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1.
Zhongguo Zhong Yao Za Zhi ; 48(13): 3684-3692, 2023 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-37475000

RESUMO

According to the traditional Chinese medicine(TCM) theory, Qi is the essential component maintaining life. Mitochondria are the cellular organelles that generate energy. Qi exhibits abundant common characteristics in bioenergetics compared with mitochondria which control the cellular energy through fusion and fission. Studies have proven that the qi-tonifying function of Chinese medicinal plants and their components facilitates mitochondrial fusion, therefore enhancing ATP synthesis. These studies provide a framework for deciphering the pharmacological mechanisms of Qi-tonifying herbs. This article introduces the common source and function shared by Qi and mitochondria and the regulatory effects of herbal remedies on energy from mitochondria dynamics. This review aims to interpret the connotation of tonifying qi in TCM theory based on the modern biomedical theory.


Assuntos
Medicamentos de Ervas Chinesas , Plantas Medicinais , Medicina Tradicional Chinesa , Medicamentos de Ervas Chinesas/farmacologia , Qi , Dinâmica Mitocondrial
3.
Biometrics ; 78(3): 1209-1220, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-33813733

RESUMO

Cell migration, the process by which cells move from one location to another, plays crucial roles in many biological events. While much research has been devoted to understand the process, most statistical cell migration models rely on using time-lapse microscopy data from cell trajectories alone. However, the cell and its associated nucleus work together to orchestrate cell movement, which motivates a joint analysis of coupled cell-nucleus trajectories. In this paper, we propose a Bayesian hierarchical model for analyzing cell migration. We incorporate a bivariate angular distribution to handle the coupled cell-nucleus trajectories and introduce latent motility status indicators to model a cell's motility as a time-dependent characteristic. A Markov chain Monte Carlo algorithm is provided for practical implementation of our model, which is used on real experimental data from MDA-MB-231 and NIH 3T3 cells. Through the fitted models, deeper insights into the migratory patterns of these experimental cell populations are gained and their differences are quantified.


Assuntos
Algoritmos , Modelos Estatísticos , Animais , Teorema de Bayes , Movimento Celular , Cadeias de Markov , Camundongos , Método de Monte Carlo
4.
Sci Rep ; 11(1): 23431, 2021 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-34873244

RESUMO

Heterogeneity of cell phenotypes remains a barrier in progressing cell research and a challenge in conquering cancer-related drug resistance. Cell morphology, the most direct property of cell phenotype, evolves along the progression of the cell cycle; meanwhile, cell motility, the dynamic property of cell phenotype, also alters over the cell cycle. However, a quantifiable research understanding the relationship between the cell cycle and cell migration is missing. Herein, we coordinate the migratory behaviours of NIH 3T3 fibroblasts to their corresponding phases of the cell cycle, the G1, the S, and the G2 phases, and explain the relationship through the spatiotemporal arrangements between the Rho GTPases' signals and cyclin-dependent kinase inhibitors, p21Cip1, and p27Kip1. Taken together, we demonstrate that both cell morphology and the dynamic subcellular behaviour are homogenous within each stage of the cell cycle phases but heterogenous between phases through quantitative cell analyses and an interactive molecular mechanism between the cell cycle and cell migration, posing potential implications in countering drug resistance.


Assuntos
Ciclo Celular , Resistencia a Medicamentos Antineoplásicos , Animais , Proteínas de Ciclo Celular/metabolismo , Movimento Celular , Biologia Computacional/métodos , Progressão da Doença , Fibroblastos/metabolismo , Citometria de Fluxo , Processamento de Imagem Assistida por Computador/métodos , Camundongos , Microscopia de Fluorescência , Proteínas Associadas aos Microtúbulos/metabolismo , Células NIH 3T3 , Fenótipo , Prognóstico
5.
Medicine (Baltimore) ; 98(48): e18118, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31770239

RESUMO

BACKGROUND: Vitamin D is a fat-soluble vitamin that is related to the health of the human body and is an indispensable nutrient for human beings. Some studies indicated that type 2 diabetes mellitus (T2DM) with diabetic peripheral neuropathy (DPN) may be associated with vitamin D deficiency, but the current understanding of this point of view remains controversial. This study aimed to evaluate the correlation between serum 25-hydroxyl vitamin D (25 [OH] D) concentration and DPN in patients with T2DM by a meta-analysis, and to provide a reference for doctors. METHODS: Relevant studies were selected from the PubMed, Cochrane Library, China National Knowledge Infrastructure, VIP databases, and Wanfang Data Knowledge Service Platform databases dating from 2000 to December 2017. A total of 75 articles related to serum 25 (OH) D and DPN were selected from 2000 to December 2017. Based on the inclusion and exclusion criteria of the literature, a quality assessment was conducted using the Newcastle-Ottawa scale, and a meta-analysis was performed by RevMan5.3 statistical software. RESULTS: Thirteen studies that involved a total of 2814 type 2 diabetic patients were finally included into the meta-analysis. Meta-analysis results, heterogeneity test showed that, P < .000 01, I = 92%, calculation by random effect model revealed that, the serum concentration of 25 (OH) D in T2DM combined with DPN group was lower than that in the group without DPN (weighted mean difference = -0.74, 95% confidence interval: -1.03 to -0.46) CONCLUSIONS:: Vitamin D is associated with type 2 DPN (DPN), and vitamin D deficiency can lead to an increased risk of type 2 DPN. However, more high-quality research is needed.


Assuntos
Diabetes Mellitus Tipo 2/sangue , Neuropatias Diabéticas/sangue , Doenças do Sistema Nervoso Periférico/sangue , Deficiência de Vitamina D/etiologia , Vitamina D/análogos & derivados , Adulto , Idoso , Diabetes Mellitus Tipo 2/complicações , Neuropatias Diabéticas/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doenças do Sistema Nervoso Periférico/etiologia , Fatores de Risco , Vitamina D/sangue , Deficiência de Vitamina D/sangue
6.
Artigo em Inglês | MEDLINE | ID: mdl-31178914

RESUMO

OBJECTIVE: To comprehensively compare the effects of conventional therapy combined with intravenous vitamin C and conventional therapy on viral myocarditis in children through a meta-analysis. METHODS: Relevant articles including clinical trials of normal treatment combined with intravenous vitamin C and conventional therapy for viral myocarditis in children that were published between January 2000 and February 2018 were selected from PubMed, Cochrane Library, China National Knowledge Infrastructure, China Science and Technology Journal Database, and WANFANG database. The quality of the included studies was assessed using the Cochrane systematic review method (version 5.1.0); data quality was evaluated by two independent researchers. The total effective rate; LDH, CK, and CK-MB levels; and other indicators were analyzed using Rev Man 5.3 software. RESULTS: Eight studies were eligible for this meta-analysis, which included a total of 426 patients in the treatment group and 363 patients in the control group. The meta-analysis results of six studies showed that the total effective rate of intravenous vitamin C combined with conventional therapy was higher than that of conventional therapy alone [Z = 5.46, 95% confidence interval (CI): 1.21 (1.13 to 1.30), P < 0.00001]; that of five studies showed that LDH levels were lower in children receiving intravenous vitamin C combined with conventional therapy than in those receiving conventional therapy alone [Z = 3.70, 95% CI: -1.88 (-2.88 to -0.88), P = 0.0002]; that of three studies showed that CK levels were lower in children receiving intravenous vitamin C combined with conventional therapy than in those receiving conventional therapy alone [Z = 4.21, 95% CI: -0.55 (-0.81 to -0.30), P < 0.0001]; that of four studies showed that CK-MB levels were lower in children receiving intravenous vitamin C combined with conventional therapy than in those receiving conventional therapy alone [Z = 13.64, 95% CI: -1.44 (-1.65 to -1.24), P < 0.00001]; that of two studies showed that CD3 levels were higher in children receiving intravenous vitamin C combined with conventional therapy than in those receiving conventional therapy alone [Z = 2.45, 95% CI: 0.41 (0.08-0.73), P = 0.01]; that of two studies showed no significant difference in changes in CD4 levels between children receiving intravenous vitamin C combined with conventional therapy and those receiving conventional therapy alone [Z = 0.28, 95% CI: -0.21 (-1.69 to 1.28), P = 0.78]; and that of two studies showed no significant difference in changes in CD4/CD8 between children receiving intravenous vitamin C combined with conventional therapy and those receiving conventional therapy alone [Z = 0.07, 95% CI: -0.03 (-0.73 to 0.67), P = 0.94]. CONCLUSION: The meta-analysis results showed that intravenous vitamin C combined with conventional therapy is better than the simple, conventional therapy for the treatment of viral myocarditis in children in terms of the total effective rate and LDH, CK, and CK-MB levels.

7.
Biomed Res Int ; 2018: 1837634, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30069463

RESUMO

AIM: To investigate whether vitamin C is effective in the treatment of the common cold. METHOD: After systematically searching the National Library of Medicine (PubMed), Cochrane Library, Elsevier, China National Knowledge Infrastructure (CNKI), VIP databases, and WANFANG databases, 9 randomized placebo-controlled trials were included in our meta-analysis in RevMan 5.3 software, all of which were in English. RESULTS: In the evaluation of vitamin C, administration of extra therapeutic doses at the onset of cold despite routine supplementation was found to help reduce its duration (mean difference (MD) = -0.56, 95% confidence interval (CI) [-1.03, -0.10], and P = 0.02), shorten the time of confinement indoors (MD = -0.41, 95% CI [-0.62, -0.19], and P = 0.0002), and relieve the symptoms associated with it, including chest pain (MD = -0.40, 95% CI [-0.77, -0.03], and P = 0.03), fever (MD = -0.45, 95% CI [-0.78, -0.11], and P = 0.009), and chills (MD = -0.36, 95% CI [-0.65, -0.07], and P = 0.01). CONCLUSIONS: Extra doses of vitamin C could benefit some patients who contract the common cold despite taking daily vitamin C supplements.


Assuntos
Ácido Ascórbico/uso terapêutico , Resfriado Comum/tratamento farmacológico , Vitaminas/uso terapêutico , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto
8.
Sci Rep ; 8(1): 1488, 2018 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-29367613

RESUMO

Various subcellular activities, such as protrusion and detachment, compose a cell migration process. The molecular mechanisms of these subcellular activities have been elucidated. However, there is no method that can assess the contributions of these subcellular activities to the global cell migration pattern of a given cell type. Hence, we develop a powerful approach based on CN correlations that quantitatively profiles the cell migration pattern of a given cell type in terms of assembled subcellular activities. In this way, we bridge migration data at the cellular level with underlying molecular mechanisms. The CN correlation profile is found to uniquely and consistently represent the cell migration pattern of each cell type probed. It can clearly reveal the effects of molecular perturbations, such as Y27632 and Cdc42 knockdown on each subcellular migratory activity. As a result, the CN correlation approach serves as a cell dynamic descriptor that can extract comprehensive quantitative data from cell migration movies for integrative biological analyses.


Assuntos
Movimento Celular , Núcleo Celular/fisiologia , Fenômenos Fisiológicos Celulares , Modelos Biológicos , Animais , Comunicação Celular , Polaridade Celular , Humanos , Camundongos , Células NIH 3T3 , Células Tumorais Cultivadas
9.
Trials ; 18(1): 567, 2017 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-29179761

RESUMO

BACKGROUND: Xingnao Kaiqiao acupuncture involves needling of the Neiguan (PC6), Renzhong (DU26), and Sanyinjiao (SP6) acupoints. The technique has a significant clinical effect in many neurological diseases. In the present report, we have developed a protocol for a scientific trial to analyze whether Xingnao Kaiqiao can be used to treat gastrointestinal dysfunction after laparoscopic surgery. In this context, we intend to execute a double-blind, randomized controlled trial to assess the efficacy and safety of Xingnao Kaiqiao acupuncture via intradermal needling. METHODS/DESIGN: This will be a single-center, double-blind, randomized controlled clinical trial. It has been designed on the basis of the Consolidated Standards of Reporting Trials (CONSORT 2010) guidelines and the Standards for Reporting Interventions in Controlled Trials of Acupuncture (STRICTA). The subjects will be recruited from among inpatients scheduled for laparoscopic surgery at the Department of Minimally Invasive Surgery, Tianjin Nankai Hospital, Tianjin, China. Using random numbers generated in SPSS 19.0, the recruited subjects will be allocated to either the "Xingnao Kaiqiao" group or the sham stimulation group. A specially appointed investigator will be in charge of the randomization. Xingnao Kaiqiao via intradermal needling (or sham needling) will be administered 6 h after laparoscopic surgery, and then every 12 h for a total of six sessions, each of which will last 3 min. The subjects will undergo their first evaluation shortly before the first treatment (6 h after laparoscopic surgery); evaluations will be repeated every 12 h until a total of seven evaluations have been completed. The primary outcome will be the time until the first postoperative flatus. The secondary outcomes will be: the time until the first postoperative defecation; levels of abdominal pain, abdominal distension, and nausea; blood ghrelin level; occurrence of vomiting; psychological status; and quality of life. DISCUSSION: This upcoming randomized clinical trial was designed as a standardized method to assess the efficacy and safety of Xingnao Kaiqiao acupuncture using intradermal needles on PC6, DU26, and SP6 in the treatment of gastrointestinal dysfunction after laparoscopic surgery. We aim to provide evidence and thus improve the clinical application of this technique. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR-IOR-17010763 . Registered on 2 March 2017.


Assuntos
Pontos de Acupuntura , Terapia por Acupuntura/métodos , Gastroenteropatias/terapia , Laparoscopia/efeitos adversos , Terapia por Acupuntura/efeitos adversos , Adolescente , Adulto , Idoso , China , Protocolos Clínicos , Método Duplo-Cego , Feminino , Gastroenteropatias/diagnóstico , Gastroenteropatias/etiologia , Gastroenteropatias/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Recuperação de Função Fisiológica , Projetos de Pesquisa , Fatores de Tempo , Resultado do Tratamento , Adulto Jovem
10.
Sci Rep ; 6: 34047, 2016 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-27670131

RESUMO

Cell migration is an essential process in organism development and physiological maintenance. Although current methods permit accurate comparisons of the effects of molecular manipulations and drug applications on cell motility, effects of alterations in subcellular activities on motility cannot be fully elucidated from those methods. Here, we develop a strategy termed cell-nuclear (CN) correlation to parameterize represented dynamic subcellular activities and to quantify their contributions in mesenchymal-like migration. Based on the biophysical meaning of the CN correlation, we propose a cell migration potential index (CMPI) to measure cell motility. When the effectiveness of CMPI was evaluated with respect to one of the most popular cell migration analysis methods, Persistent Random Walk, we found that the cell motility estimates among six cell lines used in this study were highly consistent between these two approaches. Further evaluations indicated that CMPI can be determined using a shorter time period and smaller cell sample size, and it possesses excellent reliability and applicability, even in the presence of a wide range of noise, as might be generated from individual imaging acquisition systems. The novel approach outlined here introduces a robust strategy through an analysis of subcellular locomotion activities for single cell migration assessment.

11.
PLoS One ; 8(10): e77417, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24146992

RESUMO

In eukaryotic cells the actin-cytoskeletal network provides stiffness and the driving force that contributes to changes in cell shape and cell motility, but the elastic behavior of this network is not well understood. In this paper a two dimensional form-finding model is proposed to investigate the elasticity of the actin filament network. Utilizing an initially random array of actin filaments and actin-cross-linking proteins the form-finding model iterates until the random array is brought into a stable equilibrium configuration. With some care given to actin filament density and length, distance between host sites for cross-linkers, and overall domain size the resulting configurations from the form-finding model are found to be topologically similar to cytoskeletal networks in real cells. The resulting network may then be mechanically exercised to explore how the actin filaments deform and align under load and the sensitivity of the network's stiffness to actin filament density, length, etc. Results of the model are consistent with the experimental literature, e.g. actin filaments tend to re-orient in the direction of stretching; and the filament relative density, filament length, and actin-cross-linking protein's relative density, control the actin-network stiffness. The model provides a ready means of extension to more complicated domains and a three-dimensional form-finding model is under development as well as models studying the formation of actin bundles.


Assuntos
Citoesqueleto de Actina/metabolismo , Citoesqueleto/metabolismo , Modelos Biológicos , Citoesqueleto de Actina/química , Algoritmos , Fenômenos Biomecânicos , Citoesqueleto/química , Humanos
12.
Sci Rep ; 3: 2266, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23881180

RESUMO

Detailed measurement of cell phenotype information from digital fluorescence images has the potential to greatly advance biomedicine in various disciplines such as patient diagnostics or drug screening. Yet, the complexity of cell conformations presents a major barrier preventing effective determination of cell boundaries, and introduces measurement error that propagates throughout subsequent assessment of cellular parameters and statistical analysis. State-of-the-art image segmentation techniques that require user-interaction, prolonged computation time and specialized training cannot adequately provide the support for high content platforms, which often sacrifice resolution to foster the speedy collection of massive amounts of cellular data. This work introduces a strategy that allows us to rapidly obtain accurate cell boundaries from digital fluorescent images in an automated format. Hence, this new method has broad applicability to promote biotechnology.


Assuntos
Células/citologia , Processamento de Imagem Assistida por Computador/métodos , Microscopia de Fluorescência/métodos , Animais , Camundongos , Células NIH 3T3
13.
PLoS One ; 8(6): e66598, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23805245

RESUMO

Z-ligustilide (LIG), an essential oil extract from Radix Angelica sinensis, has broad pharmaceutical applications in treating cardio-vascular diseases and ischemic brain injury. Recently, LIG has been connected to Glioblastoma multiforme (GBM) because of its structural similarity to 3-n-alkyphthalide (NBP), which is specifically cytotoxic to GBM cells. Hence, we investigated LIG's effect on GBM T98G cells. The study shows that LIG can significantly reduce T98G cells' migration in a dose-dependent manner. Furthermore, the attenuation of cellular mobility can be linked to the activity of the Rho GTPases (RhoA, Rac1 and Cdc42), the three critical molecular switches governing cytoskeleton remodeling; thus, regulating cell migration. LIG significantly reduces the expression of RhoA and affects in a milder manner the expression of Cdc42 and Rac1.


Assuntos
4-Butirolactona/análogos & derivados , Movimento Celular/efeitos dos fármacos , Glioblastoma/metabolismo , 4-Butirolactona/química , 4-Butirolactona/farmacologia , Linhagem Celular Tumoral , Citoesqueleto/metabolismo , Citoesqueleto/patologia , Glioblastoma/genética , Glioblastoma/patologia , Humanos , Proteínas de Neoplasias/metabolismo , Proteína cdc42 de Ligação ao GTP/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo
14.
Nat Protoc ; 7(1): 155-70, 2012 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-22222790

RESUMO

High-throughput ballistic injection nanorheology is a method for the quantitative study of cell mechanics. Cell mechanics are measured by ballistic injection of submicron particles into the cytoplasm of living cells and tracking the spontaneous displacement of the particles at high spatial resolution. The trajectories of the cytoplasm-embedded particles are transformed into mean-squared displacements, which are subsequently transformed into frequency-dependent viscoelastic moduli and time-dependent creep compliance of the cytoplasm. This method allows for the study of a wide range of cellular conditions, including cells inside a 3D matrix, cell subjected to shear flows and biochemical stimuli, and cells in a live animal. Ballistic injection lasts <1 min and is followed by overnight incubation. Multiple particle tracking for one cell lasts <1 min. Forty cells can be examined in <1 h.


Assuntos
Caenorhabditis elegans/citologia , Nanotecnologia/métodos , Reologia/métodos , Animais , Fenômenos Biomecânicos , Células Cultivadas , Humanos , Camundongos , Nanopartículas/análise , Células Swiss 3T3 , Substâncias Viscoelásticas
15.
Phys Biol ; 8(1): 015005, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21301057

RESUMO

NAC1, a BTB/POZ family member, has been suggested to participate in maintaining the stemness of embryonic stem cells and has been implicated in the pathogenesis of human cancer. In ovarian cancer, NAC1 upregulation is associated with disease aggressiveness and with the development of chemoresistance. Like other BTB/POZ proteins, NAC1 forms discrete nuclear bodies in non-dividing cells. To investigate the biological role of NAC1 nuclear bodies, we characterized the expression dynamics of NAC1 nuclear bodies during different phases of the cell cycle. Fluorescence recovery after photobleaching assays revealed that NAC1 was rapidly exchanged between the nucleoplasm and NAC1 nuclear bodies in interphase cells. The number of NAC1 bodies significantly increased and their size decreased in the S phase as compared to the G0/G1 and G2 phases. NAC1 nuclear bodies disappeared and NAC1 became diffuse during mitosis. NAC1 nuclear bodies reappeared immediately after completion of mitosis. These results indicate that a cell cycle-dependent regulatory mechanism controls NAC1 body formation in the nucleus and suggest that NAC1 body dynamics are associated with mitosis or cytokinesis.


Assuntos
Ciclo Celular , Núcleo Celular/ultraestrutura , Proteínas de Neoplasias/análise , Proteínas de Neoplasias/metabolismo , Neoplasias/metabolismo , Proteínas Repressoras/análise , Proteínas Repressoras/metabolismo , Linhagem Celular Tumoral , Núcleo Celular/patologia , Feminino , Humanos , Neoplasias/patologia , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia
16.
J Hazard Mater ; 185(2-3): 1587-91, 2011 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-21030147

RESUMO

Welding fumes contain heavy metals, such as chromium, manganese, and nickel, which cause respiratory diseases and cancer. In this study, a SiO(2) precursor was evaluated as an additive to the shielding gas in an arc welding process to reduce the biotoxicity caused by welding fume particles. Transmission electron micrographic images show that SiO(2) coats on the surface of welding fume particles and promotes particle agglomeration. Energy dispersive X-ray spectroscopy further shows that the relative amount of silicon in these SiO(2)-coated agglomerates is higher than in baseline agglomerates. In addition, Escherichia coli (E. coli) exposed to different concentrations of pure SiO(2) particles generated from the arc welding process exhibits similar responses, suggesting that SiO(2) does not contribute to welding fume particle toxicity. The trend of E. coli growth in different concentrations of baseline welding fume particle shows the most significant inhibition occurs in higher exposure concentrations. The 50% lethal logarithmic concentrations for E. coli in arc welding particles of baseline, 2%, and 4.2% SiO(2) precursor additives were 823, 1605, and 1800 mg/L, respectively. Taken together, these results suggest that using SiO(2) precursors as an additive to arc welding shielding gas can effectively reduce the biotoxicity of welding fume.


Assuntos
Exposição Ocupacional , Soldagem , Humanos , Exposição por Inalação , Microscopia Eletrônica de Transmissão
17.
Biophys J ; 98(12): 2822-30, 2010 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-20550894

RESUMO

The fidelity of the trajectories obtained from video-based particle tracking determines the success of a variety of biophysical techniques, including in situ single cell particle tracking and in vitro motility assays. However, the image acquisition process is complicated by system noise, which causes positioning error in the trajectories derived from image analysis. Here, we explore the possibility of reducing the positioning error by the application of a Kalman filter, a powerful algorithm to estimate the state of a linear dynamic system from noisy measurements. We show that the optimal Kalman filter parameters can be determined in an appropriate experimental setting, and that the Kalman filter can markedly reduce the positioning error while retaining the intrinsic fluctuations of the dynamic process. We believe the Kalman filter can potentially serve as a powerful tool to infer a trajectory of ultra-high fidelity from noisy images, revealing the details of dynamic cellular processes.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Glicerol/química , Espaço Intracelular/metabolismo , Modelos Lineares , Imagem Molecular
18.
Opt Express ; 18(5): 5199-212, 2010 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-20389533

RESUMO

The electron-multiplying charge-coupled device (EMCCD) camera possesses an electron multiplying function that can effectively convert the weak incident photon signal to amplified electron output, thereby greatly enhancing the contrast of the acquired images. This device has become a popular photon detector in single-cell biophysical assays to enhance subcellular images. However, the quantitative relationship between the resolution in such measurements and the electron multiplication setting in the EMCCD camera is not well-understood. We therefore developed a method to characterize the exact dependence of the signal-to-noise-ratio (SNR) on EM gain settings over a full range of incident light intensity. This information was further used to evaluate the EMCCD performance in subcellular particle tracking. We conclude that there are optimal EM gain settings for achieving the best SNR and the best spatial resolution in these experiments. If it is not used optimally, electron multiplication can decrease the SNR and increases spatial error.

19.
Biophys J ; 96(12): 5103-11, 2009 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-19527670

RESUMO

Video-based particle tracking monitors the microscopic movement of labeled biomolecules and fluorescent probes within a complex cellular environment. Information gained from this technique enables us to extract the dynamic behavior of biomolecules and the local mechanical properties inside the cell from a tracked particle's mean-square displacement (MSD). However, MSD measurements are highly susceptible to static error introduced by noise in the image acquisition process that leads to an incorrect positioning of the particle. Static error can mask the subtle effects from the local microenvironment on the MSD and potentially generate misleading conclusions about the biophysical properties of cells. An approach that greatly increases the accuracy of MSD measurements is presented herein by combining experimental data with Monte Carlo simulations to eliminate the inherent static error. This practical method of static error correction greatly advances particle-tracking techniques.


Assuntos
Reologia/métodos , Gravação em Vídeo/métodos , Animais , Linhagem Celular , Luz , Camundongos , Microesferas , Método de Monte Carlo , Tamanho da Partícula , Poliestirenos
20.
PLoS One ; 4(2): e4411, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19198659

RESUMO

BACKGROUND: The close subcellular proximity of different actin filament crosslinking proteins suggests that these proteins may cooperate to organize F-actin structures to drive complex cellular functions during cell adhesion, motility and division. Here we hypothesize that alpha-actinin and filamin, two major F-actin crosslinking proteins that are both present in the lamella of adherent cells, display synergistic mechanical functions. METHODOLOGY/PRINCIPAL FINDINGS: Using quantitative rheology, we find that combining alpha-actinin and filamin is much more effective at producing elastic, solid-like actin filament networks than alpha-actinin and filamin separately. Moreover, F-actin networks assembled in the presence of alpha-actinin and filamin strain-harden more readily than networks in the presence of either alpha-actinin or filamin. SIGNIFICANCE: These results suggest that cells combine auxiliary proteins with similar ability to crosslink filaments to generate stiff cytoskeletal structures, which are required for the production of internal propulsive forces for cell migration, and that these proteins do not have redundant mechanical functions.


Assuntos
Citoesqueleto de Actina/química , Actinina/química , Proteínas Contráteis/química , Proteínas dos Microfilamentos/química , Citoesqueleto de Actina/metabolismo , Actinina/metabolismo , Proteínas Contráteis/metabolismo , Elasticidade , Filaminas , Cinética , Proteínas dos Microfilamentos/metabolismo , Reologia
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