Ice templated nanocomposites containing rod-like hematite particles: Interplay between particle anisotropy and particle–matrix interactions

2020 ◽  
Vol 128 (3) ◽  
pp. 034702 ◽  
Author(s):  
Guruswamy Kumaraswamy ◽  
Karthika Suresh ◽  
Hisay Lama ◽  
Madivala G. Basavaraj ◽  
Dillip K. Satapathy
Author(s):  
Marc Lenburg ◽  
Rulang Jiang ◽  
Lengya Cheng ◽  
Laura Grabel

We are interested in defining the cell-cell and cell-matrix interactions that help direct the differentiation of extraembryonic endoderm in the peri-implantation mouse embryo. At the blastocyst stage the mouse embryo consists of an outer layer of trophectoderm surrounding the fluid-filled blastocoel cavity and an eccentrically located inner cell mass. On the free surface of the inner cell mass, facing the blastocoel cavity, a layer of primitive endoderm forms. Primitive endoderm then generates two distinct cell types; parietal endoderm (PE) which migrates along the inner surface of the trophectoderm and secretes large amounts of basement membrane components as well as tissue-type plasminogen activator (tPA), and visceral endoderm (VE), a columnar epithelial layer characterized by tight junctions, microvilli, and the synthesis and secretion of α-fetoprotein. As these events occur after implantation, we have turned to the F9 teratocarcinoma system as an in vitro model for examining the differentiation of these cell types. When F9 cells are treated in monolayer with retinoic acid plus cyclic-AMP, they differentiate into PE. In contrast, when F9 cells are treated in suspension with retinoic acid, they form embryoid bodies (EBs) which consist of an outer layer of VE and an inner core of undifferentiated stem cells. In addition, we have established that when VE containing embryoid bodies are plated on a fibronectin coated substrate, PE migrates onto the matrix and this interaction is inhibited by RGDS as well as antibodies directed against the β1 integrin subunit. This transition is accompanied by a significant increase in the level of tPA in the PE cells. Thus, the outgrowth system provides a spatially appropriate model for studying the differentiation and migration of PE from a VE precursor.


1997 ◽  
Vol 27 (1) ◽  
pp. 22-27
Author(s):  
K. GOLDRING ◽  
J. A. WARNER

2008 ◽  
Vol 31 (4) ◽  
pp. 23
Author(s):  
Rachel Vanderlaan ◽  
Rod Hardy ◽  
Golam Kabir ◽  
Peter Back ◽  
A J Pawson

Background: ShcA, a scaffolding protein, generates signalspecificity by docking to activated tyrosine kinases through distinct phosphotyrosine recognition motifs, while mediating signal complexity through formation of diverse downstream phosphotyrosine complexes. Mammalian ShcA encodes 3 isoforms having a modular architecture of a PTB domain and SH2 domain, separated by a CH1 region containing tyrosine phosphorylation sites important in Ras-MAPK activation. Objective and Methods: ShcA has a necessary role in cardiovascular development^1,2. However, the role of ShcA in the adult myocardium is largely unknown, also unclear, is how ShcA uses its signaling modules to mediate downstream signaling. To this end, cre/loxP technology was employed to generate a conditional ShcA allele series. The myocardial specific ShcA KO (ShcA CKO) and myocardial restricted domain mutant KI mice were generated using cre expressed from the mlc2v locus^3 coupled with the ShcA floxed allele and in combination with the individual ShcA domain mutant KI alleles^2. Results: ShcACKO mice develop a dilated cardiomyopathy phenotype by 3 months of life, typified by depressed cardiac function and enlarged chamber dimensions. Isolated cardiomyocytes from ShcA CKO mice have preserved contractility indicating an uncoupling between global heart function and single myocyte contractile mechanics. Force-length experiments suggest that the loss of shcAmediates the uncoupling through deregulation of extracellular matrix interactions. Subsequent, analysis of the ShcA myocardial restricted domain mutant KImice suggests that ShcA requires PTB domain docking to upstream tyrosine kinases and subsequent phosphorylation of the CH1 tyrosines important for downstream signaling. Conclusion: ShcA is required for proper maintenance of cardiac function, possibly regulation of extracellular matrix interactions. References: 1. Lai KV, Pawson AJ. The ShcA phosphotyrosine docking protein sensitizescardiovascular signaling in the mouse embryo. Genes and Dev 2000;14:1132-45. 2. Hardy WR. et al. Combinatorial ShcA docking interactions supportdiversity in tissue morphogenesis. Science2007;317:251-6. 3.Minamisawa, s. et al. A post-transcriptional compensatory pathway inheterozygous ventricular myosin light chain 2-deficient mice results in lack ofgene dosage effect during normal cardiac growth or hypertrophy. J Biol Chem 1999;274:10066-70.


1995 ◽  
Vol 50 (4) ◽  
pp. 551-571 ◽  
Author(s):  
G. Mensitieri ◽  
M. A. Del Nobile ◽  
A. Apicella ◽  
L. Nicolais

Author(s):  
Jonas F. Eichinger ◽  
Maximilian J. Grill ◽  
Iman Davoodi Kermani ◽  
Roland C. Aydin ◽  
Wolfgang A. Wall ◽  
...  

AbstractLiving soft tissues appear to promote the development and maintenance of a preferred mechanical state within a defined tolerance around a so-called set point. This phenomenon is often referred to as mechanical homeostasis. In contradiction to the prominent role of mechanical homeostasis in various (patho)physiological processes, its underlying micromechanical mechanisms acting on the level of individual cells and fibers remain poorly understood, especially how these mechanisms on the microscale lead to what we macroscopically call mechanical homeostasis. Here, we present a novel computational framework based on the finite element method that is constructed bottom up, that is, it models key mechanobiological mechanisms such as actin cytoskeleton contraction and molecular clutch behavior of individual cells interacting with a reconstructed three-dimensional extracellular fiber matrix. The framework reproduces many experimental observations regarding mechanical homeostasis on short time scales (hours), in which the deposition and degradation of extracellular matrix can largely be neglected. This model can serve as a systematic tool for future in silico studies of the origin of the numerous still unexplained experimental observations about mechanical homeostasis.


Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 21
Author(s):  
Brigitte Altmann ◽  
Christoph Grün ◽  
Cordula Nies ◽  
Eric Gottwald

In this second part of our systematic review on the research area of 3D cell culture in micro-bioreactors we give a detailed description of the published work with regard to the existing micro-bioreactor types and their applications, and highlight important results gathered with the respective systems. As an interesting detail, we found that micro-bioreactors have already been used in SARS-CoV research prior to the SARS-CoV2 pandemic. As our literature research revealed a variety of 3D cell culture configurations in the examined bioreactor systems, we defined in review part one “complexity levels” by means of the corresponding 3D cell culture techniques applied in the systems. The definition of the complexity is thereby based on the knowledge that the spatial distribution of cell-extracellular matrix interactions and the spatial distribution of homologous and heterologous cell–cell contacts play an important role in modulating cell functions. Because at least one of these parameters can be assigned to the 3D cell culture techniques discussed in the present review, we structured the studies according to the complexity levels applied in the MBR systems.


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