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PubMed1992

Isolation of a mucoid alginate-producing Pseudomonas aeruginosa strain from the equine guttural pouch.

The isolation and characterization of a mucoid, alginate-producing strain of Pseudomonas aeruginosa from a nonhuman host, namely, in chondroids from an equine guttural pouch, is reported for the first time. Pure cultures of P. aeruginosa 12534 were isolated from a 17-month-old pony mare with a history of chronic bilateral mucopurulent nasal discharge from the right guttural pouch. Transmission electron microscopy of chondroids showed mucoid P. aeruginosa growing as microcolonies within a matrix of extracellular material. On the basis of expression of the mucoid phenotype under different growth conditions, P. aeruginosa 12534 belongs to group 1 and resembles other isolates carrying the muc-23 mutation. The bulk of the extracellular material was characterized as being alginate by chemical and 1H nuclear magnetic resonance analyses, which showed that it had a composition similar to that produced by isolates of P. aeruginosa from human patients with cystic fibrosis.

Alginates↗
PubMed1991

Combination of cimetidine and alginic acid: an improvement in the treatment of oesophageal reflux disease. Cooperative Oesophageal Group.

A new chewable tablet containing cimetidine 200 mg and alginic acid 500 mg, at a dosage of one tablet four times daily, was compared in a 12 week randomised study with the standard dosage of cimetidine (400 mg four times daily) in the management of oesophageal reflux disease. The dose of cimetidine continued unchanged throughout the study but the dose of the combination drugs could be increased after six weeks to two tablets four times a day if response was unsatisfactory. A total of 312 patients had data suitable for analysis. Sixty three per cent of those on the combination tablet completed the study without increasing their dose - that is taking cimetidine equivalent to half the standard dosage used in the control group. The improvement in heartburn symptoms was significantly greater in the combination group than in the group taking full dose cimetidine. There were no significant differences between the treatment groups in healing and improvement of the appearances of oesophagitis after 12 weeks, and healing rates were as expected from previous studies. The addition of alginic acid to cimetidine in this fixed combination tablet is an improvement in symptomatic treatment of oesophageal reflux disease.

Adolescent↗
PubMed2002

Increased pigment and lipid content, lipid variety, and cell and population size of the microalgae Chlorella spp. when co-immobilized in alginate beads with the microalgae-growth-promoting bacterium Azospirillum brasilense.

Three strains of the freshwater microalgae used for wastewater treatment, Chlorella vulgaris and Chlorella sorokiniana co-immobilized separately in alginate beads with the microalgae-growth-promoting bacterium Azospirillum brasilense Cd, resulted in significant changes in microalgal-population size, cell size, cell cytology, pigment, lipid content, and the variety of fatty acids produced in comparison with microalgae immobilized in alginate without the bacterium. Cells of C. vulgaris UTEX 2714 did not change in size, but the population size within the beads significantly increased. On the other hand, C. vulgaris UTEX 395 cells grew 62% larger, but their numbers did not increase. The population of C. sorokiniana UTEX 1602 increased, but not their cell size. The content of pigments chlorophyll a and b, lutein, and violoaxanthin increased in all microalgal species. The lipid content also significantly increased in all three strains, and the number of different fatty acids in the microalgae increased from four to eight. This study indicates that the microalgae-growth-promoting bacterium induced significant changes in the metabolism of the microalgae.

Alginates↗
PubMed2001

Hepatocytes entrapped in alginate gel beads and cultured in bioreactor: rapid repolarization and reconstitution of adhesion areas.

The maintenance of the differentiated hepatocyte phenotype and its specific physiological properties is known to depend on several factors, such as chemical signals, cell-cell and extracellular matrix molecular interactions, as well as the use of three-dimensional matrices. The entrapment of hepatocytes within Ca-alginate at high cell density and the culture under continuous flow favour the development of three-dimensional organization and promote expression of the differentiated hepatic phenotype. This system could represent an improvement in hepatocyte cultivation for basic studies of liver physiology and metabolism; it could also be applicable in toxicology, hepatocyte transplantation or development of bioartificial organs. This report describes the effect of alginate entrapment and culture in a bioreactor on hepatocyte aggregate formation, with particular attention to the re-establishment of cell polarity, cell junctions and three-dimensional re-organization of the cytoskeleton. Oxygen supply and cell oxygen consumption rate were monitored in order to evaluate possible changes in hepatocyte energy requirement. Our data show that after only 6 h of perfusion in the bioreactor, actin and cytokeratin localize along the adhesion areas of the plasma membrane, in which reconstituted bile canaliculi were also observed. Moreover, the presence of connexin at the level of joined membranes of neighbouring cells suggests the establishment of gap junctions between hepatocytes. After the first 30 min of perfusion the oxygen consumption rate remained constant throughout the experimental period.

Alginates↗
PubMed2001

Differential expression of proteoglycan epitopes and growth characteristics of intervertebral disc cells grown in alginate bead culture.

This study assessed the growth characteristics and proteoglycan (PG) production in vitro of cells isolated from various zones; annulus fibrosus (AF), the transitional zone (TZ, an opalescent region situated between the AF and nucleus pulposus, NP) and the NP of the ovine intervertebral disc. The isolated cells were subsequently cultured in calcium alginate microspheres. Cellular metabolic activity was assessed over the 10 days of culture by the bioreduction of a tetrazolium dye substrate to a coloured formazan chromophore which could be measured colorimetrically at 490 nm. These data were correlated with the DNA content of beads measured using the fluorescent dye Hoechst 33258. Viable and non-viable cells in alginate beads were also assessed histochemically using the fluorescent dyes 5-chloromethylfluorescein diacetate and ethidium homodimer-1. PGs synthesised in culture were examined immunohistologically using monoclonal antibodies to defined glycosaminoglycan side chain PG epitopes. The results obtained clearly showed that AF and TZ cells differed from NP cells in the measured indices of cellular metabolism and in the extent of matrix deposition. In contrast to cells from the NP the cells from the AF and TZ were more metabolically active and programmed more to cellular proliferation than to matrix production.

Alginates↗
PubMed1992

Alginate--its role in neutrophil responses and signal transduction towards mucoid Pseudomonas aeruginosa bacteria.

Mucoid Pseudomonas aeruginosa bacteria impaired neutrophil functions, e.g. chemiluminescence response, and leukotriene formation to a significantly higher degree as compared to nonmucoid P. aeruginosa bacteria. To study the cell biological requirements for the different cellular response pattern by mucoid and nonmucoid (NM) P. aeruginosa bacteria, further experiments were performed with purified alginate, the mucoid exopolysaccharide of P. aeruginosa (MEP). In this regard the MEP (alginate) significantly reduced the zymosan-induced leukotriene B4 (LTB4) formation (from 40 +/- 7 to 2 +/- 4 ng). The chemiluminescence response induced by NM bacteria was abolished when the bacteria were precoated with the MEP. Mucoid and NM P. aeruginosa bacteria interacted with components of the cellular signal transduction pathway to a different degree. Mucoid bacteria induced a 2-fold enhanced GTPase activity but activated the protein kinase C (PKC) to a lesser degree than NM P. aeruginosa bacteria. Prior exposure of neutrophils to the MEP increased the sodium fluoride (NaF)-induced GTPase activity and guanylylimidodiphosphate binding [Gpp(NH)p] by approximately 60 and 30%, respectively. The phorbol myristic acid-induced PKC activation was inhibited by 30-40% in the presence of the MEP. However, the MEP by itself was inactive in all assay systems. Our results indicate that the MEP represents an important component which modulates neutrophil responses of mucoid as compared to NM P. aeruginosa bacteria, e.g. the chemiluminescence response, LTB4 generation, and the interaction with components (G proteins, PKC) of the signal transduction pathway.

Alginates↗
PubMed2000

Immunogenicity of antigens in boiled alginate microspheres.

Vaccine efficacy can be enhanced by delivery of antigens in synthetic microspheres. The process of antigen incorporation into microspheres can expose fragile antigens to damaging conditions, such as high temperatures, and to bacterial contamination. Maintenance of immunogenicity of several antigens and reduction of bacterial load in alginate microspheres following boiling was evaluated. Mice were immunized subcutaneously, initially and again 21 days later, with either non-boiled or boiled microspheres containing ovalbumin (OVA), a culture supernatant vaccine of Pasteurella haemolytica (PHV), or a potassium thiocyanate extract of P. multocida (PTE). Serum samples were obtained prior to immunization and at the time of euthanasia 28 days later. Culture of microspheres showed that boiling completely eliminated aerobic bacterial growth for OVA-containing microspheres, and reduced growth by a factor of 10(4) for PTE microspheres. More bacteria were cultured after boiling than before for PHV microspheres. ELISA performed on serum and intestinal lamina propria explant supernatants showed that immunogenicity of PHV microspheres was not altered by boiling. Boiled OVA microspheres were still able to stimulate a significant serum IgG anti-OVA titer in mice, but boiled PTE microspheres completely lacked immunogenicity. Elispot assays of spleens showed that only PHV microspheres were able to retain immunogenicity after boiling. Results indicate that boiling is not an effective means for reducing the bacterial load of alginate microspheres and that the process is associated with a diminution of vaccine immunogenicity.

Alginates↗
PubMed2002

Development of small alginate microcapsules for recombinant gene product delivery to the rodent brain.

A novel form of gene therapy using encapsulated recombinant cells in alginate microcapsules has proven effective in treating several animal models of human diseases. For treating neurological deficits in rodents with this technology, the size of the microcapsules has to be reduced for implantation in the central nervous system (CNS) to bypass the blood-brain barrier. This article reports the development of small alginate microcapsules suitable for implantation into the mouse CNS. By varying the encapsulation protocol, recombinant cells could be encapsulated in microcapsules ranging in diameter from 5 to 2000 microm. The optimal size for implantation was determined to be 100-200 microm, based on the smallest, homogeneously sized, cell-filled microcapsules that could pass the 500 microm inner diameter of a CNS-implantation needle. Compared with medium-sized (500-700 microm) microcapsules, these small microcapsules packed more tightly together with less inter-capsule space, resulting in an increased number of cells and a higher rate of recombinant gene product secretion per volume of microcapsules. The small microcapsules also displayed increased mechanical strength, compared with large microcapsules. These excellent in vitro properties of small 100-200 microm microcapsules warrant further in vivo investigation into the feasibility of using immuno-isolation gene therapy to deliver recombinant gene products to the rodent CNS.

Alginates↗
PubMed2005

Effect of experimental parameters on the formation of alginate-chitosan nanoparticles and evaluation of their potential application as DNA carrier.

This study introduces a new procedure to prepare alginate-chitosan nanoparticles and examines several experimental parameters in relation to their formation and characteristics. Using DLS and TEM analysis, nanoparticle formation was shown to be predominantly affected by the ratio of alginate to chitosan, the molecular weight of the biopolymers and the solution pH. We report a method that results in spherical particles with mean diameters ranging from 323 nm to 1.6 microm, depending on the preparation conditions. The smallest particles were formed using lower molecular weight polymers with pH between 5.0 and 5.6 and having an alginate/chitosan weight ratio of 1:1.5. We have shown that DNA can be loaded with 60% association efficiency. Our system demonstrates suitable size, loading and release characteristics for application in drug- and gene-delivery systems.

Alginates↗
PubMed2005

Morphology and metabolism of hepatocytes microencapsulated with acrylic terpolymer-alginate using gelatin and poly(vinyl alcohol) as extracellular matrices.

Microcapsules with good mechanical stability were prepared using an appropriate mixture of alginate and acrylic terpolymer. It was found from the microscopic observation that the microcapsules had a porous structure with interconnected pores, with a size of 50-150 nm. The results of the permeability experiment of microcapsules using FITC-dextrans showed that the capsule had a molecular mass cut-off of 120 kDa. The hepatocytes encapsulated in both alginate and acrylic terpolymer with gelatin and PVA rapidly aggregated in the core. The aggregated cells showed high albumin synthesis and ammonia removal, suggesting good metabolic function.

Acrylates↗
PubMed2006

Nanotube-doped alginate gel as a novel carrier for BSA immobilization.

In this paper different dopants, including carbon nanotubes (CNTs), silica nanotubes (SiNTs), graphite and silica gel, were incorporated into alginate (ALG) gel to form nanotube/alginate or nanoparticle/alginate composites used for bovine serum albumin (BSA) immobilization carrier. During encapsulation, first BSA was adsorbed on the dopants, and then BSA and dopants were suspended in alginate solution, followed by being added dropwise into the CaCl2 solution to form the biocomposites. The BSA leakage decreased significantly in these biocomposites as the following order: BSA-ALG-SiNT > BSA-ALG-CNT > BSA-ALG-SiO2 > BSA-ALG-graphite, which was mainly due to firstly the protein molecule adsorption on the dopants which could not be washed out easily and secondly, during the biocomposites formation, water loss in BSA-ALG-dopant biocomposites became less than that in BSA-ALG biocomposite. In addition, the mechanical properties of these biocomposites were remarkably reinforced in the same order as BSA leakage decrease.

Alginates↗
PubMed1997

New treatments using alginate in order to reduce the calcification of bovine bioprosthetic heart valve tissue.

Calcification limits the functional lifetime of cardiac valve substitutes fabricated from glutaraldehyde preserved bovine pericardium. Host factors, mainly younger age, and implant factors, mainly glutaraldehyde cross-linking, are implicated in the calcification process. Glutaraldehyde cross-linking is believed to activate the potential sites in the tissues for biocalcification. In the present work, we investigated the possibility of using alginate azide (AA) instead of glutaraldehyde for the preservation of pericardial tissues in order to enhance the durability of bioprosthetic heart valves. Grafting with poly(GMA-BA) copolymer to the alginate azide cross-linked pericardial (AACPC) tissue was carried out to obtain better stability, strength, and anticalcification properties. The strength property and thermal stability of the AA cross-linked tissues were studied. Calcification studies in rat subdermal models reveal that AA cross-linking reduces the calcification to negligible levels. After 30 days implantation, the calcium content was found to be 10.4 +/- 1.2 and 6.1 +/- 0.3 micrograms mg-1 for untreated AACPC and polymer grafted AACPC, respectively, compared to a value of 100 +/- 1.2 micrograms mg-1 calcium recorded for control glutaraldehyde cross-linked pericardial (GCPC) tissues.

Alginates↗
PubMed1999

Polyelectroylte complex composed of chitosan and sodium alginate for wound dressing application.

Drug-impregnated polyelectrolyte complex (PEC) sponge composed of chitosan and sodium alginate was prepared for wound dressing application. The morphological structure of this wound dressing was observed to be composed of a dense skin outer layer and a porous cross-section layer by scanning electron microscopy (SEM). Equilibrium water content and release of silver sulfadiazine (AgSD) could be controlled by the number of repeated in situ PEC reactions between chitosan and sodium alginate. The release of AgSD from AgSD-impregnated PEC wound dressing in PBS buffer (PH = 7.4) was dependent on the number of repeated in situ complex formations for the wound dressing. The antibacterial capacity of AgSD-impregnated wound dressing was examined in agar plate against Pseudomonas aeruginosa and Staphylococcus aureus. From the behavior of antimicrobial release and the suppression of bacterial proliferation, it is thought that the PEC wound dressing containing antimicrobial agents could protect the wound surfaces from bacterial invasion and effectively suppress bacterial proliferation. In the cytotoxicity test, cellular damage was reduced by the controlled released of AgSD from the sponge matrix of AgSD-medicated wound dressing. In vivo tests showed that granulation tissue formation and wound contraction for the AgSD plus dihydroepiandrosterone (DHEA) impregnated PEC wound dressing were faster than any other groups.

Alginates↗
PubMed1980

Subcutaneously implanted alginate as a continuous-release source of fluoride.

The fluoride concentrations of seven brands of alginate ranged from 8600 to 30,500 ppm. In acute and chronic in vivo studies, fluoride was continuously released from subcutaneously implanted alginate cylinders for up to three weeks. This technique is a simple and economical method for elevating soft and hard tissue fluoride levels.

Alginates↗
PubMed1980

Systemic absorption of fluoride from alginate impression material in humans.

Thirty minutes after routine alginate impressions in five adult subjects, plasma fluoride levels increased by an average of 2.6 times over control values. Urinary fluoride excretion rates increased approximately 2.9 times during the first two hours after the impressions. Average whole saliva fluoride levels at 15 minutes were over 100 times the average control concentration. When small amounts of alginate were deliberately ingested, plasma fluoride levels and urinary excretion rates increased sharply.

Absorption↗
PubMed1981

The biologic availability of fluoride from alginate impressions and APF gel applications in children.

Ten child volunteers received routine alginate impressions and APF gel topical applications during separate visits. Whole saliva, urine, and surface enamel fluoride concentrations were measured before and after these procedures. Significant increases in salivary, urinary, and enamel fluoride concentrations were observed following APF gel application but only in whole saliva following alginate impressions.

Acidulated Phosphate Fluoride↗
PubMed2006

Mechanical properties of alginate beads hosting hepatocytes in a fluidized bed bioreactor.

Fluidized bed bioartificial liver has been proposed as a temporary support to bridge patients suffering from acute liver failure to transplantation. In such a bioreactor, alginate beads hosting hepatocytes are in continuous motion during at least six hours. After having shown in vitro the functionality of such a device, the present study aims at analyzing the potential mechanical alterations of the beads in the bioreactor, perfused by different surrounding media. Compression experiments are performed and coupled for analysis with Hertz theory. They provide qualitative and quantitative data. The average value of the shear modulus, calculated for the different cases studied varied from 2.4 to 10.4 kPa, and could therefore be considered as a quantitative measure of the beads mechanical properties. From the compression experiments and the estimated values of the shear modulus, we could now evaluate the effect of different operating conditions (fluidization, presence of cells, surrounding medium) on the mechanical behavior of alginate beads. On the one hand, the motion during six hours in the bioreactor does not alter the beads significantly. On the other hand, the presence of different substances in the fluid phase might change their mechanical strength. These results can be considered as new encouragements to use such a device as a bioartificial organ.

Alginates↗
PubMed2004

Poly methacrylic acid-alginate semi-IPN microparticles for oral delivery of insulin: a preliminary investigation.

Microparticles of Poly methacrylic acid (P1) and novel semi-interpenetrating network composed of Poly methacrylic acid-alginate (P2) were prepared and their application in oral insulin delivery was evaluated. The microparticles were characterized by scanning electron microscopy (SEM) for morphological studies. Insulin loading onto the microparticles was performed by the diffusion filling method and insulin encapsulated microparticles were subjected to in vitro release study in buffer solution of pH 1.2 and 7.4. The release kinetics at pH 7.4 exhibited sustained release of insulin for more than 5 h in case of PMAA microparticles whereas burst release of insulin (90% of total insulin loaded) within 1 h of study was observed in the case of PMAA-alginate microparticles. At pH 1.2, around 30% of insulin loaded was released from both microparticles within 2 h of study.

Administration, Oral↗