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PubMed1986

Role of monosaccharide transporter in vitamin C uptake by placental membrane vesicles.

Dehydroascorbic acid (DHA), the reversibly oxidized form of vitamin C, was taken up much more rapidly than L-glucose into membrane vesicles prepared from the maternal face of the human placental syncytiotrophoblast. DHA uptake was sensitive to inhibition by cytochalasin B and was independent of a sodium concentration gradient. At equilibrium, the concentration of DHA in the vesicles did not exceed that of the medium. DHA and the D-glucose analogue, 3-O-methyl-D-glucose (3-O-MG) appeared to compete with one another for the transporter. The 3-O-MG and DHA inhibitory constants were indistinguishable. Vesicles loaded with a high concentration of 3-O-MG and suspended in low 3-O-MG displayed a marked, transitory enhancement of DHA, but not L-glucose uptake. These findings suggest that DHA is taken into the first cellular boundary of the placenta between maternal and fetal circulations by the sodium-independent monosaccharide transporter. In contrast to DHA, L-ascorbic acid, the reversibly reduced form of vitamin C, was taken into these vesicles much more slowly. This uptake was not affected by cytochalasin B nor by a sodium concentration gradient; it appeared to occur by simple diffusion.

3-O-Methylglucose↗
PubMedDate not supplied

Monosaccharide esters: new tools in biomedicine.

The first report dealing with the use of monosaccharide esters as new tools in biomedicine was published in 1997 (1). This topic was first reviewed in 1998 (2). The major aim of the present report is to briefly evoke the background and present knowledge in this field.

Animals↗
PubMed2006

The monosaccharide transporter gene family in land plants is ancient and shows differential subfamily expression and expansion across lineages.

BACKGROUND: In plants, tandem, segmental and whole-genome duplications are prevalent, resulting in large numbers of duplicate loci. Recent studies suggest that duplicate genes diverge predominantly through the partitioning of expression and that breadth of gene expression is related to the rate of gene duplication and protein sequence evolution.Here, we utilize expressed sequence tag (EST) data to study gene duplication and expression patterns in the monosaccharide transporter (MST) gene family across the land plants. In Arabidopsis, there are 53 MST genes that form seven distinct subfamilies. We created profile hidden Markov models of each subfamily and searched EST databases representing diverse land plant lineages to address the following questions: 1) Are homologs of each Arabidopsis subfamily present in the earliest land plants? 2) Do expression patterns among subfamilies and individual genes within subfamilies differ across lineages? 3) Has gene duplication within each lineage resulted in lineage-specific expansion patterns? We also looked for correlations between relative EST database representation in Arabidopsis and similarity to orthologs in early lineages. RESULTS: Homologs of all seven MST subfamilies were present in land plants at least 400 million years ago. Subfamily expression levels vary across lineages with greater relative expression of the STP, ERD6-like, INT and PLT subfamilies in the vascular plants. In the large EST databases of the moss, gymnosperm, monocot and eudicot lineages, EST contig construction reveals that MST subfamilies have experienced lineage-specific expansions. Large subfamily expansions appear to be due to multiple gene duplications arising from single ancestral genes. In Arabidopsis, one or a few genes within most subfamilies have much higher EST database representation than others. Most highly represented (broadly expressed) genes in Arabidopsis have best match orthologs in early divergent lineages. CONCLUSION: The seven subfamilies of the Arabidopsis MST gene family are ancient in land plants and show differential subfamily expression and lineage-specific subfamily expansions. Patterns of gene expression in Arabidopsis and correlation of highly represented genes with best match homologs in early lineages suggests that broadly expressed genes are often highly conserved, and that most genes have more limited expression.

Arabidopsis↗
PubMed1989

Glucopenia-mediated release of somatostatin from incubated rat hypothalamus: monosaccharide specificity and role of glycolytic intermediates.

Rat hypothalamic somatostatin (SRIF) release in vitro is inversely related to medium glucose concentration and is stimulated by agents interfering with neural glucose uptake or metabolism. The present studies examined monosaccharide specificity of this effect by comparing the ability of glucose and nonmetabolized sugars (ribose, fructose, and galactose) to reverse glucopenia-mediated SRIF release. Removal of glucose from incubation medium resulted in a 7-fold stimulation of hypothalamic SRIF release (24.9 +/- 3.0 to 169.0 +/- 46.2 pg/5 min) that was promptly and fully reversed by readdition of glucose (21.5 +/- 6.0 pg/5 min). Depolarizing concentrations of potassium (40 mM) added to medium after incubation in the presence or absence of glucose produced similar 4-fold biphasic stimulation of SRIF release, suggesting that tissue viability was unimpaired by short term glucopenia. By contrast, nonmetabolized sugars (ribose, fructose, or galactose) at concentrations up to 28 mM were unable to reverse glucopenia-mediated hypothalamic SRIF release. These findings suggest that neural metabolism of glucose specifically influences hypothalamic SRIF release, an effect likely to depend on glycolysis with resulting energy production. This explanation is supported by the finding that the glycolytic intermediates dihydroxyacetone and glyceraldehyde were partly, and pyruvate completely, able to restore glucopenia-mediated SRIF release toward basal, with a maximal effect at 14 mM. Our present studies suggest that rat hypothalamic SRIF release reflects ambient glucose status, is stimulated by glucopenia, and may explain inhibition of GH secretion in the rat during hypoglycemia.

Animals↗
PubMed2000

Ultraviolet spectrometric determination of neutral monosaccharides by HPLC with ethanolamine.

The reaction between ethanolamine and sugars in a borate solution gave intense UV absorption at 310 nm. By adding ethanolamine in the mobile phase, simple and sensitive ion-exchange HPLC of sugar-borate complexes was achieved. This method can be used to measure as little as 100 pmole of seven monosaccharides from pectic polysaccharides.

Chromatography, High Pressure Liquid↗
PubMed1997

Chronic lactose intake modifies the gastric emptying of monosaccharides but not of disaccharides in weanling rats.

Ninety-six weanling male Wistar rats were fed for four weeks one of two different chows: a normal rat chow containing 55.5% (w/w) starch (control group, N = 48) or a rat chow in which starch was partially replaced by lactose, in such a way that the experimental group (N = 48) received 35.5% (w/w) starch and 20% (w/w) lactose. The gastric emptying of fluid was then studied by measuring the gastric retention of four test meals containing lactose (5% or 10%, w/v) or glucose+galactose (5% or 10%, w/v). Homogenates of the small intestine were assayed for lactase activity. The gastric retention values were obtained 15 min after orogastric infusion of the liquid meals. The median values for gastric retention of the 5% lactose solutions were 37.7% for the control group and 37.0% for the experimental group (P > 0.02). For the 10% lactose solution the median values were 51.2% and 47.9% (P > 0.02) for the control and experimental groups, respectively. However, for the 2.5% glucose +2.5% galactose meal the median gastric retention was lower (P < 0.02) in the group fed a lactose-enriched chow (38.5%) than in the control group (41.6%). For the 5% glucose +5% galactose solution the median values were not statistically different between groups, 65.0% for the control group and 58.8% for the experimental group. The median values of the specific lactase activity in the small intestine homogenate was 0.74 U/g in the control group and 0.91 U/g in the experimental group. These values were not statistically different (P > 0.05). These results suggest that the prolonged ingestion of lactose by young adult rats changes the gastric emptying of a solution containing 5% monosaccharides. This adaptation may reflect the desensitization of intestinal nutrient receptors, possibly by an osmotic effect of lactose present in the chow.

Animals↗
PubMed1980

Terminal monosaccharides of carbohydrate chains of glycosaminoglycans in normal human urine.

To elucidate the mode of the exertion of glycosidase activities in the catabolism of the tissue glycosaminoglycans (GAG), the terminal monosaccharides of the carbohydrate chains of urinary GAG in the most prominent subfraction (40% Fr-1.25 M Fr) among the subfractions obtained in a previous paper (Endo et al. 1980a) were investigated. The results of determination of the reducing hexuronic acid and N-acetylhexosamine before and after digestion of the subfraction with beta-glucuronidase and beta-N-acetylhexosaminidase, together with previous data indicated that 0.36 and 0.37 mol of glucuronic acid and N-acetylgalactosamine, respectively, per mol of the subfraction were located at the non-reducing terminals of the carbohydrate chains. The remaining portion (0.27 mol per mol) of the non-reducing ends might be mostly occupied by the sulfated N-acetylgalactosamine residues. On the other hand, 0.25, 0.16 and 0.34 mol of glucuronic acid, N-acetylgalactosamine and xylose, respectively, per mol of the subfraction were indicated to the present at the reducing terminals of the carbohydrate chains. The remaining portion (0.25 mol per mol) of the reducing ends might be mostly occupied by the galactose residues and/or the N-acetylgalactosamine 4-sulfate residues. The present observations provided with evidence for the action of endo-beta-glucuronidase and endo-beta-N-acetylhexosaminidase on the tissue GAG, specifically on chondroitin sulfates.

Glucuronates↗
PubMed2003

11B NMR study of p-carboxybenzeneboronic acid ions for complex formation with some monosaccharides.

The 11B NMR spectra of p-carboxybenzeneboronic acid (PCBA) ions demonstrated that their chemical shifts depend on the pH. At a lower pH, PCBA exists as a mixture of neutral PCBA and the monoanion with a trigonal structure, and at higher pH as the dianion with a tetrahedral structure. In the intermediate pH region, both the mono- and dianion coexist. The pKa of the monoanion of PCBA has been estimated to be 8.53. The complex formation constants of PCBA with several monosaccharides suggest that PCBA-fructose complex is most predominant.

Boron Neutron Capture Therapy↗
PubMed2004

Effects of dietary monosaccharides on sympathetic nervous system activity in adipose tissues of male rats.

Dietary carbohydrate activates the sympathetic nervous system (SNS). As the mechanisms underlying this response are not fully characterized, studies were undertaken to compare SNS responses to ingestion of glucose, fructose, and galactose. SNS activity was examined using techniques of [(3)H]norepinephrine ([(3)H]NE) turnover in brown and white fat. In addition, gene expression for several sympathetically related proteins was also analyzed in these tissues. [(3)H]NE turnover in interscapular brown adipose tissue (IBAT) and retroperitoneal fat increased in response to glucose and fructose in the diet, whereas [(3)H]NE turnover in epididymal fat did not respond to either monosaccharide. Galactose feeding, by contrast, decreased [(3)H]NE turnover in IBAT, but increased it in epididymal, though not retroperitoneal, fat. Expression of GLUT4 was more abundant in IBAT and retroperitoneal fat from glucose- and fructose-fed animals than from diet- or galactose-fed rats. Chemical sympathectomy abolished the GLUT4 response in retroperitoneal fat, but was without effect on GLUT4 in epididymal fat. These studies are consistent with activation of a neural pathway by oral glucose or fructose, leading to SNS activation in IBAT and retroperitoneal fat and enhanced GLUT4 expression.

Adipose Tissue↗
PubMed1986

Identification of lectin-receptor monosaccharides on the endothelium of retinal capillaries.

The carbohydrate moieties of the glycocalyx of the retinal capillary endothelium were demonstrated using lectin-affinity cytochemistry. The endothelial surface was rich in sialic acid, N-acetylglucosamine, galactose and mannose. Low levels of N-acetylgalactosamine were present. There was no preferential distribution of lectin-receptor monosaccharides on the cell surface. The binding of all lectins was inhibited by the appropriate hapten sugars and by perfusion of trypsin or pronase prior to labeling. No differences were observed between vessels in the inner and outer retina.

Animals↗
PubMed1994

Monosaccharide digestibility by dairy cows fed diets high in concentrate and containing alfalfa silages.

Alfalfa was ensiled by the conventional wilting process or as a mixture of 70% fresh alfalfa plus 30% wheat straw treated with SO2. The effects of these silages on the digestibility of monosaccharide constituents of the TMR by dairy cows was examined. Ten cows in early lactation were divided into two groups of 5 that had similar performance data at the onset of the experiment. Cows were fed for ad libitum intake for 28 d a TMR composed of 70% concentrates, 15% alfalfa hay, and 15% silage. The alfalfa silage had lower glucose, xylose, and total carbohydrates than the silage of alfalfa plus wheat straw treated with SO2. Digestibilities of DM (70 to 71%), OM (72%), and total carbohydrate (83%) were similar in the two TMR. The digestibilities of NDF carbohydrate for both TMR were similar. Regardless of treatment, NDF glucose was more digestible than NDF xylose and NDF uronic acid and less digestible than NDF arabinose, galactose, and mannose. The digestibility of total neutral detergent-soluble carbohydrates was 89% in both TMR, but those of neutral detergent-soluble xylose, mannose, and galactose were lower than those of neutral detergent-soluble glucose, arabinose, and pectin.

Animals↗
PubMed1985

Monosaccharide composition of the serum of normal and estrogen-treated male birds.

Gas liquid chromatography using a methylation and silylation technique is a viable method for the quantitative determination of monosaccharides in serum. Analyses of sera of normal and estrogen-treated birds by this method indicated that estrogen administration increased uronic acid, fucose, galactose, mannose, and sialic acid contents and decreased glucose content of the serum. The greatest of the above increases was that of uronic acid.

Animals↗
PubMed2000

[Separation and determination of monosaccharides with high performance liquid chromatography by using internal standard method].

A new approach by which free plant monosaccharides were separated directly and determined with high performance liquid chromatography by using internal standard method was established and beta-indolylacetic acid was selected as the internal standard substance. The separation time for xylose(Xyl), fructose(Fru), glucose(Glu), sucrose(Suc), maltose(Mal), lactose(Lac) and raffinose(Raf) was within 18 min; and the detection limits were 1.8 micrograms, 2.3 micrograms, 2.7 micrograms, 1.8 micrograms, 3.5 micrograms, 4.1 micrograms and 4.3 micrograms respectively while the linear dynamics varied within the range of 5.0 micrograms/L-750 micrograms/L. In this work, the effects of the concentration of CH3CN and pH values in the mobile phase to the separation of the 7 sugars and beta-indolylacetic acid were studied as well. The method can be used to the determinations of jujube, apple samples. Moreover, the recovery experiment was also conducted. The results showed that the relative standard deviations of 5 determinations to Xyl, Fru, Glu and Suc were 1.66%-3.45%, 1.54%-3.01%, 1.29%-2.91%, 1.09%-2.65% and the recoveries were 97.4%-102.1%, 97.3%-101.8%, 98.7%-102.2%, 97.7%-102.5%, respectively.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

[Analysis of monosaccharides of bacterial glycocalix of Bacillus-Lactobacillus-Streptococcus group by gas-chromatography].

The glycocalix of some bacteria of the Bacillus--Lactobacillus--Streptococcus (Bacillus subtilis 3, B. subtilis 668, B. licheniformis 31, Lactobacillus plantarum 11/16, Enterococcus faecium K-50) group were isolated and composition of neutral monosaccharides was investigated. Such sugars as rhamnose, ribose, fucose, arabinose, xylose, mannose, galactose, and glucose were found in the investigated representatives of genus Bacillus--Lactobacillus--Streptococcus. Presence of significant quantity of glucose and galactose did not depend on cultivation conditions. This fact testifies to its conservatism and a possibility to use it as phylogenetic marker.

Bacillus↗
PubMedDate not supplied

[Monosaccharide composition of some Mollicutes].

When studying a small group of mollicutes which interact in different way with the host organism (Mycoplasma fermentans PG18--is considered a commensal of the human urogenital tract, and sometimes manifests as AIDS cofactor, Acholeplasma laidlawii PG8 is saprophytic but it is connected with various pathologies in human organism, A. laidlawii var. granulum 118--agent of the yellow of cereals--palegreen dwarfness) the author has found the carbohydrate composition of their cell surface. Glycocalix of all three representatives proved to be rather various. Biochemical investigation methods were used to establish the presence of galactosamine, glucosamine, minor quantity of rhamnose, ribose, arabinose, xylose, mannose as well as considerable share of fucose, galactose, glucose. Qualitative and quantitative content of monosaccharide composition of the glycocalix of certain species of mollicutes which have different ecological niches is studied in the work and the role of some sugars in performing certain important functions is discussed.

Glycocalyx↗
PubMedDate not supplied

Low level toxicity and antitumor activity of butyric mono- and polyester monosaccharide derivates in mice.

This study compares the antitumor activity of five mono- and polyesters of n-butyric acid derived from monosaccharides in the murine model of Crocker 180 TG Sarcoma. Tumor incidence at ten days, mean survival time and final survival rate were significantly affected in all cases. Combined treatment by butyric esters, alpha/beta interferon (IFN) and/or Corynebacterium parvum used as immunestimulator improved the antitumor protection. Studies of acute toxicity in mice, performed by i.p. and oral routes, showed the low toxicity of butyric esters, which were devoid of detectable side effects with no incidence on ponderal growth when administered per os in rats daily for one month. Finally, a comparative study of antitumor activity, toxicity and water-solubility of various butyric esters enabled us to select among these new molecules two isomers (carbon-3 and carbon-6 of the glucose ring substituted with n-butyric acid) derived from monoacetone glucose for further investigations of their biological mechanism in vivo and in vitro.

Animals↗
PubMed1988

[Derivatives of C-branched monosaccharides studied by 13C NMR].

13C NMR spectra of some 3-C branched D-allofuranoses and D-ribofuranoses were obtained and interpreted. The impact of attaching the alkyl substitute to the monosaccharides on chemical shifting of the adjacent carbon atoms was shown. The experimental data are useful for elucidating structures of analogous compounds by 13C NMR.

Aminoglycosides↗