Search results for "Dextrans"
showing 10 items of 67 documents
Studies on the kinetics and renal excretion of low and high molecular weight dextrans in preterm babies, newborns and young infants.
1977
Administration of low and high molecular weight dextrans in the initial phase of shock is no longer controversial. The special conditions in newborns, however, have been insufficiently considered in planning therapy. This investigation aimed at determining the biological half-lives of dextran 40 (Rheomacrodex®) and dextran 60 (Macrodex®) in this age group. The half-life of dextran 40 was found to be 60 min and that of dextran 60 3 h. Preterm babies and newborns excrete up to 25% less dextran 40 and 60 in 24 h than infants and adults. Normal adult values for excretion are only reached towards the end of the first year of life.
Studies on the structure of coumarin-modified dextran nanoparticles by fluorescence spectroscopy.
2012
The photophysical and photochemical characteristics of nano-scaled particles obtained via solvent displacement from coumarin-modified dextrans were studied by means of absorption- and fluorescence-spectroscopy. The environment-dependent fluorescence emission of the pendant 4-methyl-7-alkoxy coumarin groups was exploited as a probe to gain information about the inner structure of the polysaccharide based nanoparticles. Time-resolved fluorescence measurements showed that the particles had two domains of different polarity and it could be confirmed that the core of the nano-assemblies contained water. Moreover, preliminary experiments were carried out demonstrating the possibility to control t…
Attachment of Marine Sponge Cells of Hymeniacidon perleve on Microcarriers
2003
Toward the development of an in vitro cultivation of marine sponge cells for sustainable production of bioactive metabolites, the attachment characteristics of marine sponge cells of Hymeniacidon perleve on three types of microcarriers, Hillex, Cytodex 3, and glass beads, were studied. Mixed cell population and enriched cell fractions of specific cell types by Ficoll gradient centrifugation (6%/8%/15%/20%) were also assessed. Cell attachment ratio (defined as the ratio of cells attached on microcarrier to the total number of cells in the culture) on glass beads is much higher than that on Cytodex 3 and Hillex for both mixed cell population and cell fraction at Ficoll 15-20% interface. The h…
Lysosomal degradation of the carboxydextran shell of coated superparamagnetic iron oxide nanoparticles and the fate of professional phagocytes
2010
Contrast agents based on dextran-coated superparamagnetic iron oxide nanoparticles (SPIO) are internalized by professional phagocytes such as hepatic Kupffer cells, yet their role in phagocyte biology remains largely unknown. Here we investigated the effects of the SPIO ferucarbotran on murine Kupffer cells and human macrophages. Intravenous injection of ferucarbotran into mice led to rapid accumulation of the particles in phagocytes and to long-lasting increased iron deposition in liver and kidneys. Macrophages incorporate ferucarbotran in lysosomal vesicles containing α-glucosidase, which is capable of degrading the carboxydextran shell of the ferucarbotran particles. Intravenous injectio…
Effcts of Dextran Sulphate (Dxs) on Lymphocyte Localization in Complement-Deficient Mice: Evidence that the Fifth Component of Complement is not Impl…
1984
AbstractThe effects of subcutaneously or intraperitoneally administered dextran sulphate (DXS) (5nmg/kg) on the subseguent 1 h localization of intravenously injected radiolabelled lymph node cells was investigated in complement deficient mice which lack C5.DXS proved to be equally as potent in depressing cell localizzation in deficient as compared to normal mice. These findings. indicate that the terminal complement components are not, essential for DXS activity.
Photocrosslinking of dextran and polyaspartamide derivatives: a combination suitable for colon-specific drug delivery.
2007
Abstract The aim of this study was to prepare and characterize novel hydrogels with polysaccharide–polyaminoacid structure, able to undergo an enzymatic hydrolysis in the colon and potentially useful for treating inflammatory bowel diseases (IBD). Starting materials were methacrylated dextran (DEX-MA) and methacrylated α,β-poly(N-2-hydroxyethyl)- dl -aspartamide (PHM). These polymers were photocrosslinked by exposure of their aqueous solutions at 313 nm without photoinitiators. Different samples, shaped as microparticles, were obtained as a function of polymer concentration and irradiation time. FT-IR analysis confirmed the occurrence of a co-crosslinking between DEX-MA and PHM in all exper…
Comparative analysis of production and purification of homo- and hetero-polysaccharides produced by lactic acid bacteria
2013
2 figuras, 2 tablas
Thermal diffusion of dextran in aqueous solutions in the absence and the presence of urea.
2006
The Ludwig-Soret effect was studied for aqueous solutions of dextran in the temperature range 15T55 degrees C taking into account the effect of the addition of urea. In the absence of urea, the Soret coefficient S(T) changes sign; it is positive for T45.0 degrees C but negative for T45.0 degrees C. The positive sign of S(T) means that the dextran molecules migrate toward the cold side of the fluid; this behavior is typical for polymer solutions, whereas a negative sign indicates the macromolecules move toward the hot side. The addition of urea to the aqueous solution of dextran rises S(T) and reduces the inversion temperature. For 2 M urea the change in the sign of S(T) is observed at T = 2…
Joint Aqueous Solutions of Dextran and Bovine Serum Albumin: Coexistence of Three Liquid Phases
2014
The phase diagram of the system water/dextran (DEX)/BSA was measured as well as modeled. On the experimental side, cloud points were determined and the coexisting phases were analyzed. The theoretical calculations use an approach capable of describing solutions of chain polymers and of globular proteins with the same formalism. The required thermodynamic input comes from experiments concerning the binary subsystems, except for the polymer blend for which one interaction parameter had to be adjusted. Both sources of information yield the same essential features: the existence of a large composition area of immiscibility, starting from the subsystem DEX/BSA and extending well into the region …
Interpolymer complexes and polymer compatibility.
2012
A reliable method to decide whether two polymers A and B are miscible or incompatible would be very helpful in many ways. In this contribution we demonstrate why traditional procedures cannot work. We propose to use the intrinsic viscosities [η] of the polymer blends instead of the composition dependence of the viscosities as a criterion for polymer miscibility. Two macromolecules A and B are miscible because of sufficiently favorable interactions between the two types of polymer segments. For solutions of these polymers in a joint solvent, this Gibbs energetic preference of dissimilar intersegmental contacts should prevail upon dilution and lead to the formation of interpolymer complexes, …