The Maximum Matrix Contraction Problem

Author(s):  
Dimitri Watel ◽  
Pierre-Louis Poirion
Keyword(s):  
2004 ◽  
Vol 45 (4) ◽  
pp. 1109 ◽  
Author(s):  
Qian Garrett ◽  
Peng T. Khaw ◽  
Timothy D. Blalock ◽  
Gregory S. Schultz ◽  
Gary R. Grotendorst ◽  
...  

2017 ◽  
Vol 164 ◽  
pp. 90-94 ◽  
Author(s):  
Rintaro Tsukahara ◽  
Kazuhiko Umazume ◽  
Kevin McDonald ◽  
Henry J. Kaplan ◽  
Shigeo Tamiya

1991 ◽  
Vol 98 (4) ◽  
pp. 771-790 ◽  
Author(s):  
M J Curran ◽  
M S Brodwick

Isolated matrices of the giant secretory vesicles of mast cells of the beige mouse were reliably produced by the osmotic lysis of isolated vesicles. These matrices maintained their form, and their sizes were easily measured using Nomarski optics. The size of the matrix depended on the ionic composition of the bathing solution. The physiologically relevant ions, histamine and serotonin, contracted the matrix. Multivalent cations condensed the matrix relative to univalents. Ag+, acid pH (below 5), and basic pH (above 9) expanded the matrix. In the presence of 10 mM histamine, lowering the pH from 9 to 5 contracted the matrix more than can be attributed to the pH-dependent matrix contraction in zero histamine. The nontitratable organic cation, dimethonium, contracts the matrix with little effect of pH in the range of 5-9. These results suggest that histamine acts as a matrix contractor in the divalent form. The dose-response (contraction) relation for histamine was gradual from micromolar to 316 mM (millimolar) histamine. Experiments with mixtures of histamine and sodium show antagonistic effects on the matrix but are inconsistent with either a model where ions compete for identical sites or a parallel model where ions interact with separate independent sites. In vigorous histamine washoff experiments, the half time for vesicle expansion in 10(-4) M pH buffer was approximately 4 s; in isotonic NaCl solution, it was 0.5 s. When 1 M histamine was presented to closely apposed matrices, fusion resulted. The matrix material returned to its initial shape after being mechanically deformed with a glass probe. These results suggest that the matrix size is controlled by its ion exchange properties. The matrix expansion can quantitatively account for the vesicular size increase observed upon exocytosis (as a postfusional event) and the osmotic nonideality of intact vesicles. The mechanical expansion is probably significant in the widening of the exocytotic pore and the dispersal of the vesicular contents.


2017 ◽  
Vol 31 (6) ◽  
pp. 357-363 ◽  
Author(s):  
Ti-Young Um ◽  
Seoung-Ae Lee ◽  
Joo-Hoo Park ◽  
Jae-Min Shin ◽  
Il-Ho Park ◽  
...  

Purpose Activation of adenosine monophosphate-activated protein kinase (AMPK) by metformin, as a master regulator of metabolism, is involved in airway tissue remodeling. Here, we investigated the physical role of AMPK on cell migration, matrix contraction, and the production of matrix metalloproteinases (MMP) in nasal polyp–derived fibroblasts (NPDF). Methods Primary NPDFs from six patients with chronic rhinosinusitis and nasal polyps were isolated and cultured. To assess the effect of AMPK on fibroblast migration, we conducted scratch and migration assays in NPDF treated with metformin and/or compound C. A collagen gel contraction assay measured activity of contractile. MMP expression was measured with reverse transcription-polymerase chain reaction, Western blot, and zymography. To evaluate for specific AMPK action, we examined by AMPK small interfering RNA. Results Metformin, an activator of AMPK, significantly inhibited cell migration in NPDFs in a dose-dependent manner. Compound C, an inhibitor of AMPK, partially reversed the inhibitory effect of metformin. Metformin also significantly decreased contractile activity, with a concomitant reduction in the production of MMP-1 and MMP-2 but not of MMP-9. Specific silencing that targeted AMPK resulted in the enhancement of mobility and contractility and in the production of MMP-1 and MMP-2. Conclusion AMPK played an important role in regulating cell migration, matrix contraction, and MMP production in NPDFs, which provided data that AMPK activator might be a therapeutic target for the prevention of tissue remodeling in nasal polyps.


1973 ◽  
Vol 74 (1) ◽  
pp. 149-160 ◽  
Author(s):  
J. A. de Wet

In two previous papers (1, 2) representations of the unitary groups U4, U2 were found which described some of the properties of nucleons and electrons. In particular, the many electron wave functions were constructed from the irreducible representations of U2 restricted to the proper orthochronous Lorentz group Lp. In this paper the irreducible representations of U4 found in (1) will be shown to be also irreducible representations of the complete homogeneous Lorentz group L0 and the techniques of matrix contraction employed in (2) will be used to find the precise form of the matrices of the infinitesimal ring.


2012 ◽  
Vol 73 (1-4) ◽  
pp. 414-419 ◽  
Author(s):  
Peter D. Ngo ◽  
R. John MacLeod ◽  
Vince Mukkada ◽  
Razan Turki ◽  
Glenn T. Furuta

1994 ◽  
Vol 28 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Lynn L. H. Huang-Lee ◽  
Julia H. Wu ◽  
Marcel E. Nimni
Keyword(s):  

2006 ◽  
Vol 25 (8) ◽  
pp. 515-522 ◽  
Author(s):  
Agnes D. Berendsen ◽  
Antonius L.J.J. Bronckers ◽  
Theo H. Smit ◽  
X. Frank Walboomers ◽  
Vincent Everts

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