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At least 217 records · Page 12Linked to original sources

Charge transfer fluorescent probes using boronic acids for monosaccharide signaling.

We have developed a new series of glucose sensitive fluorophores that display shifts in emission wavelengths and/or intensity change upon the binding of monosaccharides. Complexation of glucose with the boronic acid moiety changes both its orbital hybridization and its ability to accept and donate electrons. This change results in distinct emission spectra for the fluorophores when free in solution or complexed with monosaccharide. The spectral changes upon saccharide binding can be modified by substitution of electron donor or acceptor group on the fluorophore allowing rational design of the spectral response.

Boronic Acids↗

Reaction of monosaccharides with proteins: possible evolutionary significance.

Measurements were made of the rate of condensation of various monosaccharides with amino groups of hemoglobin to form Schiff base linkages. The reactivity of each sugar was dependent on the extent to which it exists in the open (carbonyl) structure rather than in the ring (hemiacetal or hemiketal) structure. Among the 15 monosaccharides tested, aldoses showed higher reactivities than ketoses. Glucose was the least reactive of the aldohexoses. The emergence of glucose as the primary metabolic fuel may be due in part to the high stability of its ring structure which limits potentially deleterious nonenzymatic glycosylation of proteins.

Borohydrides↗

Digestion of cell-wall monosaccharides of ryegrass and alfalfa hays by the ruminal bacteria Fibrobacter succinogenes and Butyrivibrio fibrisolvens.

The ruminal bacteria Fibrobacter succinogenes strains S85 and BL2 were grown in monocultures or in coculture with strain D1 of Butyrivibrio fibrisolvens, and the solubilization of ryegrass and alfalfa cell walls (CW) and digestion of CW monosaccharides were measured. Fibrobacter succinogenes monocultures and cocultures with B. fibrisolvens D1 degraded 58-69% of ryegrass CW, solubilizing 67-78% of CW glucose, 65-71% of CW xylose, 69-75% of hemicellulose, and 68-77% of total CW monosaccharides. When grown on alfalfa CW, those cultures degraded 28-39% of alfalfa CW, solubilizing 42-58% of CW glucose, 30-36% of CW xylose, and 37-45% of hemicellulose. With respect to both substrates, F. succinogenes strains solubilized CW carbohydrates better than did B. fibrisolvens D1. Complementary interaction between B. fibrisolvens D1 and the F. succinogenes strains was identified with respect to the utilization of some solubilized carbohydrates, but not with respect to the extent of CW solubilization, which was determined mainly by the F. succinogenes strains. For both substrates, utilization of cellulose by F. succinogenes monocultures was high (96-98%), whereas that of hemicellulose was lower (24-26% in ryegrass and 49-50% in alfalfa). Under scanning electron microscopy, F. succinogenes bacterial cells attached to and colonized on CW particles were characterized by the appearance of protuberant surface structures that we have identified as "polycellulosome complexes."

Animals↗

Postnatal development of monosaccharide transport in pig intestine.

In vitro brush-border transport of three monosaccharides by pig intestine was studied as a function of postnatal age from immediately after birth before suckling to after weaning. Rates of transport normalized to tissue weight or surface area for glucose (Glc), galactose (Gal), and fructose (Fru) were highest at birth, with a steep decline after the onset of suckling, probably caused by any combination of three or more factors: reduced transporter site density, shifts in relative abundances of different monosaccharide transporters, and/or changes in activities of individual transporters. Whereas highest rates of Glc and Fru transport shifted from proximal to midintestine after weaning, Gal transport remained highest in proximal intestine. Postnatal increases in Km values for Gal, but not Glc, indicate there are multiple aldohexose transporters that undergo separate developmental trajectories. The presence of Fru transport in neonatal pigs may reflect a more advanced state of development than neonatal rats and rabbits, or may be an adaptation for early weaning. Changes in Fru-to-Glc and Gal-to-Glc transport ratios before weaning suggest transporter development is partly genetically hard-wired, apparently to prepare pigs for weaning. Curiously, Fru-to-Glc transport ratios were lower than those of rat and rabbit, but closely paralleled those of the carnivorous cat.

Aging↗

Monosaccharide transport into hemocytes of a sipunculan worm Themiste dyscrita.

The hemerythrin-containing blood cells, or hemocytes, of the sipunculan worm Themiste dyscrita were found to have a stereospecific and nonconcentrative monosaccharide transport system. The transport system transferred both D-glucose and 3-O-methyl-D-glucose (3-OMG), and transport into cells by this system was rapid, reaching 50% equilibrium in approximately 20 s at 10 degrees C with an initial concentration gradient of 0.1 mM; the contribution to total uptake by simple diffusion was very small. 3-OMG uptake showed saturation kinetics with a low half-saturation constant (Km less than or equal to 0.1 mM). The uptake of labeled 3-OMG by the hemocytes was strongly inhibited by unlabeled 3-OMG, 2-deoxy-D-glucose, alpha- and beta-D-glucose, D-galactose, and D-mannose. It was moderately inhibited by D-xylose, only slightly by alpha-methyl-D-glucoside and D-fructose, and uninhibited by sucrose, L-glucose, or D-sorbitol. Phloretin was more potent than phloridzin in blocking entry of 3-OMG. Cytochalasin B did not bind tightly to the T. dyscrita transporter and was not a potent inhibitor of transport; it half-maximally inhibited 3-OMG transport at 0.1 mM. Therefore, despite some differences the data suggest functional similarities in the mechanism of monosaccharide transport into blood cells of mammals and this invertebrate.

3-O-Methylglucose↗

Quantitative estimation of clinically important monosaccharides in plasma by rapid thin layer chromatography.

A method is described for the quantitative estimation of clinically important monosaccharides in plasma or whole blood by direct densitometry of chromatographically-separated zones on silica gel layers. Simple modifications of technique originally introduced to improve the reproducibility of paper chromatography have now been adapted for thin layers. The present method is based on peak height measurement with an internal marker correction. Galactose, fructose, D-xylose, and 3-O-methyl glucose can be estimated in addition to glucose, either singly or in combination, within three or four hours, using an initial sample volume of 0.5 ml. With reasonable experience and skill a coefficient of variation of 3 to 6%, depending on sugar concentration, can be achieved without replication, and the limit of sensitivity is about 0.05 mmol/l. When the performance was compared with an automated glucose oxidase/peroxidase system for glucose and the recovery for the other monosaccharides was calculated, the results were satisfactory.

Blood Glucose↗

Biological activities of chemically synthesized derivatives of lipid A: tetraacetyl-monosaccharides linked to 2,3-acyloxyacylglucosamine-4-phosphate.

The mitogenicity and lethal toxicity of chemically synthesized lipid A analogs, in which 2,3-acyloxyacylglucosamine-4-phosphate (acyl-GlcN-4P) is linked to a tetraacetyl (Ac4)-monosaccharide, i.e., Ac4-glucose (A-211), Ac4-mannose (A-212), Ac4-galactose (A-213) or Ac4-glucosamine (A-214), were compared with those of tetraacetyl-3-deoxy-D-manno-2-octulosonic acid (Ac4-KDO) linked to acyl-GlcN-4P (A-203). All the compounds were capable of increasing incorporation of 3H-thymidine into splenocytes of C57BL/6 mice at doses of 50 and 100 micrograms/ml, but the mitogenic activity of A-203 at these doses seems to be stronger than those of the analogs. Intravenous injection of A-203, A-211, and A-213 did not exhibit lethal toxicity even at a high dose (50 micrograms/mouse) in C57BL/6 mice loaded with D-galactosamine hydrochloride. However, A-212 and A-214 showed lethality at the doses of 10 and 50 micrograms/mouse, respectively. The findings indicate that the biological activity of these compounds is affected by the kind of monosaccharide linked to acyl-GlcN-4P.

Animals↗

Gas-phase reactivity of silver and copper coordinated monosaccharide cations studied by electrospray ionization and tandem mass spectrometry.

The analytical distinction of the most common isomeric underivatized hexoses was investigated by means of mass spectrometry experiments. Electrospray ionization and tandem mass spectrometry were used in the analysis of silver and copper-coordinated monosaccharides (D-glucose, D-galactose, D-fructose, O-methyl-alpha-D-glucose and O-methyl-beta-D-glucose). The results show that cationization by Ag(+) allows the differentiation of the three first monosaccharides while the complexes formed by association of Cu(+) with these three monosacharides display a similar reactivity that prevents stereoisomer distinction. Unlike copper, silver adduct-ions of both alpha and beta anomeric O-methyl-D-glucoses exhibit specific decomposition patterns (i.e. a loss of methanol for the alpha-anomer and a loss of silver hydride for the beta-anomer), which allow an easy characterization. A theoretical survey of selected complexes, based on the use of DFT calculations were carried out on both anomers in order to rationalize the experimental findings.

Cations↗

Influences of monosaccharides and its glycosidic linkage on infrared spectral characteristics of disaccharides in aqueous solutions.

The infrared spectral characteristics of ten different types of disaccharides (trehalose, kojibiose, nigerose, maltose, isomaltose, trehalulose, sucrose, turanose, maltulose, and palatinose) and five different types of monosaccharides (glucose, mannose, galactose, talose, and fructose) in aqueous solutions (H2O and D2O) were determined. The infrared spectra were collected using the Fourier transform infrared attenuated total reflectance (FT-IR/ATR) method and comparisons between the degrees of absorption band-shift of the saccharide spectra in the H2O solution with those in the D2O solution with respect to the saccharide concentrations were done. The study revealed that the wavenumber shifts in the bands of mono- and disaccharides in the H2O and D2O solutions could be used as an indicator of the level of interaction between the saccharides and water. The study also focused on the glycosidic linkage position and the constituent monosaccharides and found that they have a significant influence on the infrared spectroscopic characterization of disaccharides in an aqueous solution.

Complex Mixtures↗

Digestibility by dairy cows of monosaccharide components in diets containing wheat or ryegrass silages.

Digestibility by dairy cows of monosaccharide constituents in rations based on wheat or ryegrass silage as the sole roughage component was examined in this study. Six cows in early lactation were divided into two groups with similar performance data at the onset of the experiment and fed for ad libitum intake for two 28-d periods in a change-over design. Cows were fed a TMR of concentrate plus either wheat or ryegrass silage, contributing 19% of silage NDF in the TMR. Digestibilities of ration DM and total carbohydrate were 3.3 and 3.1 percentage units higher, respectively, for ryegrass than for the wheat silage. The digestibility of ration NDF was 64.1% in ryegrass silage and 49.6% in wheat silage. The trend was similar for digestibilities of NDF monosaccharide components. Ration NDF carbohydrate digestibility was 74.8% for ryegrass silage versus 59.7% for wheat silage. For both TMR, the digestibility of NDF xylose was lower than that for NDF glucose and arabinose. Based on carbohydrate digestibility, ryegrass silage can be considered to be a successful roughage alternative for wheat silage in TMR for lactating cows.

Animal Nutritional Physiological Phenomena↗

Determination of free monosaccharides and detection of sugar alcohols in mature soybean seeds.

Although the oligosaccharide contents of soybeans are well documented, the exact values of monosaccharide contents have not been reported. Elaborate methods of preparative paper chromatography together with gas chromatography established the following data for one variety, Kyushu No. 12. The air-dried cotyledon part (admixed with hypocotyls) contained 0.030% glucose and 0.039% fructose. The hull part contained 0.018% galactose, 0.028% glucose, 0.023% fructose, 0.005% arabinose, and 0.002% xylose. Gas chromatograms of trimethylsilated monosaccharide fractions revealed the existence of minute amounts of sorbitol, arabitol, xylitol, and mannitol in decreasing order (about 0.03% to 0.001% of whole seeds).

Arabinose↗

[The transport system that pumps monosaccharides from enterocytes across the basolateral membrane].

Using a new, in vitro, experimental approach the transport of glucose, galactose, fructose and glycine in seroso-mucosal direction in the small intestine, was studied under different modes of oxygenation. In case of monosaccharides under the oxygenation from serosal surface, the substrate concentration is lower in the small intestine tissue than under anoxia. The effect of the oxygenation from serosal surface on the galactose transport was shown to be sensitive to absence of sodium ions, ouabain, phloretin, and not sensitive to phlorizin. The data obtained corroborate the hypothesis of the existence of a mechanism pumping off monosaccharides enterocytes through the basolateral membrane.

Animals↗

[Effect of peptidoglycan preparations on phage inactivation: decrease in phage 187 binding using monosaccharides].

Monosaccharides were found to be capable to decreasing the binding of phage 187 with peptidoglycan. Galactosamine hydrochloride and glucosamine hydrochloride proved to be the most effective, followed in order of decreasing activity by N-acetylgalactosamine, N-acetylglucosamine, glucose and galactose; mannose produced a weak effect. Ca2+ ions increased the reduction of phage peptiglycan binding with N-acetylgalactosamine and N-acetylglucosamine. Both of these monosaccharides also reduced the adsorption of phage 187 by the Staphylococcus aureus cells. In the medium enriched with Ca2+ ions; in the absence of Ca2+, they were, however, incapable of releasing the phage irreversibly bound with the peptidoglycan.

Acetylgalactosamine↗

Effect of protein malnutrition on the intestinal absorption of monosaccharides in rats in vivo.

The present study was planned to elucidate the role of protein malnutrition on the intestinal absorption of monosaccharides particularly--glucose and xylose, in inbred female albino rats. The experimental rats were fed with protein deficient diet containing 3% protein, whereas the control rats were given a diet containing 18% protein. The study on intestinal absorption of monosaccharides was conducted on both the groups of rats after the 7th and 15th day of receiving respective diets. The results indicated no significant impairment of glucose absorption of experimental rats fed 3% diet for 7 days as compared to the controls. However a 42% decrease in glucose absorption was observed when the animals were fed with the same diet for 15 days. The impairment was significant in all segments of intestine suggesting diminution in the absorption capacity of small intestine in malnutrition perhaps as a result of some permanent injury to mucosal cells of small intestine. Regarding xylose absorption, in experimental rats an increase of intestinal uptake was noticed in most of the segments of small intestine as compared to control rats.

Animals↗

Effect of neuraminidase on adherence of Pseudomonas aeruginosa to human buccal epithelial cells. Inhibition of adhesion by monosaccharides.

The aim of this study was to evaluate the actiion of Clostridium perfringens neuraminidase on the adherence of 28 strains of Pseudomonas aeruginosa which were isolated from humans, different animals and environment to human buccal epithelial cells (BECs). Two reference strainns--NCTC 6749 and ATCC 27853 were also examined. Incubation of cells with the enzyme significantly increased bacterial adherence (a mean number of bacteria adhering to cells amounted 19.62 +/- 9.20, for controls - 7.54 +/- 5.86). The reference strains of Pseudomonas aeruginosa showed the following adherence: NCTC 6749-43.04 (control 20.83) and ATCC 27853-22.21 (control 5.51). This study demonstrates that asialogangliosides function as receptors on buccal epithelial cells for P. aeruginosa strains. Monosaccharides inhibition studies showed an inhibition of adhesion of P. aeruginosa (two reference strains - NCTC 6749 and ATCC 27853, two hospital strains - 80/85 and 351) to normal BECs in the presence of N-acetylneuraminic acid and N-acetylgalactosamine. D-galactose is the best inhibitor of bacterial adhesion to neuraminized BECs. All monosaccharides used had a significant effect on P. aeruginosa adherence to trypsinized BECs. These data suggest a difference in the receptors on the three types of BECs.

Bacterial Adhesion↗

[Monosaccharide malabsorption syndrome].

Pathogenesis of disorders in the transport of monosaccharides in the intestinal epithelial cells has been considered. Criteria for the diagnosis of primary and secondary malabsorption of monosaccharides have been discussed. Characteristics of the clinical picture, differential diagnosis and therapeutic measures have been presented. A case has been described of primary malabsorption of glucose and galactose in a woman aged 38 years. Possible ways of compensation of the transport disorders with age are discussed. It is noted that in chronic enteritis the enzymatic system in the intestinal mucosa is impaired earlier than the transport system.

Adult↗

Intestinal adaptation. Different growth responses to disaccharides compared with monosaccharides in rat small bowel.

Midgut infusions of sucrose and other disaccharides were compared with monosaccharides for their effects on intestinal mucosal growth in rats otherwise maintained on total parenteral nutrition for 7 days. Mucosal mass progressively increased in a proportional relationship to the concentration of infused sucrose. At equal concentrations by weight, disaccharide infusions stimulated mucosal growth more than monosaccharides. Disaccharide-induced mucosal adaptation was abolished when there was no hydrolysis of the disaccharide. The results suggest that the functional work load of absorbing epithelium, including the "work of hydrolysis," plays an important role in the stimulus for intestinal adaptation.

Acarbose↗

Photoaffinity labeling of the human erythrocyte monosaccharide transporter with an aryl azide derivative of D-glucose.

A photoreactive, radioiodinated derivative of glucose, N-(4-iodoazidosalicyl)-6-amido-6-deoxyglucopyranose (IASA-glc), has been synthesized and used as a photoaffinity label for the human erythrocyte monosaccharide transporter. Photoinactivation and photoinsertion are both light-dependent and result in a marked decrease in the absorption spectra of the compound. When [125I]IASA-glc was photolyzed with erythrocyte ghost membranes, photoinsertion of radiolabel was observed in three major regions, spectrin, band 3, and a protein of 58,000 daltons located in the zone 4.5 region. Of the three regions which were photolabeled, only labeling of polypeptides in the zone 4.5 region was partially blocked by D-glucose. In the non-iodinated form, N-(4-azidosalicyl)-6-amido-6-deoxy-glucopyranose inhibited the labeling of the transporter by [125I]IASA-glc more effectively than D-glucose. The ability to synthesize this [125I]containing photoprobe for the monosaccharide transporter at carrier-free levels offers several new advantages for investigating the structure of this transport protein in the erythrocyte.

Affinity Labels↗