The Relationship Between Internalization of Magnetic Nanoparticles and Changes of Cellular Optical Scatter Signal

2008 ◽  
Vol 8 (12) ◽  
pp. 6310-6315
Author(s):  
Jingguang Xia ◽  
Song Zhang ◽  
Yu Zhang ◽  
Ming Ma ◽  
Kang Xu ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Magnetic Nanoparticles ◽  
Argon Laser ◽  
Human Hepatoma Cells ◽  
Cellular Iron ◽  
High Viability ◽  
A Cell ◽  
Magnetic Labeling ◽  
Average Size ◽  
The Relationship

Carboxylmethyl starch sodium-coated magnetic nanoparticles (CMS@MNs) with average size of 10 nm were synthesized by chemical coprecipitation. Cellular iron content showed that CMS@MNs could be efficiently uptaken by human hepatoma cells. TEM image showed that clusters consisting of nanoparticles were enclosed within sub-micrometric endosomes and one cell contained several such endosomes. After incubation with the nanoparticles, a phenomenon appeared that the intensity of cellular side scatter signal (SSC) obtained by flow cytometry at 488 nm argon laser increased. It was demonstrated that the increase of SSC signal was induced by a cell itself, and mainly caused by the nanoparticles both adsorbed on the membrane and internalized into cytoplasm. Although without inducing cell death the treatments with the nanoparticles could lead to increased permeability of cell membrane to propidium iodide. Results implied a potential that flow cytometry might be used as a tool to rapidly evaluate and select cells with high magnetic labeling and high viability in cellular transplant.

scholarly journals Magnetic Nanoparticles Mediated-Gene Delivery for Simpler and More Effective Transformation of Pichia pastoris

2021 ◽  
Author(s):  
Seyda Yildiz ◽  
Kubra Solak ◽  
Melek Acar ◽  
Ahmet Mavi ◽  
Yagmur Unver
Keyword(s):  
Magnetic Nanoparticles ◽  
Pichia Pastoris ◽  
Gene Delivery ◽  
Delivery Method ◽  
Exogenous Dna ◽  
Novel Gene ◽  
A Cell

The introduction of exogenous DNA into a cell can be used to produce large quantities of protein. Here, we describe a novel gene delivery method into Pichia pastoris based on...

scholarly journals Experimental study of the interaction range and association rate of surface-attached cadherin 11

1998 ◽  
Vol 95 (16) ◽  
pp. 9256-9261 ◽  
Author(s):  
Anne Pierres ◽  
Hélène Feracci ◽  
Véronique Delmas ◽  
Anne-Marie Benoliel ◽  
Jean-Paul Thiery ◽  
...  
Keyword(s):  
Adhesion Molecules ◽  
Bond Formation ◽  
Slow Motion ◽  
Classical Type ◽  
Association Rate ◽  
Interaction Range ◽  
A Cell ◽  
Coated Surfaces ◽  
The Relationship

We describe a method allowing quantitative determination of the interaction range and association rate of individual surface-attached molecules. Spherical beads (1.4 μm radius) were coated with recombinant outer domains of the newly described classical type II cadherin 11, a cell adhesion molecule. Beads were driven along cadherin-coated surfaces with a hydrodynamic force of ≈1 pN, i.e., much less than the mechanical strength of many ligand-receptor bonds. Spheres displayed periods of slow motion interspersed with arrests of various duration. Particle position was monitored with 50 Hz frequency and 0.025 μm accuracy. Nearly 1 million positions were recorded and processed. Comparison between experimental and computer-simulated trajectories suggested that velocity fluctuations might be related quantitatively to Brownian motion perpendicular to the surface. The expected amplitude of this motion was of order of 100 nm. Theoretical analysis of the relationship between sphere acceleration and velocity allowed simultaneous determination of the wall shear rate and van der Waals attraction between spheres and surface. The Hamaker constant was estimated at 2.9 × 10−23 J. The frequency of bond formation was then determined as a function of sphere velocity. Experimental data were consistent with the view that the rate of association between a pair of adhesion molecules was ≈1.2 × 10−3 s−1 and the interaction range was ≈10 nm. It is concluded that the presented methodology allows sensitive measurement of sphere-to-surface interactions (with ≈10 fN sensitivity) as well as the effective range and rate of bond formation between individual adhesion molecules.

Overexpression of mitochondrial ferritin causes cytosolic iron depletion and changes cellular iron homeostasis

Blood ◽  
2005 ◽  
Vol 105 (5) ◽  
pp. 2161-2167 ◽  
Author(s):  
Guangjun Nie ◽  
Alex D. Sheftel ◽  
Sangwon F. Kim ◽  
Prem Ponka
Keyword(s):  
Iron Homeostasis ◽  
Rna Binding ◽  
Binding Activity ◽  
Intracellular Iron ◽  
Free Radical Damage ◽  
Iron Regulatory Proteins ◽  
Cellular Iron ◽  
Cellular Iron Uptake ◽  
A Cell ◽  
Cellular Iron Homeostasis

AbstractCytosolic ferritin sequesters and stores iron and, consequently, protects cells against iron-mediated free radical damage. However, the function of the newly discovered mitochondrial ferritin (MtFt) is unknown. To examine the role of MtFt in cellular iron metabolism, we established a cell line that stably overexpresses mouse MtFt under the control of a tetracycline-responsive promoter. The overexpression of MtFt caused a dose-dependent iron deficiency in the cytosol that was revealed by increased RNA-binding activity of iron regulatory proteins (IRPs) along with an increase in transferrin receptor levels and decrease in cytosolic ferritin. Consequently, the induction of MtFt resulted in a dramatic increase in cellular iron uptake from transferrin, most of which was incorporated into MtFt. The induction of MtFt caused a shift of iron from cytosolic ferritin to MtFt. In addition, iron inserted into MtFt was less available for chelation than that in cytosolic ferritin and the expression of MtFt was associated with decreased mitochondrial and cytosolic aconitase activities, the latter being consistent with the increase in IRP-binding activity. In conclusion, our results indicate that overexpression of MtFt causes a dramatic change in intracellular iron homeostasis and that shunting iron to MtFt likely limits its availability for active iron proteins.

scholarly journals Single-Tube Flow Cytometry Assay for the Detection of Mature Lymphoid Neoplasms in Paucicellular Samples

2016 ◽  
Vol 60 (4) ◽  
pp. 385-394
Author(s):  
Alessandra Stacchini ◽  
Anna Demurtas ◽  
Sabrina Aliberti ◽  
Antonella Barreca ◽  
Domenico Novero ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Hodgkin Lymphoma ◽  
Final Diagnosis ◽  
Molecular Data ◽  
Malignant Lymphomas ◽  
Flow Cytometry Assay ◽  
Single Tube ◽  
Fine Needle Aspirates ◽  
Non Hodgkin Lymphoma ◽  
A Cell

Objectives: Flow cytometry (FC) has become a useful support for cytomorphologic evaluation (CM) of fine-needle aspirates (FNA) and serous cavity effusions (SCE) in cases of suspected non-Hodgkin lymphoma (NHL). FC results may be hampered by the scarce viability and low cellularity of the specimens. Study Design: We developed a single-tube FC assay (STA) that included 10 antibodies cocktailed in 8-color labeling, a cell viability dye, and a logical gating strategy to detect NHL in hypocellular samples. The results were correlated with CM and confirmed by histologic or molecular data when available. Results: Using the STA, we detected B-type NHL in 31 out of 103 hypocellular samples (81 FNA and 22 SCE). Of these, 8 were not confirmed by CM and 2 were considered to be only suspicious. The FC-negative samples had a final diagnosis of benign/reactive process (42/72), carcinoma (27/72), or Hodgkin lymphoma (3/72). Conclusions: The STA approach allowed obtainment of maximum immunophenotyping data in specimens containing a low number of cells and a large amount of debris. The information obtained by STA can help cytomorphologists not only to recognize but also to exclude malignant lymphomas.

scholarly journals Development of a specific method to evaluate 8-hydroxy,2-deoxyguanosine in sperm nuclei: relationship with semen quality in a cohort of 94 subjects

Reproduction ◽  
2013 ◽  
Vol 145 (3) ◽  
pp. 227-235 ◽  
Author(s):  
M Cambi ◽  
L Tamburrino ◽  
S Marchiani ◽  
B Olivito ◽  
C Azzari ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Oxidative Damage ◽  
Oxidative Dna Damage ◽  
Semen Quality ◽  
Sperm Count ◽  
Specific Method ◽  
Sperm Dna Fragmentation ◽  
Immunofluorescence Method ◽  
Sperm Nuclei ◽  
The Relationship

Oxidative stress (OS) is involved in many disoders including male infertility. Human spermatozoa are very sensitive targets of reactive oxygen species (ROS) and most sperm functions are impaired in the case of OS. In addition unbalanced production of ROS is considered one of the most important causes of sperm DNA fragmentation, a semen trait of infertile men. The relationship between oxidative damage and semen quality is partially controversial, probably due to the different methods and/or targets used to reveal the OS. In this study, by fluorescence microscopy and flow cytometry, we compared two methods to reveal 8-hydroxy,2-deoxyguanosine (8-OHdG), the hallmark of oxidative DNA damage: an immunofluorescence method and the commercial OxyDNA kit. We found that although both methods localized the labelling in sperm nuclei they yielded different measures, and only with the immunofluorescence method was the labelling specific for sperm 8-OHdG. The immunofluorescence method, coupled to flow cytometry, was thus selected to analyse the 8-OHdG content in semen samples from 94 subfertile patients and to investigate the relationship with semen quality. We found that the percentages of spermatozoa with 8-OHdG (mean±s.d., 11.4±6.9%) were related to sperm count (Pearson's correlation coefficient (r)=−0.27, P=0.04 (ANOVA and student's t-test)), motility (progressive: r=−0.22, P=0.04; non-progressive: r=0.25, P=0.01), and normal morphology (r=−0.27, P=0.01). In conclusion, we demonstrate that immunofluorescence/flow cytometry is a reliable and specific method to detect 8-OHdG at single-cell level and show that oxidative damage only partially overlaps poor semen quality, suggesting that it could provide additional information on male fertility with respect to routine semen analysis.

scholarly journals The N-terminus of hepcidin is essential for its interaction with ferroportin: structure-function study

Blood ◽  
2006 ◽  
Vol 107 (1) ◽  
pp. 328-333 ◽  
Author(s):  
Elizabeta Nemeth ◽  
Gloria C. Preza ◽  
Chun-Ling Jung ◽  
Jerry Kaplan ◽  
Alan J. Waring ◽  
...  
Keyword(s):  
Disulfide Bonds ◽  
Progressive Decrease ◽  
Cellular Iron ◽  
Gfp Fusion Protein ◽  
N Terminus ◽  
A Cell ◽  
Terminal Amino ◽  
Peptide Treatment

Abstract Hepcidin is the principal iron-regulatory hormone. It acts by binding to the iron exporter ferroportin, inducing its internalization and degradation, thereby blocking cellular iron efflux. The bioactive 25 amino acid (aa) peptide has a hairpin structure stabilized by 4 disulfide bonds. We synthesized a series of hepcidin derivatives and determined their bioactivity in a cell line expressing ferroportin-GFP fusion protein, by measuring the degradation of ferroportin-GFP and the accumulation of ferritin after peptide treatment. Bioactivity was also assayed in mice by the induction of hypoferremia. Serial deletion of N-terminal amino acids caused progressive decrease in activity which was completely lost when 5 N-terminal aa's were deleted. Synthetic 3-aa and 6-aa N-terminal peptides alone, however, did not internalize ferroportin and did not interfere with ferroportin internalization by native hepcidin. Deletion of 2 C-terminal aa's did not affect peptide activity. Removal of individual disulfide bonds by pairwise substitution of cysteines with alanines also did not affect peptide activity in vitro. However, these peptides were less active in vivo, likely because of their decreased stability in circulation. G71D and K83R, substitutions previously described in humans, did not affect hepcidin activity. Apart from the essential nature of the N-terminus, hepcidin structure appears permissive for mutations.

3. Proteins

2021 ◽  
pp. 34-51
Author(s):  
Mark Lorch
Keyword(s):  
Amino Acids ◽  
Protein Folding ◽  
Protein Structure ◽  
Protein Structures ◽  
Structure And Function ◽  
Vast Array ◽  
A Cell ◽  
Cellular Machinery ◽  
And Function ◽  
The Relationship

This chapter examines proteins, the dominant proportion of cellular machinery, and the relationship between protein structure and function. The multitude of biological processes needed to keep cells functioning are managed in the organism or cell by a massive cohort of proteins, together known as the proteome. The twenty amino acids that make up the bulk of proteins produce the vast array of protein structures. However, amino acids alone do not provide quite enough chemical variety to complete all of the biochemical activity of a cell, so the chapter also explores post-translation modifications. It finishes by looking as some dynamic aspects of proteins, including enzyme kinetics and the protein folding problem.

scholarly journals Relationships between snowfall density and solid hydrometeors, based on measured size and fall speed, for snowpack modeling applications

2016 ◽  
Vol 10 (6) ◽  
pp. 2831-2845 ◽  
Author(s):  
Masaaki Ishizaka ◽  
Hiroki Motoyoshi ◽  
Satoru Yamaguchi ◽  
Sento Nakai ◽  
Toru Shiina ◽  
...  
Keyword(s):  
Mass Flux ◽  
Weather Forecasting ◽  
Initial Density ◽  
Quantitative Relationship ◽  
Temperate Climate ◽  
Snowfall Event ◽  
Fall Speed ◽  
Average Size ◽  
Meteorological Elements ◽  
The Relationship

Abstract. The initial density of deposited snow is mainly controlled by snowfall hydrometeors. The relationship between snowfall density and hydrometeors has been qualitatively examined by previous researchers; however, a quantitative relationship has not yet been established due to difficulty in parameterizing the hydrometeor characteristics of a snowfall event. Thus, in an earlier study, we developed a new variable, the centre of mass flux distribution (CMF), which we used to describe the main hydrometeors contributing to a snowfall event. The CMF is based on average size and fall speed weighted by the mass flux estimated from all measured hydrometeors in a snowfall event. It provides a quantitative representation of the predominant hydrometeor characteristics of the event. In this study, we examine the relationships between the density of newly fallen snow and predominant snow type as indicated by the CMFs. We measured snowfall density at Nagaoka, Japan, where riming and aggregation are predominant, simultaneously observing the size and fall speed of snowfall hydrometeors, and deduced the predominant hydrometeor characteristics of each snowfall event from their CMFs. Snow density measurements were carried out for short periods, 1 or 2 h, during which the densification of the deposited snow was negligible. Also, we grouped snowfall events based on similar hydrometeor characteristics. As a result, we were able to obtain not only the qualitative relationships between the main types of snow and snowfall density as reported by previous researchers, but also quantitative relationships between snowfall density and the CMF density introduced here. CMF density is defined as the ratio between mass and volume, assuming the diameter of a sphere is equal to the CMF size component. This quantitative relationship provides a means for more precise estimation of snowfall density based on snow type (hydrometeor characteristics), by using hydrometeor size and fall speed data to derive initial densities for numerical snowpack models, and the snow-to-liquid ratio for winter weather forecasting. In fact, we found that this method can more accurately estimate snowfall density compared with using meteorological elements, which is the method generally used in current snowpack models, even though some issues remain in parameterization for practical use. Transferability of the method developed in the temperate climate zone, where riming and aggregation are predominant, to other snowy areas is also an issue. However, the methodology presented in this study would be useful for other kinds of snow.

Magnetic nanoparticles for the measurement of cell mechanics using force-induced remnant magnetization spectroscopy

Nanoscale ◽  
2020 ◽  
Vol 12 (27) ◽  
pp. 14573-14580
Author(s):  
Min Xu ◽  
Xueyan Feng ◽  
Feng Feng ◽  
Hantao Pei ◽  
Ruping Liu ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Cell Lines ◽  
Cancer Cell ◽  
Cell Mechanics ◽  
Magnetic Nanoparticle ◽  
Adhesion Force ◽  
Force Spectroscopy ◽  
Remnant Magnetization ◽  
A Cell ◽  
Novel Method

Interactions of magnetic nanoparticles with cells were investigated from a cell mechanics perspective, and magnetic nanoparticle-based force spectroscopy was developed as a novel method to measure the adhesion force among various cancer cell lines.

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