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PubMed2001

Characterization of bioconversion of fumarate to succinate by alginate immobilized Enterococcus faecalis RKY1.

In this study, the immobilization characteristics of Enterococcus faecalis RKY1 for succinate production were examined. At first, three natural polymers--agar, kappa-carrageenan, and sodium alginate--were tried as immobilizing matrices. Among these, sodium alginate was selected as the best gel for immobilization of E. faecalis RKY1. Efficient conditions for immobilization were established to be with a 2% (w/v) sodium alginate solution and 2-mm-diameter bead. The bioconversion characteristics of the immobilized cells at various pH values and temperatures were examined and compared with those of free cells. The optimum pH and temperature of the immobilized cells were the same as for free cells, 7.0 and 38 degrees C respectively, but the conversion ratio was higher by immobilization for all the other pH and temperature conditions tested. When the seed volume of the immobilized cells was adjusted to 10% (v/v), 30 g/L of fumarate was completely converted to succinate (0.973 g/g conversion ratio) after 12 h. In addition, the immobilized cells maintained a conversion ratio of >0.95 g/g during 4 wk of storage at 4 degrees C in a 2% (w/v) CaCl2 solution. In repetitive bioconversion experiments, the activity of the immobilized cells decreased linearly according to the number of times of reuse.

Alginates↗
PubMed1977

Comparative study of selected alginate materials and devices.

Four different brands of alginate impression materials were mixed by hand and ten impressions of each were made of a block for detail reproductions. In addition, two different mechanical devices were used to prepare one of these alginate impression materials. Thus a total of six groups was tested, with ten impressions per group. Stone casts of these 60 impressions were compared by the line study method and the number of surface defects. A statistical analysis was performed on the collected data. The results indicated that the Whip-Mix vacuum mechanical spatulator produced significantly superior results to the Columbus system centrifugal mechanical spatulator, and that among the four alginates hand mixed, the Jeltrate impression material gave better results.

Alginates↗
PubMed2003

Growth and morphology of thermophilic dairy starters in alginate beads.

The aim of this research was to produce concentrated biomasses of thermophilic lactic starters using immobilized cell technology (ICT). Fermentations were carried out in milk using pH control with cells microentrapped in alginate beads. In the ICT fermentations, beads represented 17% of the weight. Some assays were carried out with free cells without pH control, in order to compare the ICT populations with those of classical starters. With Streptococcus thermophilus, overall populations in the fermentor were similar, but maximum bead population for (8.2 x 10(9) cfu/g beads) was 13 times higher than that obtained in a traditional starter (4.9 x 10(8) cfu/ml). For both Lactobacillus helveticus strains studied, immobilized-cell populations were about 3 x 10(9) cfu/g beads. Production of immobilized Lb. bulgaricus 210R strain was not possible, since no increases in viable counts occurred in beads. Therefore, production of concentrated cell suspension in alginate beads was more effective for S. thermophilus. Photomicrographs of cells in alginate beads demonstrated that, while the morphology of S. thermophilus remained unchanged during the ICT fermentation, immobilized cells of Lb. helveticus appeared wider. In addition, cells of Lb. bulgaricus were curved and elongated. These morphological changes would also impair the growth of immobilized lactobacilli.

Alginates↗
PubMedDate not supplied

Chitosan/calcium alginate microcapsules for intestinal delivery of nitrofurantoin.

A new sustained-release dosage form of nitrofurantoin (NF) as microcapsules has been prepared by a mild chitosan/calcium alginate microencapsulation process. These microcapsules have been prepared by adding, dropwise, a solution of sodium alginate containing NF into a chitosan-CaCl(2) system. About 70-80% of the drug is released into phosphate buffer, pH = 7.4 within 6 h. Drug release into the gastric medium is found to be relatively slow compared to that into the intestinal medium. From scanning electron microscopic studies, it appears that the chitosan modifies the NF-alginate microspheres. These findings suggest the possibility of modifying the formulation to obtain the controlled release of NF in an oral sustained-delivery system.

Administration, Oral↗
PubMedDate not supplied

Modulation of protein release from chitosan-alginate microcapsules using the pH-sensitive polymer hydroxypropyl methylcellulose acetate succinate.

The release characteristics of protein from chitosan-alginate microcapsules prepared using an electrostatic droplet generator were evaluated. The release studies were undertaken in-vitro in simulated gastrointestinal fluids covering the pH range 1.2-8. Chitosan-alginate microcapsules showed unsatisfactory release properties, losing 94% of the encapsulated proteins (bovine serum albumin) over a 24 h period at pH 1.2. Incorporation of a pH-sensitive polymer, hydroxypropyl methylcellulose acetate succinate (HPMCAS), in the microcapsules, by coating the capsule membrane as well as blending with the capsule core polymer in varying ratios, produced significant changes in the release profiles of the microcapsules. At pH 1.2, the modified microcapsules retained up to 60% of the encapsulated protein after 24 h. The results obtained highlight the potential of HPMCAS as a release-modifier in chitosan-alginate microcapsules.

Aerosols↗
PubMedDate not supplied

Effect of gelation conditions and dissolution media on the release of paracetamol from alginate gel beads.

Paracetamol was entrapped in alginate beads gelled with calcium or zinc at 0.1, 0.34 or 0.7M. The payloads were of the order of 60-70% w/w which represented an entrapment yield of > 75%. The release of drug from the beads was observed in three media; water, Simulated Gastric Fluid USP without pepsin (SGF) and 0.1% trisodium citrate solution. Release was slowest in water and was complete within 4-5 h. The zinc beads released more slowly than calcium beads prepared at the same molar concentration of cation. Complete release of drug from the alginate gel beads in SGF occurred within 2 h and was unaffected by the cation type and concentration. Except for beads prepared from 0.1M zinc, paracetamol was released rapidly in the citrate solution. All release profiles could be described by first-order kinetics with half-lives which ranged from 25-73 min. Due to the rapid release in acidic conditions, it is unlikely that alginate beads loaded with a relatively water soluble drug will provide satisfactory prolonged release orally.

Acetaminophen↗
PubMedDate not supplied

Production of BCG alginate-PLL microcapsules by emulsification/internal gelation.

A biocompatible emulsification method for microencapsulation of live cells and enzymes within a calcium alginate matrix applied to Bacillus Calmette-Guérin (BCG) has been developed. Small-diameter alginate beads (microcapsules) were formed via internal gelation of an alginate solution emulsified within vegetable oil. Five different oils (sesame, sweet almond, perhydrosqualene, camomile and jojoba) were used. The rheological analysis of the oils showed a Newtonian behaviour, with viscosities = 30.0, 37.7, 51.2, 59.3 and 67.1 mPa.s for perhydrosqualene, jojoba, camomile, sesame and sweet almond oil respectively. The particle size of the microcapsules obtained ranged from 30.3 microns for the microcapsules prepared with sweet almond oil to 57.0 microns for those made with perhydrosqualene. The mean particle diameter obtained was found to be dependent on the viscosity of the oil employed, according to the equation: phi (micron) = 76.6-0.628 eta (mPa.s) (r2 = 0.943). The encapsulated BCG was identified by the Difco TB stain set K, followed by observation under optical microscopy. Freeze-drying of the microcapsules was carried out to ensure their stability during storage. Two batches of microcapsules (those prepared with sesame and jojoba oil) and four types of cryoprotectors (glucose, trehalose, mannitol and sorbitol), at three concentration levels (5, 10 and 20% w/v) were studied. The parameters evaluated were particle size, physical appearance, reconstitution of lyophilizates and microscopical evaluation. For both batches of microcapsules the best results were obtained with trehalose 5%, showing particle sizes of 42.1 microns in the case of the microcapsules prepared with sesame oil, and of 45.3 microns for those prepared with jojoba.

Adjuvants, Immunologic↗
PubMed1988

A quick preparative method for electron microscopy observations of delicate objects using alginate embedding medium.

A quick, safe method has been devised for embedding small or fragile specimens and keeping delicate structures intact. Cells or organisms to be embedded are placed in a viscous sodium alginate solution (1-2%), which is then polymerized in 100 mM calcium chloride. The resulting gel is easily dehydrated, embedded in resin and sectioned for electron microscopy. This method, the alginate gel portion of which was originally developed for the immobilization of Euglena, allows direct observation of each element of the specimens in micrographs. If desired, the alginate can be removed after sectioning by sequestration of calcium in a 20 mM solution of sodium citrate or a 10 mM solution of EGTA. Cells and organelles in the sections respond normally to standard staining procedures.

Alginates↗
PubMed1998

Formulation and characterization of calcium alginate beads containing ampicillin.

The purpose of this work was the preparation and characterization of calcium alginate beads containing ampicillin. Aqueous solutions of drug and sodium alginate (three viscosity grades) were added drop by drop to aqueous solutions of calcium chloride; the droplets instantaneously formed gel beads, which were then dried. Morphological studies and drug contents, in vitro release, and erosion tests were carried out for the characterization of the prepared beads. The dried particles were characterized by irregular shape and a smooth or rough surface, depending on the viscosity grade of the alginate used. The control of the drug for different time intervals depended on the molecular weight of the polymer used; however, the pH-change test showed that this capacity was much lower in the case of acid-treated particles. The results obtained show that the ampicillin beads prepared are suitable for intramammary therapy.

Alginates↗
PubMed2003

Effect of rinsing alginate impressions using acidic electrolyzed water on dimensional change and deformation of stone models.

This study investigated the effect of rinsing alginate impressions using acidic electrolyzed water on the dimensional change and deformation of stone models. Two brands of alginate impression materials were used. The impressions were rinsed using tap water or acidic electrolyzed water with a pH of 2.3, an oxidation-reduction potential of 1,230 mV, and a residual chlorine concentration of 45.0 ppm for 30 sec or 3 min. The sectional profiles of the stone models obtained from them were measured using a three-dimensional coordinate measuring system. For the same rinsing time, there was no significant difference in dimensional change between the two types of rinsing water. The change in shape from the master die was approximately the same for the stone models obtained from rinsed impressions using either water. The results suggest that the use of acidic electrolyzed water rather than tap water for rinsing is an acceptable treatment for alginate impressions.

Acids↗
PubMed2004

Pseudomonas aeruginosa flagellin and alginate elicit very distinct gene expression patterns in airway epithelial cells: implications for cystic fibrosis disease.

Infection with the opportunistic pathogen Pseudomonas aeruginosa remains a major health concern. Two P. aeruginosa phenotypes relevant in human disease include motility and mucoidy. Motility is characterized by the presence of flagella and is essential in the establishment of acute infections, while mucoidy, defined by the production of the exopolysaccharide alginate, is critical in the development of chronic infections, such as the infections seen in cystic fibrosis patients. Indeed, chronic infection of the lung by mucoid P. aeruginosa is a major cause of morbidity and mortality in cystic fibrosis patients. We have used Calu-3 human airway epithelial cells to investigate global responses to infection with motile and mucoid P. aeruginosa. The response of airway epithelial cells to exposure to P. aeruginosa motile strains is characterized by a specific increase in gene expression in pathways controlling inflammation and host defense. By contrast, the response of airway epithelia to the stimuli presented by mucoid P. aeruginosa is not proinflammatory and, hence, may not be conducive to the effective elimination of the pathogen. The pattern of gene expression directed by flagellin, but not alginate, includes innate host defense genes, proinflammatory cytokines, and chemokines. By contrast, infection with alginate-producing P. aeruginosa results in an overall attenuation of host responses and an antiapoptotic effect.

Acute Disease↗
PubMed1998

Improved healing with a collagen-alginate dressing in the chemical matricectomy.

A prospective clinical trial was conducted to evaluate the efficacy of a collagen-alginate wound dressing in the postoperative management of chemical matricectomies. The study involved 20 patients and 23 separate procedures. The collagen-alginate-dressing treatment group had an average healing time of 24.4 days, compared with 35.8 days for the control group, which received treatment consisting of soaks and daily dressing changes (P < .05). The authors suggest that using a collagen-alginate wound dressing in the postoperative management of chemical matricectomies will shorten healing time, thus reducing infection rates and increasing patient compliance and satisfaction.

Adolescent↗
PubMed2001

Poly-L-Lysine induces fibrosis on alginate microcapsules via the induction of cytokines.

Alginate-poly-L-lysine (PLL) microcapsules can be used for transplantation of insulin-producing cells for treatment of type I diabetes. In this work we wanted to study the inflammatory reactions against implanted microcapsules due to PLL. We have seen that by reducing the PLL layer, less overgrowth of the capsule is obtained. By incubating different cell types with PLL and afterwards measuring cell viability with MTT, we found massive cell death at concentrations of PLL higher than 10 microg/ml. Staining with annexin V and propidium iodide showed that PLL induced necrosis but not apoptosis. The proinflammatory cytokine, tumor necrosis factor (TNF), was detected in supernatants from monocytes stimulated with PLL. The TNF response was partly inhibited with antibodies against CD14, which is a well-known receptor for lipopolysaccharide (LPS). Bactericidal permeability increasing protein (BPI) and a lipid A analogue (B-975), which both inhibit LPS, did not inhibit PLL from stimulating monocytes to TNF production. This indicates that PLL and LPS bind to different sites on monocytes, but because they both are inhibited by a p38 MAP kinase inhibitor, they seem to have a common element in the signal transducing pathway. These results suggest that PLL may provoke inflammatory responses either directly or indirectly through its necrosis-inducing abilities. By combining soluble PLL and alginate both the toxic and TNF-inducing effects of PLL were reduced. The implications of these data are to use alginate microcapsules with low amounts of PLL for transplantation purposes.

Alginates↗
PubMed2001

Adhesive retention dressings are more comfortable than alginate dressings on split skin graft donor sites--a randomised controlled trial.

A prospective randomised trial examining the effectiveness, comparative comfort and ease of care of two different split skin graft donor site dressings was performed. One of the dressings was an alginate (Kaltostat), and the other an adhesive retention tape (Mefix). Alginates are the standard plastic surgical dressing, whereas the use of adhesive retention tapes as a donor site dressing presents a novel use of a readily available product. A total of 30 consecutive patients requiring split skin grafts were randomised to receive either alginate or retention donor site dressings. Dressings were assessed by interview and questionnaire at 24 h and 48 h and at 2 weeks, and by wound review at 2 weeks. Retention dressings were found to be more comfortable. They also required less nursing care and attention. The retention dressings allowed the patients easier mobility and a greater range of daily activities, especially washing. There was no significant difference in wound healing nor in complications. Adhesive retention tape applied directly to the split skin graft donor site wound is an effective, cheap and comfortable dressing requiring little postoperative care.

Adhesiveness↗
PubMedDate not supplied

Microbial retention characteristics of sterilizing-grade membrane filters with alginate substituted for oil-based products.

For oil-based products, FDA recommends substitution of the oil with a compound which has similar viscosity and physical characteristics. In this study, a substitute for oil-based products was screened by measuring the viscosity and filterability, and examined for the presence of cell clumps in the various test fluids using an optical microscopy. The viscosity of the test fluids measured in the range of about 60-75 cP. Brevundimonas diminuta (formerly Pseudomonas diminuta), a standard challenge test organism for validation of 0.2 micron rated membrane filters, formed clumps in oils (corn, olive, sesame, and soybean) and polyethylene glycol (PEG, Molecular Weight (MW) = 400 and 1,000). During the viability test, cells suspended in 80% glycerol showed a ten-fold mortality rate after an exposure for 6 hours, but there was no significant change in viability in alginate (low, medium, and high viscosity) for 24 hours. These results suggested that alginate is better suited as a substitute for oil-based products than 80% glycerol. Since high viscosity fluids take longer to filter, the glycerol mortality rate would influence the challenge test negatively. A scaled-down filtration system has been developed for the described trials, and the bacterial challenge and bubble point tests have been performed in 1.6% alginate (66.7 cP), which was the choice of carrier fluid.

Alginates↗
PubMed2004

Alginate impressions for fixed prosthodontics. A 20 year follow up study.

The aim of this study was to estimate whether the survival ratios after 20 years of fixed prosthodontics made of alginate impressions was higher, equivalent or lower, compared to the survival ratios, shown in studies, where different impression materials were used. 151 females and 104 males were screened regarding the condition and age of the restorations at the annual check-up in one of the author's surgeries. Average ages were 55 and 54 years respectively, when the fixed prosthodontics were seated. A total of 1.271 units were produced during the twenty years, 911 abutment teeth and 360 pontics. The type of prosthetic work was divided into three groups: 1) larger fixed prosthodontics 6-14 units (469), 2) smaller fixed prosthodontics 2-5 units (541) and 3) single crowns (261). The results show that alginate impressions can produce fixed prosthodontics with survival ratios similar to those presented in other studies, after 5 years (99%), 1o years (93-96%) and 15 years (74-96%). After 20 years the survival ratio was 61-63%. In conclusion, fixed prosthodontics made according to the syringe-tray alginate impression method may have the same success rates after 20 years compared to that of fixed prosthodontics presented in previous longitudinal clinical studies where other impression materials had been used. In this study, caries and root fractures were the main reasons for removing abutment teeth and pontics.

Adult↗
PubMed2005

[Preparation of alginate-chitosan-poly (lactic-co-glycolic acid) composite microsphere and its regulation of protein release].

AIM: To elevate the encapsulation efficiency, decrease the burst release and improve the release of protein entrapped in poly (lactic-co-glycolic acid) (PLGA) microspheres. The bovine serum albumin (BSA) composite microspheres of alginate-chitosan-PLGA were prepared and the release characteristics of BSA from this composite microspheres were studied. METHODS: The much smaller calcium alginate microcapsules were first prepared by a modified emulsification method in an isopropyl alcohol-washed way and coated with chitosan, then the alginate-chitosan microcapsules were further entrapped in PLGA to form the composite microspheres. The protein concentration was determined using a BCA protein assay kit. The release profiles were changed with various formulation factors. RESULTS: The average diameter of the composite microcapsules was about 30 microm. Comparing with 60% to 70% of the conventional PLGA microspheres, the average encapsulation efficiency was more than 80%, and the burst releases in phosphate buffer solution of the composite microspheres decreased from 40% and 50% to 25% and further to 5% in saline solution. CONCLUSION: The novel composite microspheres were prepared, the drug encapsulation efficiency increased and the burst release decreased. The desired release profiles could be obtained by regulating the ratios of PLG and PLA in the composite microspheres.

Alginates↗
PubMed2005

[Preparation of oligosaccharides from alginate by fermenting combined with membrane separation method and analysis of the oligomers].

Changes in biomass, oligosaccharides content and alginate lyase activity in broth of Alteromonas sp. incubated in shaking flask and fermentation jar were studied. According to those changes, parameters were established for preparing oligosaccharides from alginate by fermentation combined with nano-filtration membrane separation method. Resulting oligosaccharides were analyzed by gel permeation chromatography and thin layer chromatography. One liter culture medium(pH 7.5) contains 5 g yeast extract, l0 g peptone, 0.1 g FeSO4, 12 g sodium alginate and 1.5 g NaCl. When incubating at 28 degrees C, the result showed that the optimal fermentation time was 30 h to obtain the highest production of oligosaccharides in the broth. After ultra-filtration and nano-filtration, 94.0% of the total oligosaccharides was recovered from the broth, and meanwhile 93.3% of the salt was removed. Gel permeation chromatography and TLC analyses indicated that the resulting oligosaccharides were composed of five fractions with different degree of polymerization.

Alginates↗