626 Experiments in vitro on behavior and deformability of RBC in Microchannel : Effect of its Deformability on Shape Recovery Process

2006 ◽  
Vol 2006.5 (0) ◽  
pp. 173-174
Author(s):  
Takaya OHNO ◽  
Chihiro SAKAKIBARA ◽  
Tsutomu TAJIKAWA ◽  
Kenkichi OHBA
Keyword(s):  
Shape Recovery ◽  
Recovery Process

scholarly journals Cell membrane shape control--effects of chloromethyl ketone peptides

Blood ◽  
1984 ◽  
Vol 63 (5) ◽  
pp. 1203-1208 ◽  
Author(s):  
E Alhanaty ◽  
MP Sheetz
Keyword(s):  
Shape Control ◽  
Shape Recovery ◽  
Cultured Cells ◽  
Shape Change ◽  
Lactic Acid Production ◽  
Recovery Process ◽  
Chloromethyl Ketone ◽  
Membrane Shape

Abstract The shape of the human erythrocyte is normally maintained in vivo as a biconcave disc for 120 days. In vitro, the cell shape can be altered readily by amphipathic compounds; however, given time and an energy source, the cells can recover the discoid morphology. An active shape control mechanism is postulated to regulate erythrocyte shape. The shape recovery process is a necessary element in reversing perturbations of shape and is basic to our understanding of how membrane shape is altered. We report here that the process of shape recovery from crenation is dramatically accelerated upon pretreatment of the cells with micromolar (20–100 microM) concentrations of chloromethyl ketone peptides [such as N-alpha-tosyl-L-phenylalanine- chloromethyl ketone (tos-pheCH2Cl)]. Such pretreatments do not appear to affect cellular viability, as judged by their normal biconcave disc shape, their sensitivity to crenators, their lactic acid production, or the ATP-dependent shape change of the purified membranes. Treatment with high concentrations of tos-pheCH2Cl does cause normal cells to become stomatocytic by an energy-requiring process, i.e., it requires glucose, incubation at 37 degrees C, and will not occur in ATP-depleted cells. We suggest that the chloromethyl ketone peptides affect a metabolic process that is associated with the hexose monophosphate (HMP) shunt. Through the alteration of the HMP shunt metabolism, they modify an active stomatocytic process in the erythrocyte that can correct for the perturbation caused by crenators. Implications of these findings for analogous phenomena in cultured cells are discussed.

scholarly journals Cell membrane shape control--effects of chloromethyl ketone peptides

Blood ◽  
1984 ◽  
Vol 63 (5) ◽  
pp. 1203-1208
Author(s):  
E Alhanaty ◽  
MP Sheetz
Keyword(s):  
Shape Control ◽  
Shape Recovery ◽  
Cultured Cells ◽  
Shape Change ◽  
Lactic Acid Production ◽  
Recovery Process ◽  
Chloromethyl Ketone ◽  
Membrane Shape

The shape of the human erythrocyte is normally maintained in vivo as a biconcave disc for 120 days. In vitro, the cell shape can be altered readily by amphipathic compounds; however, given time and an energy source, the cells can recover the discoid morphology. An active shape control mechanism is postulated to regulate erythrocyte shape. The shape recovery process is a necessary element in reversing perturbations of shape and is basic to our understanding of how membrane shape is altered. We report here that the process of shape recovery from crenation is dramatically accelerated upon pretreatment of the cells with micromolar (20–100 microM) concentrations of chloromethyl ketone peptides [such as N-alpha-tosyl-L-phenylalanine- chloromethyl ketone (tos-pheCH2Cl)]. Such pretreatments do not appear to affect cellular viability, as judged by their normal biconcave disc shape, their sensitivity to crenators, their lactic acid production, or the ATP-dependent shape change of the purified membranes. Treatment with high concentrations of tos-pheCH2Cl does cause normal cells to become stomatocytic by an energy-requiring process, i.e., it requires glucose, incubation at 37 degrees C, and will not occur in ATP-depleted cells. We suggest that the chloromethyl ketone peptides affect a metabolic process that is associated with the hexose monophosphate (HMP) shunt. Through the alteration of the HMP shunt metabolism, they modify an active stomatocytic process in the erythrocyte that can correct for the perturbation caused by crenators. Implications of these findings for analogous phenomena in cultured cells are discussed.

Investigate of Electrical Conductivity of Shape-Memory Polymer Filled with Carbon Black

2008 ◽  
Vol 47-50 ◽  
pp. 714-717 ◽  
Author(s):  
Xin Lan ◽  
Jin Song Leng ◽  
Yan Ju Liu ◽  
Shan Yi Du
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Shape Memory ◽  
Shape Recovery ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Recovery Process ◽  
Thermomechanical Properties ◽  
Electrically Conductive ◽  
New System

A new system of thermoset styrene-based shape-memory polymer (SMP) filled with carbon black (CB) is investigated. To realize the electroactive stimuli of SMP, the electrical conductivity of SMP filled with various amounts of CB is characterized. The percolation threshold of electrically conductive SMP filled with CB is about 3% (volume fraction of CB), which is much lower than many other electrically conductive polymers. When applying a voltage of 30V, the shape recovery process of SMP/CB(10 vol%) can be realized in about 100s. In addition, the thermomechanical properties are also characterized by differential scanning calorimetery (DSC).

scholarly journals Degradable Poly(ether-ester-urethane)s Based on Well-Defined Aliphatic Diurethane Diisocyanate with Excellent Shape Recovery Properties at Body Temperature for Biomedical Application

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1002 ◽  
Author(s):  
Minghui Xiao ◽  
Na Zhang ◽  
Jie Zhuang ◽  
Yuchen Sun ◽  
Fang Ren ◽  
...  
Keyword(s):  
Body Temperature ◽  
Shape Memory ◽  
Tensile Properties ◽  
Shape Recovery ◽  
Biomedical Application ◽  
Degradation Products ◽  
Chain Extension ◽  
Chemical Structures ◽  
Ether Ester

The aim of this study is to offer a new class of degradable shape-memory poly(ether-ester-urethane)s (SMPEEUs) based on poly(ether-ester) (PECL) and well-defined aliphatic diurethane diisocyanate (HBH) for further biomedical application. The prepolymers of PECLs were synthesized through bulk ring-opening polymerization using ε-caprolactone as the monomer and poly(ethylene glycol) as the initiator. By chain extension of PECL with HBH, SMPEEUs with varying PEG content were prepared. The chemical structures of the prepolymers and products were characterized by GPC, 1H NMR, and FT-IR, and the effect of PEG content on the physicochemical properties (especially the shape recovery properties) of SMPEEUs was studied. The microsphase-separated structures of the SMPEEUs were demonstrated by DSC and XRD. The SMPEEU films exhibited good tensile properties with the strain at a break of 483%–956% and an ultimate stress of 23.1–9.0 MPa. Hydrolytic degradation in vitro studies indicated that the time of the SMPEEU films becoming fragments was 4–12 weeks and the introduction of PEG facilitates the degradation rate of the films. The shape memory properties studies found that SMPEEU films with a PEG content of 23.4 wt % displayed excellent recovery properties with a recovery ratio of 99.8% and a recovery time of 3.9 s at body temperature. In addition, the relative growth rates of the SMPEEU films were greater than 75% after incubation for 72 h, indicating good cytocompatibility in vitro. The SMPEEUs, which possess not only satisfactory tensile properties, degradability, nontoxic degradation products, and cytocompatibility, but also excellent shape recovery properties at body temperature, promised to be an excellent candidate for medical device applications.

scholarly journals IL-33 promotes recovery from acute colitis by inducing miR-320 to stimulate epithelial restitution and repair

2018 ◽  
Vol 115 (40) ◽  
pp. E9362-E9370 ◽  
Author(s):  
Loris R. Lopetuso ◽  
Carlo De Salvo ◽  
Luca Pastorelli ◽  
Nitish Rana ◽  
Henry N. Senkfor ◽  
...  
Keyword(s):  
Recovery Period ◽  
Recovery Process ◽  
Mucosal Healing ◽  
Normal Function ◽  
Intestinal Epithelial ◽  
In Vitro Proliferation ◽  
Resolution Of Inflammation ◽  
Epithelial Barrier Function ◽  
Epithelial Restitution

Defective and/or delayed wound healing has been implicated in the pathogenesis of several chronic inflammatory disorders, including inflammatory bowel disease (IBD). The resolution of inflammation is particularly important in mucosal organs, such as the gut, where restoration of epithelial barrier function is critical to reestablish homeostasis with the interfacing microenvironment. Although IL-33 and its receptor ST2/ILRL1 are known to be increased and associated with IBD, studies using animal models of colitis to address the mechanism have yielded ambiguous results, suggesting both pathogenic and protective functions. Unlike those previously published studies, we focused on the functional role of IL-33/ST2 during an extended (2-wk) recovery period after initial challenge in dextran sodium sulfate (DSS)-induced colitic mice. Our results show that during acute, resolving colitis the normal function of endogenous IL-33 is protection, and the lack of either IL-33 or ST2 impedes the overall recovery process, while exogenous IL-33 administration during recovery dramatically accelerates epithelial restitution and repair, with concomitant improvement of colonic inflammation. Mechanistically, we show that IL-33 stimulates the expression of a network of microRNAs (miRs) in the Caco2 colonic intestinal epithelial cell (IEC) line, especially miR-320, which is increased by >16-fold in IECs isolated from IL-33–treated vs. vehicle-treated DSS colitic mice. Finally, IL-33–dependent in vitro proliferation and wound closure of Caco-2 IECs is significantly abrogated after specific inhibition of miR-320A. Together, our data indicate that during acute, resolving colitis, IL-33/ST2 plays a crucial role in gut mucosal healing by inducing epithelial-derived miR-320 that promotes epithelial repair/restitution and the resolution of inflammation.

Programmable Shape Recovery Process of Water-Responsive Shape-Memory Poly(vinyl alcohol) by Wettability Contrast Strategy

2017 ◽  
Vol 9 (6) ◽  
pp. 5495-5502 ◽  
Author(s):  
Zhiqiang Fang ◽  
Yudi Kuang ◽  
Panpan Zhou ◽  
Siyi Ming ◽  
Penghui Zhu ◽  
...  
Keyword(s):  
Shape Memory ◽  
Vinyl Alcohol ◽  
Shape Recovery ◽  
Recovery Process ◽  
Poly Vinyl Alcohol

scholarly journals The disassembly and reassembly of functional centrosomes in vitro

1998 ◽  
Vol 95 (16) ◽  
pp. 9295-9300 ◽  
Author(s):  
Bradley J. Schnackenberg ◽  
Alexey Khodjakov ◽  
Conly L. Rieder ◽  
Robert E. Palazzo
Keyword(s):  
Divalent Cations ◽  
Three Dimensional ◽  
Recovery Process ◽  
Animal Cells ◽  
Microtubule Nucleation ◽  
Independent Manner ◽  
Cellular Processes ◽  
Ring Structures ◽  
Pericentriolar Material

Animal cells contain a single centrosome that nucleates and organizes a polarized array of microtubules which functions in many cellular processes. In most cells the centrosome is composed of two centrioles surrounded by an ill-defined “cloud” of pericentriolar material. Recently, γ-tubulin-containing 25-nm diameter ring structures have been identified as likely microtubule nucleation sites within the pericentriolar material of isolated centrosomes. Here we demonstrate that when Spisula centrosomes are extracted with 1.0 M KI they lose their microtubule nucleation potential and appear by three-dimensional electron microscopy as a complex lattice, built from 12- to 15-nm thick elementary fiber(s), that lack centrioles and 25-nm rings. Importantly, when these remnants are incubated in extracts prepared from Spisula oocytes they recover their 25-nm rings, γ-tubulin, and microtubule nucleation potential. This recovery process occurs in the absence of microtubules, divalent cations, and nucleotides. Thus, in animals the centrosome is structurally organized around a KI-insoluble filament-based “centromatrix” that serves as a scaffold to which those proteins required for microtubule nucleation bind, either directly or indirectly, in a divalent cation and nucleotide independent manner.

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