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PubMedDate not supplied

Synthesis of heterobifunctional poly(ethylene glycol) with a reducing monosaccharide residue at one end.

A new synthetic method for a heterobifunctional poly(ethylene glycol) (PEG) having a monosaccharide moiety at one end was created. PEG with a reducing monosaccharide residue at the alpha-end, which is linked to a defined position of the sugar molecule, could be prepared via the anionic polymerization of ethylene oxide (EO) initiated with a potassium alkolate of a protected monosaccharide such as 1,2;5,6-di-O-isopropylidene-D-glucofuranose (DIGL), 1,2;3,4-di-O-isopropylidene-D-galactopyranose (DIGA), and 1,2-O-isopropylidene-3,5-O-benzylidene-D-glucofuranose (IBGL). The resulting PEGs possess the corresponding sugar molecule at the alpha-chain end and a hydroxyl group at the omega-chain end. The omega-chain end could be converted to several functional groups such as allyl, amino, and hydroxycarbonyl groups in high yield. Such heterobifunctional PEGs possessing a reducing monosaccharide residue at the alpha-end are one of the promising tools for bioconjugate chemistries.

Anions↗

PubMed1985

Low apparent aldose reductase activity produced by monosaccharide autoxidation.

Low apparent aldose reductase activity, as measured by NADPH oxidation, can be produced by the spontaneous autoxidation of monosaccharides. NADPH is oxidized to metabolically active NADP+ in a solution of autoxidizing DL-glyceraldehyde at rates of up to 15 X 10(-4) A340/min. The close parallelism between the effects of buffer salt type and concentration, monosaccharide structure and temperature activation on autoxidation and NADPH oxidation imply that autoxidation is a prerequisite for the NADPH oxidation, probably via the hydroperoxy radical. Nucleotide-binding proteins enhanced NADPH oxidation induced by DL-glyceraldehyde, up to 10.6-fold with glucose-6-phosphate dehydrogenase. Glutathione reductase-catalysed NADPH oxidation in the presence of autoxidizing monosaccharide showed many characteristics of the aldose reductase reaction. Aldose reductase inhibitors acted as antioxidants in inhibiting this NADPH oxidation. These results indicate that low apparent aldose reductase activities may be due to artifacts of monosaccharide autoxidation, and could provide an explanation for the non-linear steady-state kinetics observed with DL-glyceraldehyde and aldose reductase.

Aldehyde Reductase↗

PubMed2000

Characterization and expression of monosaccharide transporters (osMSTs) in rice.

This study deals with the cloning and characterization of monosaccharide transporter cDNAs in rice. OsMST1-3 (Oryza sativa monosaccharide transporters 1-3) have two sets of putative six transmembrane domains separated by a central long hydrophilic region. Heterologous expression of OsMST3 in the yeast Saccharomyces cerevisiae indicated that OsMST3 has transport activity for some monosaccharides in an energy-dependent H+ co-transport manner. Northern blot and in situ hybridization analyses showed that OsMST3 mRNA is detectable in leaf blades, leaf sheaths, calli and roots, especially the xylem as well as in sclerenchyma cells in the root. These results suggested that OsMST3 is involved in the accumulation of monosaccharides required for cell wall synthesis at the stage of cell thickening.

Amino Acid Sequence↗

PubMed1971

Monosaccharide and chitin content of cell walls of Histoplasma capsulatum and Blastomyces dermatitidis.

Cell walls of Histoplasma capsulatum and Blastomyces dermatitidis, obtained by mechanical breakage of yeast- and mycelial-phase cultures, were lipid-extracted and then fractionated with ethylenediamine. Unextracted cell walls, lipid-extracted cell walls, and the three fractions resulting from ethylenediamine treatment were examined for monosaccharide and chitin content. The yeast-phase cell walls of five strains of H. capsulatum fell into two categories, designated chemotypes I and II, one of which, chemotype II, was similar to yeast-phase cell walls derived from three strains of B. dermatitidis. H. capsulatum chemotype I cell walls were characterized by lower content of material soluble in ethylenediamine, higher chitin content, and lower monosaccharide content than H. capsulatum chemotype II or B. dermatitidis cell walls. Approximately 80% of the monosaccharides of chemotype I cell walls was combined in forms susceptible to attack by mild acid hydrolysis, compared with about 50% of the monosaccharides of chemotype II and B. dermatitidis. H. capsulatum and B. dermatitidis yeast-phase cell walls could be distinguished, however, by their susceptibility to attack by a crude enzyme system derived from a Streptomyces sp. incubated with chitin as the only carbon source. Both glucose and acetylglucosamine were released from H. capsulatum cell walls, regardless of chemotype, during enzymatic hydrolysis, whereas only acetylglucosamine was released from B. dermatitidis yeast-phase cell walls. Mycelial-phase cell walls of H. capsulatum and B. dermatitidis were characterized by lower content of material soluble in ethylenediamine, higher proportions of mannose, and lower chitin content than their respective yeast phases. Glucose and acetylglucosamine were both released from all mycelial-phase cell walls, whether H. capsulatum or B. dermatitidis, by the crude enzyme system.

Bile Acids and Salts↗

PubMed1977

Duodenal bacterial flora in early stages of transient monosaccharide intolerance in infants.

The aerobic and anaerobic bacterial flora of the duodenum were studied in 10 infants with transient monosaccharide intolerance. 5 infants had protracted diarrhoea after an episode of acute gastroenteritis and 5 had acute gastroenteritis. The duration of monosaccharide intolerance ranged from 1 to 20 days. Serial intubations were performed on 8 infants. In 5 of 8 cases the bacterial flora were of a normal type at the first intubation at 0--4 days after the onset of monosaccharide intolerance. In 4 of those 5 patients there was an increase in bacterial count a few days later and anaerobes appeared. These findings are not consistent with the suggestion that monosaccharide intolerance is caused by abnormal bacteria in the upper small bowel.

Bacteria↗

PubMed1971

Bacteria, bile salts, and intestinal monosaccharide malabsorption.

Intestinal monosaccharide transport was studied in a series of rats with a self-filling jejunal blind loop using 3mM arbutin (p-hydroxyphenyl-B-glucoside) or 1mM D-fructose as substrate in vitro and 10 mM arbutin or 5mM D-fructose in vivo. These results were compared with changes in the bacterial flora and state of conjugation of intraluminal bile salts in those animals. Observations were also made of the microscopic and ultrastructural appearances of the small-intestinal epithelium. In the small intestine of blind-loop rats intestinal monosaccharide transport is impaired, and in vitro is most marked in the blind loop, less so in the efferent jejunum, and not significantly altered in the afferent jejunum. A similar pattern of disturbed monosaccharide absorption was demonstrated by perfusions in vivo. The degree of the transport defect correlates closely with the luxuriance of the anaerobic flora, which averaged 10(8) per millilitre in the blind loop, 10(7) in the efferent jejunum, and 10(6) in the afferent jejunum. A similar pattern of abnormality of bile salt conjugation occurred. In the blind loop the ratio of free to conjugated bile salts was grossly abnormal; this disturbance was somewhat less marked in the efferent jejunum and considerably less in the intraluminal contents of the afferent jejunum. An irregularly distributed lesion, consisting of swelling and vacuolation of microvilli and intracellular organelles, was demonstrated in the small-intestinal epithelium of blind-loop animals. Impaired absorption of monosaccharides is a further consequence of bacterial contamination of the upper gut. It is suggested that this defect is caused by the presence of high levels of deconjugated bile salts produced by an abnormal anaerobic bacterial flora in the small intestine.

Anaerobiosis↗

PubMed2002

Expression of monosaccharide transporters in intestine of diabetic humans.

Noninsulin-dependent diabetes mellitus (NIDDM) is an increasingly common disease, which brings a number of life-threatening complications. In rats with experimentally induced diabetes, there is an increase in the capacity of the intestine to absorb monosaccharides. We have examined the activity and the expression of monosaccharide transporters in the intestine of patients suffering from NIDDM. Na(+)-dependent D-glucose transport was 3.3-fold higher in brush-border membrane (BBM) vesicles isolated from duodenal biopsies of NIDDM patients compared with healthy controls. Western analysis indicated that SGLT1 and GLUT5 protein levels were also 4.3- and 4.1-fold higher in diabetic patients. This was associated with threefold increases in SGLT1 and GLUT5 mRNA measured by Northern blotting. GLUT2 mRNA levels were also increased threefold in the intestine of diabetic patients. Analysis of other BBM proteins indicated that the activity and abundance of sucrase and lactase were increased by 1.5- to 2-fold and the level of the structural proteins villin and beta-actin was enhanced 2-fold in diabetic patients compared with controls. The increase in the capacity of the intestine to absorb monosaccharides in human NIDDM is due to a combination of intestinal structural change with a specific increase in the expression of the monosaccharide transporters SGLT1, GLUT5, and GLUT2.

Actins↗

PubMed1988

Effect of monosaccharide on dehydroascorbic acid uptake by placental membrane vesicles.

Dehydroascorbic acid (DHA), the oxidized form of vitamin C, is transported across the microvillous surface of the human placental syncytiotrophoblast by the D-glucose transporter. The existence of this mechanism suggests that maternal hyperglycemia may influence placental transfer of vitamin C. Therefore, we examined the effect of monosaccharides, equilibrated across the membrane, on the uptake of 0.5 mmol/L DHA by placental membrane vesicles. Relative to uptake in the absence of monosaccharide, the rate of DHA uptake was enhanced by up to 90% in the presence of 3-O-methyl-D-glucose equilibrated across the membrane. Comparable results were obtained with D-glucose and D-galactose. An inward-directed monosaccharide concentration gradient inhibited DHA uptake. However, with elevated equilibrium concentrations of monosaccharide, the magnitude of such uptake inhibition was reduced. Relative to DHA uptake at normal blood glucose concentrations (5 mmol/L), the results suggest that moderate maternal hyperglycemia does not alter, but that severe hypo- or hyperglycemia decreases, placental uptake of DHA from the maternal circulation.

3-O-Methylglucose↗

PubMed1990

Hypoglycemic effect of intestinally administered monosaccharide-modified insulin derivatives in rats.

The effect of the modification of insulin (INS) with p-succinylamidophenyl (SA)-alpha-D-glucopyranoside (SAPG), SA-alpha-D-mannopyranoside and SA-alpha-L-arabinopyranoside on the enzymatic degradation and the hypoglycemic effect in rats was studied. When SAPG-INS was administered intraintestinally in the absence of bile and pancreatic juice, blood glucose level decreased to 56% of initial value. Other monosaccharide derivatives were less effective than SAPG-INS. The digestion of monosaccharide derivatives by pepsin and chymotrypsin indicated that the resistance of insulin to enzymatic degradation was increased by its modification with monosaccharide. One possibility for the hypoglycemic effect of SAPG-INS could be the increased resistance of insulin to enzymatic degradation as a result of its modification with monosaccharide.

Animals↗

PubMed2003

Characterization of rice functional monosaccharide transporter, OsMST5.

cDNA of a monosaccharide transporter in rice, OsMST5 (Oryza sativa monosaccharide transporter 5) was cloned and its sugar transport activity was characterized by heterologous expression analysis. The amino acid sequence and topology were similar to the sequences and topology of other plant monosaccharide transporters. Yeast cells co-expressed with OsMST5 cDNA transported some monosaccharide substrates. The transport rate increased when ethanol as an electron donor was added, so the transporter was an energy-dependent active one. Most of the OsMST5 was expressed in panicles before pollination, indicating that it is associated with pollen development in rice.

Amino Acid Sequence↗

PubMedDate not supplied

[The monosaccharide composition of the glycocalyx in Mollicutes and phylogenetically related bacteria in the genus Bacillus].

A number of monosaccharides composing the glycocalix carbohydrates of some Mollicutes (Mycoplasma pneumoniae FH, M. hominis PG21, M. fermentans PG18, Acholeplasma laidlawii PG8, A. laidlawii var. granulum st. 118) and phylogenetically related bacteria from the genus Bacillus (Bacillus cereus 89, B. cereus DM423, B. subtilis 1/2, B. licheniformis 31, B. licheniformis 49) were detected using plant lectins of definite carbohydrate specificity labelled by colloid gold. The structure of extracellular glycopolymers of microorganisms was discussed concerning their role in the adhesion process and their specializations in colonization of the appropriate organs and tissues of macroorganisms as well as the action of probiotics on the basis of bacteria from the genus Bacillus. It was marked, that the mollicute cells typically interacted with all vegetable lectins tested while bacilli studied bind certain lectins only. The surface carbohydrates prevailing in monosaccharides from tested one for superficial structures of Bacillus pathogenic strains were: sialic acid, beta-D-galactose and alpha-N-acetyl-D-galactosamine, while L-fucose and alpha-D-glucose were observed in insignificant quantity or were absent. The nonpathogenic Bacillus strains being a basis of biopreparations were distinguished by the insignificant amount of sialic acid and other monosaccharides in the composition of carbohydrates of their glycocalix. Thus, as a result of research it was confirmed, that the superficial glycopolymers of Mollicutes and some related bacilli were alike as to presence of some monosaccharides that depended on taxonomic position of microorganisms and their biological activity.

Bacillus↗

PubMedDate not supplied

[Comparative study of the gastric emptying of disaccharides and their respective monosaccharides in rats with ontogenic lactase deficiency].

In order to evaluate the gastric emptying of disaccharides and their monosaccharides, 64 male, Wistar rats weighing approximately 180 g, were divided into the following eight groups containing eight animals each: maltose, sucrose, lactose, and lactulose, and their correspondent group of monosaccharides: glucose, fructose plus glucose, galactose plus glucose and galactose plus fructose. Each animal received, after a 20 hours fast, 2 ml/100 g weight of a test meal containing a 10% solution of the correspondent sugar and phenol red (6 mg/dl) as a marker. Gastric retention was determined at 10 minutes after orogastric infusion and expressed as a percentage of the infused volume. The observed values (mean +/- SE) of gastric retention (%) of sucrose (35.0 +/- 1.8), lactose (30.4 +/- 1.5), and lactulose (29.5 +/- 1.6) were significantly lower (t test alpha = 0.05), than those observed with their respective monosaccharides, i.e. glucose plus fructose (46.9 +/- 2.6), glucose plus galactose (48.3 +/- 2.4), galactose plus fructose (43.5 +/- 1.5). No difference was noted between gastric retention of maltose (49.9 +/- 4.7) and that of glucose (53.0 +/- 3.0). As far the disaccharides are concerned, statistical analysis (ANOVA followed by Tukey test alpha = 0.05) revealed no differences among the values of gastric retention of sucrose, lactose and lactulose. Gastric retention of maltose was significantly greater than that of the other disaccharides. No differences were found among the gastric retention of monosaccharides.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1975

[Monosaccharide-dependent potassium ion influx across the microvilli membrane of the rat jejunum].

1. The condidtions were studied under which the Na+-dependently transported monosaccharides influence the K+-influx across the microvilli membrane of rat jejunum. 2. The Na+-dependent, energy requiring transport of monosaccharides causes a decrease of the K+-influx, whereas monosaccharides metabolizable by the intestinal mucosal cells - under suitable conditions - induce an increase in the K+-influx. 3. These results indicate that the K+-influx may be controlled by an energy dependent system in the microvilli membrane, which is influenced by metabolism and monosaccharide transport. It is discussed that this control system may be a (Na+ + K+)-ATPase.

Adenosine Triphosphatases↗

PubMed2003

[The determination of konjac glucomannan in konjac refined powder and monosaccharide compositions by HPLC].

OBJECTIVE: To establish a quantitative method for the content determination and monosaccharide composition analysis of Konjac glucomannan (KGM) in Konjac refined powder by pre-column derivatization high performance liquid chromatographic method (HPLC). METHOD: The two derivatives combined reducing monosaccharides with 1-phenyl-3-methyl-5-pyrazolone (PMP) were separated by reverse-phase HPLC using a developed fragment gradient elution process, and monitored by ultraviolet detector at 250 nm. The broad reagent peak of PMP was separated very well from all the PMP-sugars, and good separation was achieved for derivatives of mannose and glucose. The quantitative methods of two reducing monosaccharides were studied by the method combined internal and external standard; while the KGM content in Konjac refined powder was determined. RESULT: Linearity of glucose was good (r = 0.9990) in range of 1.002-8.016 nmol; while mannose (r = 0.9994) in range of 1.001-8.008 nmol. The average recovery of this method was 98.1%, RSD of repeatability was 1.72%. KGM content in Konjac refined powder was 79.5%, ratio of glucose to mannose in KGM was 1:1.51. CONCLUSION: This method is a sample, convenient and rapid method that can determine KGM content and analyze monosaccharide compositions in KGM, which will be helpful to quality assessment of Konjac refined powder.

Amorphophallus↗

PubMedDate not supplied

[Potential use of the monosaccharide composition of bacteria for their identification].

The monosaccharide composition of cell hydrolysates can be used as a criterion for the chemical differentiation of gram-positive bacteria. The monosaccharide composition of six bacterial species belonging to the genus Bacillus has been determined using gas chromatography, mass spectrometry and computers. The qualitative composition was similar, glucose, galactose, ribose and glucosamine being the main components in all of the species. Some Bacillus species differed in their minor components. Although the monosaccharide composition appeared to be homogeneous, bacteria can be identified in terms of their carbohydrate profile using computers. To this end, the monosaccharide composition of bacterial cells is represented as a two-dimensional data file including the qualitative composition of components and the quantity of each component.

Bacillus↗

PubMed1988

Monosaccharide inhibition of cytotoxic T-cell function: demonstration of clone-specific effects.

A range of monosaccharides has been tested for their capacity to influence the induction and effector function of alloreactive cytotoxic T (Tc) cells. Strain-specific differences in the capacity of monosaccharides to inhibit Tc cell induction have been demonstrated. Monosaccharides can also inhibit effector function of target cell lysis, but this could only be demonstrated by assessing the effect of sugars added to limiting dilution cultures of alloantigen-stimulated T cells. B10.A(4R) anti-BALB/c Tc cells have been reproducibly inhibited by D-glucosamine and D-galactosamine, as well as D-galacturonic acid, at both the induction and effector phases of the Tc cell response. Analysis of monosaccharide inhibition of cytotoxicity in limiting dilution cultures has confirmed that D-glucosamine is the most effective inhibitor of B10.A(4R) anti-BALB/c Tc cells, while D-galactosamine and D-galacturonic acid inhibit cytotoxicity in only some limiting dilution wells. Analysis of several B10.A(4R) anti-BALB/c Tc cell clones has revealed at least two different 'clone-specific' patterns of inhibition by D-glucose, D-glucuronic acid and D-galacturonic acid. Since Tc cell recognition of antigen is generally specific for class I major histocompatibility complex (MHC) antigens, this data implicates a role for MHC-associated carbohydrate structures expressed by target cells in T-lymphocyte interactions with antigen.

Animals↗

PubMed1986

Effector cell sensitivity to sugar moieties. III. Inhibition by monosaccharides of interleukin-2 enhanced natural killing against viral and nonviral tumor target cells.

Human NK cells recognize multiple target antigens. The ligands (antigens) involved in this interaction have not been clearly identified. Previously, we have shown that some monosaccharides inhibit NK mediated cytolysis in a concentration-dependent fashion and that NK cell activity involves recognition of carbohydrate structures on target cells via receptors on the effector cell surface. Using human IL-2 or recombinant IL-2, we have found that monosaccharides inhibit IL-2 enhanced functional activity in a concentration-dependent fashion; that increased expression of endogenous monosaccharide binding receptors on effector cells occurs after treatment with IL-2; and that greater quantities of monosaccharide were required to obtain equivalent inhibition of IL-2 enhanced NK activity. Our data reinforces the growing belief that effector cells express receptors with different sugar specificities and that quantitative differences in sugar specificities is a likely reason for NK cells having heterogeneous polyclonal activity.

Arabinose↗

PubMed1981

The relationship of serum hexuronic acid and monosaccharide levels to urinary free cortisol and cortisone excretion in healthy subjects and in patients with diabetes mellitus and atherosclerotic peripheral vascular disease.

The relationship of hexuronic acid and monosaccharide concentrations in serum to the excretion of urinary free cortisol and cortisone was studied in 14 healthy subjects, in 16 patients with diabetes mellitus, and in 14 patients with atherosclerotic peripheral vascular disease. In both groups of patients increased values of hexuronic acids, reducing monosaccharides and keto-sugars were registered. In diabetics the relative proportion of monosaccharides was increased, the proportion of hexuronic acids was lowered. In atherosclerotic peripheral vascular disease a significant preponderance of hexuronic acid and keto-sugar amounts in the composition of total sugar components was observed in comparison with healthy subjects. In healthy subjects there is a close correlation of urinary free cortisol and cortisone with reducing monosaccharides in blood, measured on the same day. In diabetes not any correlation of the increased values of free corticoids with the sugar components was registered. In atherosclerotic peripheral vascular disease a highly significant correlation between urinary free cortisol and cortisone and the hexuronic acid content in serum was observed. In patients with atherosclerotic peripheral vascular disease the results suggest an altered metabolism of glucose, which is shunted into insulin-insensitive glucuronate pathway in conditions of endogenous hypercortisolism.

Adult↗