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PubMed1985

The effect of Pseudomonas alginate on rat alveolar macrophage phagocytosis and bacterial opsonization.

Alginate obtained from a mucoid strain of Pseudomonas aeruginosa was shown to inhibit the phagocytosis of an isogenic non-mucoid revertant by rat alveolar macrophages. Phagocytosis of Staphylococcus albus, binding of sensitized sheep erythrocytes to Fc receptors and uptake of latex particles were also inhibited. These results suggest that the alginate acts as a barrier, surrounding the macrophage preventing the attachment of bacteria or other particles to the plasma membrane. This conclusion was supported by showing that alginic acid, a polysaccharide from seaweed structurally similar to alginate also inhibited the phagocytosis of non-mucoid Ps. aeruginosa. The alginate also inhibited opsonisation of the non-mucoid revertant by a non-agglutinating hyperimmune serum. It is proposed that alginate confers a selective advantage on mucoid producing forms of Ps. aeruginosa by impairing the host immune response by its action on alveolar macrophages and opsonization of bacteria.

Alginates↗

PubMed1966

Studies on the inhibition of intestinal absorption of radioactive strontium. V. The effect of administration of calcium alginate.

A method of selective suppression of absorption of radioactive strontium from ingested food material is described which allows calcium to be available to the body. In the present study the effects of administering calcium alginate were determined. Studies on the relative binding of Ca and Sr by calcium alginate in vivo are also important to the investigation of calcium-strontium exchange.Samples of calcium alginate were obtained commercially or prepared from sodium salts and the binding properties with Ca(45) and Sr(89) were tested in vivo. There was a free exchange of radioactive calcium as well as of strontium with bound inactive calcium. The amount of Ca(45) retained in the gut by calcium alginate is proportionally less than Sr(89), so that the ratio Sr(89)/Ca(45) in the bone is consistently and significantly lower in treated rats. Calcium alginate acts differently from other calcium salts, although in a manner similar to sodium alginate.

Alginates↗

PubMed1966

The effect of sodium alginate on the absorption of strontium and calcium in human subjects.

The effect of sodium alginate on the gastrointestinal absorption of the tracers strontium-85 and calcium-47 was investigated in 19 human subjects. The tracers were administered orally with 100 mg. of a calcium carrier-calcium chloride. At the same time, sodium alginate was given in a commercial jelly. The sevenday per cent retentions of tracers were measured with a whole-body counter. After one month, the experiments were repeated without alginate so that each subject acted as his own control. Fifteen volunteers were given 1.5 g. of alginate, two were given 3.0 g. and two 0.3 g. 1.5 g. of alginate reduced the absorption of strontium by a factor of two with no significant effect on calcium absorption. The smaller dose of alginate (0.3 g.) appeared to have no effect on strontium or calcium absorption and the larger dose (3.0 g.) had no greater effect than the 1.5 g. dose.

Alginates↗

PubMed1997

Alginate Encapsulation of the White Rot Fungus Phanerochaetechrysosporium

In the laboratory, the white rot fungus Phanerochaetechrysosporium degrades numerous organic pollutants. Lack of aslow-release delivery system to toxic waste sites, for this and other fungi,however, constitutes an important barrier to practical implementation. Inthis study, the use of calcium alginate as an encapsulant for mycelia wasinvestigated; samples were in the form of pellets 1-3 mm in diameter. Whenrefrigerated, alginate-embedded mycelia of P. chrysosporium wereviable for one year, both with and without nutrient supplementation. At roomtemperature, in the absence of nutrient supplementation, viability decreasedsharply within 2 months. Addition of sawdust or corncob grits extended theviability of alginate-embedded mycelia; nevertheless, after 9 months onlyabout 20% of the pellets stored at room temperature yielded fungalgrowth. Spores of P. chrysosporium, embedded in alginate pelletstogether with corncob grits, gave 75% viability after 9 months ofstorage at room temperature. Alginate-embedded mycelia were used in Petriplate toxicity tests with 2,4,6-trinitrotoluene (TNT) and gave more rapid andreproducible results than tests performed with mycelial plugs. Theseexperiments demonstrated the feasibility of encapsulating P.chrysosporium in calcium alginate pellets, thus providing a potentialmethod of delivering white rot fungi to toxic waste sites, as well as fordeveloping a system of standardized toxicity testing in plate assays.

Journal Article↗

PubMed2004

Physical alginate hydrogels based on hydrophobic or dual hydrophobic/ionic interactions: bead formation, structure, and stability.

Hydrophobically associating alginate (AA) derivatives were prepared by covalent fixation of dodecyl or octadecyl chains onto the polysaccharide backbone (AA-C12/AA-C18). In semidilute solution, intermolecular hydrophobic interactions result in the formation of physical hydrogels, the physicochemical properties of which can be controlled through polymer concentration, hydrophobic chain content, and nonchaotropic salts such as sodium chloride. The mechanical properties of these hydrogels can then be reinforced by the addition of calcium chloride. The combination of both calcium bridges and intermolecular hydrophobic interactions leads to a decrease in the swelling ratio accompanied by an increase of elastic and viscous moduli. Beads made of hydrophobically modified alginate were obtained by dropping an aqueous solution of alginate derivative into a NaCl/CaCl2 solution. As compared to unmodified alginate beads, modified alginate particles proved to be stable in the presence of nongelling cations or calcium-sequestering agents. However, evidence is presented for a more heterogeneous structure than that of plain calcium alginate hydrogels with, in particular, an increase in the effective gel mesh size, as determined by partition and diffusion coefficient measurements.

Journal Article↗

PubMed1987

Alginate lyase releases cell-bound lipase from mucoid strains of Pseudomonas aeruginosa.

Alginate lyase (EC 4.2.2.3) was partially purified from the culture medium of Bacillus circulans JBH2 by ammonium sulphate precipitation, gel filtration and ion-exchange chromatography. The purified enzyme was unstable in the absence of protecting substances such as gelatin. At a pH optimum of 5.8, the enzyme depolymerized algal as well as bacterial alginates, the latter in the deacetylated form more effectively than in the acetylated form. Incubation of various mucoid strains of Pseudomonas aeruginosa in the presence of purified alginate lyase caused rapid degradation of the alginate slime without killing the cells. The degradation of alginate was accompanied by a release of cell-bound lipase into the medium indicating that one of the functions of the alginate layer of mucoid bacteria might be to serve as a temporary reservoir for lipase.

Bacillus↗

PubMed2004

Cultivation of yeast and plant cells entrapped in the low-viscous liquid-core of an alginate membrane capsule prepared using polyethylene glycol.

A liquid-core alginate-membrane capsule was prepared by a novel method using polyethylene glycol as a thickener and the cells of Saccharomyces cerevisiae were encapsulated in its core and cultured. After 24 h of cultivation, the cell concentration in the capsule core-liquid reached 222 microg/mm3 on a dry weight basis, which was 1.4 times as large as that in the core of double-layered alginate beads, i.e., alginate-coated alginate-gel beads. The diameter increase of the capsule prepared by the proposed method using immobilized cell growth was suppressed compared to those using the double-layer method and simple alginate-gel bead entrapment, most likely because of the mobility of the entrapped cells in the capsule. We also confirmed that this encapsulation method is applicable for the cultivation of cultured cells of the plant Fragaria ananassa. Additionally, the time-course of the changes in thickener concentration in the liquid-core of the capsule was measured after encapsulation, and revealed the residual thickener, i.e., polyethylene glycol, was able to leak through the alginate shell membrane. This results in low-viscosity of the core liquid enabling good mass-transfer performance, whereas xanthan gum as a thickener could not leak through.

Journal Article↗

PubMed1990

Oxygen-dependent up-regulation of mucoid exopolysaccharide (alginate) production in Pseudomonas aeruginosa.

We previously showed substantial differences in Pseudomonas aeruginosa exopolysaccharide production in vitro at oxygen tensions reflective of the right versus left cardiac circuits in vivo (40 versus 80 mm Hg, respectively; A. S. Bayer, T. O'Brien, D. C. Norman, and C. C. Nast, J. Antimicrob. Chemother. 23:21-35, 1989). However, those studies did not specifically confirm this exopolysaccharide to be the characteristic P. aeruginosa mucoid alginate seen in patients with cystic fibrosis. With a murine monoclonal antibody prepared against P. aeruginosa alginate, strongly positive immunofluorescence (IF) staining of a nonmucoid P. aeruginosa strain (PA-96) was seen after its exposure in vitro to oxygen tensions (pO2) of approximately 80 mm Hg; the intensity of the IF staining under these conditions was similar to that observed with a phenotypically mucoid P. aeruginosa strain (C1712M) from a cystic fibrosis patient. In contrast, the same nonmucoid strain (PA-96), after exposure to pO2 of approximately 40 mm Hg, showed little IF staining for alginate. Following enzyme treatment with alginase, PA-96 cells previously exposed to the higher pO2 and exhibiting enhanced alginate production, as determined by IF staining, now showed no IF staining. Moreover, treatment of the oxygen-up-regulated PA-96 cells with alginase released amounts of unsaturated alginate breakdown products (uronic acids) quantitatively similar to those released by typically mucoid strains treated with the same enzyme. These data indicated that the P. aeruginosa exopolysaccharide in our studies was, indeed, mucoid alginate and that variations in oxygen tensions represent one of the trigger mechanisms for the up-regulation of mucoid exopolysaccharide production.

Fluorescent Antibody Technique↗

PubMed1997

Cloning and sequence analysis of the gene (alyII) coding for an alginate lyase of Pseudomonas sp. OS-ALG-9.

Pseudomonas sp. OS-ALG-9 produces several kinds of alginate-degrading enzymes both intra- and extracellularly. As a second alginate lyase of this bacterium, the gene encoding alyII has been cloned in Escherichia coli JM109 by shotgun techniques and then sequenced. The alyII gene has an open reading frame of 2141 bp encoding 713 amino acid residues with a calculated molecular mass of 79,803 Da. The deduced amino acid sequence did not show any extensive similarity with those of other known alginate lyases, however, hydrophobic cluster analysis showed that alyII belonged to class 3 of alginate lyases. The alginate lyase from E. coli harboring the alyII gene showed a single active band, which coincided with one of four major alginate lyases from the crude cell extracts of Pseudomonas sp. OS-ALG-9 on a zymogram.

Amino Acid Sequence↗

PubMed2002

Application of alginate three-dimensional culture system for in vitro culture of mandibular condylar chondrocytes from human osteoarthritic temporomandibular joint.

OBJECTIVE: To evaluate the use of alginate three-dimensional culture system for mandibular condylar chondrocytes culture in vitro from human osteoarthritic temporomandibular joint. METHODS: The cultured mandibular condylar chondrocytes from the operatively removed cartilage from a patient with osteoarthritic temporomandibular joint were harvested by mechanical dissection and enzyme digestion. Partial chondrocytes were suspended in the aqueous sodium alginate beads with high seeding density and cultured for 4 weeks, while the others were cultured in monolayer culture condition for 1 week. Thereafter, the alginate beads were embedded in paraffin and sectioned, then studied immunologically with type II collagen antibody and aggrecan antibody, same studies were adopted for the monolayer cultures. RESULTS: The monolayer cultures were confirmed as chondrocytes. The chondrocytes cultured in the alginate medium showed well. These cells exhibited the excellent differentiated phenotype after 4 weeks culture in alginate gel. CONCLUSIONS: The condylar chondrocytes from human osteoarthritic temporomandibular joint were successfully cultured in vitro. The alginate three-dimensional culture system was successfully adopted for in vitro culture of condylar chondrocytes from human osteoarthritic temporomandibular joint, in which the chondrocytes exhibited the excellent differentiated phenotype.

Cartilage, Articular↗

PubMed1964

EFFECT OF SODIUM ALGINATE ON STAPHYLOCOCCUS AUREUS DURING MILD HEATING AND FREEZING.

The effects of sodium alginate on Staphyiococcus aureus 196 exposed to mild heating or to freezing at -21 C were studied. The addition of sodium alginate to a diluent appeared to confer some protection of viable cells during mild heating. The effect of the presence of sodium alginate in the suspending media during freezing was less clear. There was a slight trend, not statistically significant, for greater reduction in numbers of viable cells at the low temperature when 4% alginate was present in phosphate buffer. Results indicated that the value of sodium alginate in controlling this food-poisoning microorganism in frozen food is questionable.

Alginates↗

PubMed1964

STUDIES ON INHIBITION OF INTESTINAL ABSORPTION OF RADIOACTIVE STRONTIUM. II. EFFECTS OF ADMINISTRATION OF SODIUM ALGINATE BY OROGASTRIC INTUBATION AND FEEDING.

A method is reported that enables selective suppression of absorption of radioactive strontium from ingested food material, permitting calcium to remain available to the body. Studies were carried out by measuring blood levels and bone uptake of Sr(89) and Ca(45) at different time intervals after orogastric intubation of rats. The addition of sodium alginate, derived from brown marine algae, to the radioactive isotopes increased the overall physiological discrimination against strontium by amounts up to 60% after 24 hours. This discrimination was further increased by feeding sodium alginate mixed with standard diet in the proportions of 20:80 and 30:70. The observed ratio was reduced by administration of sodium alginate from 0.25 to 0.09.Determination of the limiting dosage in rats is restricted to the amounts which rats will consume. In the event of an inadvertent release of radioactive strontium, human subjects probably could increase their intake of alginate at will, permitting a greater effectiveness of sodium alginate than could be obtained in experimental animals.

Absorption↗

PubMed1965

STUDIES OF INHIBITION OF INTESTINAL ABSORPTION OF RADIOACTIVE STRONTIUM. IV. ESTIMATION OF THE SUPPRESSANT EFFECT OF SODIUM ALGINATE.

A method is reported which permits selective suppression of absorption of radioactive strontium from ingested food material, allowing calcium to be available to the body. Studies were carried out on the inhibitory effect of various amounts of sodium alginate and the dose-response relationship of Sr(89) and bone uptake. The results obtained indicated that under laboratory conditions sodium alginate effectively reduces Sr(89) uptake in a constant proportion. This effect was observed at the three levels of administration of 1.4%, 12% and 24% of sodium alginate. The linear relationship between the dosage of the radioisotope and the bone uptake in the presence of sodium alginate suggests that the same proportion is maintained at the lower levels of intake of radioactive strontium.Previous studies with small constant doses of sodium alginate were extended in rats to a period corresponding approximately to three years of human life span. Low doses were sufficient to reduce appreciably bone uptake of radiostrontium.

Alginates↗

PubMed2000

Inhomogeneous alginate gel spheres: an assessment of the polymer gradients by synchrotron radiation-induced X-ray emission, magnetic resonance microimaging, and mathematical modeling.

It has been previously demonstrated that calcium alginate gels prepared by dialysis often exhibit a concentration inhomogeneity being the polymer concentration considerably lower in the center of the gel than at the edges. Inhomogeneity may be a preferred structure in microcapsules due to low porosity and higher stability so that it is interesting to evaluate the polymer gradient in spherically symmetrical small alginate beads (1.0-0.7 mm diameter) obtained in different conditions. In this paper, two complementary techniques have been used to investigate this aspect. The concentration gradient of alginate has been analyzed by measuring both the spatial distribution of calcium ions in sections of alginate gel spheres, by means of x-ray fluorescence spectroscopy, and the T2 relaxation behavior on intact gel beads using magnetic resonance microimaging. The experimentally determined gradients from three-dimensional gels provide data to reevaluate the parameter estimates in the recently reported mathematical model for alginate gel formation (A. Mikkaelsen and A. Elgsaeter, Biopolymers, 1995, Vol. 36, pp. 17-41). The model may account for the gels being less inhomogeneous when nongelling sodium or magnesium ions are added during gelation.

Alginates↗

PubMed2000

Hepatocyte behavior within three-dimensional porous alginate scaffolds.

A potential approach to facilitate the performance of implanted hepatocytes is to enable their aggregation and re-expression of their differentiated function prior to implantation. Here we examined the behavior of freshly isolated rat adult hepatocytes seeded within a novel three-dimensional (3-D) scaffold based on alginate. The attractive features of this scaffold include a highly porous structure (sponge-like) with interconnecting pores, and pore sizes with diameters of 100-150 microm. Due to their hydrophilic nature, seeding hepatocytes onto the alginate sponges was efficient. DNA measurements showed that the total cell number within the sponges did not change over 2 weeks, indicating that hepatocytes do not proliferate under these culture conditions. Nearly all seeded cells maintained viability, according to the MTT assay. Within 24 h post-seeding, small clusters of viable cells, were seen scattered within the sponge. More than 90% of the seeded cells participated in the aggregation; the high efficiency is attributed to the non-adherent nature of alginate. The spheroids had smooth boundaries and by day 4 in culture reached an average diameter of 100 microm, which is at the same magnitude of the sponge pore size. The cells appeared to synthesize fibronectin which was deposited on the spheroids. No laminin or collagen type IV were detected in the deposit. The 3-D arrangement of hepatocytes within the alginate sponges promoted their functional expression; within a week the cells secreted the maximal albumin secretion rate of 60 microg albumin/10(6) cells/day. Urea secretion rate did not depend on cell aggregation and was similar to that obtained when hepatocytes were cultured on collagen type I coated dishes (100 microg/10(6) cells/day). Our studies show that alginate sponges can provide a conducive environment to facilitate the performance of cultured hepatocytes by enhancing their aggregation.

Albumins↗

PubMed2000

A vortex-bowl disk atomizer system for the production of alginate beads in a 1500-liter fermentor.

Using a model system, a concept for the immobilization of microbial cultures within alginate beads directly in a 1500-L fermentor with a height to diameter ratio of 1.85 is described. The system is comprised of a 60-cm diameter bowl fixed to the top of an agitation shaft, where calcium-ion-rich media is continuously recirculated from the bulk solution to the bowl. The rotation of the shaft and bowl creates a climbing film (vortex) of solution. An atomizing disk centrally recessed within the bowl sprays an alginate solution into the climbing film where the droplets harden into beads. The effect of heat treatment on the alginate solution on resulting bead properties was examined. The sterilization operation did not appear to have a major effect on the alginate bead mechanical properties of firmness and elasticity which was much more a function of alginate concentration. Beads of various sizes were produced by the unit. The system was characterized by the dimensionless numbers Reomega = (omega x rho x D(2))/mu and ReQ = (Q x rho)/(mu x D). At Reomega and ReQ values less than 500 and 0.15, respectively, the mechanism was direct drop. Parent droplets followed by satellite droplets were observed. When either the flow rate or speed was increased, filaments formed predominantly, which was unwanted in this system because filament breakdown into smaller droplets does not occur due to the proximity of the disk to the climbing film in the bowl. This system could be applied to the immobilization of microorganisms, as well as plant or animal cell cultures, and for other sizes or fermentors. The overflow from the bowl carries the gellified beads into the bulk solution where immobilized cells could act upon the fermentation media.

Alginates↗

PubMed2000

Reconstruction of rat peripheral nerve gap without sutures using freeze-dried alginate gel.

Many materials have been used for artificial tubular prostheses to assist peripheral nerve gap reconstruction. However, the clinical use of these devices has been restricted because a microsurgical procedure requires specialized techniques and expensive equipment, such as operating microscope systems. Therefore the authors developed a new gluing method, without sutures, that uses freeze-dried alginate gel. A 7-mm gap in the sciatic nerve of rats was bridged with freeze-dried alginate gel. Regeneration was evaluated by electrophysiologic testing and histologic study. Eighteen weeks after surgery, functional reinnervation of motor and sensory nerves had occurred, as demonstrated by recovery of compound muscle action potentials (CMAP), compound nerve action potentials (CNAP), and somatosensory-evoked potentials (SEP). Histologically, many regenerated nerve fasciculi, including myelinated and unmyelinated fibers, were observed and the implanted alginate gel had disappeared. In conclusion, a gluing technique using alginate gel is a potential alternative to the conventional nerve autograft technique. Advantages include simple application and rapid repair. Freeze-dried alginate gel is a promising material for artificial nerve guides for peripheral nerves and also could be used for repair of disrupted pathways in central nervous tissue that is amorphous and cannot be sutured.

Action Potentials↗

PubMed1998

Dedifferentiated chondrocytes cultured in alginate beads: restoration of the differentiated phenotype and of the metabolic responses to interleukin-1beta.

Chondrocytes cultivated in monolayer rapidly divide and lose their morphological and biochemical characteristics, whereas they maintain their phenotype for long periods of time when they are cultivated in alginate beads. Because cartilage has a low cellularity and is difficult to obtain in large quantities, the number of available cells often becomes a limiting factor in studies of chondrocyte biology. Therefore, we explored the possibility of restoring the differentiated properties of chondrocytes by cultivating them in alginate beads after two multiplication passages in monolayer. This resulted in the reexpression of the two main markers of differentiated chondrocytes: Aggrecan and type II collagen gene expression was strongly reinduced from day 4 after alginate inclusion and paralleled protein expression. However, 2 weeks were necessary for total suppression of type I and III collagen synthesis, indicators of a modulated phenotype. Interleukin-1beta, a cytokine that is present in the synovial fluid of rheumatoid arthritis patients, induces many metabolic changes on the chondrocyte biology. Compared with cells in primary culture, the production of nitric oxide and 92-kDa gelatinase in response to interleukin-1beta was impaired in cells at passage 2 in monolayer but was fully recovered after their culture in alginate beads for 2 weeks. This suggests that the effects of interleukin-1beta on cartilage depend on the differentiation state of chondrocytes. This makes the culture in alginate beads a relevant model for the study of chondrocyte biology in the presence of interleukin-1beta and other mediators of cartilage destruction in rheumatoid arthritis and osteoarthrosis.

Aggrecans↗