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At least 19 recordsLinked to original sources
PubMed1983

Improved carbohydrate tolerance and stimulation of carbohydrate oxidation and lipogenesis during short-term carbohydrate overfeeding.

The carbohydrate intake of seven healthy men was increased from 220-265 g/d to 620-770 g/d for 17 days, while protein and fat intake remained constant. Carbohydrate loading did not affect the preprandial plasma glucose levels after an overnight fast, but reduced the postprandial increment in plasma glucose levels after 5, 11, and 17 days of overfeeding. Preprandial plasma insulin levels were slightly increased during carbohydrate overfeeding, but no increase in the postprandial rise in insulin levels was found until 11 days after the start of carbohydrate loading. Whole-body rates of carbohydrate oxidation and of glucose conversion to fat were estimated by indirect calorimetry. Basal carbohydrate oxidation rate was increased by 95% at the end of 17 days of overfeeding, but there was no potentiation in the stimulation of the carbohydrate oxidation rate induced by a meal. There was no net fat synthesis from glucose before carbohydrate loading; carbohydrate overfeeding produced nonprotein respiratory exchange ratios greater than 1.00, suggesting net fat synthesis from glucose. Meals did not stimulate net lipogenesis from glucose, either before or after overfeeding. These results indicate that the improvement in carbohydrate tolerance associated with short-term carbohydrate loading does not appear to depend on elevated insulin levels. Increased carbohydrate oxidation and lipogenesis elevated carbohydrate disposal is more than necessary to account for the improvement in carbohydrate tolerance.

Adult↗
PubMed1996

Amino acid sequence and carbohydrate structure of a recombinant human tissue factor pathway inhibitor expressed in Chinese hamster ovary cells: one N-and two O-linked carbohydrate chains are located between Kunitz domains 2 and 3 and one N-linked carbohydrate chain is in Kunitz domain 2.

Human tissue factor pathway inhibitor is a protease inhibitor with three tandem Kunitz-type inhibitory domains. The recombinant protein (r-hTFPI) was produced using Chinese hamster ovary cells, and its polypeptide and carbohydrate chain structures were analyzed. The complete amino acid sequence, composed of 276 residues, was determined using a protein sequencer after protease digestion and it was identical to that predicted from the cDNA sequence. Among three potential N-glycosylation sites, both Asn117 and Asn167 were fully N-glycosylated but Asn228 was not. Thr175 was also fully O-glycosylated, but Ser174 was partially O-glycosylated. Carbohydrate composition and mass spectrometric analyses of the undecapeptide OG-11 (residues Leu 170approximately Leu180) showed that two O-linked carbohydrate chains consisted of a type-1 core structure (Gal-GalNAc-Ser/Thr) with 0-3 mol of N-acetylneuraminic acid(s). The N-linked carbohydrate chains were analyzed by two-dimensional carbohydrate mapping combined with sequential glycosidase digestion, after the reducing-ends of carbohydrate residues were tagged with 2-aminopyridine and non-reducing-end sialic acids were removed with sialidase. All the N-linked structures in r-hTFPI were complex-type carbohydrate chains with one fucose residue attached to the reducing-end GlcNAc and consisted of bi-, tri-, and tetraantennary carbohydrate chains in the ratio 1.9:1.3:1.0. Fucosylated tri- and tetraantennary carbohydrate chains with one or two N-acetyllactosaminyl repeats were also found (30% of carbohydrate chains determined). Thus, the region between Kunitz domains 2 and 3 encoded by exon 7 was highly glycosylated by two O-linked carbohydrate chains at Ser174 and Thr175 and one N-linked carbohydrate chain at Asn167. These results indicated that the region is occupied by a cluster of three bulky and acidic carbohydrate chains.

Amino Acid Sequence↗
PubMed1995

Characterization of a novel sulfated carbohydrate unit implicated in the carbohydrate-carbohydrate-mediated cell aggregation of the marine sponge Microciona prolifera.

Species-specific cell reaggregation in the marine sponge Microciona prolifera is mediated by an adhesion proteoglycan. Two interactions are involved in the process: a Ca(2+)-dependent homophilic binding between proteoglycan molecules and a Ca(2+)-independent binding between the molecule and cells. Both interactions are mediated by the glycan moieties of the proteoglycan. The interaction of the proteoglycan with itself has been characterized as a carbohydrate-carbohydrate interaction of multiple low affinity sites. The monoclonal antibodies Block 1 and Block 2 raised against the purified aggregation proteoglycan and selected for inhibition of aggregation bind to these glycans. In a previous report the structure, [formula: see text] was assigned to the oligosaccharide reacting with Block 1 antibody (Spillmann, D., Hård, K., Thomas-Oates, J., Vliegenthart, J. F. G., Misevic, G., Burger, M. M., and Finne, J. (1993) J. Biol. Chem. 268, 13378-13387). By the technique of attaching the water-soluble acid-degraded fragments to a lipid carrier for immunochemical detection and by chemical, enzymatic and spectroscopic methods the structure, [formula: see text] was assigned to the oligosaccharide reacting with the aggregation-blocking monoclonal antibody Block 2. The structure, [formula: see text] was assigned to a major nonreactive oligosaccharide, which outlined the molecular requirements of antibody binding of the two aggregation-associated epitopes. These data demonstrate that two different functional sites with distinct structural characteristics and antibody reactivities are involved in the reaggregation of sponge cells, a model of carbohydrate-carbohydrate-mediated cell interactions.

Animals↗
PubMed2004

Carbohydrate chips for studying high-throughput carbohydrate-protein interactions.

Carbohydrate-protein interactions play important biological roles in living organisms. For the most part, biophysical and biochemical methods have been used for studying these biomolecular interactions. Less attention has been given to the development of high-throughput methods to elucidate recognition events between carbohydrates and proteins. In the current effort to develop a novel high-throughput tool for monitoring carbohydrate-protein interactions, we prepared carbohydrate microarrays by immobilizing maleimide-linked carbohydrates on thiol-derivatized glass slides and carried out lectin binding experiments by using these microarrays. The results showed that carbohydrates with different structural features selectively bound to the corresponding lectins with relative binding affinities that correlated with those obtained from solution-based assays. In addition, binding affinities of lectins to carbohydrates were also quantitatively analyzed by determining IC(50) values of soluble carbohydrates with the carbohydrate microarrays. To fabricate carbohydrate chips that contained more diverse carbohydrate probes, solution-phase parallel and enzymatic glycosylations were performed. Three model disaccharides were in parallel synthesized in solution-phase and used as carbohydrate probes for the fabrication of carbohydrate chips. Three enzymatic glycosylations on glass slides were consecutively performed to generate carbohydrate microarrays that contained the complex oligosaccharide, sialyl Le(x). Overall, these works demonstrated that carbohydrate chips could be efficiently prepared by covalent immobilization of maleimide-linked carbohydrates on the thiol-coated glass slides and applied for the high-throughput analyses of carbohydrate-protein interactions.

Carbohydrate Metabolism↗
PubMed1980

[Spontaneous changes in carbohydrate tolerance and insulin secretion in persons with indications of disturbed carbohydrate tolerance. Preliminary results and follow-up observations for 7 years].

115 patients with normal weight and 15 adipose persons with suspicion of a disturbance of the carbohydrate metabolism were characterized by means of a glucose infusion test lasting two hours concerning the carbohydrate tolerance and insulin secretion. Longitudinal analyses of the spontaneous behaviour of the carbohydrate tolerance and insulin secretion depending on the degree of the carbohydrate tolerance up to duration of the observation of 7 years. A deterioration of the carbohydrate tolerance was to be proved in 21% of 87 persons with normal carbohydrate tolerance within two years. With normal carbohydrate tolerance within two years. With an increase of the duration of the observation up to 7 years the frequency of disturbances of the carbohydrate tolerance increases to 30%. This development cannot be coordinated to a certain type of insulin secretion. In the individual case a deterioration of the carbohydrate tolerance may be associated with an increase or reduction of the glucose stimulated insuline secretion. An improvement of the carbohydrate tolerance was observed in 15 (54%) of 28 patients with disturbed carbohydrate tolerance within 2 years. In a group with pathological carbohydrate tolerance this development was associated with a significant reduction of the basic and glucose stimulated insulin secretion. In all patients with improved carbohydrate tolerance on the side of the insulin secretion primarily the type of "normal response" was present. The lacking relation between changes of the B-cell function and the carbohydrate tolerance emphasizes the importance of other factors, such as a peripheral insulin resistance, for the development of disturbances in the carbohydrate metabolism.

Carbohydrate Metabolism↗
PubMed1994

A gel retardation assay for the interaction of proteins and carbohydrates by fluorophore-assisted carbohydrate electrophoresis.

A gel retardation method for studying the interaction between proteins and carbohydrates employing fluorophore-assisted carbohydrate electrophoresis (FACE) has been developed. A carbohydrate (or carbohydrate mixture) is labeled fluorescently at its reducing end with 8-aminonaphthalene-1,3,6-trisulfonic acid, incubated with its binding protein(s), separated, visualized, and quantified by the FACE system. Protein-bound carbohydrate remains at the top of the high-percentage polyacrylamide gel, whereas free carbohydrate migrates into the gel and is thereby separated. Employing mixtures of carbohydrates, a side-by-side comparison between protein-present and protein-absent samples easily identifies the carbohydrate ligands of the protein. The method proposed provides a rapid, convenient, and visual alternative for screening and identifying protein-carbohydrate interactions. The feasibilities of the method and of the determination of the apparent association constants of protein-carbohydrate complexes were examined by the use of lectins and their known carbohydrate ligands. The potential of determining association constants for proteins and native carbohydrates through competition experiments with unlabeled carbohydrate is also discussed.

Acrylic Resins↗
PubMed2006

Gold glyconanoparticles for mimics and measurement of metal ion-mediated carbohydrate-carbohydrate interactions.

To mimic and measure calcium ion-mediated carbohydrate-carbohydrate interactions, four lactose derivatives have been synthesized for assembly on gold nanoparticles. The series of lactose derivatives varied by the length of the thiolated ethylene glycol anchor chain [O(CH2CH2O)(m)CH2CH2SH; where m = 0, 1, 2, and 3] used to self-assemble the carbohydrates to the preformed gold nanoparticles of ca. 16 nm diameter. Upon addition of calcium ions to the lactose-stabilized nanoparticles, rapid carbohydrate-carbohydrate interactions were visualized and subsequently measured using UV-visible spectrometry and transmission electron microscopy (TEM). The nanoparticle aggregates formed via metal-mediated carbohydrate-carbohydrate interactions could be readily redispersed through the addition of EDTA. Multiple reaggregation and redispersion cycles were achieved, confirming that the aggregation process was due to metal ion-mediated carbohydrate interactions rather than calcium chelation by residual citrate ions on the particle surface. The essential involvement of the lactose moiety in Ca2+ complexation was shown by control measurements on related D-glucose-derivatized nanoparticles, where a significantly reduced aggregation response was obtained only at high ion concentrations. Other group 2 metal ions with radii larger than that of calcium, viz., barium and strontium, were also shown to mediate the aggregation of the lactose-stabilized nanoparticles. The induced aggregation of the lactose nanoparticles was determined to be quantitatively dependent upon the calcium ion concentration. Furthermore, the analytical sensitivity of the calcium-induced aggregation and the linear dynamic range were dependent on the length of the ethylene glycol anchor chain. The shortest ethylene glycol chain (m = 0) gave the most sensitive response with the optimum limit of detection (0.8 mM Ca2+), whereas the longest ethylene glycol chain (m = 3) provides a measurement of calcium ion concentration over the largest linear dynamic range (10-35 mM Ca2+). This work has shown that the self-assembled deposition of lactose derivatives on gold nanoparticles provides multivalent carbohydrate surfaces that can be used as mimics for the measurement of biologically relevant carbohydrate-carbohydrate interactions. Additionally, this study has highlighted the importance of the structure and length of the ligand that anchors the carbohydrate sugar to the gold particle surface to facilitate such carbohydrate interactions and for "tuning" the analytical characteristics of bioassays developed using metal nanoparticle technology.

Acetylation↗
PubMed1983

Prior carbohydrate consumption affects the amount of carbohydrate that rats choose to eat.

Consumption of protein-rich, carbohydrate-restricted reducing diets has been associated anecdotally with an increased appetite for carbohydrate. We have tested the effect of such a diet on carbohydrate intake by rats. Rats were given either a calorie-restricted ketogenic diet containing protein and fat or a control diet containing carbohydrate along with the protein and fat. When allowed to choose from a pair of isocaloric, isonitrogenous diets containing 25 or 75% dextrin, ketotic rats ate significantly more carbohydrate and total food than control animals during the first 30 minutes of feeding, apparently requiring more of the carbohydrate to obtain an increase in brain tryptophan similar to controls. Ketotic rats ate a significantly higher proportion of total calories as carbohydrate. Similar results were obtained when sucrose replaced dextrin. When ketotic and control rats chose between two diets differing in proportions of fat or protein, no differences were observed between the groups in total food intake nor in the amounts or proportions of fat or protein eaten. We also compared the effects of a small, isocaloric premeal containing only carbohydrate (1.4 g dextrose) or mixed nutrients on subsequent carbohydrate consumption in otherwise untreated rats allowed to choose from 25 and 75% dextrin diets. Rats eating the carbohydrate premeal subsequently ate as much total food as the mixed-nutrient controls, but significantly less carbohydrate. These observations suggest that carbohydrate intake is influenced by prior nutrient consumption and that prolonged deprivation of carbohydrate can lead to overconsumption of this nutrient when it is reintroduced into the diet.

Animals↗
PubMed2004

Carbohydrate arrays for functional studies of carbohydrates.

Carbohydrates, as components of glycoproteins, glycolipids and proteoglycans, play an important biological role as recognition markers through carbohydrate-protein interactions. For the most part, biophysical and biochemical methods have been used to analyze these biomolecular interactions. In contrast, less attention has been given to the development of high-throughput procedures to elucidate carbohydrate-protein recognition events. Recently, carbohydrate arrays were developed and employed as a novel high-throughput analytic tool for monitoring carbohydrate-protein interactions. This technique has been used to profile protein binding and enzymatic activity. The results have shown that carbohydrate binding to the corresponding lectins is highly selective and that the relative binding affinities are well correlated with those obtained from solution-based assays. In addition, this effort demonstrated that carbohydrate arrays could be also utilized to identify and characterize novel carbohydrate-binding proteins or carbohydrate-processing enzymes. Finally, the results of this investigation showed that lectin-carbohydrate binding affinities could be quantitatively assessed by determining IC50 values for soluble carbohydrates with the carbohydrate arrays. The results of these studies suggest that carbohydrate arrays have the potential of playing an important role in basic researches, the diagnoses of diseases and drug discovery.

Binding Sites↗
PubMed1955

Variation in the group-specific carbohydrate of group A streptococci. I. Immunochemical studies on the carbohydrates of variant strains.

The phenomenon of apparent loss of group-specific carbohydrate in the course of mouse passage of group A streptococci has been subjected to further study, and several additional variants showing this property have been described. The loss of group reactivity is shown to be due to an alteration in the chemical structure and serological specificity of the cell wall carbohydrate. This alteration appears to be essentially the same in each of the variants available for study. The carbohydrate of the variant strains (V) contains the same two monosaccharide components as the group A carbohydrate (A), but they are present in different proportions. Precipitating sera reactive with V carbohydrate have been prepared, and the A and V carbohydrates have been compared by qualitative and quantitative precipitin analysis. A second type of variation has been encountered during mouse passage. This variation is characterized by the occurrence of a cell wall carbohydrate (I) intermediate in chemical and serological properties between the A and V carbohydrates. The I carbohydrate reacts with both A and V antisera and does not appear to be a simple mixture of A and V carbohydrate. Similarly, antisera against the intermediate strain contain antibodies reactive with both A and V carbohydrates, and evidence is presented indicating that in part this represents antibody with double specificity.

Animals↗
PubMed2004

Carbohydrate-carbohydrate interaction as a major force initiating cell-cell recognition.

Sponges were the earliest multicellular organisms to evolve through the development of cell recognition and adhesion processes mediated by cell surface proteoglycans. Information on sponges has an extra added value because, as a group, they are the oldest Metazoans alive and contribute more to our understanding of life on earth than knowledge of other animal groups. Although the proteoglycans are emerging as key players in various physiological and pathophysiological cellular events, little is known about the carbohydrate moiety of the proteoglycan molecule. Until recently there was no evidence provided for the existence of specific and biologically significant carbohydrate-carbohydrate interaction. We show here that the interaction between single oligosaccharides of surface proteoglycans is relatively strong (in the 200-300 piconewtons range) and in the same range as other relevant biological interactions, like those between antibodies and antigens. This carbohydrate-carbohydrate recognition is highly species-specific and perfectly mimics specific cell-cell recognition. Both the strength and the species-specificity of the carbohydrate-carbohydrate interaction are guaranteed by polyvalency, by compositional and architectural differences between carbohydrates, and by the arrangement of the carbohydrate chain in a three-dimensional context. Ca(2+)-ions are essential and probably provide coordinating forces. Our findings confirm the existence and character of species-specific carbohydrate-carbohydrate recognition fundamental to cell recognition and adhesion events.

Animals↗
PubMed1989

The effects of diet differing in fat, carbohydrate, and fiber on carbohydrate and lipid metabolism in type II diabetes.

This study was designed to determine the effects of varying the proportions of carbohydrate, fiber, and fat on metabolic control in Type II diabetes. Ten men, aged 50 to 69 years, with Type II diabetes participated. Four isocaloric diets were consumed for 2 weeks each, with a break of 6 to 14 weeks between diets to ensure no carryover effects. Two of the diets were high in carbohydrate (63% to 65% energy) and low in fat (10% to 12% energy) but differed in their fiber contents (20 vs. 45 gm/day). The other two diets were low in carbohydrate (23% to 27% energy) with either a low or a high fat content (15% vs. 55% energy) and a high or normal protein content (62% vs. 18% energy). The composition of the subjects' usual diets in the week before each of the experimental diets did not vary significantly: carbohydrate 47% to 50% energy, protein 22% to 25% energy, fat 27% to 31% energy, and fiber 24 to 25 gm/day. A 75-gm oral glucose tolerance test and a 12-hour metabolic profile in response to 3 meals typical of the particular diet were conducted before and at the conclusion of each 2-week dietary period. The most significant improvements in metabolic control (as assessed by the effects of the diets on fasting glucose and on lipids, and on the glucose and insulin responses to oral glucose and the mixed meals) were obtained with the high-fiber, high-carbohydrate, low-fat diet and with the low-carbohydrate, high-protein, low-fat diet. Metabolic control was not significantly affected by the low-fiber, high-carbohydrate, low-fat diet, but it deteriorated significantly on the low-carbohydrate, high-fat diet. The results of this study confirmed the importance of high fiber and low fat in improving metabolic control in Type II diabetes. In conclusion, if high-carbohydrate, low-fat diets are to be recommended to patients with diabetes, it is essential that the type of carbohydrate recommended be unrefined and high in fiber.

Blood Glucose↗
PubMed1997

Pre-exercise carbohydrate meal and endurance running capacity when carbohydrates are ingested during exercise.

This study examined whether combining a pre-exercise carbohydrate meal with the ingestion of a carbohydrate-electrolyte solution during exercise is better in improving endurance running capacity than a carbohydrate-electrolyte solution alone. Ten men completed three treadmill runs at 70% VO2max to exhaustion. They consumed 1.) a carbohydrate meal three hours before exercise and a carbohydrate-electrolyte solution during exercise (M + C), or 2.) a liquid placebo three hours before exercise and the carbohydrate-electrolyte solution during exercise (P + C), or 3.) a placebo three hours before exercise and placebo during exercise (P + P). When the meal was consumed (M + C) serum insulin concentrations were higher at the start of exercise, and carbohydrate oxidation rates were higher during the first 60 min of exercise compared with the values found in the P + C and P + P trials (p < 0.01). Exercise time was longer in the M + C (147.4+/-9.6 min) compared with the P + C (125.3+/-7 min) (p < 0.01). Also, exercise time was longer in M + C and P + C compared with the P + P (115.1+/-7.6 min) (p < 0.01 and p < 0.05 respectively). These results indicate that the combination of a pre-exercise carbohydrate meal and a carbohydrate-electrolyte solution further improves endurance running capacity than the carbohydrate-electrolyte solution alone.

Adult↗
PubMed1996

[Carbohydrate-carbohydrate interaction].

The review deals with the new area in biorecognition--the carbohydrate-carbohydrate interaction. Seven experimental approaches are described that were used for detecting and investigating this phenomenon, with special reference to its mechanism and peculiarities, particularly, in comparison with other types of molecular interactions; some historical aspects are also considered. The whole body of experimental evidence published on carbohydrate-carbohydrate interaction by the end of 1995, is reviewed. A special chapter is dedicated to intercellular adhesion mediated or initiated by carbohydrate-carbohydrate recognition. The main peculiarities of carbohydrate-carbohydrate interaction are as follows. Monovalent interaction is so low affinity that it cannot be recorded by routine physical methods, such as NMR. However, if polyvalent ensembles of oligosaccharides (e.g., two membranes with a high density of built-in glycolipids) come in contact, one can observe a specific Ca(2+)-dependent interaction which is inhibited by either EDTA antibodies against carbohydrates or by oligosaccharides. The carbohydrate/carbohydrate-mediated cell adhesion is a rapid primary process which immediately precedes carbohydrate-lectin (selective) and protein-protein (integrin) adhesion. Le(x)/Le(x)-Mediated compactization of embrions and Gm3/Gg3 mediated adhesion of tumour cells provide illustrative examples of such intercellular contacts.

Animals↗
PubMed2005

Perceived hunger is lower and weight loss is greater in overweight premenopausal women consuming a low-carbohydrate/high-protein vs high-carbohydrate/low-fat diet.

The impact of a low-carbohydrate/high-protein diet compared with a high-carbohydrate/low-fat diet on ratings of hunger and cognitive eating restraint were examined. Overweight premenopausal women consumed a low-carbohydrate/high-protein (n=13) or high-carbohydrate/low-fat diet (n=15) for 6 weeks. Fasting body weight (BW) was measured and the Eating Inventory was completed at baseline, weeks 1 to 4, and week 6. All women experienced a reduction in BW (P<.01), although relative BW loss was greater in the low-carbohydrate/high-protein vs high-carbohydrate/low-fat group at week 6 (P<.05). Based on Eating Inventory scores, self-rated hunger decreased (P<.03) in women in the low-carbohydrate/high-protein but not in the high-carbohydrate/low-fat group from baseline to week 6. In both groups, self-rated cognitive eating restraint increased (P<.01) from baseline to week 1 and remained constant to week 6. Both diet groups reported increased cognitive eating restraint, facilitating short-term weight loss; however, the decrease in hunger perception in the low-carbohydrate/high-protein group may have contributed to a greater percentage of BW loss.

Adult↗
PubMed2002

Potent inhibition of HIV-1 fusion by cyanovirin-N requires only a single high affinity carbohydrate binding site: characterization of low affinity carbohydrate binding site knockout mutants.

Cyanovirin-N (CVN) is a novel cyanobacterial protein that potently inhibits viral entry by human immunodeficiency viruses (HIV) via high affinity carbohydrate-mediated binding to the surface envelope glycoprotein gp120. Bearing C(2) pseudo-symmetry, CVN contains two carbohydrate binding sites of differing affinities located at opposite ends of the protein. CVN selectively binds with nanomolar affinity the mammalian high mannose oligosaccharides oligomannose-8 D1D3 and oligomannose-9, which also govern binding to gp120. At nanomolar concentrations CVN binds these oligosaccharides only through its high affinity site, while at micromolar to millimolar concentrations the oligosaccharides are bound through both sites leading to divalent protein-carbohydrate interactions. Similarly, two modes of binding to gp120 can be envisioned where CVN either binds gp120 solely through the high affinity site, or binds divalently using both carbohydrate binding sites. To determine the role of the low affinity site in binding to gp120, we sought to design a variant of CVN that lacks the low affinity carbohydrate binding site but retains a fully functional high affinity site. Thus, we constructed a series of CVN mutants possessing cumulative mutations in the low affinity site only, and characterized by NMR the overall structure and carbohydrate binding ability of each of these mutants. We demonstrate that carbohydrate binding by the low affinity site is completely absent in two mutants bearing three or four mutations (namely, m3-CVN=Lys3Asn, Glu23Ile, Asn93Ala; and m4-CVN=Lys3Asn, Thr7Ala, Glu23Ile, Asn93Ala), while the high affinity site binds the high affinity ligand Manalpha(1-2)Manalpha with a K(d) value equal to that measured for CVN. Using an HIV-1 cell fusion assay, we show that all of the mutants inhibit HIV-1 fusion with nearly identical IC50 values as wild-type CVN. We interpret these results as indicating that the low affinity carbohydrate binding site of CVN is not necessary for high affinity binding to gp120, and HIV-1 fusion can therefore be blocked by monovalent protein-carbohydrate interactions.

Amino Acid Sequence↗
PubMed1998

No relationship between carbohydrate intake and effect of acarbose on HbA1c or gastrointestinal symptoms in type 2 diabetic subjects consuming 30-60% of energy from carbohydrate.

OBJECTIVE: To determine the relationship between carbohydrate intake and the effect of acarbose on HbA1c in subjects with type 2 diabetes treated with acarbose alone, acarbose plus sulfonylurea, acarbose plus metformin, or acarbose plus insulin. RESEARCH DESIGN AND METHODS: We conducted a double-blind randomized placebo-controlled study in which subjects with diabetes in four treatment strata (77 on diet alone, 83 treated with metformin, 103 treated with sulfonylurea, and 91 treated with insulin) were randomized to treatment with placebo or acarbose for 12 months. Before randomization, and 3, 6, 9, and 12 months after randomization, fasting blood was obtained for HbA1c, and 3-day diet records were collected. Subjects who completed at least 6 months of acarbose therapy and provided at least three 3-day diet records were included. RESULTS: In the 114 subjects included in this analysis, carbohydrate intake varied from approximately 30-60% of energy There was no significant relationship between carbohydrate intake and change in HbA1c in any of the four treatment strata (diet: n=26, r=0.35, P=0.076; metformin: n=27, r=0.26, P=0.19; sulfonylurea: n=35, r=0.24, P=0.16; insulin: n=25, r=-0.27, P=0.19). In the 80 subjects consuming <50% of energy from carbohydrate, the fall in HbA1c (7.83 +/-0.17% at baseline to 6.72+/-0.13% on acarbose, P < 0.001) was no different from that of the 34 subjects consuming >50% of energy from carbohydrate (7.55+/-0.25% at baseline to 6.66+/-0.23% on acarbose, P < 0.001). There was no difference in carbohydrate intake between those who dropped out of the study because of gastrointestinal side effects and those who did not, and there was no relationship between severity of symptoms and the composition of the diet. CONCLUSIONS: In subjects with type 2 diabetes consuming 30-60% of energy from carbohydrate, the effect of acarbose on HbA1c and gastrointestinal symptoms was not related to carbohydrate intake. Because most people consume at least 30% of energy from carbohydrate, we conclude that no special diet is needed for acarbose to be effective in improving blood glucose control in the treatment of type 2 diabetes.

Acarbose↗
PubMed1984

The involvement of brain serotonin in excessive carbohydrate snacking by obese carbohydrate cravers.

A specific hunger for carbohydrate-rich foods has been observed in animals and human beings and appears to be regulated by the brain neurotransmitter serotonin. Consumption of a carbohydrate-rich meal increases the synthesis and release of brain serotonin (by enhancing the brain uptake of its precursor, tryptophan). As a consequence of this increased release of serotonin, carbohydrate intake is decreased at the next meal. Consumption of protein does not increase brain serotonin levels or decrease carbohydrate intake. A subgroup of obese individuals who consume carbohydrate-rich snack foods at specific times of day or evening has been identified. Such individuals do not routinely snack on protein-rich foods, and their consumption of calories and nutrients at meals is not excessive. Evidence is presented that carbohydrate snacking seems to be related to a "need" to increase the level of brain serotonin; treatment with a drug, d-1 fenfluramine, that increases serotoninergic neurotransmission significantly decreases carbohydrate snack consumption. Weight loss among the population of carbohydrate cravers might be most successful if treatment includes either a diet or drugs that increase brain serotonin activity when the need to snack on carbohydrate is most likely to occur.

Adult↗