scholarly journals TEMPO-Oxidized Cellulose Hydrogel Fiber Cell Load, a Cell Support System Proof of Concept 

2021 ◽  
Author(s):  
Mariana Alves Rios ◽  
Paula Aboud Barbugli ◽  
Mônica Rosas Costa Iemma ◽  
Rafael Grande ◽  
Antônio José Felix Carvalho ◽  
...  
Keyword(s):  
Cellulose Nanofibers ◽  
Oxidized Cellulose ◽  
Cell Carrier ◽  
Cellulose Hydrogel ◽  
A Cell ◽  
Carrier Cell ◽  
Cell Carriers ◽  
Cell Support

Abstract The development of new cell carriers systems are crucial for application in regenerative medicine, once they deliver the cells to the injured tissue to trigger the repair and stimulate the regeneration of the new tissue, and so far various carrier systems have been investigated in this regard. Here we report on the synthesis and characterization of a new cell carrier system in fiber shape where the cells osteo-1 are incorporated into the oxidized cellulose nanofibers suspension and then complexed with calcium ions in a pulling process giving rise to the fiber loaded with cells. The microscopic images showed the success of the proposed method to incorporate the cells into the fibers. The results of the in-vitro viability tests indicated the capability of the fibers to keep the cells alive and to mineralize them, indicating that their osteogenic capability was not affected. In addition, the fiber disintegration studies showed the system is capable of releasing the cells, suggesting the potential of the fibers as a new assembled hydrogel carrier cell therapy.

TEMPO-oxidized cellulose poly-ionic drawn fiber, a cell support system proof of concept

2021 ◽  
Author(s):  
Mariana Alves Rios ◽  
Paula Aboud Barbugli ◽  
Mônica Rosas Costa Iemma ◽  
Rafael Grande ◽  
Antônio José Felix Carvalho ◽  
...  
Keyword(s):  
Support System ◽  
Oxidized Cellulose ◽  
Proof Of Concept ◽  
A Cell ◽  
Cell Support

Non-oxidized cellulose nanofibers as a topical hemostat: in vitro thromboelastometry studies of structure vs function

2021 ◽  
pp. 118043
Author(s):  
Elmira Mohamed ◽  
Lucy A. Coupland ◽  
Philip J. Crispin ◽  
Ailene Fitzgerald ◽  
David R. Nisbet ◽  
...  
Keyword(s):  
Cellulose Nanofibers ◽  
Oxidized Cellulose

A somatic cell-derived system for studying both early and late mitotic events in vitro

1989 ◽  
Vol 94 (3) ◽  
pp. 449-462
Author(s):  
J. Nakagawa ◽  
G.T. Kitten ◽  
E.A. Nigg
Keyword(s):  
Chromatin Condensation ◽  
Nuclear Lamina ◽  
Free System ◽  
Cell Free System ◽  
Protein Substrates ◽  
Nuclear Envelope Breakdown ◽  
Biochemical Fractionation ◽  
A Cell

We describe a cell-free system for studying mitotic reorganization of nuclear structure. The system utilizes soluble extracts prepared from metaphase-arrested somatic chicken cells and supports both the disassembly and subsequent partial reassembly of exogenous nuclei. By fluorescence microscopy, biochemical fractionation, protein phosphorylation assays and electron microscopy, we show that chicken embryonic nuclei incubated in extracts prepared from metaphase-arrested chicken hepatoma cells undergo nuclear envelope breakdown, lamina depolymerization and chromatin condensation. These prophase-like events are strictly dependent on ATP and do not occur when nuclei are incubated in interphase extracts. Compared to interphase extracts, metaphase extracts show increased kinase activities toward a number of nuclear protein substrates, including lamins and histone H1; moreover, they specifically contain four soluble phosphoproteins of Mr 38,000, 75,000, 95,000 and 165,000. Following disassembly of exogenous nuclei in metaphase extracts, telophase-like reassembly of a nuclear lamina and re-formation of nuclear membranes around condensed chromatin can be induced by depletion of ATP from the extract. We anticipate that this reversible cell-free system will contribute to the identification and characterization of factors involved in regulatory and mechanistic aspects of mitosis.

scholarly journals A cell-free framework for biological systems engineering

2015 ◽  
Author(s):  
Henrike Niederholtmeyer ◽  
Zachary Sun ◽  
Yutaka Hori ◽  
Enoch Yeung ◽  
Amanda Verpoorte ◽  
...  
Keyword(s):  
Negative Feedback ◽  
Biological Systems ◽  
Biological Engineering ◽  
Free System ◽  
Node Negative ◽  
A Cell ◽  
Free Environment ◽  
Synthetic Networks

While complex dynamic biological networks control gene expression and metabolism in all living organisms, engineering comparable synthetic networks remains challenging1,2. Conducting extensive, quantitative and rapid characterization during the design and implementation process of synthetic networks is currently severely limited due to cumbersome molecular cloning and the difficulties associated with measuring parts, components and systems in cellular hosts. Engineering gene networks in a cell-free environment promises to be an efficient and effective approach to rapidly develop novel biological systems and understand their operating regimes3-5. However, it remains questionable whether complex synthetic networks behave similarly in cells and a cell-free environment, which is critical for in vitro approaches to be of significance to biological engineering. Here we show that synthetic dynamic networks can be readily implemented, characterized, and engineered in a cell-free framework and consequently transferred to cellular hosts. We implemented and characterized the “repressilator”6, a three-node negative feedback oscillator in vitro. We then used our cell-free framework to engineer novel three-node, four-node, and five-node negative feedback architectures going from the characterization of circuit components to the rapid analysis of complete networks. We validated our cell-free approach by transferring these novel three-node and five-node oscillators to Escherichia coli, resulting in robust and synchronized oscillations reflecting the in vitro observation. We demonstrate that comprehensive circuit engineering can be performed in a cell-free system and that the in vitro results have direct applicability in vivo. Cell-free synthetic biology thus has the potential to drastically speed up design-build-test cycles in biological engineering and enable the quantitative characterization of synthetic and natural networks.

Scanning Studies of Cell Surfaces

1973 ◽  
Vol 31 ◽  
pp. 608-609
Author(s):  
Virginia Fonte ◽  
Nancy Weller ◽  
Keith R. Porter
Keyword(s):  
Cell Cycle ◽  
Structural Organization ◽  
Cell Surfaces ◽  
Detailed Characterization ◽  
A Cell ◽  
Relationship Of ◽  
The Relationship ◽  
Scanning Electron

The surfaces of a cell in its topography and anti-genicity expresses subtle variations in the effective genome, as well as the physiology and structural organization of the underlying cytoplasm. Understanding the relationship of these various factors to the surface depends in part on obtaining a detailed characterization of the topography of cells and how this topography changes with phases in the cell cycle, with transformation to malignancy and with the cell's response to such physiologically active agents as cyclic AMP.We have therefore explored the usefulness of the scanning electron microscope in investigations of the cell's topography. Cells grown under favourable in vitro conditions have been fixed in glutaraldehyde, dehydrated in acetone and dried by the critical point method of Anderson.

Disassembly of the Drosophila nuclear lamina in a homologous cell-free system

1995 ◽  
Vol 108 (5) ◽  
pp. 2027-2035 ◽  
Author(s):  
N. Maus ◽  
N. Stuurman ◽  
P.A. Fisher
Keyword(s):  
Nuclear Lamina ◽  
Meiotic Metaphase ◽  
Two Dimensional ◽  
Cell Free Extract ◽  
Free System ◽  
Nuclear Lamin ◽  
A Cell

Stage 14 Drosophila oocytes are arrested in first meiotic metaphase. A cell-free extract of these oocytes catalyzes apparent disassembly of purified Drosophila nuclei as well as of nuclear lamin polymers formed in vitro from isolated interphase lamins. Biochemically, the oocyte extract catalyzes lamin solubilization and phosphorylation as well as characteristic changes in one- and two-dimensional gel mobility. A previously unidentified soluble lamin isoform is easily seen after in vitro disassembly. This isoform is detectable but present only in very small quantities in vivo and is apparently derived specifically from one of the two interphase lamin isoforms. Cell-free nuclear lamina disassembly is ATP-dependent and addition of calcium to extracts blocks disassembly as judged both morphologically and biochemically. This system will allow enzymological characterization of cell-free lamina disassembly as well as molecular analysis of specific Drosophila mutants.

scholarly journals Anti-HIV Activity of MDL 74968, a Novel Acyclonucleotide Derivative of Guanine: Drug Resistance and Drug Combination Effects in Vitro

1996 ◽  
Vol 7 (5) ◽  
pp. 253-260 ◽  
Author(s):  
D.L. Taylor ◽  
S.P. Ahmed ◽  
T.M. Brennan ◽  
J.-F. Navé ◽  
P. Casara ◽  
...  
Keyword(s):  
Nucleoside Analogues ◽  
Drug Resistant ◽  
Cell Viability Assay ◽  
Viability Assay ◽  
Immunodeficiency Virus ◽  
A Cell ◽  
Experimental Protocols ◽  
Hiv 1

MDL 74968 (9-[2-methylidene-3-(phosphonomethoxy)-propyl]guanine), a novel acyclonucleotide derivative of guanine, inhibited human immunodeficiency virus type 1 (HIV-1) replication in vitro with activity comparable to that of adefovir (PMEA; 9-(2-phosphonomethoxyethyl)adenine). MDL 74968 was investigated in combination with two licensed nucleoside analogues, zidovudine and didanosine, using a cell viability assay, and drug interactions were evaluated by the isobologram technique, by calculating combination indices and by the MacSynergy™ program. Inhibition of HIV-1 replication was only additive in both cases. MDL 74968 had equivalent antiviral activity against strains of HIV-1 HXB2 engineered to have mutations which conferred resistance to the nucleoside analogues lamivudine, didanosine and zidovudine and the non-nucleoside inhibitor of reverse transcriptase (RT) nevirapine, as against the wild type strain. Continued passage of HIV-1 RF in C8166 cells in the presence of MDL 74968 for 5 months (30 passages) failed to select drug resistant mutants. Continued passage of virus in the presence of the same concentration of adefovir for the same length of time selected a virus in a single culture, which was 3-fold resistant to adefovir and cross-resistant to MDL 74968. Genotypic characterization of this virus revealed a lysine to arginine exchange (AAA to AGA) at position 65 in the RT gene. This virus was not cross-resistant to either zidovudine or nevirapine but showed reduced sensitivity to zalcitabine, didanosine and lamivudine. Continued passage of HIV-1 RF in the presence of nevirapine or zidovudine, using similar experimental protocols selected drug resistant viruses after eight and 17 passages, respectively, but these viruses remained sensitive to adefovir and MDL 74968.

Characterization of an insect ferritin subunit synthesized in a cell-free system

1990 ◽  
Vol 68 (7-8) ◽  
pp. 1005-1011 ◽  
Author(s):  
C. A. Ketola-Pirie
Keyword(s):  
Molecular Mass ◽  
Proteinase K ◽  
Translation Product ◽  
Western Blots ◽  
Free System ◽  
Cell Free System ◽  
A Cell ◽  
Vacuolar System

Ferritin, an iron-sequestering and -binding protein, is localized to the vacuolar system in Calpodes ethlius larvae. The amount of iron-loaded ferritin in intact larval midgut can be increased by pretreatment with iron. When poly(A)+ RNA from control or iron-treated larvae was translated in vitro, a 24 kilodalton (kDa) protein was a major translation product. If the cell-free system was supplemented with dog pancreatic microsomes, the 24-kDa protein was not detectable: the major translation product was 28–30 kDa. The 24-kDa and 28- to 30-kDa proteins were identified as ferritin subunits by immunoprecipitation with anti-Manduca ferritin antibodies. Proteinase K digestion of the translation products showed that the 28- to 30-kDa subunit was targeted into the lumen of, and protected by, the microsomes. The change in molecular mass of the ferritin monomer was attributed to glycosylation of the 24-kDa subunit within the lumen of the microsomes. This was demonstrated by (i) the ability of the 28- to 30-kDa subunit, but not the 24-kDa subunit, to bind concanavalin A on Western blots and (ii) inhibition of the change in molecular mass from 24 to 28–30 kDa if tunicamycin is added to the microsomes. The results indicate that the Calpodes ferritin subunit was synthesized, targeted to microsomes, and glycosylated within their lumen in a rabbit reticulocyte cell-free system primed with midgut poly(A)+ RNA extracted from control or iron-treated larvae.Key words: insect ferritin, cell-free synthesis, glycosylation.

scholarly journals Spindle assembly in egg extracts of the Marsabit clawed frog, Xenopus borealis

2018 ◽  
Author(s):  
Maiko Kitaoka ◽  
Rebecca Heald ◽  
Romain Gibeaux
Keyword(s):  
Spindle Assembly ◽  
Morphometric Variation ◽  
Free System ◽  
Egg Extract ◽  
Egg Extracts ◽  
A Cell ◽  
Clawed Frog ◽  
Xenopus Borealis

ABSTRACTEgg extracts of the African clawed frog Xenopus laevis have provided a cell-free system instrumental in elucidating events of the cell cycle, including mechanisms of spindle assembly. Comparison with extracts from the diploid Western clawed frog, Xenopus tropicalis, which is smaller at the organism, cellular and subcellular levels, has enabled the identification of spindle size scaling factors. We set out to characterize the Marsabit clawed frog, Xenopus borealis, which is intermediate in size between the two species, but more recently diverged in evolution from X. laevis than X. tropicalis. X. borealis eggs were slightly smaller than those of X. laevis, and slightly smaller spindles were assembled in egg extracts. Interestingly, microtubule distribution across the length of the X. borealis spindles differed from both X. laevis and X. tropicalis. Extract mixing experiments revealed common scaling phenomena among Xenopus species, while characterization of spindle factors katanin, TPX2, and Ran indicate that X. borealis spindles possess both X. laevis and X. tropicalis features. Thus, X. borealis egg extract provides a third in vitro system to investigate interspecies scaling and spindle morphometric variation.

scholarly journals Amiodarone and Bepridil Inhibit Anthrax Toxin Entry into Host Cells

2007 ◽  
Vol 51 (7) ◽  
pp. 2403-2411 ◽  
Author(s):  
Ana M. Sanchez ◽  
Diane Thomas ◽  
Eugene J. Gillespie ◽  
Robert Damoiseaux ◽  
Joseph Rogers ◽  
...  
Keyword(s):  
Small Molecules ◽  
Lethal Toxin ◽  
Host Cells ◽  
Anthrax Lethal Toxin ◽  
Raw 264.7 Macrophages ◽  
Endosomal Acidification ◽  
A Cell

ABSTRACT Anthrax lethal toxin is one of the fundamental components believed to be responsible for the virulence of Bacillus anthracis. In order to find novel compounds with anti-lethal toxin properties, we used a cell-based assay to screen a collection of approximately 500 small molecules. Nineteen compounds that blocked lethal toxin-mediated killing of RAW 264.7 macrophages were identified, and we report here on the characterization of the two most potent antitoxic compounds, amiodarone and bepridil. These drugs are used to treat cardiac arrhythmia or angina in humans at doses similar to those that provide protection against lethal toxin in vitro. Our results support a model whereby the antitoxic properties of both drugs result from their ability to block endosomal acidification, thereby blocking toxin entry. Amiodarone was tested in vivo and found to significantly increase survival of lethal toxin-challenged Fischer rats.

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