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Biomedical subjects

A Misaki

Publications and source records attributed to A Misaki.

At least 37 records · Page 2Linked to original sources
PubMed1994

Antitumor activities and immunochemical properties of the cell-wall polysaccharides from Aureobasidium pullulans.

Delipidated cell walls from Aureobasidium pullulans were fractionated systematically. The cell surface heteropolysaccharide contains D-mannose, D-galactose, D-glucose, and D-glucuronic acid (ratio, 8.5:3.9:1.0:1.0). It consists of a backbone of (1-->6)-alpha-linked D-mannose residues, some of which are substituted at 0-3 with single or beta-(1-->6)-linked D-galactofuranosyl side chains, some terminated with a D-glucuronic acid residue, and also with single residues of D-glucopyranose, D-galactopyranose, and D-mannopyranose. This glucurono-gluco-galactomannan interacted with antiserum against Elsinoe leucospila, which also reacted with its galactomannan, indicating that both polysaccharides contain a common epitope, i.e., at least terminal beta-galactofuranosyl groups and also possibly internal beta-(1-->6)-linked galactofuranose residues. It was further separated by DEAE-Sephacel column chromatography to gluco-galactomannan and glucurono-gluco-galactomannan. The alkali-extracted beta-D-glucan was purified by DEAE-cellulose chromatography to afford two antitumor-active (1-->3)-beta-D-glucans. One of the glucans (M(r), 1-2 x 10(5)) was a O-6-branched (1-->3)-beta-D-glucan with a single beta-D-glucosyl residue, d.b., 1/7, and the other (M(r), 3.5-4.5 x 10(5)) had similar branched structure, but having d.b., 1/5. Side chains of both glucans contain small proportions of beta-(1-->6)- and beta-(1-->4)-D-glucosidic linkages.

Antineoplastic Agents↗
PubMed1994

Alteration of beta-D-glucan from edible mushroom after injection into mouse peritoneal cavity.

Tritium-labeled antitumor beta-D-glucan derivative (T-labeled glucan) was prepared from the branched beta-1,3-D-glucan of an edible mushroom, Volvariella volvacea, by its periodate oxidation followed by reduction with NaBT4. Twenty-three hours after T-labeled glucan had been injected into the mouse peritoneal cavity, about 3% of the total radioactivity injected was found in the mouse serum. In spite of the fact that T-labeled glucan had no affinity to the anion-exchange column before injection, about 50% of the labeled beta-D-glucan in the serum thus obtained was adsorbed onto the column. The labeled beta-D-glucan fraction eluted from the column by salt gradient showed antitumor activity in vivo.

Animals↗
PubMed1993

The alpha-mannosyl-binding lectin from leaves of the orchid twayblade (Listera ovata). Application to separation of alpha-D-mannans from alpha-D-glucans.

The carbohydrate-binding specificity of an alpha-D-mannose-specific lectin isolated from leaves of the orchid twayblade (Listera ovata) was elucidated by quantitative precipitation of mannose-containing polysaccharides and glycoproteins, hapten inhibition, and affinity chromatography on the immobilized lectin. L. ovata agglutinin (LOA) interacted with various alpha-mannans and galactomannans of yeasts, fungi and bacteria, but not with alpha-glucans, e.g., dextran and glycogen, as do mannose/glucose-binding lectins. This lectin, LOA, appears to be highly specific for alpha 1-3 mannosidic linkages. It reacted with a linear alpha 1-3-mannan (D. P. 15) and, surprisingly, even with a linear alpha 1-3-mannoheptasaccharide. The LOA/C. tropicalis mannan precipitation reaction was inhibited by alpha-linked mannooligosaccharides, in the order, alpha 1-3 > alpha 1-6 > alpha 1-2 linkages; alpha 1-3 [Man]4 and [Man]5 were the best inhibitors among various mannooligosaccharides tested, having 7-times greater potency than alpha 1-3 [Man]2, and 18-times that of methyl, alpha-mannoside. LOA/mannan interaction was also inhibited by periodate-oxidized and reduced alpha 1-3 [Man]5 which had an inhibitory potency similar to that of alpha 1-3 [Man]3, confirming that LOA also recognizes the internal alpha 1-3-mannosidic linkages of carbohydrate chains. Complete resolution of mannan and glycogen from yeast cells, by affinity chromatography on an immobilized LOA column, and retention of several high-mannose-glycoproteins suggest this lectin to be a useful tool for purification and structural investigation of alpha-mannosyl-containing polysaccharides and glycoconjugates.

Binding Sites↗
PubMed1993

Preparation and characterization of some alpha-D-glucans containing 3,6-anhydro D-glucose.

Alfa-D-glucans containing a 3,6-anhydro D-glucosyl residue were prepared from three kinds of alpha-D-glucan (elsinan, pullulan, and amylose), and the physical properties of these 3,6-anhydro glucans were examined. The method employed for introducing the 3,6-anhydro linkage into a D-glucosyl residue involved sulfation of the O-6 position with dimethylsulfoxide-sulfur trioxide complex and a subsequent alkali treatment of the resulting partially sulfated glucan. This introduction of the 3,6-anhydro linkage caused a decrease in viscosity of the original polysaccharides and made them resistant to the action of hydrolytic enzymes. Hydrolysis of the 3,6-anhydro glucans with dilute acid afforded several oligosaccharides whose reducing end was 3,6-anhydro D-glucose.

Carbohydrate Sequence↗
PubMed1992

Isolation, characterization, and antitumor activities of the cell wall polysaccharides from Elsinoe leucospila.

A cell-wall preparation from the cells of Elsinoe leucospila, which produces elsinan extracellularly when grown on sucrose or glucose-potato extract medium, was fractionated systematically. The heteropolysaccharide that was released by treatment with Actinase E digestion, comprised D-mannose, D-galactose, and D-glucose (molar ratio, 1.5:1.0:0.1). Methylation, mild acid hydrolysis, and 13C-NMR studies suggested that the polysaccharide contains a backbone of alpha-(1----6)-linked D-mannose residues having two kinds of side chains, one attached at the O-4 with single or short beta-(1----6)-linked D-galactofuranosyl residues, and the other attached at O-2 with short side chains, most probably, of alpha-(1----3)-linked D-mannopyranosyl residues. A moderately branched D-glucan fraction, obtained from the cold alkali extract, was fractionated to give an antitumor-active purified beta-(1----3)-glucan having branches of single beta-D-glucosyl groups, one out of eight D-glucose residues being substituted at the O-6.

Animals↗
PubMed1992

Inhibitory effect of oligosaccharides derived from plant xyloglucan on intestinal glucose absorption in rat.

We studied the effects of oligosaccharides which were obtained from tamarind xyloglucan by cellulase digestion on absorption of 3-O-methyl-D-glucose using the everted sacs from rat small intestine. Among oligosaccharides tested, octasaccharide and nonasaccharide, which contain D-galactose residue at non-reducing terminals, inhibited effectively absorption of 3-O-methyl-D-glucose, and their inhibitory effects were concentration-dependent. On the other hand, heptasaccharide not having D-galactose residue at its non-reducing terminal showed no inhibitory effect on absorption of 3-O-methyl-D-glucose. These results indicate that the octasaccharide and nonasaccharide may not only serve as a soluble dietary fiber with small molecular weight but also lower the blood sugar level.

3-O-Methylglucose↗
PubMed1991

Clinical usefulness of serum phospholipase A2 determination in patients with pancreatic diseases.

A new kit for radioimmunoassay of serum phospholipase A2 (PLA2) with monoclonal antibody (S-0932, Shionogi, Osaka, Japan) was used to examine PLA2 levels in patients with various diseases. Patients with acute pancreatitis showed significantly increased serum PLA2 levels. In patients with chronic pancreatitis, significant correlations were observed between the levels of factors evaluated by the secretin test and serum PLA2 levels. In patients with pancreatic cancer, serum PLA2 levels varied with disease severity. Serum PLA2 concentrations were within the normal range in patients with other malignant tumors, diabetes mellitus, and chronic liver diseases but were increased in patients with chronic renal failure. S-Sepharose column analysis of sera showed a small peak of pro-PLA2 and a large peak of PLA2 in sera from patients with severe acute pancreatitis, but a large peak of pro-PLA2 in healthy controls and patients with other diseases. On G-100 gel filtration, high-molecular-weight PLA2 immunoreactivity was detected in sera of patients with chronic renal failure, whereas a single peak of PLA2 immunoreactivity coinciding with that of standard PLA2 was detected in sera of patients with acute pancreatitis. These results suggest that (a) measurement of serum PLA2 is clinically useful for diagnosis and monitoring of pancreatitis, (b) active PLA2 in the circulation is dominant in severe acute pancreatitis, and (c) the kidney may be the main site of PLA2 degradation or excretion.

Acute Disease↗
PubMed1991

Xyloglucan antibodies inhibit auxin-induced elongation and cell wall loosening of azuki bean epicotyls but not of oat coleoptiles.

Polyclonal antibodies were raised in rabbits against isoprimeverose (Xyl(1)Glc(1)), xyloglucan heptasaccharides (Xyl(3)Glc(4)), and octasaccharides (Gal(1)Xyl(3)Glc(4)). Antibodies specific for hepta- and octasaccharides suppressed auxin-induced elongation of epicotyl segments of azuki bean (Vigna angularis Ohwi and Ohashi cv Takara). These antibodies also inhibited auxin-induced cell wall loosening (decrease in the minimum stress-relaxation time and the relaxation rate of the cell walls) of azuki segments. However, none of the antibodies influenced auxin-induced elongation or cell wall loosening of coleoptile segments of oat (Avena sativa L. cv Victory). Auxin caused a decrease in molecular mass of xyloglucans in the cell walls of azuki epicotyls and oat coleoptiles. The antibodies inhibited such a change in molecular mass of xyloglucans in both species. Preimmune serum exhibited little or no inhibitory effect on auxin-induced elongation, cell wall loosening, or breakdown of xyloglucans. The results support the view that the breakdown of xyloglucans is associated with the cell wall loosening responsible for auxin-induced elongation in dicotyledons. The view does not appear to be applicable to poaceae, because the inhibition of xyloglucan breakdown by the antibodies did not influence auxin-induced elongation or cell wall loosening of oat coleoptiles.

Journal Article↗
PubMed1989

Purification of an antitumor-active, branched (1----3)-beta-D-glucan from Volvariella volvacea, and elucidation of its fine structure.

A (1--3)-beta-D-glucan branched by O-6 substitution (FCAP), obtained from the cold-alkali extract of the fruiting body of V. volvacea, exhibited potent growth-inhibitory activity against implanted tumors in mice. It contained protein and appeared to be heterogeneous. Fractionation by DEAE-Toyopearl column chromatography yielded an unbound, protein-free glucan fraction ([alpha]D - 30 degrees in M NaOH, mol. wt. 1.5-2 x 10(6)), which showed the highest antitumor activity. The polysaccharide had a moderately branched structure, consisting of a backbone chain of beta-(1--3)-linked-D-glucose residues, one out of five or six being substituted at O-6 with single glucosyl of beta-(1--6)-linked diglucosyl groups. Digestion of the glucan with exo-(1--3)-beta-D-glucanase yielded glucose and ++gentiobiose (molar ratio, 8:2:1.0), and a highly branched (d.b. 1/3), degraded glucan. Digestion with endo-(1--3)-beta-D-glucanase gave D-glucose, laminarabiose, a trisaccharide beta-D-Glcp-(1--6)-beta-D-Glcp-(1--3)-D-Glc, a tetrasaccharide beta-D-Glcp-(1--3)-beta-D-Glcp-(1--3)-[beta-D-Glcp-(1--6)]-D-Glc, and a highly branched (d.b. 1/2), enzyme-resistant glucan. The results suggest that the Volvariella glucan is structurally heterogeneous with regard to the distribution of branches, having less branched, moderately branched, and highly branched segments.

Agaricales↗
PubMed1989

Preparation and characterization of antibodies against 6-O-alpha-D-xylopyranosyl-beta-D-glucopyranose (beta-isoprimeverose), the disaccharide unit of xyloglucan in plant cell-walls.

The p-aminophenyl beta-glycoside of 6-O-alpha-D-xylopyranosyl-D-glucopyranose (isoprimeverose), the disaccharide unit of plant xyloglucan, was coupled to bovine serum albumin, and the resulting glycoconjugate was used as an immunogen for the immunization of a rabbit. The immunochemical specificities of the rabbit antiserum raised against the glycoconjugate were characterized by immunodiffusion, quantitative precipitation, and hapten inhibition. After removal of anti-bovine serum albumin antibodies, the antiserum exhibited a specificity for the introduced disaccharide unit of the artificial antigen. The antibody-combining site was also shown to recognize the aglycon portion of the introduced hapten. The antiserum interacted with some xyloglucans, such as those from tamarind seed and the cell wall of pea stem. beta-Isoprimeverose and alpha-D-xylopyranosides were good inhibitors of the xyloglucan-antibody precipitation system, indicating that the antibodies recognize the beta-isoprimeverose unit of the xyloglucan.

Antibodies↗
PubMed1986

Synthesis of water-soluble, branched polysaccharides having D-mannopyranose, D-arabinofuranose, or oligo-D-arabinofuranose side-chains and their antitumor activity.

Branched polysaccharides having D-mannopyranose, D-arabinofuranose, or oligo-D-arabinofuranose side-chains were synthesized by the reaction of 3,4,6-tri-O-acetyl-(1,2-O-ethylorthoacetyl)-beta-D-mannopyranose, 3,5-di-O-benzoyl-(1,2-O-ethylorthobenzoyl)-beta-D-arabinofuranose, or 3-O-benzoyl-(1,2,5-O-orthobenzoyl)-beta-D-arabinofuranose with cellulose acetate or curdlan acetate, followed by desterification. The structure and antitumor activity of the water-soluble portion of the polysaccharides thus obtained were investigated. Polysaccharides synthesized from (1----3)-beta-D-glucan as the main chain with oligo-D-arabinofuranose side-chains exhibited high antitumor activity.

Animals↗
PubMed1984

Structure of pestalotan, a highly branched (1----3)-beta-D-glucan elaborated by Pestalotia sp. 815, and the enhancement of its antitumor activity by polyol modification of the side chains.

Pestalotia sp. 815, a newly isolated fungus, produces extracellularly a highly (1----6)-branched (1----3)-beta-D-glucan in high yield when grown in a D-glucose-containing medium. This extracellular glucan, designated "Pestalotan", has [alpha]25D-0.1 degree (c 0.5, M NaOH) and a molecular weight greater than 2 X 10(6). Chemical and enzymic studies indicated that pestalotan has a very highly branched structure containing a back-bone chain of beta-D-(1----3)-linked D-glucosyl residues, and three out of five D-glucosyl residues are substituted at O-6, mostly with single D-glucosyl groups, and a very few with short beta-(1----6)-linked oligosaccharide units. This D-glucan becomes water-insoluble after isolation from the culture filtrate followed by dehydration, and shows moderate growth-inhibitory activities against mouse-implanted tumors. However, when the D-glucosyl groups of the side chains were modified by periodate oxidation and borohydride reduction, the resulting, still water-insoluble, D-glucan polyol exhibited potent antitumor activities, confirming that the attachment of many polyhydroxy groups to the beta-D-(1----3)-linked D-glucan back-bone gives a remarkable enhancement effect on the antitumor activity of the branched D-glucan. Prolonged treatment of the D-glucan polyol by ultrasonic irradiation afforded a low-molecular-weight D-glucan polyol (SD-pestalotan polyol), without alteration of its chemical structure. The water-soluble, SD-pestalotan polyol, having a molecular weight of 4.7 X 10(5), exhibited remarkable antitumor activities against both allogeneic and syngeneic, mouse-implanted tumors, at small dosages (1-5 mg/kg for 10 days) by intraperitoneal administration. A comparison of values of the molecular weight of SD-pestalotan polyol, estimated by 3-MPa l.c. for the aqueous solution and the dimethyl sulfoxide solution, strongly suggested that the D-glucan polyol must form a triple-chain conformation in aqueous solution.

Animals↗