scholarly journals Neovascularization of poly(ether ester) block-copolymer scaffoldsin vivo: Long-term investigations using intravital fluorescent microscopy

2003 ◽  
Vol 68A (1) ◽  
pp. 10-18 ◽  
Author(s):  
Daniel Druecke ◽  
Stefan Langer ◽  
Evert Lamme ◽  
Jeroen Pieper ◽  
Marija Ugarkovic ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Fluorescent Microscopy ◽  
Ether Ester ◽  
Intravital Fluorescent Microscopy

Permeability of blood-brain barrier to various sized molecules

1985 ◽  
Vol 248 (5) ◽  
pp. H712-H718 ◽  
Author(s):  
W. G. Mayhan ◽  
D. D. Heistad
Keyword(s):  
Blood Brain Barrier ◽  
Fluorescent Microscopy ◽  
Brain Barrier ◽  
Sprague Dawley ◽  
Acute Hypertension ◽  
Size Dependent ◽  
Blood Brain ◽  
Sprague Dawley Rats ◽  
Intravital Fluorescent Microscopy ◽  
Dextran Clearance

We studied disruption of the blood-brain barrier (BBB) by acute hypertension and a hyperosmolar solution. The goals were to determine whether 1) disruption of the BBB occurs primarily in arteries, capillaries, or veins, and 2) transport of different-sized molecules is homogeneous or size dependent. Sprague-Dawley rats were studied using intravital fluorescent microscopy of pial vessels and fluorescein-labeled dextrans (FITC-dextran, mol wt = 70,000, 20,000, and 4,000 daltons). The site of disruption was determined by the appearance of microvascular leaky sites. Transport of different-sized molecules was calculated from clearance of FITC-dextran. During gradual hypertension and osmotic disruption, all leaky sites were venular. Rapid hypertension produced venular leaky sites and, in some experiments, diffuse arteriolar extravasation of FITC-dextran. Clearance of different-sized molecules was homogeneous during acute hypertension. In contrast, clearance of molecules during osmotic disruption was size dependent. The findings suggest that 1) venules and veins are the primary sites of disruption following acute hypertension and a hyperosmolar solution; 2) transport of different-sized molecules is homogeneous following acute hypertension, which suggests a vesicular mechanism; and 3) transport following hyperosmolar disruption is size dependent, which suggests that hyperosmolar disruption may involve formation of pores as well as vesicular transport.

Poly(ether-ester anhydride)-based amphiphilic block copolymer nanoparticle as delivery devices for paclitaxel

2012 ◽  
Vol 7 (2) ◽  
pp. 183 ◽  
Author(s):  
Juan Zhang ◽  
Yanqin Liang ◽  
Ning Li ◽  
Xiumei Zhao ◽  
Renjie Hu ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Amphiphilic Block Copolymer ◽  
Ether Ester

Hepatocytes Ingest Longterm Refrigerated Platelets: A Novel Platelet Clearance Mechanism.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1523-1523 ◽  
Author(s):  
Viktoria Rumjantseva ◽  
Emma C. Josefsson ◽  
Hans Wandall ◽  
John H. Hartwig ◽  
Thomas P. Stossel ◽  
...  
Keyword(s):  
Cold Storage ◽  
Fluorescent Microscopy ◽  
Hepatic Clearance ◽  
Human Platelets ◽  
Lectin Domain ◽  
Clearance Mechanism ◽  
Rapid Clearance

Abstract We previously reported that the lectin domain of αMβ2 receptors on hepatic macrophages mediates rapid clearance of washed murine platelets transfused after refrigeration for 2 hours, recognizing exposed βN-acetylglucosamine (βGlcNAc) residues of N-linked glycans on clustered platelet GPIbα molecules and that the same receptors elicit phagocytosis of refrigerated human platelets human macrophages in vitro. A platelet-associated galactosyltransferase catalyzes the covering of βGlcNAc residues with galactose in the presence of UDP-galactose, thereby blocking clearance of cold mouse platelets in vivo and phagocytosis of human platelets in vitro. These intriguing findings contradicted earlier evidence that refrigeration of human platelets procured for transfusion only promotes their rapid clearance after prolonged (>8h) incubation and also are inconsistent with the well-known recognition system for exposed galactose residues through asialoglycoprotein (ASGP) receptors. Reconciling these contradictions, we report that the absence of plasma during storage accounts for the differences in time of exposure to cold to promote clearance and that mouse platelets cold-stored in plasma also only clear rapidly after long-term (48h) storage. We also found that hepatic clearance of long-term cold-stored (LTCS) mouse platelets occurs in hepatocytes. Streptavidin-POD staining revealed abundant LTCS biotinylated platelets in hepatocyte phagosomes. Furthermore, cells of the hepatocyte HepG2 line avidly ingest fluorescently-labeled LTCS human platelets (7-fold above the baseline of room-temperature-stored platelets), as evidenced by flow cytometry, fluorescent microscopy and by time-laps video microscopy. Long-term cold storage increases by ~1.7-fold platelet binding of the galactose-specific lectin RCA I, implying that with long-term cold storage, exposed galactose residues cluster sufficiently to induce recognition by hepatocyte ASGPR receptors. The results define a new clearance mechanism, representing the first example of blood cell removal by a non-myeloid cell. Since we find that human platelets also express a cell surface sialotransferase that adds sialic acid to galactose residues, we suggest that a combination of sialylation and glactosylation, achievable by addition of sugar substrates alone, might accommodate long-term cold storage of platelets for transfusion.

Block copolymer and terpolymers and poly(ether-ester-amide) blends

Polimery ◽  
1999 ◽  
Vol 44 (07/08) ◽  
pp. 481-488 ◽  
Author(s):  
ZBIGNIEW ROSLANIEC
Keyword(s):  
Block Copolymer ◽  
Ether Ester

Formation and stability of co-continuous blends with a poly(ether-ester) block copolymer around its order–disorder temperature

Polymer ◽  
1999 ◽  
Vol 40 (5) ◽  
pp. 1119-1130 ◽  
Author(s):  
Harm Veenstra ◽  
Jaap Van Dam ◽  
Abe Posthuma de Boer
Keyword(s):  
Block Copolymer ◽  
Ether Ester

Effective oxidation protection of polymer micelles for copper nanoparticles in water

RSC Advances ◽  
2014 ◽  
Vol 4 (27) ◽  
pp. 14193-14196 ◽  
Author(s):  
Hang Lu ◽  
Li Yu ◽  
Bo Yang ◽  
Jianing Si ◽  
Jianzhong Du
Keyword(s):  
Block Copolymer ◽  
Copper Nanoparticles ◽  
Diffusion Barrier ◽  
Copper Nanoparticle ◽  
Hydrophobic Core ◽  
Polymer Micelles ◽  
Oxidation Protection ◽  
Water Dispersible ◽  
Copolymer Micelle

Copper nanoparticles are often susceptible to rapid oxidation in water. We report a water-dispersible and long-term stable copper nanoparticle protected by a block copolymer micelle that can effectively inhibit the access of oxygen to the copper inside its hydrophobic core, providing a sufficient diffusion barrier against oxidation in water.

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