SEARCH · Search PubMed

Results for “Dextrans”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,279 records · Page 71Linked to original sources

PubMed1986

Measurement of total HDL, HDL2 and HDL3 by dextran sulfate-MgCl2 precipitation technique in human serum.

We describe a simple and reliable method for determination of total HDL, HDL2, and HDL3 by a precipitation technique using dextran-sulfate (Mr 50,000)-Mg2+. A combined solution of dextran sulfate and Mg2+ at their respective final concentration of 0.9 g/l and 27 mmol/l was optimal for separating total HDL from the other lipoproteins. The present method compares favorably with a heparin-MnCl method (r = 0.998). The HDL was further resolved into HDL2 and HDL3 by addition of a combined solution of dextran sulfate and Mg2+ (1.5 m/l and 10 g/l) to the total HDL solution. Comparison of this precipitation method with the well-established ultracentrifugation method yielded the mean correlation coefficient of 0.941 and 0.869 for HDL2 and HDL3, respectively.

Chemical Precipitation↗

PubMed1989

Efficient gene transfer by sequential treatment of mammalian cells with DEAE-dextran and deoxyribonucleic acid.

A variation of the classical DEAE-dextran method of gene transfer was developed for efficient transfection of HeLa cells with plasmid DNA. A brief exposure of the cells to medium containing DEAE-dextran was found to be sufficient for subsequent uptake of pRSVcat and to be superior to cocultivation of the cells with DEAE-dextran plus DNA. This sequential method of gene transfer is nontoxic and yielded up to 60% of HeLa cells positive for a surface protein encoded by the transfected sequence. The implications of this sequential transfection technique regarding the mechanisms of gene transfer are discussed.

Animals↗

PubMed1986

Interaction of a macromolecular polyanion, dextran sulfate, with human hemoglobin.

Interactions of dextran sulfate with amino groups of oxy- and deoxyhemoglobin were followed by both potentiometric measurements between pH 6 and 7.3 and oxygen-binding studies. The uptake of protons observed upon addition of dextran sulfate to hemoglobin shows that the interaction with the deoxy form is strong and that the main site is probably located in the phosphate-binding beta-cavity, whereas the interaction with the oxy form is more diffuse, probably with a great number of relatively weak binding sites. The influence of dextran sulfate on the oxygen dissociation curve of hemoglobin confirms these findings, as the effect of the polymer is to lower hemoglobin affinity for oxygen to a great extent, which proves that it stabilizes the deoxy form more strongly than the oxy one.

Dextran Sulfate↗

PubMed1986

Thrombin inhibitory activity of heparin cofactor II depends on the molecular weight and sulfate amount of dextran sulfate.

The effect of molecular weight and sulfate amount of sulfated polysaccharide on the thrombin inhibitory activity of heparin cofactor II was investigated by using various dextran sulfate fractions with different molecular weight and sulfur content. The activity of dextran sulfate fractions of each size increased as the sulfur content was increased from 9 to 18%, and the activity decreased in molecules below 10 kDa. The maximum second order rate constant of heparin cofactor II-thrombin reaction in the presence of the fractions of over-10 kDa and 18% sulfur was 2.7 X 10(8) M-1 min-1 that was almost same as in the presence of heparin or dermatan sulfate. On the other hand, dextran sulfate accelerated antithrombin III-thrombin reaction only about 40-fold less than heparin. These results indicate that a large molecular size and significant amount of sulfate groups are only essential in the acceleration of the thrombin inhibitory activity of heparin cofactor II, whereas a specific sequence of heparin is required to that of antithrombin III.

Animals↗

PubMed1982

Efficient infection of monkey cells with SV40 DNA. II. Use of low-molecular-weight DEAE-dextran for large-scale experiments.

With standard protocols for DNA infection, only a small percentage (about 4%) of monkey ells exposed to purified DNA of simian virus 40 (SV40) displays cytopathic effect or expresses viral T antigen. We have recently reported (Sompayrac and Danna, 1981) that by extending the time of exposure of BSC-1 cells to DNA in the presence of low concentrations of diethylaminoethyl (DEAE)-dextran, we can infect up to 50% of the cells. Because our protocol was devised for DEAE-dextran of mol. wt. 2 X 10(6), which is no longer commercially available, we have tested a low-molecular-weight polymer (mol. wt. 0.5 X 10(6) that can be purchased. Use of this reagent in our protocol resulted in marginally higher levels of infection than we found with the high-molecular-weight polymer. However, slightly more DNA (about 1.5 times as much) was needed to achieve saturation. With both reagents, the percentage of cells infected was proportional to time of exposure. Therefore, low-molecular-weight DEAE-dextran should be useful for large-scale DNA infections.

Animals↗

PubMed1987

Inhibitory effect of dextran sulfate and heparin on the replication of human immunodeficiency virus (HIV) in vitro.

The polyanionic substances dextran sulfate and heparin were investigated for their antiviral effect on the human immunodeficiency virus (HIV) in vitro. Dextran sulfate and heparin effected a 50% reduction in the cytopathogenicity of HIV for MT-4 cells at a concentration of 4.7 and 7.5 micrograms/ml, respectively. In Molt-4 (clone 8) cells, these values were slightly higher (14.1 and 15.6 micrograms/ml, respectively). No toxicity for the host cells was noted with these compounds at a concentration up to 400 micrograms/ml, so that the selectivity indexes, as based on the ratio of the 50% cytotoxic dose to the 50% antiviral effective dose, were well in excess of 100. These findings may have far reaching implications both diagnostically, when attempts are made to isolate HIV from heparinized blood samples, as therapeutically, to the extent that dextran sulfate or heparin may be useful in blocking HIV replication in vivo.

Cell Line↗

PubMed1989

Calcium-dependent polymerization of human serum amyloid P component is inhibited by heparin and dextran sulfate.

The calcium-dependent polymerization of human serum amyloid P component (SAP) was spectrophotometrically monitored in 0.15 M NaCl at pH 7.5. The rate of the polymerization depended on the concentrations of SAP and Ca2+. It was shown for the first time that the calcium-dependent polymerization of SAP was inhibited by some sulfated polysaccharides. Most potent inhibitors were heparin and high molecular weight dextran sulfate of Mr 1.0.10(6). The inhibitory activity of glycosaminoglycans is accordant to their binding affinity for SAP, which was reported previously (Hamazaki, H. (1987) J. Biol. Chem. 262, 1456-1460). The polymerized SAP was reversibly dissociated by heparin and high molecular weight dextran sulfate. The results suggest that heparin and high molecular weight dextran sulfate may be a useful dissociating agent of polymerized SAP in amyloid deposits.

Calcium↗

PubMed1987

Humoral immune response to non-viable Mycoplasma pulmonis in mice enhanced by dextran sulfate.

The enhancing effect of dextran sulfate on the humoral immune response to nonviable Mycoplasma pulmonis in mice was evaluated by means of the indirect haemagglutination test. The serum antibody titres in mice immunized subcutaneously with a mixture of non-viable M. pulmonis and dextran sulfate were greater and persisted longer than those in mice immunized with non-viable M. pulmonis alone. DEAE-dextran also enhanced the humoral immune response to non-viable M. pulmonis in mice.

Animals↗

PubMed2005

Fabrication of hydroxyapatite sponges by dextran sulphate/amino acid templating.

We report a new template-directed method for the fabrication of hydroxyapatite (HAp) sponges by using amino-acid-coated HAp nanoparticles dispersed within a viscous polysaccharide (dextran sulfate) matrix, and describe the use of these materials for the viability and proliferation of human bone marrow stromal cells. The nanoparticles were prepared in the presence of excess amounts of aspartic acid, alanine or arginine, and subsequently organised into macroporous frameworks with typical pore sizes of 100-200 microm during thermal degradation of the dextran matrix. The sponge macrostructure was influenced by changes in the heating rate and sintering time, as well as the use of different amino acids or variations in dextran functional groups. Biocompatibility testing showed retention of cell viability, production of extracellular matrix and alkaline phosphatase expression, suggesting that it should be possible to exploit this novel fabrication method for potential applications in cartilage or soft tissue engineering.

Alanine↗

PubMed1990

Pharmacokinetic analysis of dextran sulfate in rats as pertains to its clinical usefulness for therapy of HIV infection.

We administered radiolabeled dextran sulfate (3H labeled on the reducing end, MW approximately 8000) [( 3H]DS) to rats. High-performance liquid chromatography (HPLC) analysis of plasma from animals that were given [3H]DS intravenously revealed an initial plasma half-life of about 30 min. Eleven percent of [3H]DS administered was recovered in the urine in 24 h; this material represented minor breakdown with a molecular weight of 4000 as determined by size exclusion HPLC analysis. When administered orally, the apparent bioavailability of [3H]DS was 6.8%, based on the recovered radioactivity; however, the molecular weight of the radioactive material obtained from the plasma was all less than 200, indicating that no detectable intact dextran sulfate was absorbed upon oral administration. Only 2% of orally administered [3H]DS was found in the 24-h urine; this material also had a molecular weight less than 200. Further less than 2300 had no anti-HIV effect and that in the presence of higher concentrations of human serum, more DS was required for antiviral effect. Although the pharmacokinetics of dextran sulfate in rats can differ from those in humans to some extent, these data suggest that oral administration of DS is unlikely to produce significant antiretroviral effect against HIV in vivo and higher plasma levels of DS may be necessary than those inferred from earlier in vitro data.

Administration, Oral↗

PubMed1985

Ribosomal RNA synthesis in mammalian cells permealized by diethylaminoethyl (DEAE)-dextran treatment.

Ehrlich ascites tumor cells were made permeable to nucleoside triphosphates by treating them with diethylaminoethyl (DEAE)-dextran. Permeable cells incorporated labeled UTP into RNA at a constant rate for at least 30 min at 37 degrees C and 100 min at 25 degrees C, whereas no incorporation was detected without DEAE-dextran treatment. This RNA synthesis is dependent on added nucleoside triphosphates and is affected differentially by different concentrations of alpha-amanitin. The results of both hybridization and S1-nuclease protection mapping experiments with pulse-labeled RNA synthesized in this system indicate that reinitiation of rRNA transcription takes place from the physiological initiation site in cells made permeable by treatment with DEAE-dextran. By using this system, we examined the kinetics of rRNA synthesis in mouse FM3A cells during inhibition of protein synthesis. The results reflected those previously obtained by analyses of nucleolar RNA synthesis in vivo during protein synthesis inhibition. This permeable cell system should provide a rapid and reproducible assay method for rRNA synthesis in mammalian cells.

Animals↗

PubMed1984

Polysaccharides with sulfate groups are human T cell mitogens and murine polyclonal B cell activators (PBAs) II. Cellulose sulfate and dextran sulfate with two different lower molecular weights.

In our previous paper, we reported that various types of carrageenan, dextran sulfate and fucoidan, which are sulfated homopolysaccharides with high molecular weights, were human T cell mitogens and murine polyclonal B cell activators (PBAs) and that heparin, a sulfated heteropolysaccharide, was a very weak human mitogen and mouse PBA. Here we used cellulose sulfate (Mr 7-9 X 10(3], dextran sulfate with two different low molecular weights (Mr 5 X 10(3) and 8 X 10(3], two different condroitin sulfates (Mr 3.5 X 10(4], polyvinyl sulfate and polygalacturonic acid to investigate mitogenic activities of polysaccharides in detail. The following results were obtained. Low-molecular-weight sulfated homopolysaccharides, dextran sulfate and cellulose sulfate, were very weak or not human T cell mitogens. However, they were better murine PBAs. Sulfated heteropolysaccharides, chondroitin 4-sulfate and chondroitin 6-sulfate, hardly induced mitogenic changes in human T cells and mouse B cells, even though the molecular weight of these substances was more than 1 X 10(4). There were no other polymers examined so far which activated both human T cells and murine B cells. The relationship among molecular size, sulfate groups and lymphocyte activation is discussed in detail.

Adult↗

PubMed1963

Rats resistant to the dextran anaphylactoid reaction.

In one colony of Wistar albino rats 23% were resistant to dextran and to egg-white, these animals (non-reactors) failing to show an anaphylactoid reaction after the intraperitoneal or intravenous injection of either of the two substances. Non-reactors were also found in a few other colonies of Wistar rats but not in colonies of other strains. Procedures which potentiated the anaphylactoid reaction in sensitive rats (reactors) did not alter the response of non-reactors. Dextran failed to release histamine from the perfused hind-quarters of non-reactors although other chemical liberators of histamine were effective. Lack of anaphylactoid reaction was not due to a deficiency of skin histamine or 5-hydroxytryptamine, and the blood sugar and serum protein levels of non-reactors were also normal. Non-reactors could be sensitized to antigens and their serum was antigenic to guinea-pigs. It is suggested that non-reactors lack a blood or tissue component with which dextran normally combines to produce an intermediate substance active in releasing amines.

Amines↗

PubMed1985

A bovine ephemeral fever vaccine incorporating adjuvant Quil A: a comparative study using adjuvants Quil A, aluminium hydroxide gel and dextran sulphate.

Various vaccines containing the 919 strain of ephemeral fever virus were evaluated in experimental calves and in commercial cattle. The vaccine virus was mixed with one of the adjuvants, Quil A (a saponin derivative), aluminium hydroxide gel, dextran sulphate or combinations of these. The response of experimental calves was evaluated by measuring the production of neutralising antibodies and by resistance to challenge with virulent virus; the response of commercial cattle was judged only by the production of neutralising antibody. Twelve calves given two doses of vaccine containing Quil A produced neutralising antibodies to bovine ephemeral fever virus and all were resistant to challenge with virulent virus given 28 to 76 days after the second vaccination. The vaccine given in three of these calves also contained aluminium hydroxide gel. Six of eight unvaccinated control calves succumbed to experimental challenge. In commercial cattle (17 to 26 animals per group) the serological response after two doses of vaccine containing Quil A or Quil A and dextran sulphate was significantly better than that after vaccines containing only dextran sulphate or after vaccines containing combinations of aluminium hydroxide gel and Quil A. The adjuvant Quil A alone was tested in cattle and shown to produce a transient soft swelling at the injection site as well as a rise in rectal temperature of greater than 1 degree C one day after inoculation. At least 99.99 per cent of viral infectivity was destroyed when the vaccine was mixed with Quil A, suggesting that live virus may not be essential in the immunogenicity of the vaccine. This vaccine overcame two of the problems associated with previous attenuated vaccines tested in Australia; the necessity for adjuvant and virus to be mixed immediately before use and the large volume of the vaccine.

Adjuvants, Immunologic↗

PubMed1986

A different cleavage site for high molecular weight kininogen in vivo following intravenous injection of dextran sulfate in the rabbit.

Purified radiolabeled rabbit Hageman factor, prekallikrein, and high molecular weight kininogen were used to examine Hageman factor system molecular dynamics after the intravenous injection of heparin-like dextran sulfate polymer in the rabbit. Hageman factor system proteins rapidly disappeared from the circulation following dextran sulfate injection, as measured by radial immunodiffusion, by kaolin-releasable kinin formation, and by measuring circulating levels of radiolabeled Hageman factor, prekallikrein, and high molecular weight kininogen. 125I-Hageman factor was distributed mainly to lung, liver, and spleen following dextran sulfate injection. Proteolysis of circulating 125I-Hageman factor occurred at a site within a disulfide loop into fragments of 50,000 and 30,000 molecular weight. Proteolysis of 125I-prekallikrein also occurred with visualization of a 50,000 molecular weight fragment. Although extensive proteolysis of 131I-high molecular weight kininogen was observed, the cleavage fragments were not the same as those generated during contact activation in vitro. The major fragment of high molecular weight kininogen observed in vivo was at 80,000 molecular weight, in contrast to the 65,000 molecular weight fragment generated by kallikrein in vitro. These results indicate that high molecular weight kininogen can undergo proteolysis in vivo into fragments not known to be associated with kinin release.

Animals↗

PubMed1985

Effects of dextran sulfate on aprotinin activity.

Dextran sulfate has an action on aprotinin activity similar to that seen with heparin: preincubation of dextran sulfate with aprotinin enhanced the inhibitory effect of aprotinin on the esterolytic activity of trypsin, but did not change the effect on the proteolytic activity of trypsin or on the esterolytic and proteolytic activities of chymotrypsin. The enhancing effects of heparin and dextran sulfate were not due to increase in the active form of aprotinin which reacts with trypsin, but rather due to a change in the aprotinin molecule which would lead to an increase in aprotinin activity.

Aprotinin↗

PubMed1986

Characterization of vascular permeability-increasing component isolated from solid tumors and the effect of highly polymerized dextran sulfate on its activity.

Increase in vascular permeability is usually seen at the growth site of a tumor implant in murine dermal tissue. Increased vascular permeability was inducible by the subcutaneous injection of a solid tumor extract rich in protein precipitable at 20-50% saturation of ammonium sulfate. The vascular permeability-increasing activity of the tumor extract was reducible in the presence of highly polymerized dextran sulfate (DS-500) which showed a strong anticomplementary activity, but not by other substances such as dextran sulfate with a low molecular weight, non-sulfated dextran, chondroitin sulfate or heparin. As the tumor extract includes gamma-globulins in aggregated or bound form and adsorbs complements, it is probable that the aggregated gamma-globulins increase vascular permeability by triggering the complement activation system in the skin. DS-500 might antagonize the process.

Ammonium Sulfate↗

PubMed1990

Establishment of a bioassay to determine serum levels of dextran sulfate and pentosan polysulfate, two potent inhibitors of human immunodeficiency virus.

Dextran sulfate and pentosan polysulfate are two promising candidate anti-acquired immune deficiency syndrome (AIDS) drugs that have already been the subject of initial clinical trials in patients with AIDS. There is at present no reliable assay method to monitor blood drug levels in humans following the administration of either drug. We have now developed a sensitive bioassay system based on the inhibitory activity of the compounds against human immunodeficiency virus type 2 (HIV-2) in MT-4 cells. This method permits the detection in (rabbit) serum samples of dextran sulfate and pentosan polysulfate concentrations as low as 3.0 and 0.5 micrograms/ml, respectively. Pharmacokinetic studies with dextran sulfate and pentosan polysulfate in rabbits indicated that the half-life of these compounds after intravenous bolus injection is approximately 1 h 24 min.

Acquired Immunodeficiency Syndrome↗