scholarly journals Positively Charged Dendron Micelles Display Negligible Cellular Interactions

2012 ◽  
Vol 2 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Ryan M. Pearson ◽  
Niladri Patra ◽  
Hao-jui Hsu ◽  
Sayam Uddin ◽  
Petr Král ◽  
...  
Keyword(s):  
Cellular Interactions ◽  
Dendron Micelles ◽  
Positively Charged

scholarly journals Understanding the Underlying Immune Response in HIT: Uptake of PF4/Heparin Complexes By Monocytes & Dendritic Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4197-4197
Author(s):  
Manali V. Joglekar ◽  
Sanjay Khandelwal ◽  
Mortimer Poncz ◽  
Lubica Rauova ◽  
Gowthami M Arepally
Keyword(s):  
Flow Cytometry ◽  
Immune Response ◽  
Dendritic Cells ◽  
Cellular Uptake ◽  
Dependent Manner ◽  
Cellular Interactions ◽  
Platelet Factor ◽  
Cellular Activation ◽  
Late Endosomes ◽  
Positively Charged

Abstract Platelet Factor 4 (PF4), a strongly positive-charged small protein, and the negatively-charged polymer heparin (Hep) form ultra-large complexes (ULCs) that have several unusual features including their remarkable stability and their ability to elicit a robust antibody response in vivo (Rauova L; Blood 2005 and Suvarna S, Blood 2005). Recently, we and others have shown that similar complexes of another positively charged protein, protamine sulfate with heparin can also lead to a clinically relevant immune response. To better understand the cellular basis for PF4/Hep antibody formation, we investigated mechanisms of cellular interactions and uptake of PF4 and PF4/Hep ULCs. For these studies, we examined cellular uptake of unlabeled or labeled PF4, heparin, or PF4/Hep using monocytes (PBMCs), dendritic cells (DCs) and/or neutrophils derived from peripheral blood. For these studies, cells were incubated with varying concentrations of unlabeled or fluorescently-labeled antigen (PF4, Hep or PF4/Hep ULCs). In cellular studies using unlabeled antigen, uptake was detected by fluorescently-labeled KKO, a monoclonal antibody to PF4/Hep complexes. Cellular uptake was visualized by confocal microscopy or flow cytometry. In initial studies, we defined the time course of uptake. As shown in Figure 1, we demonstrate that PF4/Hep-FITC ULCs are taken up by PBMCs in a time-dependent manner, with maximal uptake occurring between 12-24 hours (Figure 1, only 24 hour time point shown). This uptake is independent of the fluorescent label, as labeled or unlabeled intracellular PF4/Hep ULCs were readily visualized by KKO-AF647. To examine the effect of Hep on PF4 uptake, PBMCs were incubated with unlabeled PF4 alone or in the presence of increasing concentrations of Hep-FITC (0.1-2.5 U/mL). As shown in Figure 2A, Hep markedly enhances the efficiency of cellular uptake of PF4 in a Hep-dependent manner. Increased number of intracellular vesicles containing labeled PF4/Hep-FITC was noted at Hep-FITC concentration of 0.25-1 U/mL (Figure 2B; fluorescent vesicles/cell: 0.6 ± 0.22 for 0.35 U/mL and 0.5 ± 0.26 for 1U/mL) as compared to PF4 alone (25 µg/mL; number of fluorescent vesicles/cell: 0.35 ± 0.07). On examining the uptake of ULCs by other phagocytic cells, we could not demonstrate PF4/Hep uptake by neutrophils, suggesting that only monocytes/DCs provide clearance of complexes. Cellular uptake of Hep-containing ULCs was not limited to complexes of PF4 and heparin but also other positively-charged proteins, as intracellular complexes could be demonstrated when Hep-FITC was incubated with murine PF4, protamine, or lysozyme to form corresponding protein/Hep-FITC ULCs. This uptake was an active process of monocytes as PF4/Hep ULC endocytosis was inhibited by 4C, and cytochalasin D, an actin polymerization inhibitor and was associated with cellular activation and expression of MHC II and CD83 co-stimulatory molecules as shown by flow cytometry (Figure 3). Finally, co-staining with KKO and lysosomal associated membrane protein-2 (LAMP-2) localized intact PF4/Hep ULCs into late endosomes. Taken together, these studies demonstrate that PF4/Hep and other protein/heparin ULCs are taken up actively by monocytes and/or DCs, intact ULCs can be detected in late endosomes and uptake is accompanied by cellular activation. These studies establish a distinct role for heparin in increasing the uptake and cellular activation of PF4 and other positively charged complexes. These studies additionally provide insights into why the majority of clinical cases of HIT occur in the wake of heparin exposure. Disclosures Arepally: TEVA Pharma: Consultancy.

scholarly journals Pharmacokinetic Analysis of Peptide-Modified Nanoparticles with Engineered Physicochemical Properties in a Mouse Model of Traumatic Brain Injury

2021 ◽  
Vol 23 (5) ◽  
Author(s):  
Lauren E. Waggoner ◽  
Marianne I. Madias ◽  
Alan A. Hurtado ◽  
Ester J. Kwon
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Mouse Model ◽  
Physicochemical Properties ◽  
Direct Injection ◽  
Pharmacokinetic Analysis ◽  
Cellular Interactions ◽  
Systemic Delivery ◽  
Charged Peptides ◽  
Positively Charged

AbstractPeptides are used to control the pharmacokinetic profiles of nanoparticles due to their ability to influence tissue accumulation and cellular interactions. However, beyond the study of specific peptides, there is a lack of understanding of how peptide physicochemical properties affect nanoparticle pharmacokinetics, particularly in the context of traumatic brain injury (TBI). We engineered nanoparticle surfaces with peptides that possess a range of physicochemical properties and evaluated their distribution after two routes of administration: direct injection into a healthy mouse brain and systemic delivery in a mouse model of TBI. In both administration routes, we found that peptide-modified nanoparticle pharmacokinetics were influenced by the charge characteristics of the peptide. When peptide-modified nanoparticles are delivered directly into the brain, nanoparticles modified with positively charged peptides displayed restricted distribution from the injection site compared to nanoparticles modified with neutral, zwitterionic, or negatively charged peptides. After intravenous administration in a TBI mouse model, positively charged peptide-modified nanoparticles accumulated more in off-target organs, including the heart, lung, and kidneys, than zwitterionic, neutral, or negatively charged peptide-modified nanoparticles. The increase in off-target organ accumulation of positively charged peptide-modified nanoparticles was concomitant with a relative decrease in accumulation in the injured brain compared to zwitterionic, neutral, or negatively charged peptide-modified nanoparticles. Understanding how nanoparticle pharmacokinetics are influenced by the physicochemical properties of peptides presented on the nanoparticle surface is relevant to the development of nanoparticle-based TBI therapeutics and broadly applicable to nanotherapeutic design, including synthetic nanoparticles and viruses. Graphical abstract

Protamine-DNA interaction

1978 ◽  
Vol 36 (2) ◽  
pp. 200-201
Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer
Keyword(s):  
Small Volume ◽  
Double Helix ◽  
Dna Interaction ◽  
Dark Field ◽  
Sperm Head ◽  
Nuclear Proteins ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Dna Double Helix ◽  
Positively Charged

Dark field electron microscopy has been used for the study of the structure of individual macromolecules with a resolution to at least the 5Å level. The use of this technique has been extended to the investigation of structure of interacting molecules, particularly the interaction between DNA and fish protamine, a class of basic nuclear proteins of molecular weight 4,000 daltons.Protamine, which is synthesized during spermatogenesis, binds to chromatin, displaces the somatic histones and wraps up the DNA to fit into the small volume of the sperm head. It has been proposed that protamine, existing as an extended polypeptide, winds around the minor groove of the DNA double helix, with protamine's positively-charged arginines lining up with the negatively-charged phosphates of DNA. However, viewing protamine as an extended protein is inconsistent with the results obtained in our laboratory.

Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

1974 ◽  
Vol 32 ◽  
pp. 320-321
Author(s):  
J. P. Revel
Keyword(s):  
Developmental Stages ◽  
Three Dimensional ◽  
Cell Movement ◽  
Cellular Interactions ◽  
Serial Sections ◽  
Cell Sheets ◽  
Freeze Etching ◽  
Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

Ultrastructural modification of cellular interactions in cancer tumor

1978 ◽  
Vol 36 (2) ◽  
pp. 318-319
Author(s):  
N. P. Dmitrieva
Keyword(s):  
Cancer Cells ◽  
Human Thyroid ◽  
Adjacent Cell ◽  
Main Role ◽  
Cellular Interactions ◽  
Electron Microscopic ◽  
Cancer Tumor ◽  
Normal Human ◽  
Characteristic Features

One of the most characteristic features of cancer cells is their ability to metastasia. It is suggested that the modifications of the structure and properties of cancer cells surfaces play the main role in this process. The present work was aimed at finding out what ultrastructural features apear in tumor in vivo which removal of individual cancer cells from the cell population can provide. For this purpose the cellular interactions in the normal human thyroid and cancer tumor of this gland electron microscopic were studied. The tissues were fixed in osmium tetroxide and were embedded in Araldite-Epon.In normal human thyroid the most common type of intercellular contacts was represented by simple junction formed by the parallelalignment of adjacent cell membranees leaving in between an intermembranes space 15-20 nm filled with electronlucid material (Fig. 1a). Sometimes in the basal part of cells dilatations of the intercellular space 40-50 nm wide were found (Fig. 1a). Here the cell surfaces may form single short microvilli.

Structure and Interaction of Protamine by Dark Field Electron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 160-161
Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer
Keyword(s):  
Electron Microscopy ◽  
Dark Field ◽  
Amino Acid Sequences ◽  
Dimensional Structure ◽  
3 Dimensional ◽  
Field Electron ◽  
Proposed Model ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Positively Charged

It has been shown for some time that it is possible to obtain images of small unstained proteins, with a resolution of approximately 5Å using dark field electron microscopy (1,2). Applying this technique, we have observed a uniformity in size and shape of the 2-dimensional images of pure specimens of fish protamines (salmon, herring (clupeine, Y-l) and rainbow trout (Salmo irideus)). On the basis of these images, a model for the 3-dimensional structure of the fish protamines has been proposed (2).The known amino acid sequences of fish protamines show stretches of positively charged arginines, separated by regions of neutral amino acids (3). The proposed model for protamine structure (2) consists of an irregular, right-handed helix with the segments of adjacent arginines forming the loops of the coil.

Morphometric analysis of cellular interactions with the endothelium during the development of arterial lesions using Scanning Electron Microscopy and digital image analysis

1987 ◽  
Vol 45 ◽  
pp. 918-919
Author(s):  
M.E. Rosenfeld ◽  
C. Karboski ◽  
M.F. Prescott ◽  
P. Goodwin ◽  
R. Ross
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Quantitative Data ◽  
Digital Image Analysis ◽  
Lower Cost ◽  
Matched Control ◽  
Digital Analysis ◽  
Cellular Interactions ◽  
Arterial Lesions ◽  
Scanning Electron

Previous research documenting the chronology of the cellular interactions that occur on or below the surface of the endothelium during the initiation and progression of arterial lesions, primarily consisted of descriptive studies. The recent development of lower cost image analysis hardware and software has facilitated the collection of high resolution quantitative data from microscopic images. In this report we present preliminary quantitative data on the sequence of cellular interactions that occur on the endothelium during the initiation of atherosclerosis or vasculitis utilizing digital analysis of images obtained directly from the scanning electron microscope. Segments of both atherosclerotic and normal arteries were obtained from either diet-induced or endogenously (WHHL) hypercholesterolemic rabbits following 1-4 months duration of hypercholesterolemia and age matched control rabbits. Vasculitis was induced in rats following placement of an endotoxin soaked thread adjacent to the adventitial surface of arteries.

Enhanced type I photoreaction of indocyanine green via electrostatic-force-driven aggregation

Nanoscale ◽  
2020 ◽  
Vol 12 (17) ◽  
pp. 9517-9523 ◽  
Author(s):  
Huizhen Fan ◽  
Yu Fan ◽  
Wenna Du ◽  
Rui Cai ◽  
Xinshuang Gao ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Indocyanine Green ◽  
Electrostatic Force ◽  
Type I ◽  
Positively Charged

ICG forms aggregates in positively charged mesoporous silica, which show an enhanced type I photoreaction pathway.

Influence of nascent polypeptide positive charges on translation dynamics

2020 ◽  
Vol 477 (15) ◽  
pp. 2921-2934
Author(s):  
Rodrigo D. Requião ◽  
Géssica C. Barros ◽  
Tatiana Domitrovic ◽  
Fernando L. Palhano
Keyword(s):  
Mrna Decay ◽  
Translation Termination ◽  
Published Data ◽  
Translation Efficiency ◽  
Amino Acid Residues ◽  
High Concentration ◽  
Strong Argument ◽  
Translation Arrest ◽  
Exit Tunnel ◽  
Positively Charged

Protein segments with a high concentration of positively charged amino acid residues are often used in reporter constructs designed to activate ribosomal mRNA/protein decay pathways, such as those involving nonstop mRNA decay (NSD), no-go mRNA decay (NGD) and the ribosome quality control (RQC) complex. It has been proposed that the electrostatic interaction of the positively charged nascent peptide with the negatively charged ribosomal exit tunnel leads to translation arrest. When stalled long enough, the translation process is terminated with the degradation of the transcript and an incomplete protein. Although early experiments made a strong argument for this mechanism, other features associated with positively charged reporters, such as codon bias and mRNA and protein structure, have emerged as potent inducers of ribosome stalling. We carefully reviewed the published data on the protein and mRNA expression of artificial constructs with diverse compositions as assessed in different organisms. We concluded that, although polybasic sequences generally lead to lower translation efficiency, it appears that an aggravating factor, such as a nonoptimal codon composition, is necessary to cause translation termination events.

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