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1.
J Sports Sci ; : 1-9, 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38916261

RESUMO

Despite the growing popularity of women's rugby, there is a lack of research understanding the contribution of place-kicking to match outcomes. This study aims to establish the characteristics and contribution of place-kicking to women's international Rugby Union and evaluate the performance of place-kickers while accounting for factors that contribute to kick difficulty. Data from 674 place-kicks across 80 matches were analysed. A binomial generalised linear mixed model (GLMM) was used to predict the probability of kick success. 60.5% of place-kicks were successful, and they contributed 23.9% of all points scored; conversions accounted for 16.8% and penalties 7.1%. Kick success percentages for conversions (56.9%) and penalties (78.3%) significantly differed (p < 0.01). Kick distance and angle were significant (p < 0.01) predictors of kick success and the GLMM had a prediction accuracy of 73.6%. The performance rankings of kickers changed when comparing observed and expected success, highlighting the need to consider contextual factors contributing to kick difficulty when evaluating performance. The GLMM results provide valuable insights for coaches and players to make informed decisions, for example, whether to attempt a place-kick when a penalty is awarded, by enabling predictions of place-kick success. This could enhance a team's chances of winning matches.

2.
Int J Sports Physiol Perform ; 18(9): 1072-1078, 2023 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-37597840

RESUMO

PURPOSE: The efficacy of isolated and relative performance indicators (PIs) has been compared in rugby union; the latter more effective at discerning match outcomes. However, this methodology has not been applied in women's rugby. The aim of this study was to identify PIs that maximize prediction accuracy of match outcome, from isolated and relative data sets, in women's rugby union. METHODS: Twenty-six PIs were selected from 110 women's international rugby matches between 2017 and 2022 to form an isolated data set, with relative data sets determined by subtracting corresponding opposition PIs. Random forest classification was completed on both data sets, and feature selection and importance were used to simplify models and interpret key PIs. Models were used in prediction on the 2021 World Cup to evaluate performance on unseen data. RESULTS: The isolated full model correctly classified 75% of outcomes (CI, 65%-82%), whereas the relative full model correctly classified 78% (CI, 69%-86%). Reduced respective models correctly classified 74% (CI, 65%-82%) and 76% (CI, 67%-84%). Reduced models correctly predicted 100% and 96% of outcomes for isolated and relative test data sets, respectively. No significant difference in accuracy was found between data sets. In the relative reduced model, meters made, clean breaks, missed tackles, lineouts lost, carries, and kicks from hand were significant. CONCLUSIONS: Increased relative meters made, clean breaks, carries, and kicks from hand and decreased relative missed tackles and lineouts lost were associated with success. This information can be utilized to inform physical and tactical preparation and direct physiological studies in women's rugby.


Assuntos
Rugby , Extremidade Superior , Humanos , Feminino , Algoritmo Florestas Aleatórias
3.
J Sci Med Sport ; 26(1): 63-68, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36528551

RESUMO

OBJECTIVES: The aims of this study were to: i) identify performance indicators associated with match outcomes in the United Rugby Championship; ii) compare the efficacy of isolated and relative datasets to predict match outcome; and iii) investigate whether reduced statistical models can reproduce predictive accuracy. DESIGN: Retrospective analysis of key performance indicators in the United Rugby Championship. METHODS: Twenty-seven performance indicators were selected from 96 matches (2020-21 United Rugby Championship). Random forest classification was completed on isolated and relative datasets, using a binary match outcome (win/lose). Maximum relevance and minimum redundancy performance indicator selection was utilised to reduce models. In addition, models were tested on 53 matches from the 2021-22 season to ascertain prediction accuracy. RESULTS: Within the 2020-21 datasets, the full models correctly classified 83% of match performances for the relative dataset and 64% for isolated data, the equivalent reduced models classified 85% and 66% respectively. The reduced relative model successfully predicted 90% of match performances in the 21-22 season, highlighting that five performance indicators were significant: kicks from hand, metres made, clean breaks, turnovers conceded and scrum penalties. CONCLUSIONS: Relative performance indicators were more effective in predicting match outcomes than isolated data. Reducing features used in random forest classification did not degrade prediction accuracy, whilst also simplifying interpretation for practitioners. Increased kicks from hand, metres made, and clean breaks compared to the opposition, as well as fewer scrum penalties and turnovers conceded were all indicators of winning match outcomes within the United Rugby Championship.


Assuntos
Desempenho Atlético , Futebol Americano , Humanos , Estudos Retrospectivos , Rugby , Modelos Estatísticos
4.
J Fish Biol ; 101(5): 1361-1365, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35906859

RESUMO

The authors investigated left-right turning preferences of n = 260 juvenile European sea bass (Dicentrarchus labrax) reared in ambient conditions and ocean acidification (OA) conditions or in ambient conditions but tested in OA water. Groups of 10 individuals were observed alone in a circular tank, and individuals' left and right turning during free-swimming was quantified using trajectory data from the video. The authors showed that near-future OA levels do not affect the number of turns made, or behavioural lateralization (turning preference), in juvenile D. labrax tested in groups.


Assuntos
Bass , Animais , Natação , Dióxido de Carbono , Concentração de Íons de Hidrogênio , Água do Mar
5.
Arch Toxicol ; 95(1): 321-336, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32910239

RESUMO

Current in vitro genotoxicity tests can produce misleading positive results, indicating an inability to effectively predict a compound's subsequent carcinogenic potential in vivo. Such oversensitivity can incur unnecessary in vivo tests to further investigate positive in vitro results, supporting the need to improve in vitro tests to better inform risk assessment. It is increasingly acknowledged that more informative in vitro tests using multiple endpoints may support the correct identification of carcinogenic potential. The present study, therefore, employed a holistic, multiple-endpoint approach using low doses of selected carcinogens and non-carcinogens (0.001-770 µM) to assess whether these chemicals caused perturbations in molecular and cellular endpoints relating to the Hallmarks of Cancer. Endpoints included micronucleus induction, alterations in gene expression, cell cycle dynamics, cell morphology and bioenergetics in the human lymphoblastoid cell line TK6. Carcinogens ochratoxin A and oestradiol produced greater Integrated Signature of Carcinogenicity scores for the combined endpoints than the "misleading" in vitro positive compounds, quercetin, 2,4-dichlorophenol and quinacrine dihydrochloride and toxic non-carcinogens, caffeine, cycloheximide and phenformin HCl. This study provides compelling evidence that carcinogens can successfully be distinguished from non-carcinogens using a holistic in vitro test system. Avoidance of misleading in vitro outcomes could lead to the reduction and replacement of animals in carcinogenicity testing.


Assuntos
Testes de Carcinogenicidade , Carcinógenos/toxicidade , Determinação de Ponto Final , Projetos de Pesquisa , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular , Forma Celular/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Micronúcleos com Defeito Cromossômico/induzido quimicamente , Testes para Micronúcleos , Fosforilação , Medição de Risco , Proteína Supressora de Tumor p53/metabolismo
6.
Front Bioinform ; 1: 662210, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-36303763

RESUMO

Many chemotherapeutic drugs target cell processes in specific cell cycle phases. Determining the specific phases targeted is key to understanding drug mechanism of action and efficacy against specific cancer types. Flow cytometry experiments, combined with cell cycle phase and division round specific staining, can be used to quantify the current cell cycle phase and number of mitotic events of each cell within a population. However, quantification of cell interphase times and the efficacy of cytotoxic drugs targeting specific cell cycle phases cannot be determined directly. We present a data driven computational cell population model for interpreting experimental results, where in-silico populations are initialized to match observable results from experimental populations. A two-stage approach is used to determine the efficacy of cytotoxic drugs in blocking cell-cycle phase transitions. In the first stage, our model is fitted to experimental multi-parameter flow cytometry results from untreated cell populations to identify parameters defining probability density functions for phase transitions. In the second stage, we introduce a blocking routine to the model which blocks a percentage of attempted transitions between cell-cycle phases due to therapeutic treatment. The resulting model closely matches the percentage of cells from experiment in each cell-cycle phase and division round. From untreated cell populations, interphase and intermitotic times can be inferred. We then identify the specific cell-cycle phases that cytotoxic compounds target and quantify the percentages of cell transitions that are blocked compared with the untreated population, which will lead to improved understanding of drug efficacy and mechanism of action.

7.
Curr Protoc Neurosci ; 94(1): e105, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33147381

RESUMO

Neuronal mitochondrial fragmentation is a phenotype exhibited in models of neurodegeneration such as Parkinson's disease. Delineating the dysfunction in mitochondrial dynamics found in diseased states can aid our understanding of underlying mechanisms of disease progression and possibly identify novel therapeutic approaches. Advances in microscopy and the availability of intuitive open-access software have accelerated the rate of image acquisition and analysis, respectively. These developments allow routine biology researchers to rapidly turn hypotheses into results. In this protocol, we describe the utilization of cell culture techniques, high-content imaging (HCI), and the subsequent open-source image analysis pipeline for the quantification of mitochondrial fragmentation in the context of a rotenone-based in vitro Parkinson's disease model. © 2020 The Authors. Basic Protocol 1: SN4741 neuron culture and treatment in a rotenone-based model of Parkinson's disease Basic Protocol 2: Identification of cell nuclei, measurement of mitochondrial membrane potential, and measurement of mitochondrial fragmentation in mouse-derived midbrain dopaminergic neurons.


Assuntos
Técnicas de Cultura de Células/métodos , Processamento de Imagem Assistida por Computador/métodos , Mitocôndrias/patologia , Doença de Parkinson Secundária/induzido quimicamente , Doença de Parkinson Secundária/patologia , Rotenona/toxicidade , Animais , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/patologia , Inseticidas/toxicidade , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Potencial da Membrana Mitocondrial/fisiologia , Camundongos , Mitocôndrias/efeitos dos fármacos
8.
Thromb Res ; 193: 25-30, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32505081

RESUMO

INTRODUCTION: Thrombosis is a severe and frequent complication of heparin-induced thrombocytopenia (HIT). However, there is currently no knowledge of the effects of HIT-like antibodies on the resulting microstructure of the formed clot, despite such information being linked to thrombotic events. We evaluate the effect of the addition of pathogenic HIT-like antibodies to blood on the resulting microstructure of the formed clot. MATERIALS AND METHODS: Pathogenic HIT-like antibodies (KKO) and control antibodies (RTO) were added to samples of whole blood containing Unfractionated Heparin and Platelet Factor 4. The formed clot microstructure was investigated by rheological measurements (fractal dimension; df) and scanning electron microscopy (SEM), and platelet activation was measured by flow cytometry. RESULTS AND CONCLUSIONS: Our results revealed striking effects of KKO on clot microstructure. A significant difference in df was found between samples containing KKO (df = 1.80) versus RTO (df = 1.74; p < 0.0001). This increase in df was often associated with an increase in activated platelets. SEM images of the clots formed with KKO showed a network consisting of a highly branched and compact arrangement of thin fibrin fibres, typically found in thrombotic disease. This is the first study to identify significant changes in clot microstructure formed in blood containing HIT-like antibodies. These observed alterations in clot microstructure can be potentially exploited as a much-needed biomarker for the detection, management and monitoring of HIT-associated thrombosis.


Assuntos
Trombocitopenia , Trombose , Fibrina , Heparina/efeitos adversos , Humanos , Fator Plaquetário 4 , Trombocitopenia/induzido quimicamente
9.
Horm Behav ; 119: 104636, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31765656

RESUMO

Androgens, traditionally viewed as hormones that regulate secondary sexual characteristics and reproduction in male vertebrates, are often modulated by social stimuli. High levels of the 'social hormone' testosterone (T) are linked to aggression, dominance, and competition. Low T levels, in contrast, promote sociopositive behaviours such as affiliation, social tolerance, and cooperation, which can be crucial for group-level, collective behaviours. Here, we test the hypothesis that - in a collective context - low T levels should be favourable, using non-reproductive male and female stickleback fish (Gasterosteus aculeatus) and non-invasive waterborne hormone analysis. In line with our predictions, we show that the fishes' T levels were significantly lower during shoaling compared to when alone, with high-T individuals showing the largest decrease. Ruling out stress-induced T suppression and increased T conversion into oestradiol, we find evidence that shoaling directly affects androgen responsiveness. We also show that groups characterized by lower mean T exhibit less hierarchical leader-follower dynamics, suggesting that low T promotes egalitarianism. Overall, we show that collective action results in lower T levels, which may serve to promote coordination and group performance. Our study, together with recent complementary findings in humans, emphasizes the importance of low T for the expression of sociopositive behaviour across vertebrates, suggesting similarities in endocrine mechanisms.


Assuntos
Androgênios/farmacologia , Comportamento Animal/efeitos dos fármacos , Comportamento Cooperativo , Smegmamorpha/fisiologia , Comportamento Social , Agressão/efeitos dos fármacos , Androgênios/metabolismo , Animais , Feminino , Peixes/fisiologia , Abrigo para Animais , Masculino , Distribuição Aleatória , Reprodução/efeitos dos fármacos , Reprodução/fisiologia , Smegmamorpha/metabolismo , Meio Social , Testosterona/metabolismo , Testosterona/farmacologia
10.
Nat Commun ; 10(1): 2341, 2019 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-31138801

RESUMO

Understanding nanoparticle uptake by biological cells is fundamentally important to wide-ranging fields from nanotoxicology to drug delivery. It is now accepted that the arrival of nanoparticles at the cell is an extremely complicated process, shaped by many factors including unique nanoparticle physico-chemical characteristics, protein-particle interactions and subsequent agglomeration, diffusion and sedimentation. Sequentially, the nanoparticle internalisation process itself is also complex, and controlled by multiple aspects of a cell's state. Despite this multitude of factors, here we demonstrate that the statistical distribution of the nanoparticle dose per endosome is independent of the initial administered dose and exposure duration. Rather, it is the number of nanoparticle containing endosomes that are dependent on these initial dosing conditions. These observations explain the heterogeneity of nanoparticle delivery at the cellular level and allow the derivation of simple, yet powerful probabilistic distributions that accurately predict the nanoparticle dose delivered to individual cells across a population.


Assuntos
Endossomos/metabolismo , Nanopartículas/metabolismo , Células A549 , Transporte Biológico , Linhagem Celular , Endossomos/ultraestrutura , Ensaios de Triagem em Larga Escala , Humanos , Processamento de Imagem Assistida por Computador , Microscopia Confocal , Nanopartículas/ultraestrutura
11.
Arch Toxicol ; 92(2): 935-951, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29110037

RESUMO

Human exposure to carcinogens occurs via a plethora of environmental sources, with 70-90% of cancers caused by extrinsic factors. Aberrant phenotypes induced by such carcinogenic agents may provide universal biomarkers for cancer causation. Both current in vitro genotoxicity tests and the animal-testing paradigm in human cancer risk assessment fail to accurately represent and predict whether a chemical causes human carcinogenesis. The study aimed to establish whether the integrated analysis of multiple cellular endpoints related to the Hallmarks of Cancer could advance in vitro carcinogenicity assessment. Human lymphoblastoid cells (TK6, MCL-5) were treated for either 4 or 23 h with 8 known in vivo carcinogens, with doses up to 50% Relative Population Doubling (maximum 66.6 mM). The adverse effects of carcinogens on wide-ranging aspects of cellular health were quantified using several approaches; these included chromosome damage, cell signalling, cell morphology, cell-cycle dynamics and bioenergetic perturbations. Cell morphology and gene expression alterations proved particularly sensitive for environmental carcinogen identification. Composite scores for the carcinogens' adverse effects revealed that this approach could identify both DNA-reactive and non-DNA reactive carcinogens in vitro. The richer datasets generated proved that the holistic evaluation of integrated phenotypic alterations is valuable for effective in vitro risk assessment, while also supporting animal test replacement. Crucially, the study offers valuable insights into the mechanisms of human carcinogenesis resulting from exposure to chemicals that humans are likely to encounter in their environment. Such an understanding of cancer induction via environmental agents is essential for cancer prevention.


Assuntos
Testes de Carcinogenicidade/métodos , Carcinógenos/toxicidade , Linfócitos/efeitos dos fármacos , Mutagênicos/toxicidade , Linhagem Celular , Humanos , Testes para Micronúcleos , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/genética , Proteína Supressora de Tumor p53/metabolismo
12.
Artigo em Inglês | MEDLINE | ID: mdl-27055751

RESUMO

Many applications in biomedical research require the long-term identification and tracking of cells over time. In previous work we have demonstrated that by sequentially dosing a cell population with different emission wavelength nanoparticles it is possible to use the random number of nanoparticle loaded vesicles generated by the cells as a barcode for individual cells within the population. In this paper we develop a simple model to describe the number of codes that can be generated using this sequential loading protocol. The methodology is validated by comparison with experiment and subsequently used to predict the effect of varying the number of colors used to encode the cells and also to assess the effect of misreading the cellular code due to errors in imaging the vesicles.


Assuntos
Células/citologia , Processamento Eletrônico de Dados/métodos , Nanopartículas/análise , Animais , Linhagem Celular , Cor , Processamento Eletrônico de Dados/normas , Humanos , Métodos , Nanopartículas/administração & dosagem
13.
Methods Mol Biol ; 1342: 279-85, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26254931

RESUMO

This chapter provides a method for quantitative single cell analysis to track the transition of single cells from G2, indicated by high cyclin B1 levels, to G1 polyploidy phase (G1(p)), indicated by low cyclin B1 levels, in a 4n population. The cell tracking methodology described provides a fluorescence fingerprint suitable for deriving G2/M or G2/G1p transitions. Notably, during late G2 the absolute cyclin B1-eGFP reporter levels obtained were high and the switch-off point identifiable, with destruction rates of a similar order across all cell cycle routing avenues. The three principle parameters extracted were defined as (1) G2-to-G1(p) transition duration (tGFP(off)); (2) rate of sensor destruction (kGFP(off)), and (3) peak sensor expression (GFP(peak)).


Assuntos
Ciclina B1/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Mitose , Análise de Célula Única/métodos , Linhagem Celular Tumoral , Fase G1 , Fase G2 , Genes Reporter/genética , Proteínas de Fluorescência Verde/genética , Humanos , Processamento de Imagem Assistida por Computador , Microscopia de Fluorescência , Poliploidia
14.
J Microsc ; 261(2): 167-76, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25762522

RESUMO

Semiconductor quantum dot nanoparticles are in demand as optical biomarkers yet the cellular uptake process is not fully understood; quantification of numbers and the fate of internalized particles are still to be achieved. We have focussed on the characterization of cellular uptake of quantum dots using a combination of analytical electron microscopies because of the spatial resolution available to examine uptake at the nanoparticle level, using both imaging to locate particles and spectroscopy to confirm identity. In this study, commercially available quantum dots, CdSe/ZnS core/shell particles coated in peptides to target cellular uptake by endocytosis, have been investigated in terms of the agglomeration state in typical cell culture media, the traverse of particle agglomerates across U-2 OS cell membranes during endocytosis, the merging of endosomal vesicles during incubation of cells and in the correlation of imaging flow cytometry and transmission electron microscopy to measure the final nanoparticle dose internalized by the U-2 OS cells. We show that a combination of analytical transmission electron microscopy and serial block face scanning electron microscopy can provide a comprehensive description of the internalization of an initial exposure dose of nanoparticles by an endocytically active cell population and how the internalized, membrane bound nanoparticle load is processed by the cells. We present a stochastic model of an endosome merging process and show that this provides a data-driven modelling framework for the prediction of cellular uptake of engineered nanoparticles in general.


Assuntos
Endocitose , Nanopartículas/análise , Pontos Quânticos/análise , Linhagem Celular , Endossomos/ultraestrutura , Citometria de Fluxo , Microscopia Eletrônica de Varredura/métodos , Microscopia Eletrônica de Transmissão/métodos , Nanopartículas/química , Nanopartículas/ultraestrutura , Pontos Quânticos/ultraestrutura , Semicondutores
15.
Sci Rep ; 5: 18260, 2015 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-26675584

RESUMO

Social density processes impact the activity and order of collective behaviours in a variety of biological systems. Much effort has been devoted to understanding how density of people affects collective human motion in the context of pedestrian flows. However, there is a distinct lack of empirical data investigating the effects of social density on human behaviour in cooperative contexts. Here, we examine the functioning and performance of human teams in a central-place foraging arena using high-resolution GPS data. We show that team functioning (level of coordination) is greatest at intermediate social densities, but contrary to our expectations, increased coordination at intermediate densities did not translate into improved collective foraging performance, and foraging accuracy was equivalent across our density treatments. We suggest that this is likely a consequence of foragers relying upon visual channels (local information) to achieve coordination but relying upon auditory channels (global information) to maximise foraging returns. These findings provide new insights for the development of more sophisticated models of human collective behaviour that consider different networks for communication (e.g. visual and vocal) that have the potential to operate simultaneously in cooperative contexts.


Assuntos
Comportamento Cooperativo , Comportamento Alimentar/fisiologia , Relações Interpessoais , Comportamento Social , Adolescente , Adulto , Algoritmos , Análise de Variância , Tomada de Decisões/fisiologia , Feminino , Processos Grupais , Humanos , Masculino , Pessoa de Meia-Idade , Desempenho Psicomotor/fisiologia , Adulto Jovem
16.
Soft Matter ; 11(48): 9393-403, 2015 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-26439643

RESUMO

Measurements have been performed on thermally equilibrated conjugated-polymer/insulating-polymer bilayers, using specular and off-specular neutron reflectivity. While specular reflectivity is only sensitive to the structure normal to the sample, off-specular measurements can probe the structure of the buried polymer/polymer interface in the plane of the sample. Systematic analysis of the scattering from a set of samples with varying insulating-polymer-thickness, using the distorted-wave Born approximation (DWBA), has allowed a robust determination of the intrinsic width at the buried polymer/polymer interface. The quantification of this width (12 Å ± 4 Å) allows us to examine aspects of the conjugated polymer conformation at the interface, by appealing to self-consistent field theory (SCFT) predictions for equilibrium polymer/polymer interfaces in the cases of flexible and semi-flexible chains. This analysis enables us to infer that mixing at this particular interface cannot be described in terms of polymer chain segments that adopt conformations similar to a random walk. Instead, a more plausible explanation is that the conjugated polymer chain segments become significantly oriented in the plane of the interface. It is important to point out that we are only able to reach this conclusion following the extensive analysis of reflectivity data, followed by comparison with SCFT predictions. It is not simply the case that conjugated polymers would be expected to adopt this kind of oriented conformation at the interface, because of their relatively high chain stiffness. It is the combination of a high stiffness and a relatively narrow intrinsic interfacial width that results in a deviation from flexible chain behaviour.

17.
Nanotechnology ; 26(15): 155101, 2015 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-25797791

RESUMO

The application of nanoparticles (NPs) within medicine is of great interest; their innate physicochemical characteristics provide the potential to enhance current technology, diagnostics and therapeutics. Recently a number of NP-based diagnostic and therapeutic agents have been developed for treatment of various diseases, where judicious surface functionalization is exploited to increase efficacy of administered therapeutic dose. However, quantification of heterogeneity associated with absolute dose of a nanotherapeutic (NP number), how this is trafficked across biological barriers has proven difficult to achieve. The main issue being the quantitative assessment of NP number at the spatial scale of the individual NP, data which is essential for the continued growth and development of the next generation of nanotherapeutics. Recent advances in sample preparation and the imaging fidelity of transmission electron microscopy (TEM) platforms provide information at the required spatial scale, where individual NPs can be individually identified. High spatial resolution however reduces the sample frequency and as a result dynamic biological features or processes become opaque. However, the combination of TEM data with appropriate probabilistic models provide a means to extract biophysical information that imaging alone cannot. Previously, we demonstrated that limited cell sampling via TEM can be statistically coupled to large population flow cytometry measurements to quantify exact NP dose. Here we extended this concept to link TEM measurements of NP agglomerates in cell culture media to that encapsulated within vesicles in human osteosarcoma cells. By construction and validation of a data-driven transfer function, we are able to investigate the dynamic properties of NP agglomeration through endocytosis. In particular, we statistically predict how NP agglomerates may traverse a biological barrier, detailing inter-agglomerate merging events providing the basis for predictive modelling of nanopharmacology.


Assuntos
Meios de Cultura/química , Nanomedicina/métodos , Nanopartículas/química , Nanotecnologia/métodos , Transporte Biológico , Linhagem Celular Tumoral , Simulação por Computador , Sistemas de Liberação de Medicamentos , Endocitose , Endossomos/metabolismo , Humanos , Microscopia Eletrônica de Transmissão , Modelos Estatísticos , Osteossarcoma/metabolismo , Probabilidade , Pontos Quânticos
18.
Cytometry A ; 87(5): 385-92, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25572722

RESUMO

A protocol for the assessment of cell proliferation dynamics is presented. This is based on the measurement of cell division events and their subsequent analysis using Poisson probability statistics. Detailed analysis of proliferation dynamics in heterogeneous populations requires single cell resolution within a time series analysis and so is technically demanding to implement. Here, we show that by focusing on the events during which cells undergo division rather than directly on the cells themselves a simplified image acquisition and analysis protocol can be followed, which maintains single cell resolution and reports on the key metrics of cell proliferation. The technique is demonstrated using a microscope with 1.3 µm spatial resolution to track mitotic events within A549 and BEAS-2B cell lines, over a period of up to 48 h. Automated image processing of the bright field images using standard algorithms within the ImageJ software toolkit yielded 87% accurate recording of the manually identified, temporal, and spatial positions of the mitotic event series. Analysis of the statistics of the interevent times (i.e., times between observed mitoses in a field of view) showed that cell division conformed to a nonhomogeneous Poisson process in which the rate of occurrence of mitotic events, λ exponentially increased over time and provided values of the mean inter mitotic time of 21.1 ± 1.2 hours for the A549 cells and 25.0 ± 1.1 h for the BEAS-2B cells. Comparison of the mitotic event series for the BEAS-2B cell line to that predicted by random Poisson statistics indicated that temporal synchronisation of the cell division process was occurring within 70% of the population and that this could be increased to 85% through serum starvation of the cell culture.


Assuntos
Proliferação de Células/genética , Rastreamento de Células/métodos , Interpretação de Imagem Assistida por Computador/métodos , Processamento de Imagem Assistida por Computador/métodos , Linhagem Celular , Humanos , Mitose , Análise de Célula Única , Software
19.
Nat Methods ; 11(11): 1177-81, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25218182

RESUMO

For phenotypic behavior to be understood in the context of cell lineage and local environment, properties of individual cells must be measured relative to population-wide traits. However, the inability to accurately identify, track and measure thousands of single cells via high-throughput microscopy has impeded dynamic studies of cell populations. We demonstrate unique labeling of cells, driven by the heterogeneous random uptake of fluorescent nanoparticles of different emission colors. By sequentially exposing a cell population to different particles, we generated a large number of unique digital codes, which corresponded to the cell-specific number of nanoparticle-loaded vesicles and were visible within a given fluorescence channel. When three colors are used, the assay can self-generate over 17,000 individual codes identifiable using a typical fluorescence microscope. The color-codes provided immediate visualization of cell identity and allowed us to track human cells with a success rate of 78% across image frames separated by 8 h.


Assuntos
Rastreamento de Células/métodos , Corantes Fluorescentes , Pontos Quânticos , Linhagem Celular , Humanos , Microscopia de Fluorescência
20.
J Neuroinflammation ; 10: 40, 2013 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-23509933

RESUMO

BACKGROUND: Ghrelin is an orexigenic stomach hormone that acts centrally to increase mid-brain dopamine neurone activity, amplify dopamine signaling and protect against neurotoxin-induced dopamine cell death in the mouse substantia nigra pars compacta (SNpc). In addition, ghrelin inhibits the lipopolysaccharide (LPS)-induced release of pro-inflammatory cytokines from peripheral macrophages, T-cells and from LPS stimulated microglia. Here we sought to determine whether ghrelin attenuates pro-inflammatory cytokine release from dopaminergic neurones. FINDINGS: The dopaminergic SN4741 cell-line, which derives from the mouse substantia nigra (SN) and expresses the ghrelin-receptor (growth hormone secretagogue receptor (GHS-R)) and the ghrelin-O-acyl transferase (GOAT) enzyme, was used to determine the neuro-immunomodulatory action of ghrelin. We induced innate immune activation via LPS challenge (1 µg/ml) of SN4741 neurones that had been pre-cultured in the presence or absence of ghrelin (1, 10, 100 nM) for 4 h. After 24 h supernatants were collected for detection of IL-1 beta (IL-1ß ), TNF alpha (TNF-α) and IL-6 cytokines via enzyme linked immunosorbent assay (ELISA) analysis. Nuclear translocation of the transcription factor nuclear factor kappa B (NF-κB) was analyzed by Western blotting, and to determine viability of treatments a cell viability assay and caspase-3 immunohistochemistry were performed.We provide evidence that while IL-1ß and TNF-α were not detectable under any conditions, SN4741 neurones constitutively released IL-6 under basal conditions and treatment with LPS significantly increased IL-6 secretion. Pre-treatment of neurones with ghrelin attenuated LPS-mediated IL-6 release at 24 h, an affect that was inhibited by the GHS-R antagonist [D-Lys3]-GHRP-6. However, while ghrelin pre-treatment attenuated the LPS-mediated increase in NF-κB, there was no alteration in its nuclear translocation. Cell viability assay and caspase-3 immunocytochemistry demonstrated that the results were independent from activation of cytotoxic and/or apoptotic mechanisms in the neuronal population, respectively. CONCLUSION: Our results provide evidence that the gut-hormone, ghrelin, attenuates IL-6 secretion to LPS challenge in mid-brain dopaminergic neurones. These data suggest that ghrelin may protect against dopaminergic SN nerve cell damage or death via modulation of the innate immune response.


Assuntos
Neurônios Dopaminérgicos/metabolismo , Grelina/fisiologia , Interleucina-6/antagonistas & inibidores , Interleucina-6/metabolismo , Lipopolissacarídeos/fisiologia , Animais , Linhagem Celular , Lipopolissacarídeos/antagonistas & inibidores , Camundongos
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