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Effects of a carbohydrate supplement upon resting brain activity.

Glucose is a major energy source for the brain, and along with several monosaccharide derivatives as components of brain gangliosides, they play important roles in neurologic function. However, there is little information available on the role of glucose and other monosaccharides on resting brain activity. This study was designed to evaluate the effects of a single dose of a carbohydrate supplement containing glucose and several of its derivatives on resting brain activity in 20 healthy male college students. The supplement provided an insignificant amount of carbohydrate (3.9 g), protein (0.28 g), fat (0 g), and calories (14 kcal). The amount of glucose in the supplement was 0.5 g (1% the amount of glucose used in adult studies of cognitive functioning and memory). We hypothesized that the glyconutrient supplement would enhance brain activity associated with alertness and attention. The study design was double blind, with subjects randomly assigned to one of two orders, either carbohydrate supplement week one followed by placebo a week later, or the opposite. Electrical brain activity was monitored by 15 electrodes positioned at nine standard international 10-20 system locations, including three bilateral pairs at frontal, parietal, and occipital sites. Thirty minutes following ingestion of a placebo or carbohydrate supplement drink, EEG activity was recorded for 10-mins while subjects focused on a stationary visual target. Spectral power of resting brain activity was computed and analyzed contrasting the placebo and supplement groups. Relative to placebo, the carbohydrate supplement significantly enhanced power in three brain wave frequencies (theta, alpha, and beta) that are known to be associated with attention and arousal. Since changes were observed in the supplement but not placebo group, our study suggests that additional sugars in the glyconutritional supplement facilitate enhancement of brain electrical activity. Whether the apparent enhancement of arousal in baseline recordings is associated with improved task performance remains to be determined.

Adult↗

Fermentation of sugars in orange peel hydrolysates to ethanol by recombinant Escherichia coli KO11.

The conversion of monosaccharides in orange peel hydrolysates to ethanol by recombinant Escherichia coli KO11 has been investigated in pH-controlled batch fermentations at 32 and 37 degrees C. pH values and concentration of peel hydrolysate were varied to determine approximate optimal conditions and limitations of these fermentations. Very high yields of ethanol were achieved by this microorganism at reasonable ethanol concentrations (28-48 g/L). The pH range between 5.8 and 6.2 appears to be optimal. The microorganism can convert all major monosaccharides in orange peel hydrolysates to ethanol and to smaller amounts of acetic and lactic acids. Acetic acid is coproduced in equimolar amounts with ethanol by catabolism of salts of galacturonic acid.

Acetates↗

Neutrophil migration induced in vivo and in vitro by marine algal lectins.

OBJECTIVE AND DESIGN: Since some plant and mammalian lectins specific for monosaccharides are able to induce neutrophil migration, we studied the neutrophil migration-inducing activities of marine algal lectins, specific for complex oligosaccharides from glycoproteins, from Amansia multifida (AM), Bryothamnion seaforthii (BS), Bryothamnion triquetrum (BT) and Gracilaria caudata (GC). MATERIALS AND METHODS: The neutrophil migration-inducing activity of AM, BS, BT and GC was assayed in vitro and in vivo in the peritoneal cavity or dorsal air pouch of rats or mice, and was inhibited by glycans. RESULTS: AM, BS, BT and GC induced neutrophil migration in vivo and in vitro, determining bell-shaped dose-dependent curves. Maximal neutrophil influx was determined by BT in rats and by AM in mice. Maximal human neutrophil chemotaxis was obtained with GC. These activities were not inhibited by glycoproteins previously identified as being recognized by these lectins. D-mannose was a strong inhibitor, especially of BT activity both in vitro and in vivo. CONCLUSIONS: Algal lectins induced neutrophil migration, which was inhibited by a monosaccharide, contrasting with the view that they only recognize complex oligosaccharides. Neutrophil chemotaxis assays are appropriate to study low molecular mass lectins containing a single carbohydrate recognition domain, as is the case of some lectins from algae and mammals.

Animals↗

Expression of the Na+/glucose co-transporter (SGLT1) in the intestine of domestic and wild ruminants.

The activity and abundance of the Na+/glucose co-transporter (SGLT1) was assessed in brush-border-membrane vesicles (BBMV) isolated from the intestine of grass- and roughage- (GR) consuming ruminants (sheep and dairy cattle), during the transition from the pre-ruminant to the mature ruminant state. The abundance of SGLT1 messenger ribonucleic acid (mRNA) was also compared in the intestinal tissue of the same animals. The dramatic developmental decline in the activity and expression of SGLT1 appears to be typical of GR-consuming ruminants and is coincident with the significant decline in the levels of lumenal monosaccharides. Expression of the ovine SGLT1 complementary deoxyribonucleic acid (cDNA) in Xenopus laevis oocytes confirmed that the isolated cDNA encodes for a functional Na+/glucose co-transporter. Determination of a bovine intestinal SGLT1 protein sequence (amino acids 347-658) indicated 99% similarity to the ovine SGLT1 protein with differences in the carboxyl terminus. In contrast to GR-consuming ruminants, the abundance of SGLT1 protein and SGLT1 mRNA remained significantly high in the intestine of ruminants in both the intermediate-mixed (IM) feeding goat and fallow deer and the concentrate-selecting (CS) moose and roe deer, dietary groups correlating with the availability of monosaccharides in the intestinal lumen.

Amino Acid Sequence↗

The reconstitution of the human erythrocyte sugar transporter in planar bilayer membranes.

The degradation of human erythrocyte membrane proteins in relation to the identification of the monosaccharide transporter has been investigated in whole membrane preparations and membrane protein extracts by polyacrylamide gel electrophoresis in sodium n-dodecyl sulphate and iodine-125 labelling. Evidence is presented for the degradation of band 3 polypeptide to lower molecular weight material some of which appears in region 4.5 of the polyacrylamide gel electrophoresis profile. It is found that the degradation process is inhibited by phenylmethylsulphonyl fluoride and is only significant in membrane extracts in the absence of detergent (Triton X-100) and on prolonged incubation at 37 degrees C, conditions which do not prevail during the isolation of membrane protein extracts for reconstitution studies. Extracts of band 3 and band 4.5 have been prepared and reconstituted in bilayer lipid membranes. The permeabilities of the reconstituted systems to D-glucose have been investigated and it is found that only bilayers incorporating band 4.5 exhibited enhanced monosaccharide transport. A linear relationship between D-glucose transport and the concentration of protein in the aqueous phase bathing the bilayers suggests a partitioning of the protein into the bilayer. Reconstitution is stereospecific and inhibited by cytochalasin B.

Anion Exchange Protein 1, Erythrocyte↗

Determination of the structures of trisaccharides by 13C-n.m.r. spectroscopy.

A literature survey of the 13C-n.m.r. chemical-shift data for aqueous solutions of monosaccharides, disaccharides, oligosaccharides, and their methyl derivatives is reported. Analysis of these data reveals a set of empirical rules which may be used in the elucidation of the structure of trisaccharides of known monosaccharide composition, and an example is reported. However, it is not possible to extend the rules to tetrasaccharides and higher saccharides without additional chemical-shift data for related model compounds.

Carbohydrate Conformation↗

Computer-assisted structural analysis of polysaccharides with an extended version of CASPER using 1H- and 13C-n.m.r. data.

The computer program CASPER, used in the structural analysis of polysaccharides composed of repeating units, has been extended. The extended version uses either unassigned 1H- or 13C-n.m.r. chemical shifts or the complete unassigned C,H-correlation spectrum, and can predict the structure of linear and branched oligo- and poly-saccharides. The number of possible structures, consistent with sugar and methylation analysis, can be decreased by the use of 1JC,H and 3JH,H values. The database, which contains 1H- or 13C-n.m.r. chemical shift data for monosaccharides and 1H- or 13C-glycosylation shifts for all types of glycosidic linkages obtained by combination of the monosaccharides, has been increased and now also contains correction values for sugar residues present in branch-point regions. The program has been tested on four polysaccharides of known structure but with different degrees of complexity. For three polysaccharides, the correct structure was suggested; for the fourth, two structures were consistent with the n.m.r. data, one of them being correct.

Carbohydrate Conformation↗

Metal-saccharide chemistry and biology: saccharide complexes of zinc and their effect on metallothionein synthesis in mice.

Monosaccharide (D-Fru, D-Gal, D-Glc, D-Xyl, and D-Rib) and disaccharide (Mal) complexes of Zn2+ were synthesized using different precursors and isolated in the solid state. These were found to be anionic with a Zn-to-saccharide ratio of 1:1 and 2:1 for monosaccharide and disaccharide complexes, respectively. Electrochemical behaviour in aqueous solution was studied by extensive cyclic voltammetric studies in the pH range 3.7-10.3. The effect of subcutaneously injected Zn-D-Fru, Zn-D-Gal and Zn-D-Glc complexes on the metallothionein synthesis in mice was found to be significant in the liver, but not in the brain.

Animals↗

Structure of amylovoran, the capsular exopolysaccharide from the fire blight pathogen Erwinia amylovora.

The acidic exopolysaccharide (EPS) of Erwinia amylovora, amylovoran, was purified from culture supernatants of bacteria in minimal medium and cleaved chemically either by treatment with trifluoracetic acid or hydrofluoric acid, and enzymatically by digestion with depolymerase from E. amylovora phage phi-Ealh. Structural characterization of the resulting oligosaccharides was performed by a combination of mass spectrometric and NMR [one- and two-dimensional (1D and 2D)] spectroscopic techniques. A branched repeating unit with five monosaccharide residues and various substituents was determined: [sequence: see text] The terminal monosaccharide of the side branch, which bears a 4,6-bound pyruvate residue in the R-configuration, was found to be modified with 2-linked (26%), 3-linked (24%), 2-,3-linked (40%) O-acetyl groups, or these were absent (10%). An additional glucose residue is linked to approximately 10% of the core alpha-galactose of the repeating unit.

Bacterial Capsules↗

alpha-Fucose inhibits human mixed-lymphocyte culture reactions and subsequent suppressor cell generation.

Carbohydrate moieties serve as important sites of interaction for many lymphocyte activities. The potential role of saccharides in the cellular interactions involved in mitogen-, antigen-, and alloantigen-induced proliferation was investigated. Eight different monosaccharides were tested for their inhibitory potential when added to uni- and bidirectional mixed-lymphocyte culture (MLC) reaction as well as to mitogen (Con A, PHA, PWM)-stimulated cultures. Only alpha-L-fucose blocked the MLC reaction in a dose-dependent fashion while having no effect on mitogen stimulation, although antigen-specific stimulation was also blocked by fucose. Similarly alpha-L-fucose specifically inhibited the MLC-induced generation of suppressor cells. Pretreatment of the MLC responder cells with fucose dehydrogenase abolished the MLC reaction while stimulator cell pretreatment had no effect, suggesting that the recognition site of the former contained alpha-L-fucose. The generation and the effector phase of Con A-induced suppressor cells was not affected by fucose, indicating that different receptors are involved in the latter. Apparent competitive inhibition by exogenous fucose of the cell-cell interaction required for the MLC reaction suggested that this monosaccharide is an essential constituent of allogeneic recognition sites.

Antigens, Viral↗

Carbohydrate patterns of endoscopic mucosal biopsies in cancer of the stomach and chronic gastritis.

The monosaccharide composition of the soluble glycoproteins of endoscopic gastric biopsies was studied with gas-liquid chromatography in patients with carcinoma of the stomach and in patients with chronic gastritis (controls). The analyses showed (1) that monosaccharide patterns were similar in the antrum and corpus of patients with chronic gastritis, (2) that the mannose content relative to the galactose content was increased in the tumor as compared with the antrum of the same stomach (p less than 0.05) and with the antrum (p less than 0.05) and corpus (p less than 0.02) of the control stomachs, and (3) that the N-acetylgalactosamine and N-acetylglucosamine content tended to be decreased in the tumor area as compared with the antrum and corpus of control stomachs. The changes in the histologically tumor-free part of the corpus of the cancer stomachs tended to be similar in direction to those in the tumor itself.

Acetylgalactosamine↗

Plasmodium falciparum: carbohydrates as receptor sites of invasion.

Monosaccharides, disaccharides, and trisaccharides were tested as inhibitors of the in vitro growth of Plasmodium falciparum (strain FCB). While certain monosaccharides (N-acetyl-D-glucosamine, D-mannose, and 3-O-methyl-D-glucose) proved to exhibit a toxic or reversibly retarding effect on the intraerythrocytic development of the parasite, the corresponding alpha- or beta-methylglycosides did not. Several methylglycosides, synthetic di- and tri-saccharides, and artificial blood group antigens were further tested for inhibitory effects on invasion of host red blood cells in vitro. The synthetic disaccharides beta DGlcNAc(1----4) alpha DManOMe and beta DGlcNAc(1----4) DGlcNAc (chitobiose) were good inhibitors of invasion at 10 mM concentration, whereas beta DGal(1----4)beta DGlcNAcOMe was negligibly inhibitory. The inhibition rate of N-acetyl-D-glucosamine, beta-glycosidically linked to bovine serum albumin (BSA) by an alipathic spacer, -(CH2)8CO-, was not enhanced, compared to the corresponding hapten, beta DGlcNAcO(CH2)8COOCH3. The inhibition rates of blood group A- and B-trisaccharide haptens, which were inhibitors of invasion, were also not significantly enhanced when coupled to BSA by way of the corresponding amide spacer, -(CH2)2NHCO(CH2)7CO-. A remarkable enhancement of the inhibition rate was, however, observed when beta DGal(1----3) alpha DGalNAcO(CH2)2NHCO(CH2)7COOCH3 (T-hapten) was coupled to BSA. A clear-cut decrease in the inhibition rates of different beta-glycosides of N-acetyl-D-glucosamine, beta DGlcNAcOR, was observed, depending on the nature of the aglycon R(p-nitrophenyl greater than -(CH2)8COOCH3 greater than -(CH2)2NHCO(CH2)2COOCH3 greater than -CH3). Also, p-nitrophenyl-alpha-D-glucopyranoside was a much better inhibitor of invasion than the corresponding methyl glycoside, alpha DGlcOMe, which was not inhibitory. The properties of the aglycon spacer, used for the covalent attachment of the carbohydrate to the carrier protein, may thus be crucial for the outcome of the inhibition rate.

Animals↗

Demonstration of N-acetylchondrosine-degrading beta-glucuronidase in rabbit liver.

N-Acetylchondrosine was incubated at pH 4.0 with a rabbit-liver crude enzyme extract. Gel filtration of the reaction products on Sephadex G-15 revealed the presence of monosaccharide liberated from the disaccharide. The monosaccharide fraction was analyzed by gas-liquid chromatography, and identified as a mixture of glucuronic acid and N-acetylgalactosamine. These results indicate the presence of beta-glucuronidase, which degrades N-acetylchondrosine, in rabbit liver. The discovery of the presence of this enzyme may help to establish the complete degradation process of chondroitin sulfates.

Animals↗

Isolation and chemical study of the glycosaminoglycans from squid cornea.

1. Oversulphated chondroitin sulphate (ca 93% of tissue glycosaminoglycans) with average molecular weight 72,500, chondroitin sulphate (5%) and small amounts of lowsulphated chondroitin sulphate were isolated from squid cornea. 2. The sulphation pattern of oversulphated chondroitin sulphate was delta di-4S (52%), delta di-diSD (28%), delta di-6S (9%) and delta di-OSCS (11%) and that of chondroitin sulphate 49, 1, 20 and 30% respectively. 3. All glycosaminoglycans contained neutral monosaccharides, glucose being the predominant neutral monosaccharide in oversulphated chondroitin sulphate and chondroitin sulphate and fucose in low-sulphated chondroitin sulphate. 4. Although L-iduronic acid was not detected, the digestion of oversulphated chondroitin sulphate with chondroitinases ABC and AC gave unexpected results.

Animals↗

Formation and identification of carcinogenic heterocyclic aromatic amines in boiled pork juice.

Bacterial frameshift mutagens have been found in boiled pork juice. The mutagenic compounds of boiled pork juice were purified and analyzed by HPLC. The mutagenic fractions corresponding to the peaks of the standard mutagens 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) were confirmed by comparison of UV and mass spectra. One gram equivalent of original lean ground pork was estimated to contain 4.1 ng of MeIQx, 3.7 ng of IQ, and 1.2 ng of MeIQ, which accounted for 21.0%, 30.4%, and 38.1%, respectively, of the total mutagenicity. The remaining mutagenic fractions might be diMeIQx isomers. This will be further confirmed by mass spectrometry in future studies. The amount of IQ-type mutagens in boiled pork juice was about 4-fold higher than in broiled beef. Furthermore, we investigated the effects of 20 amino acids, three monosaccharides, and creatinine on mutagen formation when added to the pork juice to elucidate possible precursors leading to the formation of mutagens. Results showed that five amino acids (glutamine, tyrosine, glycine, alanine, and threonine) and two monosaccharides (ribose and glucose) might participate in mutagen formation in boiled pork juice.

Amines↗

Extracellular polysaccharides produced by tuberose callus.

A high yield of extracellular polysaccharide (ECP) was obtained from callus cultures of tuberose (Polianthes tuberosa), which could be separated into an unadsorbed and two acidic fractions (TPS-1, -2) by ion-exchange column chromatography. The yields of each fraction were markedly increased by the addition of 10(-5) M 2,4-dichlorophenoxyacetic acid to the medium. Of the three fractions, the amount of TPS-1 accounted for over 60% of total yield of ECP, which was a predominant polysaccharide consisting of arabinose (Ara), mannose (Man) and galactose (Gal) as major neutral monosaccharides. Judging from the patterns of electrophoresis and ultra-centrifugation, TPS-1 was identified to be homogeneous. Methylation and GC-mass spectrometry analyses of this fraction revealed the presence of 1,2,3-linked Man, 1-linked Ara, 1,3-linked Ara, 1-linked Gal and 1,3,4-linked glucuronosyl (GlcUA) residues in a molar ratio of 1.0:1.08:0.85:0.75:1.08. Based on additional analyses of the mild acid hydrolysate and the absolute configuration of the constituent monosaccharides, a possible structure for TPS-1 was a glucuronomannan possessing the unit of -->4)-beta-D-GlcUAp-(1-->2)-alpha-D-Manp-(1--> with branching at the C-3 position, where -->1)-alpha-L-Araf, -->1)-beta-D-galp, -->1)-alpha-L-Araf-(3-->1)-alpha-L-Araf or -->1)-alpha-L-Araf-(3-->1)-beta-D-Galp were attached randomly. About 35% of the GlcUA moieties were present as methyl esters. Further confirmation was made by 1H and 13C NMR spectroscopy.

Carbohydrate Conformation↗

Computer modelling of sulfated carbohydrates: applications to carrageenans.

In this study, X-ray crystallographic data of sulfated monosaccharides have been used to derive appropriate parameters for sulfate groups in the Tripos force field, previously parameterized for carbohydrates. A database of nine sulfated monosaccharides occurring as building blocks of sulfated polysaccharides such as carrageenans and sulfated glycosaminoglycans has been built. These tools have then been used to evaluate the conformational energies of the repeating units of the kappa-, iota- and lambda-carrageenan polymers, taking into account the rotation around the sulfate groups. In a third step, helical conformations of carrageenans have been explored and the results compared with the experimental data obtained by X-ray fibre diffraction. Stable, single, right-handed helices, with geometric and helical parameters in close correspondence with the best models derived from X-ray diffraction data, have been generated. Finally, the configurational statistics of random-coil carrageenan chains have been investigated and compared with experimental data currently available on these polymers. A highly flexible character is predicted for kappa- and iota-carrageenans, with lambda-carrageenan showing slightly more extension.

Carbohydrate Conformation↗

Isolation, biochemical and immunological characterisation of two sea urchin glycoproteins bearing sulphated poly(sialic acid) polysaccharides rich in N-glycolyl neuraminic acid.

Two different sialoproteins were isolated from the sea urchin shell by guanidine hydrochloride extraction in the presence of Triton X-100. The sialoproteins (SP I and SP II) were purified on DEAE-Sephacel and Sepharose CL-6B and separated from each other by density gradient centrifugation. The ratio between recovered SP I and SP II was 1:4.5 and their M(r)s 650 and 600 kDa, respectively. They were degraded by neuraminidase, endoglycosidase F and peptide N-glycosidase F resulting in fragments of similar relative molecular mass (M(r)s). Although their protein cores have approximately the same relative molecular mass of 500 kDa, they differ markedly in their contents of aspartic acid/asparagine, glycine, leucine and phenylalanine, as well as in the primary amino acid sequence of their N-terminal peptides. Carbohydrate analyses showed that the sialic acid content was higher in SP I (11.4% of dry tissue weight) than in the more prominent SP II (5.3%). Two types of carbohydrates, O-glycosidically-linked polysaccharides and N-glycosidically-linked oligosaccharides are present in both sialoproteins. SP I contains 10-11 polysaccharide chains whereas SP II contains 5-6. The polysaccharides are linked to protein cores via galactosamine, have approximately the same M(r) of 12 kDa and contain 32-33 N-glycolyl neuraminic acid, 10-11 glucosamine, 6-7 sulphate and 6-8 neutral monosaccharide residues. Sialic acid residues are organized in a poly(sialic acid) unit which is present in the non-reducing terminal of the polysaccharides and degraded by neuraminidase. Hexosamines, sulphates and neutral monosaccharides are all constituents of the sialic acid free region of the chain near the reducing end. Two oligosaccharide populations were isolated from SP I, one major (70% of the total oligosaccharides) with M(r) of approximately 3 kDa and the other with M(r) of 1.5 kDa. In SP II, however, only a 3-kDa oligosaccharide population was present. The oligosaccharides from both sialoproteins are N-glycosidically linked to asparagine via the glucosamine and contain mannose, glucosamine, galactosamine and sialic acids. Antibodies against SP II were raised in rabbits and it was shown that the antigenicity of SP II was lost on either neuraminidase or trypsin digestion, indicating that both the poly(sialic acid) units of the polysaccharide and the protein core are antigenically active. As expected, SP II showed considerable cross-reactivity with SP I due to the common poly(sialic acid) structure. There were no significant reactivities of SP II and SP I with antibodies to bovine bone sialoprotein and osteopontin. The biological role of the two sea urchin sialoproteins as developmentally regulated products of the tissue remains to be elucidated.

Amino Acid Sequence↗