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At least 415 records · Page 23Linked to original sources
PubMed1991

Partial characterization of the glucosyltransferases of an oral Streptococcus salivarius strain.

The oral Streptococcus salivarius strain S3 possessed extracellular glucosyltransferase (GTF) and cell-associated fructosyltransferase activities. Chromatofocusing column chromatography of crude GTF yielded multiple peak fractions, which were categorized into two types which catalysed (1) water-insoluble glucan synthesis and (2) water-soluble glucan formation. The GTF isozyme eluted in fraction 29 synthesized mutanase- and dextranase-sensitive insoluble glucan from sucrose, while fraction 81 GTF synthesized soluble glucan which was insensitive to both glucanases. The ability to agglutinate Streptococcus sobrinus cells was high for insoluble glucan but negligible for soluble glucan. The insoluble glucan-synthesizing activity of fraction 29 GTF was inhibited by the presence of dextran T10. Isoelectric focusing yielded a single activity band but SDS-polyacrylamide gel electrophoresis gave multiple bands for both GTF fractions 29 and 81. The extracellular crude GTF activity was inactivated by 0.1% SDS or 1% Tween 80, but the activity was completely restored by the addition of 1% Triton X-100.

Detergents↗
PubMed1975

Purification of membrane proteins from Acholeplasma laidlawii by agarose suspension electrophoresis in Tween 20 and polyacrylamide and dextran gel electrophoresis in detergent-free media.

Four of the membrane proteins from Acholeplasma laidlawii that are soluble in the nonionic detergent Tween 20 have been purified by preparative electrophoretic techniques utilizing different supporting media. The last purification step for two of the major proteins was a preparative polyacrylamide gel electrophoresis performed in the absence of any detergent. The proteins were recovered by continuous elution. The purity of the fractions was examined by analytical polyacrylamide gel electrophoresis and crossed immunoelectrophoresis. Two of the minor proteins were purified by dextran gel electrophoresis as the final step, which was also performed in a detergent-free buffer. The separation was followed by scanning the dextran gel in ultraviolet light. The proteins were recovered by slicing the gel and degrading the gel slices with dextranase. The homogeneity of the fractions was checked by electroimmunoassay.

Acholeplasma laidlawii↗
PubMed1977

[Optimal conditions of alpha-amylase production by Aspergillus oryzae in liquid media].

The alpha-amylase secretion in a mineral culture medium containing starch and glucose follow the lysis of mycelium. This lysis seems to result from the hydrolysing action of dextranase and levulanase on cell wall. Cell lysis and amylase secretion are greatly enhanced by pH elevation of culture medium (optimal pH 8,8). In such conditions of production the amylase is not stable but can be stabilized by addition of starch. A method is described using pH and starch content modifications, which allows to obtain an amylase production three times greater than in standard culture medium.

Amylases↗
PubMed1986

[Iatrogenic generalized storage of dextran in regularly dialyzed patients].

Intensive generalized intracellular storage of a PAS positive birefringent material with unusual ultrastructure was found in 17 patients deceased after long-term hemodialysis. It was identified as "condensed" dextran administered repeatedly for hypotension during dialysis. Intensity of storage was related to residual diuresis and not to the number of dialyses. Identification of the material was enabled by digestion with dextranase. Dextran cytoplasmic inclusions in macrophages resisted to common solvents but dissolved in lyes. The storage occurred in lymph-nodes, in the heart, kidney interstitium, bone marrow and others. Fatal complications of massive dextran storage were discussed. Quantity, morphogenesis and location of storage are learning about storing systems.

Dextrans↗
PubMed1987

Isolation and characterization of mutants of Streptococcus mutans using selective removal of wild-type cells by agglutination with an agglutinin from Persea americana.

Persea americana agglutinin (PAA), a substance known to bind basic proteins and inhibit the sucrose-independent adherence of Streptococcus mutants to saliva = coated hydroxyapatite (Staat et al., 1980) was used to selectively enrich for mutants defective in a variety of cell surface associated virulence characteristics from cultures UAB62 (PS14 Riff, serotype c), UAB66 (6715 Strr Spcr, serotype g) and UAB77 (GS5, serotype c). Following mutagenesis and growth for segregation and phenotypic expression, washed cells of each strain were exposed to PAA overnight at 37 degrees C. Aggregated cells were removed by low-speed centrifugation and cells remaining in the supernatant fluids were concentrated, grown to stationary phase and the enrichment with PAA repeated. Mutants isolated following enrichment were phenotypically diverse and included strains defective in one or more of the following characteristics: adherence to glass in a sucrose-containing medium, aggregation with sucrose, dextran or PAA. dextranase production, colony morphology, cell or chain morphology, fermentation of sorbitol, lactose, galactose, raffinose, melibiose, or fructose, and production of surface protein antigen A (SpaA). The diversity of mutant phenotypes identified along with the observation that PAA could still cause aggregation (with a lower efficiency) of all mutants leads us to infer that the interaction of this agglutinin with proteins on the S. mutans cell surface is relatively nonspecific and that the observed inhibition of S. mutants attachment to saliva-coated hydroxyapatite caused by PAA is not due to a highly specific unique interaction of PAA with the protein(s) responsible for sucrose-independent adherence.

Agglutination↗
PubMed1987

Iatrogenic generalized storage of dextran in patients on regular dialysis.

Intensive generalized intracellular storage of PAS positive birefringent material with an unusual ultrastructure was found in 17 patients deceased after long-term haemodialysis. Both direct and indirect evidence documented intracellular storage and "condensation" of dextran administered repeatedly for hypotension during dialysis. Intensity of storage was related to residual diuresis of the patients and not to the number of dialyses. Identification of the material was enabled by digestion with dextranase. Dextran cytoplasmatic inclusions in macrophages resisted to common solvents but dissolved in alkalies. The storage occurred not only in lymph nodes, but also in interstitial tissues of other organs, such as the heart, adrenals, bone marrow and others. The relation of massive dextran storage to frequent complications was discussed. Quantity, morphogenesis and location of storage are instructive with respect to the common knowledge of storing systems.

Adipose Tissue↗
PubMed1989

[Adherence of Candida albicans to acrylic surfaces].

The ability of Candida albicans IFO 1385 to adhere to acrylic and the partial characterization of an adhesive substance, named AS, which was isolated from the yeast, were studied in vitro. The results obtained were as follows: 1. The cells cultured in the synthetic media (YNB) containing 500 mM galactose showed a much greater tendency to adhere than did those cells cultured in the YNB containing 500 mM glucose. 2. More cells prepared by the standing cultivation adhered to acrylic than did those prepared by the stirring cultivation. 3. A large number of the adherent cells was obtained when the acrylic plates were incubated at 37 degrees C for 90 min in the cell suspension at a concentration of 1.0 x 10(7) cells/ml. The plates were observed without staining. 4. AS was isolated from the surface of C. albicans, grown on different carbon sources (50 mM glucose, 500 mM glucose and 500 mM galactose), by treatment with ultrasonication. 5. Three different kinds of AS isolated from the three carbon sources were slightly soluble in distilled water. All were similar in composition to each other, and contained 62-68% carbohydrate (as glucose) and 23-26% protein (as BSA). 6. Silica particles adhered to acrylic coated with AS and pretreatment of acrylic with AS promoted C. albicans adhesion. However, similar pretreatment inhibited subsequent Candida glabrata and Candida krusei adhesion. As to subsequent adhesion of Candida tropicalis, no significant data were obtained. 7. Adhesion assay using the silica particles, the adhesive ability of the AS was significantly reduced by treatment with trypsin or pronase E, but not with papain, alpha-amylase, dextranase or zymolyase.

Acrylic Resins↗
PubMed1989

[Macrophage respiratory burst-triggering activity of transparent and opaque colonial variants of Mycobacterium avium complex].

The two types of colonial variants of Mycobacterium avium complex, SmT (smooth, transparent, irregular) and SmD (smooth, opaque, dome-shaped) variants, were examined for their triggering activity for macrophage (M phi) respiratory burst, based on chemiluminescence (CL). SmD variants elicited an intense CL from zymosan A-induced M phi s in a dose-dependent manner, although SmT variants induced much lower M phi CL. The M phi s could steadily phagocytose SmT variants, although the phagocytizing rate was considerably lower compared to the case of SmD variants. Treatments of SmD variants with Tween 80, pronase and some endoglycosidases such as alpha-amylase, cellulase, dextranase and pectinase, heating (100 degrees C, 15 min), and delipidation by CHCl3-methanol extraction resulted in a marked reduction in the M phi CL-triggering activity of the SmD variants. Thus, the M phi CL-triggering ligand(s) seems to possess glycolipoprotein-like moieties. Tween 80-treatment of SmT variants, which is known to deprive the polysaccharide outer layer specific to the colonial variants, failed to recover the M phi CL-triggering activity of SmT variants. Therefore, the remarkably reduced M phi CL-triggering ability of the SmT variants may be caused by the extremely lowered expression of the M phi CL-triggering ligands rather than by masking of the CL-triggering ligands by SmT-specific outer layer.

Animals↗
PubMed1984

The microbial production of amylase inhibitor and its application. I. Isolation and cultivation of Streptomyces nigrifaciens NTU-3314.

In the course of screening amylase inhibitor producing, microorganisms, a strain identified as Streptomyces nigrifaciens NTU-3314 was found to have the highest inhibitor-producing ability among the other isolated strains. This strain was aerobically cultured at 30 degrees C in a 5l jar fermentor with a working volume of 2l. The optimum cultural medium consisted of defatted soybean flake 3.0%, potato starch 4.0%, casein 0.6%, sucrose 0.6%, serine 0.02% and NaCl 0.8% (pH 7.0). With an aeration rate of 1.5 vvm, an agitation speed of 300 rpm and an inoculum of 15% seed (previously grown in seed medium 3), the highest amount of inhibitor was obtained after 24 hours of cultivation. The amylase inhibitor produced had inhibitory effects on both alpha-amylase and glucoamylase, but not on beta-amylase, alpha-glucosidase, beta-glucosidase or dextranase. It was quite stable in 0.1M phosphate buffer (pH 7.0) and nearly 100% of its activity was retained even after boiling at 100 degrees C for 20 min.

Amylases↗
PubMed1981

Regulation of clones responding to dextran B1355S. II. Response of T-dependent and T-independent precursors.

The existence of precursors for TI and TD alpha 1 leads to 3 dextran antigens in BALB/c mice was demonstrated. A T-dependent dextran antigen was prepared by coupling dextran B1355S to hemocyanin and subsequent digestion with dextranase. The PFC response of BALB/c mice primed with hemocyanin to dextran-hemocyanin was found to be 8 times higher than in unprimed animals. The splenic focus assay was adapted for the analysis of precursors responding to T-dependent and T-independent dextran antigens. Pretreatment of recipients with anti-thymocyte serum abolished the response in fragment cultures to dextran-hemocyanin but did not affect the response to dextran B1355S. The frequencies of precursors in the adult BALB/c mouse responding to dextran and dextran-hemocyanin were determined by limiting dilution analysis. The frequency of T-dependent precursors was found to be almost 3 times greater than the frequency of T-independent precursors.

Animals↗
PubMedDate not supplied

[Comparative study of the pullulans synthesized by Pollularia (Aureobasidium) pullulans strains of different ploidies].

Pullularia pullulans strains of different ploidy synthesize pullulans similar in their characteristics to those described in literature. These are glucans whose glucose residues are linked with alpha(1 leads to 4) and alpha(1 leads to 6) bonds in the proportion of 2.2:1. The pullulans differ from one another in their water solubility, molecular mass and in the ability to be cleaved by alpha-amylase and dextranase. The minor structural modifications of pullulan molecules in the polyploid strains as compared to the pullulan synthesized by the parent haploid culture are caused, apparently, by mutations induced with mitotic poisons.

Chemical Phenomena↗
PubMed1976

Preparation and characterization of a dextran-trypsin conjugate.

Bovine pancreatic trypsin was coupled to dextran after activation of the polysaccharide by cyanogen bromide. The soluble dextran-trypsin conjugated was purified by molecular sieve chromatography. After coupling, 53% of the esterase activity of trypsin remained, but the conjugate had only 7% of the caseinolytic activity of the native enzyme. The modified trypsin showed greater resistance than the native enzyme to inactivation by heat treatment, autodigestion, or denaturing agents, and was also more resistant to inhibition by trypsin inhibitors, particularly ovomucoid. Treatment with dextranase partly removed the improved stability properties and resistance to inhibition of the trypsin-dextran conjugate. The conjugated enzyme preparation consists of a heterogenous mixture of macromolecular aggregates, each containing many trypsin and many dextran molecules linked together. Intramolecular cross-linking of enzyme molecules by polysaccharide chains is considered to be responsible for stabilization of the tertiary structure of the enzyme molecules in the conjugate.

Animals↗
PubMed1997

Effect of enamel microabrasion on bacterial colonization.

PURPOSE: To determine if microabraded surfaces inhibit Streptococcus mutans colonization. MATERIALS AND METHODS: Ten extracted molars were obtained and sectioned in half mesio-distally. The mesial side was treated with microabrasion (PREMA Compound). The distal surface was designated as the control site. A plastic tube was secured on each surface with resin composite, exposing a surface of 13.2 mm 2. S. mutans 10,499 was cultured in TSB-YE supplemented with 5% sucrose and 2.5% glucose was added to each secured site in addition to 50 microliters of cell suspension. Samples were incubated in a 5% CO2 chamber for 7 days at 37 degrees C. Samples were taken from each site, incubated with dextranase (75 micrograms 1 ml), sonicated, and vortexed to disrupt cellular aggregates as much as possible. Samples were then plated on Mitis-Salivarius agar using a spiral plating system. Enumeration of numbers of colonizing bacteria was achieved following standard spiral plating system methodology. RESULTS: The mean for the microabraded group was 1.12 x 10(2) cfu/tooth and for the control it was 1.15 x 10(4). Analyzing the data revealed a significant difference (P = 0.0188).

Colony Count, Microbial↗
PubMed1978

Genetic alterations of Streptococcus mutans' virulence.

The use of mutants defective in caries-associated traits has enabled the genetic dissociation of agglutination from adhesion, the demonstration of serotype-specific contributions of IPS to virulence, the importance of glucanohydrolase to virulence to a greater degree than to plaque formation, and the apparent lack of importance of agglutination to virulence. We have also been able to demonstrate the ability of plaque formation-defective mutants and other variants both to infect and to emerge, yet not to cause disease. Additional mutants, currently under study in our laboratory include fructanase, invertase, and sucrose permease-defectives. Ultimately, the identification of key, probably surface-associated virulence factors will offer more potent and specific antigens for directed immune responses by the host.

Adhesiveness↗