunto(s)
Infecciones Meningocócicas/inmunología , Infecciones Meningocócicas/prevención & control , Vacunas Meningococicas/uso terapéutico , Neisseria meningitidis Serogrupo B/inmunología , Neisseria meningitidis Serogrupo B/patogenicidad , Humanos
15.
Neuropsychologia ; 108: 1-5, 2018 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-29157999

RESUMEN

Chromatic gratings can be uncomfortable to view and can evoke a large haemodynamic response. Both the discomfort and the amplitude of the haemodynamic response increase monotonically with the perceptual difference in the colour of the component bars of the grating, as registered by the separation in their chromaticity in the CIE 1976 UCS diagram. Individuals with photosensitive epilepsy exhibit epileptiform EEG activity in response to flickering light of alternate colours. The probability of the epileptiform response again increases monotonically with the separation of the colours in the CIE UCS diagram. We investigated whether alpha power, which is known to reflect the excitation of large populations of neurons, is similarly affected by the separation in chromaticity. Chromatic square-wave gratings with bars that differed in CIE UCS chromaticity were presented, together with a central fixation cross. In 18 non-clinical participants, alpha responses were recorded over the visual cortex (O1, Oz, O2, PO3, POz, PO4, P1, P2) and compared to responses in prefrontal cortex (F1, F2). Gratings comprised bars of two alternate colours that either had a small difference in chromaticity (mean CIE UCS separation of 0.03), a medium difference (mean separation of 0.19), or a large difference (mean separation of 0.43). The colour pairs had chromaticities that lay on the red-green, red-blue, or blue-green borders of the screen gamut. Regardless of the hue, the larger the separation in chromaticity, the greater the alpha desynchronization and the lower the alpha power (p = 0.004), but only in posterior electrodes (p < 0.001). Together this indicates that differences in colour evoke a cortical excitation that increases monotonically with the colour difference. In this respect the alpha response resembles the haemodynamic response.


Asunto(s)
Ritmo alfa , Percepción de Color/fisiología , Epilepsia Refleja/fisiopatología , Corteza Prefrontal/fisiopatología , Corteza Visual/fisiopatología , Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estimulación Luminosa , Adulto Joven
16.
Curr Biol ; 10(22): 1427-37, 2000 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-11102804

RESUMEN

BACKGROUND: Dictyostelium possesses a surprisingly large number of Ras proteins and little is known about their activators, the guanine nucleotide exchange factors (GEFs). It is also unclear, in Dictyostelium or in higher eukaryotes, whether Ras pathways are linear, with each Ras controlled by its own GEF, or networked, with multiple GEFs acting on multiple Ras proteins. RESULTS: We have identified the Dictyostelium gene that encodes RasGEFB, a protein with homology to known RasGEFs such as the Son-of-sevenless (Sos) protein. Dictyostelium cells in which the gene for RasGEFB was disrupted moved unusually rapidly, but lost the ability to perform macropinocytosis and therefore to grow in liquid medium. Crowns, the sites of macropinocytosis, were replaced by polarised lamellipodia. Mutant cells were also profoundly defective in early development, although they eventually formed tiny but normally proportioned fruiting bodies. This defect correlated with loss of discoidin Igamma mRNA, a starvation-induced gene, although other genes required for development were expressed normally or even precociously. RasGEFB was able to rescue a Saccharomyces CDC25 mutant, indicating that it is a genuine GEF for Ras proteins. CONCLUSIONS: RasGEFB appears to be the principal activator of the RasS protein, which regulates macropinocytosis and cell speed, but it also appears to regulate one or more other Ras proteins.


Asunto(s)
Endocitosis/fisiología , Factores de Intercambio de Guanina Nucleótido ras/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Movimiento Celular , Clonación Molecular , ADN Complementario , Dictyostelium/genética , Dictyostelium/crecimiento & desarrollo , Dictyostelium/metabolismo , Dictyostelium/fisiología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Expresión Génica , Marcación de Gen , Datos de Secuencia Molecular , Mutagénesis , Fagocitosis/fisiología , Saccharomyces cerevisiae , Factores de Intercambio de Guanina Nucleótido ras/genética , Factores de Intercambio de Guanina Nucleótido ras/fisiología , ras-GRF1/genética , ras-GRF1/metabolismo
17.
Trends Genet ; 17(1): 41-8, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11163921

RESUMEN

Although the process of sequencing the Dictyostelium genome is not complete, it is already producing surprises, including an unexpectedly large number of Ras- and Rho-subfamily GTPases. Members of these families control a wide variety of cellular processes in eukaryotes, including proliferation, differentiation, cell motility and cell polarity. Comparison of small GTPases from Dictyostelium with those from higher eukaryotes provides an intriguing view of their cellular and evolutionary roles. In particular, although mammalian Ras proteins interact with several signalling pathways, the Dictyostelium pathways appear more linear, with each Ras apparently performing a specific cellular function.


Asunto(s)
Dictyostelium/enzimología , GTP Fosfohidrolasas/metabolismo , Animales , Dictyostelium/genética
18.
Trends Genet ; 14(2): 54-9, 1998 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-9520598

RESUMEN

The past ten years of developmental genetics have revealed that most of our genes are shared by other species throughout the animal kingdom. Consequently, animal diversity might largely rely on the differential use of the same components, either at the individual level through divergent functional recruitment, or at a more integrated level, through their participation in various genetic networks. Here, we argue that this inevitably leads to an increase in the interdependency between functions that, in turn, influences the degree to which novel variations can be tolerated. In this 'transitionist' scheme, evolution is neither inherently gradualist nor punctuated but, instead, progresses from one extreme to the other, together with the increased complexity of organisms.


Asunto(s)
Evolución Biológica , Animales
19.
J Neurol ; 254(12): 1729-35, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17934874

RESUMEN

We investigated the possible benefit for 26 patients with multiple sclerosis of placing Intuitive Overlays (spectral filters) over the page during reading and visual search. Initially all patients were allowed to select an overlay of a colour that reduced perceptual distortion and were tested with and without that overlay. With the coloured overlay, 25/26 patients reported fewer symptoms of visual stress, 50% read at least 20% more quickly and 50% omitted at least 57% fewer targets during visual search. Subsequently, under double-masked conditions 13 randomly-selected patients were given grey overlays,while the remaining 13 gender- and agematched patients were each given an overlay of their individually selected colour. Patients were permitted to use their overlays as and when they wished during the next 2 weeks. The reading and visual search performance of those patients who had received a grey overlay did not change,whereas the performance of those who received an overlay of their selected colour subsequently improved, both when using the overlays and also when not. After testing, the 13 patients who had received a grey overlay returned it prior to subsequent testing. The 13 patients were then each given an overlay of their selected colour and their performance subsequently improved.A large proportion of patients with multiple sclerosis may benefit from the use of spectral overlays.


Asunto(s)
Esclerosis Múltiple/fisiopatología , Esclerosis Múltiple/rehabilitación , Lectura , Auxiliares Sensoriales , Percepción Visual/fisiología , Adulto , Anciano , Color , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos
20.
Vet Res Commun ; 31(7): 895-908, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17279463

RESUMEN

The proposal that saponins produced by the lily bog asphodel (Narthecium ossifragum) may be the direct cause of the hepatogenous photosensitization disease alveld seen in Norwegian lambs was investigated by comparing sapogenin levels in two control and two toxic pastures, and in faeces from lambs grazing the four pastures in the Halsa and Surnadal municipalities, Møre og Romsdal county, Norway. Generally similar levels of sapogenins, determined after hydrolysis of parent plant saponins, were found in Narthecium leaves collected in June/July 2001 from the two alveld outbreak areas and two nearby control areas. Differences in the median sapogenin levels determined for leaf samples in outbreak and control areas were not statistically significant. The total level of free and conjugated sapogenins in faeces recovered from the rectums of lambs grazing the outbreak and control pastures areas varied greatly. The results obtained do not support the hypothesis that a dose-response relationship exists between Narthecium saponin levels and the occurrence of alveld outbreaks.


Asunto(s)
Dioscoreaceae/toxicidad , Magnoliopsida/toxicidad , Trastornos por Fotosensibilidad/veterinaria , Sapogeninas/toxicidad , Enfermedades de las Ovejas/inducido químicamente , Animales , Dioscoreaceae/química , Heces/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Magnoliopsida/química , Noruega , Trastornos por Fotosensibilidad/inducido químicamente , Hojas de la Planta/química , Hojas de la Planta/toxicidad , Sapogeninas/análisis , Ovinos
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA