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PubMed1994

Production of ampicillin through Escherichia coli NCIM 2563 immobilized and cross-linked in alginate beads.

6-Amino penicillanic acid (6-APA) was condensed with D-alpha-phenyl glycine chloride in presence of E. coli NCIM 2563 to form ampicillin. At pH 5, 30% of 6-APA was converted to ampicillin during 1 hr incubation. When E. coli cells were immobilized in calcium alginate beads, the activity remained unaffected even after six batches of bioconversion. Inclusion of glutaraldehyde as multifunctional cross-linking agent, improved the stability of the biocatalyst beads.

Alginates↗
PubMed1994

Physico-chemical interaction between sodium alginate (ALG-Na), polyvinylpyrrolidone (PVP), sodium carboxymethylcellulose (CMC-Na) and solvent.

Physico-chemical interactions between sodium alginate (ALG-Na), polyvinylpyrrolidone (PVP), sodium carboxymethylcellulose (CMC-Na) and solvent were examined. The performed studies involve effect of concentration of macromolecule compounds, electrolytes and pH value of the system. Non-Newtonian system were described by pseudoplasic coefficient and thixotropic coefficient - B and M. These coefficients allow to estimate quantitatively rebuilding of macromolecular structure.

Alginates↗
PubMed1993

[Morphologic rationale for selecting composition and structure of biologically active material based on sodium alginate for wound treatment].

Morphological evaluation of composition and structure of a biologically active compound (BAC) based on sodium alginate, comprising 1% sizomycin and 0.25% protease C, on wound healing in infected rats wounds was made in experiment. The results have clearly shown that for the infected wound treatment during the first period of wound healing BAC of polyfunctional action must be applied. Biologically active substances (sizomycin and protease C) promote removal of inflammatory etiopathogenic factors, i. e. necrotic tissues and microbic bodies, while polysaccharide basis of the composition promotes stimulation of reparative processes in the wounds. Powder with granules size 315 m including 24% potassium gluconate is believed most suitable BAC structure.

Alginates↗
PubMed1994

Identification of amino acid residues involved in the activity of phosphomannose isomerase-guanosine 5'-diphospho-D-mannose pyrophosphorylase. A bifunctional enzyme in the alginate biosynthetic pathway of Pseudomonas aeruginosa.

Phosphomannose isomerase-guanosine 5'-diphospho-D-mannose pyrophosphorylase (PMI-GMP), which is encoded by the algA gene, catalyzes two noncontiguous steps in the alginate biosynthetic pathway of Pseudomonas aeruginosa; the isomerization of D-fructose 6-phosphate to D-mannose 6-phosphate and the synthesis of GDP-D-mannose and PPi from GTP and D-mannose 1-phosphate. Amino acids that are required for the GMP enzyme activity were identified through site-directed mutagenesis of the algA gene. Mutation of Lys-175 to arginine, glutamine, or glutamate produced an enzyme whose Km for D-mannose 1-phosphate was 470-3,200-fold greater than that measured for the wild type enzyme. In addition, these mutant enzymes had a lower Vmax for the GMP activity as compared with the wild type PMI-GMP. These results indicate that Lys-175 is primarily involved in the binding of the substrate D-mannose 1-phosphate, although it is likely that other residues are required for the specificity of binding. Mutation of Arg-19 to glutamine, histidine, or leucine resulted in a 2-fold lower Vmax for the GMP enzyme activity and a 4-7-fold increase in the Km for GTP as compared with the wild type enzyme. Thus, it appears that Arg-19 functions in the binding of GTP. In addition, chymotryptic digestion of PMI-GMP showed that the carboxyl terminus is critical for PMI activity but not for GMP activity. Taken together, these results support the hypothesis that the bifunctional PMI-GMP protein is composed of two independent enzymatic domains.

Alginates↗
PubMed1993

Purification of endo-polygalacturonase by affinity precipitation using alginate.

The precipitation of alginate by Ca2+ at pH 3.8 was found to occur concomitantly with the precipitation of endo-polygalacturonase from Aspergillus niger. Under optimum conditions, 92% of the enzyme activity was precipitated. The enzyme could be recovered from the precipitate by washing with 0.5 M NaCl/0.2 M Ca2+. All the precipitated endo-polygalacturonase activity could be recovered in this way. The enzyme thus obtained was purified 10-fold. A comparison of SDS/PAGE gel patterns of the crude preparation and enzyme purified by the affinity precipitation also showed a significant purification of the enzyme.

Alginates↗
PubMed1993

The algD promoter: regulation of alginate production by Pseudomonas aeruginosa in cystic fibrosis.

Pseudomonas aeruginosa mutants that overproduce the exopolysaccharide alginate and assume mucoid phenotype are associated with the establishment of chronic respiratory disease in cystic fibrosis. The initially invading strains are nonmucoid and frequently convert into the mucoid form. Mucoidy is regulated at the transcriptional level, mainly at the promoter of the algD gene. Control of the algD promoter represents a cooperative effort of several types of regulatory elements including bacterial signal transduction factors (principally through the response regulator AlgR) and histone like elements (e.g., Hp1 and possibly IHF). Our more recent studies have shown that conversion to mucoidy is a result of mutations in the muc genes within the algU-mucA-mucB cluster. The algU gene encodes a protein that resembles Spo0H, a sigma factor from Bacillus subtilis, which controls development of sporulation and competence. The mucA and mucB genes appear to control the activity of AlgU. Frameshift mutations that inactivate these proteins result in a strong transcriptional activation of algD, and conversion to mucoidy in both laboratory and clinical strains of P. aeruginosa.

Alginates↗
PubMed1996

[Immobilization in alginate gels].

Summarization of literary data on immobilization in calcium alginates as published in the last two years. The review focuses on those papers in which the new knowledge of immobilized enzymes, cells and tissues expands their biotechnological applications.

Alginates↗
PubMedDate not supplied

Rheological characterization of cellulosic and alginate polymers.

The purpose of this study was to assess the properties of aqueous solutions of various polymeric materials intended for use as components of a sustained release device for various proteins. Polymers that were studied included Sodium Carboxymethylcellulose (CMC), Methylcellulose (MC), Hydroxypropylmethylcellulose (HPMC) and Sodium Alginate (ALG). The effects of polymer concentration, temperature and autoclaving on solution viscosity were determined. With all the polymers, viscosity/ concentration relationships were linearized by using an equation of the type mu = (Ca + beta)gamma, where mu and C referred to solution viscosity and concentration, respectively. alpha and gamma were constants related to polymer type and molecular weight, whereas beta reflected viscosity of water at the temperature of measurement. gamma, which reflects the sensitivity of the viscosity/concentration relationship, was determined to be 4 for both low and high molecular weight CMC and ALG, and 8 for MC and HPMC. alpha, on the other hand, was directly proportional to polymer molecular weight. The same equation could also adequately describe viscosity/temperature relationships for each polymer. For both CMC and ALG, increasing solution concentration had a greater effect on the reduction of viscosity upon increasing temperature. A concentration dependent thermal "gelation" phenomena was observed with MC solutions. Autoclaving effects were more pronounced in ALG solutions as compared to CMC samples in the 0.5 to 3.0% w/v concentration range. No significant long term effects on solution viscosity were observed with MC and HPMC, however.

Alginates↗
PubMedDate not supplied

Buffer uptake and mass loss characteristics of freeze-dried cellulosic and alginate devices.

The buffer uptake and mass loss characteristics of freeze dried unitary devices prepared from aqueous solutions of Sodium Carboxymethylcellulose (CMC), cross-linked Sodium Alginate (ALG) and Methylcellulose (MC) were evaluated. Some of the devices also contained 50% (by weight) Poly (d,l Lactide-co-Glycolide) (PLGA) microspheres. Devices prepared from cross-linked ALG solutions imbibed the highest amounts of isotonic Phosphate Buffered Saline, followed by those from prepared from CMC solutions, and lastly, MC. In all cases, the presence of microspheres within the devices significantly decreased buffer uptake. Uptake was determined to be approximately proportional to the weight percent of the hydrophilic matrix polymer. Highest levels of overall mass loss were observed with devices prepared from cross-linked ALG solutions (approximately 80% in 60 days), followed by those prepared from CMC solutions (approximately 45 to 65%) and MC (approximately 35 to 60%). A majority of the unitary devices retained their shape and integrity, however, over the two month test period, indicating possible use as long term delivery systems for incorporated bone growth factors.

Alginates↗
PubMed1996

Physical properties of casts prepared from disinfected alginate.

The dimensional accuracy, surface hardness and reproduction of surface detail of stone casts produced from alginate impressions treated with 4.65% sodium hypochlorite, were investigated. To test dimensional accuracy, a Reflex Microscope was used to compare casts from 10 untreated impressions with casts from 10 impressions immersed in the solution for 30 mins. Surface detail and hardness were investigated on casts produced from impressions of a master stainless steel plate with 10 micro-indentations of increasing size. Surface detail of the casts were assessed by observation and surface hardness by a Vickers Hardness Machine. The dimensional accuracy test showed no significant differences between the experimental and control groups. Surface detail was unaffected after immersion of up to 10 mins. Surface hardness decreased linearly with respect to immersion time, when this was greater than 5 mins.

Alginates↗
PubMed1977

[Evaluation of the protective effect of Prussian blue, sodium alginate and calcium phosphate according to tumor development after single and chronic exposure to strontium 90 and cesium 137 mixture].

The mixture of radionuclides was employed in the concentrations of 100.0, 400.0 and 0.8, 2.0 mc/rat for strontium-90 and cesium-137 in single and chronic administration correspondingly. Prussian blue, sodium alginate and calcium were employed in amounts of 50 mg, 800 mg and 258 mg per rat a day. The data obtained are correlated with the results of the same experiments without using the protection. In compared doses of the irradiation the protective action of the substances under study was noted only in chronic experiments. In this case, the appearance of malignant neoplasms was nearly twice less, and the survival was 120 days longer. The absorbed doses were decreased by 17 times for cesium-137 in the whole body and nearly by 4 times for strontium-90 in the skeleton.

Alginates↗
PubMed1997

Characterization of modified alginate-poly-L-lysine microcapsules.

Various modifications of alginate-poly-L-lysine microcapsules were made, such as the inclusion of polyethylenimine (PEI) or carboxyl methyl cellulose (CMC) in the core and the coating of bis(polyoxyethylene bis[amine]) (PEGA) onto the microcapsule membrane surface. A characterization of the modified microcapsules in terms of mechanical and mass transfer properties as well as their chemical composition was performed. The PEI treatment greatly enhanced the mechanical stability of the microcapsules, and this treatment did not affect the coating process of poly-L-lysine or PEGA. PEGA was found to be able to coat the microcapsules while the mass transfer property was similar to the poly-L-lysine coated ones.

Alginates↗
PubMed1997

[Pure calcium-sodium alginate dressing. Multicenter evaluation of chronic cutaneous lesions].

By means of a descriptive, non-comparative study of a series of clinical cases, the authors analyze the behavior of a dressing of pure calcic-sodium alginate with a stabilizing network in the treatment of pressure sores and profusely bleeding and/or infected vascular uclers. Based on the results of their studies, the authors confirm the effectiveness of this dressing under these conditions: no adverse reactions; the shrinking of the lesion in area or degree of severity; if there is tissue debridement accompanied by sloughing and necrotic tissue, the elimination of infection; ease of application and the reduction of the lesions; use as part of a non-daily cure treatment plan.

Aged↗
PubMed2000

Hydrophobically Associating Alginate Derivatives: Surface Tension Properties of Their Mixed Aqueous Solutions with Oppositely Charged Surfactants.

The comparative study of the interfacial properties of an anionic polysaccharide, sodium alginate (Alg), and its hydrophobically modified derivative (Alg-C(12)), covalently substituted by dodecyl chains (12% mol/mol saccharide unit), was carried out in the absence or in the presence of an oppositely charged surfactant, dodecyltrimethylammonium bromide (DTAB). The drastically different behaviors which were observed are interpreted in terms of the arrangement and mobility of the hydrophobic long alkyl chains, depending on the nature of their fixation, covalent or ionic, on the polysaccharide backbone. Copyright 2000 Academic Press.

Journal Article↗
PubMed1994

Antibody response of rabbits and cystic fibrosis patients to an alginate-specific outer membrane protein of a mucoid strain of Pseudomonas aeruginosa.

The aim of this work was to study the immunogenicity of an outer membrane (OM) protein (AlgE; 54 kDa) which is produced solely by mucoid, i.e. alginate-producing strains of P. aeruginosa. The source of AlgE used for our study was the mucoid strain CF3/M1 originally isolated from sputum of a cystic fibrosis (CF) patient. The purified non-denatured protein served as antigen to raise polyclonal monospecific anti-AlgE antibodies in rabbits and to assay sera from 41 cystic fibrosis (CF) patients for anti-AlgE antibodies. According to clinical protocols the sputa of 22 CF patients were positive for P. aeruginosa, 18 were negative and one case was unknown. Our ELISA studies showed that high titers of anti-AlgE antibodies (IgG) corresponded well with the infection status of the CF patients. None of 23 control sera derived from healthy volunteers contained significant levels of anti-AlgE antibodies. Thus the ELISA should be considered as a sensitive diagnostic tool for the early detection of mucoid P. aeruginosa infections in CF patients. Furthermore, we suggest to include AlgE in a multicomponent experimental vaccine for potential protection of non-colonized CF patients from colonization with mucoid P. aeruginosa.

Animals↗
PubMed2000

In Situ Polymerase Chain Reaction Visualization of Vibrio halioticoli Using Alginate Lyase Gene AlyVG2.

A prokaryotic in situ polymerase chain reaction (PI-PCR) technique was applied to visualize Vibrio halioticoli cells using alginate lyase gene alyVG2 as a target gene. Prior to PI-PCR, a primer set, VG2-OS3, for specific amplification of an approximately 1.0-kb fragment from V. halioticoli genomic DNA was developed with amplified fragments from V. pelagius and V. fischeri DNAs as reference strains. One-stage PI-PCR using the primer set, digoxigenin-labeled dUTP, and indirect alkaline-phosphatase-linked fluorescence detection technique (HNPP/Fast Red TR as a substrate) failed to differentiate V. halioticoli IAM14596(T) cells from ATCC25916(T) cells of the closely related species V. pelagius. However, two-stage PI-PCR adding the extension and digoxigenin-labeling step of the amplified fragment into the first amplification stage allowed us to differentiate V. halioticoli cells from V. pelagius cells.

Journal Article↗