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At least 19 recordsLinked to original sources
PubMed1977

[Quantitative relationship between the monosaccharide induced change in ion transport and the monosaccharide accumulation in the rat jejunum].

1. In the rat's jejunum, the changes induced by Na+-dependently transported monosaccharides (10 mM) of the unidirectional Na+- and K+-influx across the microvilli membrane were studied under varying metabolic conditions. 2. The monosaccharide induced change of Na+- and K+-influx is a function of the ion gradients active across the microvilli membrane. 3. In the in vitro preparation during the process of energy-dependent accumulation the monosaccharide induced change of permeability in the microvilli membrane decreases the K+ concentration, while the Na+ concentration increases. 4. The monosaccharide concentration in the tissue reaches a final value which is proportional to the change of Na+- and K+-influx and to the change in ion concentrations, and which is retained even upon compensation of the gradient and at low intracellular K+ concentrations. 5. The correlation between the breakdown of the ion gradient and the rise of monosaccharide accumulation is explained by the monosaccharide induced restriction of the active ion transport and the ensuing change of energy dissipation in favour of the monosaccharide transport. The (Na+ + K+)-ATPase in the microvilli membrane is discussed as being transmitter of the energy from the ion gradients.

Animals↗
PubMed1978

Monosaccharides and monosaccharide derivatives in human seminal plasma.

Gas chromatography--mass spectrometry with an on-line data system was used to identify monosaccharides and monosaccharide derivatives in human seminal plasma. The carbohydrates were converted into the methoxime-trimethylsilyl derivatives before separation in open tubular glass capillary columns coated with SE-30. Twenty-one different compounds were detected in the seminal fluid, of which twelve have not been recognized before. Seventeen of the monosaccharides have previously been identified in urine. Similar patterns of sugars were found both in fertile and infertile individuals, including one with azoospermia. The compounds identified are, with the possible exception of D-ribose, present as free monosaccharides at the time of ejaculation, and they do not seem to be preformed by spermatozoa.

Chromatography, Gas↗
PubMedDate not supplied

Monosaccharide transport across membranes of human spermatozoa. I. Development of a radiochemical method of measuring monosaccharide uptake by spermatozoa.

A method for determination of the monosaccharide uptake into human spermatozoa is described. Intracellular monosaccharide concentrations were calculated on the basis of determination of intracellular radioactivity after incubation of the cells with labelled monosaccharide and using a mathematical procedure to approximate the intracellular space of spermatozoa. The D-fructose uptake depends on the extracellular D-fructose concentration in a hyperbolic manner. Half maximal saturation is present at 4,1 mM. This corresponds closely with the lowest limit of D-fructose concentration in human fertile semen.

Biological Transport↗
PubMed1987

[Intestinal liberation and resorption of monosaccharides from carbohydrates of different degrees of polymerization. I. Relation between intestinal hydrolysis of carbohydrates and resorption of monosaccharides].

The study was designed to compare the intestinal absorption of monosaccharides from carbohydrates of different chain length. Furthermore, a correlation between the efficiency of hydrolysis of the polymers and the efficiency of the intestinal absorption was expected to be established. Glucose, the disaccharides maltose and sucrose and the polysaccharides maltodextrin DE 20 , maltodextrin DE 5 and starch were employed as substrates. The whole small intestines of anaesthetized rats were perfused in situ for 60 min with 0.5% solutions of these substrates in an open perfusion system. Initially 3-minute fractions of the perfusion medium, later 10-minute fractions were collected. The parameters determined were: secretion of pancreatic alpha-amylase activity, substrate hydrolysis (by alpha-amylase and by disaccharidases of the brush border membrane), intestinal absorption of the monosaccharides. alpha-amylase activity was significantly higher when the perfusion was carried out with starch solution. The possibility is discussed that this high-polymer substrate might stimulate the pancreas to an elevated alpha-amylase secretion. The highest rate of hydrolysis (45 mumol glucose/min) was determined from maltose as a substrate. The cleavage of the high-polymer substrates was less intensive. The hydrolysis of starch was limited by the capacity of the alpha-amylase, that of the sucrose by low activity of the saccharose. Absorption of glucose was more effective from the maltose solution than from the glucose solution. To understand this phenomenon, an additional "hydrolases-related transport system" could be taken into consideration. Glucose absorption from maltodextrin DE 20 was less effective than might have been expected from the rate of hydrolysis. This fact might possibly be explained by an inhibitory effect of oligosaccharides of chain length 4-10, contained in relatively high amounts in maltodextrin DE 20.

Animals↗
PubMed1987

Synthesis of modified tuftsins containing monosaccharides or monosaccharide derivatives.

Synthesis of some modified tuftsins is described in which a monosaccharide or a monosaccharide derivative was incorporated in the molecule. Acylation of H-Thr-Lys(Z)-Pro-Arg(NO2)-OBzl with D(+)-gluco-1,5-lactone followed by catalytic hydrogenation gave N alpha-gluconyl-tuftsin. Glycosylation of the carboxyl function of the C-terminal arginine has been achieved by reacting, through the mixed anhydride procedure, Boc-Thr-Lys(Z)-Pro-OH with 2-deoxy-2-(NG-nitroargininamido)-D-glucopyranose followed by catalytic hydrogenation and trifluoroacetic acid treatment. O-Glucosyl-tuftsin has been prepared by reacting o-nitrophenyl N-benzyloxycarbonyl-O-[(alpha + beta) 2,3,4,6-tetra-O-benzyl-D-glucopyranosyl]-threoninate with H-Lys(Z)-Pro-Arg(NO2)-OBzl in the presence of 1-hydroxybenzotriazole. Flash chromatography on silica gel allowed a partial separation of the diastereoisomers, one of which has been isolated in a reasonable yield. The single diastereoisomer and the alpha + beta anomeric mixture were separately deblocked by catalytic hydrogenation and purified by RP-HPLC.

Carbohydrates↗
PubMed1987

[Intestinal liberation and resorption of monosaccharides from carbohydrates of different degrees of polymerization. II. Relations between monosaccharide resorption, blood glucose level and serum insulin concentration].

The small intestines of anaesthetized rats were perfused in situ for 60 min with 0.5% solutions of glucose, maltose, sucrose, maltodextrin DE 20, maltodextrin DE 5 or starch. Blood samples were repeatedly taken from the v. portae and the v. femoralis to estimate blood glucose and serum insulin levels as a function of perfusion time. The experiment was also performed to clarify whether a correlation exists between these parameters and the substrate uptake from the intestinal lumen (determined in the first part of the study). The highest glucose levels in v. portae and the highest portal-peripheral differences were found when glucose and maltose solutions were administered. Glucose levels in v. femoralis were almost independent of the substrate perfused. Perfusion with glucose caused a considerable insulin secretion starting immediately with the onset of perfusion. It was concluded that glucose might also stimulate insulin secretion on the intestinal level. Perfusion with maltose also effected a significant insulin output, the start of which was delayed however, compared with the effect of glucose.

Animals↗
PubMed1987

Synthesis and biological activity of tuftsin and rigin derivatives containing monosaccharides or monosaccharide derivatives.

Synthesis of some modified rigins is described in which either D-gluconic acid or 2-amino-2-deoxy-beta-D-glucopyranose have been linked to the parent molecule through amide bonds involving the alpha-amino function, alpha-carboxyl function or the gamma-amide function of glutamine in position 2. Glu2-rigin and D-gluconyl-Glu2-rigin have also been synthesized. Binding and phagocytosis assays have been carried out on the rigin derivatives and on some glycosylated tuftsin derivatives as well. Of all the tested peptides only rigin enhanced the phagocytic capacity of mouse peritoneal macrophages to the same extent as tuftsin. The peptides H-Thr-Lys-Pro-Arg-NH-Glc and N alpha-gluconyl-Gly-Glu-Pro-Arg-OH slightly enhanced phagocytosis. H-Thr[(alpha + beta)-O-glucosyl]-Lys-Pro-Arg-OH was found to displace 3H-tuftsin even better than tuftsin but lacked the ability to stimulate phagocytosis.

Animals↗
PubMed1985

Monosaccharide autoxidation in health and disease.

The reduction of oxygen by the ene-diol tautomer of simple monosaccharides produces hydrogen peroxide and alpha-oxoaldehydes. This process, termed monosaccharide autoxidation, occurs at physiological pH and temperature and may contribute to the development of several pathological processes. Enolization of the monosaccharide to an ene-diol tautomer is a prerequisite for the reaction of the monosaccharides with oxygen. The reaction kinetics suggest a two step process: the enolization of the monosaccharide to the ene-diol followed by the reaction of the ene-diol with oxygen. Free-radical reactive intermediates are formed by the reaction of the ene-diol with oxygen: superoxide, semidione, and 1-hydroxyalkyl radicals are formed under physiological conditions (hydroxyl radicals are also detected at high pH). The autoxidation of monosaccharides stimulates the oxidation of oxyhemoglobin in erythrocytes, producing methemoglobin and hydrogen peroxide, and the oxidation of reduced pyridine nucleotides NAD(P)H to the oxidized congener NAD(P)+ and enzymatically inactive nucleotide. This stimulates oxidative metabolism (via the hexose monophosphate shunt) and alpha-oxoaldehyde metabolism (via the glyoxalase system) in erythrocytes in vitro. The oxidative challenge is relatively mild even with very high concentrations (50 mM) of monosaccharide. However, crosslinking of membrane proteins by alpha-oxoaldehydes is enhanced; this effect may exacerbate ageing and decrease the lifetime of erythrocytes in circulation. In vivo, the autoxidation of monosaccharides is expected to be a chronic oxidative process occurring in biological tissue which utilises simple monosaccharides, e.g., in glycolysis and gluconeogenesis. Monosaccharide autoxidation is suggested to be a determinant in the control of cellular mitosis and ageing, providing physiological substrates for the glyoxalase system, and may contribute to the chronic disease processes associated with diabetes mellitus and the smoking of tobacco.

Aging↗
PubMed1987

Digestibility by sheep of total and cell wall monosaccharides of wheat straw treated chemically or chemically plus enzymatically.

Digestibility of total and cell wall monosaccharides was studied in sheep with ruminal and duodenal cannulae and fed three wheat straw-based diets: untreated, treated with SO2, treated with SO2 plus cellulase and a fourth diet, which was barley-based. In untreated straw, 90% of total monosaccharides are cell wall bound. Sulfur dioxide treatment solubilized mainly the matrix sugars, reducing their content from 22.1 to 9.76 g/100 g DM in straw. The combined treatment (SO2 plus cellulase) solubilized most of the cell wall sugars so that the most of the cell wall sugars so that the residual cell wall contained only 31% of the total sugars originally present. Treatments increased total monosaccharide digestibility from 63 to 90% and of cell wall monosaccharides from 58 to 84 and 88%. The proportion of digestible monosaccharides degraded in the rumen was increased up to 95% by the treatments. Total monosaccharide digestibility was similar in both treated straws, but degradation of the residual cell wall monosaccharides was somewhat lower in the combined treatment compared with the SO2-treated straw.

Animal Feed↗
PubMed1992

Inhibition of specific T-cell activation by monosaccharides is through their reactivity as aldehydes.

The effect of monosaccharides on the inductive interaction between antigen-presenting cells and T cells was investigated in a human system. Some monosaccharides, but not others, were found to inhibit antigen-specific T-cell activation. Responses to mitogen were unaffected. In order for inhibition to occur, a high concentration (approximately 50 mM) of monosaccharide was necessary. The role of monosaccharide aldehyde groups in inhibition was investigated using the alpha-methyl pyranoside and the alditol forms of inhibitory monosaccharides. Unlike the native monosaccharides, these molecular configurations possess the ring structure and the open chain structure respectively but do not contain aldehydes. Together they represent all the molecular characteristics of both forms of the monosaccharide except the possession of aldehyde groups. These two molecular species produced no significant inhibition. Modified forms of the sugar moiety of ribofuranosidoadenine (adenosine) were also tested. The periodate oxidized form of the molecule in which the ribose bears two aldehyde groups, was a potent inhibitor of antigen-induced T-cell activation whereas periodate-oxidized, borohydride-reduced ribofuranosidoadenine, in which the ribose aldehydes are converted to alcohols, produced no inhibition. The former was shown to form Schiff bases with ligands on peripheral blood mononuclear cells (PBMC) as predicted whereas the latter did not. Periodate oxidized dextran, but not native dextran, was also inhibitory. Together these data show that inhibition of T-cell activation by sugars requires reactive aldehydes and this is consistent with the Schiff base model of specific antigen-presenting cell (APC)-T cell inductive interaction in which exogenous aldehydes and other carbonyl donors prevent the necessary formation of Schiff bases between cellular ligands.

Aldehydes↗
PubMed1979

[Relationship between Na+ and monosaccharide influx across the microvilli membrane depending on the energy state of the intestinal mucosa wall].

1. An energy dependence of the Na+ influx and of the "extra-Na+ influx" across the microvilli membrane was demonstrated in an in vitro preparation of the rat jejunum by adjustment of low ATP/ADP quotients. The monosaccharide influx does not show this dependence. 2. The similar relationship of monosaccharide-dependent Na+ influx and Na+ influx without monosaccharide with the energy state in the mucosa cells suggests a common control system. 3. A constant stoichiometry between monosaccharide and "extra-Na+ influx" can be maintained only under constant intracellular conditions. 4. The changes of the Na+ and K+ influxes by so-called Na+ dependently transported monosaccharides correspond to those which can be elicited by lowering the ATP/ADP ratio in the in vitro preparation. 5. A mechanism is discussed in which an ATP-utilizing reaction is stimulated in the microvilli owing to the monosaccharide transport, thus locally discontinuing the condition for uncoupling of an (Na, K)-ATPase and eliciting an "extra-Na+ influx".

Adenosine Diphosphate↗
PubMed1990

Sugar-mediated induction of Agrobacterium tumefaciens virulence genes: structural specificity and activities of monosaccharides.

The virulence genes of Agrobacterium tumefaciens are induced by specific plant phenolic metabolites and sugars (G. A. Cangelosi, R. G. Ankenbauer, and E. W. Nester, Proc. Natl. Acad. Sci. USA, in press). In this report, monosaccharides, derivatives, and analogs which induce the vir regulon have been identified and the structural requirements for monosaccharide-mediated induction have been determined. Pyranose sugars with equatorial hydroxyls at C-1, C-2, and C-3 displayed strong vir gene-inducing activity; the C-4 hydroxyl could be epimeric and a wide variety of substitutions at C-5 were permissible. The acidic monosaccharide derivatives D-galacturonic acid and D-glucuronic acid were the strongest inducers among the monosaccharides tested. Eight of the 11 inducing compounds are known plant metabolites, and 7 are monomers of major plant cell wall polysaccharides. A role for monosaccharides and plant phenolic compounds as wound-specific plant metabolites which signal the ChvE/VirA/VirG regulatory system is proposed.

Bacterial Proteins↗
PubMed1969

Mitochondrial autonomy: incorporation of monosaccharides into glycoprotein by isolated mitochondria.

Isolated intact mitochondria selectively incorporate monosaccharides from nucleotide diphosphate monosaccharides into protein. Fucose, mannose, glucose, and galactose were incorporated by the mitochondria into glycoprotein; xylose was not. Structural integrity of the mitochondria was not necessary for the incorporation of monosaccharide into glycoprotein; mitochondria broken by homogenization also incorporated monosaccharide. The monosaccharides incorporated into glycoprotein were localized in the inner mitochondrial membranes, the same membranes which contain the protein into which leucine is incorporated by the isolated mitochondria.

Animals↗
PubMed1988

Monosaccharide analysis of glycoconjugates by anion exchange chromatography with pulsed amperometric detection.

The method of anion exchange chromatography followed by pulsed amperometric detection (AE-PAD; Johnson, D. C., and Polta, T. Z. (1986) Chromatogr. Forum 1, 37-44) has been applied to the compositional analysis of glycoconjugates. Using 22 mM NaOH as a column effluent, underivatized fucose, galactosamine, glucosamine, galactose, glucose, and mannose were readily separated in 15 min at a flow rate of 1 ml/min. The limit of quantification of the monosaccharides was better than 100 pmol (signal to noise ratio 184:1). AE-PAD was employed to quantify the monosaccharides of several glycoproteins, glycopeptides, and oligosaccharides after hydrolysis with 2 M trifluoroacetic acid. Both neutral and amino sugars could be rapidly estimated in a single chromatographic step using AE-PAD. Complete release of N-acetylglucosamine required more vigorous hydrolysis conditions (Lee, Y. C. (1972) in Methods in Enzymology (Ginsburg, V., Ed.), Vol. 28, pp. 63-73, Academic Press, New York). In both glycopeptides and oligosaccharides, approximately one less residue of Man than predicted was determined. Both AE-PAD and liquid chromatographic analysis of borate-monosaccharide complexes with fluorometric detection (Mikami, H., and Ishida, Y. (1983) Bunseki Kagaku 32, E207-E210) gave similar quantification of mannose and other sugars. The capability of rapid, sensitive quantification of underivitized monosaccharides should facilitate structural analysis of glycoconjugates.

Amino Sugars↗
PubMed1992

Structure-retention index relationships for derivatized monosaccharides on non-polar gas chromatography columns.

A gas chromatographic method for predicting the retention index of a derivatized monosaccharide is presented. The procedures are especially useful to detect and predict minute quantities of sugars in biological or chemical samples. Monosaccharides are first converted to the alditols and then derivatized by acetylation, permethylation or silylation. The derivatized monosaccharide structure-retention index relationship that has been developed is useful in the identification of unknown monosaccharides that can be readily confirmed by gas chromatography-mass spectrometry.

Acetylation↗
PubMed1989

Age influence on sucrose hydrolysis and on monosaccharide absorption along the small intestine of rat.

The consequences of aging on the hydrolysis and absorption of hexoses was assessed in vitro using everted intestinal segments. Glucose and fructose were given either as a mixture of free monosaccharides or as a disaccharide solution (sucrose). The jejuno-ileum of 3- and 24-month-old rats was everted and divided into four equal segments. For each segment, the mucosal medium contained either sucrose (140 mM) or an equimolar mixture of glucose and fructose (70 mM). Monosaccharide concentrations in the mucosal ans serosal media were measured after 1 h of incubation at 37 degrees C. In the young adult, glucose absorption was enhanced when given as sucrose. In contrast, in the aged rat, free glucose or glucose released from sucrose hydrolysis were similarly absorbed. Independently of age, fructose was better absorbed when provided in a mixture of free monosaccharides. The intestinal segments (and especially the ileum), of the aged animals exhibited higher abilities to hydrolyse sucrose and to absorb monosaccharides indicating a normal or increased intestinal hydrolytic activity and absorptive capacity for dietary sugars.

Aging↗
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↗