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PubMed1986

[Effect of hydroxyethyl starch, oxypolygelatin and human albumin on the phagocytic function of the reticuloendothelial system in healthy subjects].

RES phagocytic function was determined in healthy volunteers prior to and up to 5 h after application of 10 ml/kg body weight of 6% hydroxyethyl starch (450,000; 0.7), 5.5% oxypolygelatin (30,000), or 5.0% human albumin solution. Phagocytosis (phagocytic index K) was evaluated in vivo by intravascular lipid clearance (Lipofundin clearance test). Immediately after infusion, the phagocytic rate increased by 30% in the hydroxyethyl starch group (n = 10; p less than 0.05), 14% in the oxypolygelatin group (n = 10; ns), and 24% in the albumin group (n = 8; ns). 2 h after infusion phagocytosis was still increased by 35% in the hydroxyethyl starch group (n = 10; p less than 0.05), by 18% in the oxypolygelatin group (n = 10; ns), and 13% in the albumin group (n = 8; ns). 5 h after infusion, K values had returned to normal in the albumin group (n = 4), but were still increased by 40% in the hydroxyethyl starch group (n = 4; ns). No statistically significant differences could be established among the 3 groups. The increase in the phagocytic rate, particularly after application of hydroxyethyl starch, might be explained by a dilution effect.

Adult↗

PubMed1982

[The effects of 500 ml 10% hydroxyethyl starch 200/0.5 and 10% dextran 40 on blood volume, colloid osmotic pressure and renal function in human volunteers (author's transl)].

The effects of administration of a new, middle-molecular 10% hydroxyethyl starch 200/0.5 (HAES-steril) were compared to 10% dextran 40 (Rheomacrodex) in 20 hypovolaemic volunteers after withdrawal of 400 ml blood. The total increase of blood volume after 500 ml of 10% hydroxyethyl starch 200/0.5 was 10.19 +/- 1.1 ml/kg (754 ml), after 500 ml of 10% dextran 40 14.10 +/- 1.1 ml/kg (1032 ml), which was significantly higher (p less than 0.01) and in correspondence with the known volume expanding properties of 10% dextran 40. The volume effect after administration of both substances was stable, as demonstrated by the ability to compensate the loss of 400 ml blood for more than 8 hours. The maximal increase of the colloid osmotoc pressure after 10% hydroxyethyl starch 200/0.5 was 5.3 +/- 0.2 mm Hg, after 10% dextran 40 7.2 +/- 0.4 mm Hg and paralleled the increase of the blood volume. After 10% hydroxyethyl starch 200/0.5 an increase of serum amylase was observed. This hyperamylasemia is caused by the formation of a high molecular hydroxyethyl starch-amylase complex, which cannot be eliminated easily. Urinary volume and endogenous creatinine clearance were increased by administration of both colloids. After dextran 40 a pronounced increase of the urinary viscosity occurred.

Adult↗

PubMed1979

[Intravascular persistence, tissue storage and excretion of hydroxyethyl starch (HAS)].

Hydroxyethyl starch is a derivative of amylopectin, the branched glycogen-like alpha-1,4-glucose polymer, the amylase hydrolysis of which is retarded by hydroxyethylation. If 70 to 90 per cent of the glucose polymer units contain hydroxyethyl groups, the intravascular persistence and urinary excretion of hydroxyethyl starch of a molecular weight of 435,000 is similar to that of Dextran 70. Hydroxyethyl starch and Dextran 70 are stored briefly in reticuloendothelial and hepatic cells, and cause swelling and vacuolation of renal tubules with little alteration of renal function. Elimination of hydroxyethyl starch from sites of tissue storage is much faster than elimination of the non-metabolized polymers acacia and polyvinylpyrrolidone. The distribution and excretion kinetics of hydroxyethyl starch are thus appropriate for a plasma substitute.

Animals↗

PubMed1999

Effect of sugars on the thermal and rheological properties of sago starch.

Studies have been undertaken to investigate the effect of sugars on the thermal and rheological properties of sago starch. Sugars were found to increase the gelatinization temperature T(gel), and gelatinization enthalpy DeltaH. T(gel) and DeltaH increased in the following order: control (water alone) < ribose < fructose < glucose < maltose < sucrose. The increase in DeltaH was greater for 50% starch compared to 10% starch samples. The swelling factors in the presence of sugar were higher compared to the control for sugar concentrations below 25% but were lower at sugar concentration greater than 25%. These effects are discussed in terms of the antiplaticizing effect of the sugars compared to water, the influence of sugar-starch interactions and also the effect of the sugars on water structure. The storage modulus G', the rate constant of gelation k, and the gel strength were significantly reduced in the presence of sugars. Generally G' and k decreased in the following order: control (water alone) > hexose > disaccharide > pentoses. This has been attributed to the reduced proportion of amylose leached following gelatinizatison. In the presence of hexoses the freeze-thaw stability of starch gels decreased while in the presence of disaccharides and pentoses the freeze-thaw stability was slightly improved.

Carbohydrates↗

PubMed1999

Digestibility index and factors affecting rate of starch digestion in vitro in conventional food preparation.

The rate of starch hydrolysis in ten cereal-based food preparations was studied using an in vitro dialysis system. The foods were incubated with human saliva and porcine pancreatin. The sugars released after 3 h digestion were expressed as digestibility index (DI), the percentage starch digested was determined and correlated with the degree of gelatinization (DG). Granule morphology was also investigated and related with starch availability for hydrolysis. Significant differences were observed in the in vitro starch digestibility of the 10 foods (P < 0.05). The DI ranged from 53 for chapathi to 78 for rice flakes. DI was inversely related to the protein (r = -0.79, P < 0.01), fat (r = -0.63, P < 0.05) and energy (r = -0.61, P < 0.01). Percent starch digested was inversely related to the insoluble (r = -0.49, P < 0.05) and total dietary fiber (r = -0.63, P < 0.01) content of the foods. The SEM results provided a better understanding of granular morphology on cooking and the effect of protein on limiting DG. The results suggest that carbohydrate foods of potential use in the therapeutic diets may be identified by their in vitro digestion characteristics.

Animals↗

PubMed1998

Effect of different starches on Escherichia coli (S1) beta-glucuronidase expression.

Studies with pure cultures growing in laboratory media indicated that beta-glucuronidase expression of Escherichia coli S1 was considerably affected by starch added to the medium as the only carbon source. This result, which may be an aspecific modulation of enzyme expression, was independent of the starch molecular structure and effects were analogous for maize, rice, wheat or potato starches. It was observed that enzyme expression was little affected by the growth rate. The beta-glucuronidase activities of starch-grown bacteria found in the present study agree with those observed in animal and human models performed for in vivo evaluation of effects of dietary starch effects on gut microbial ecosystems.

Culture Media↗

PubMed2000

Determination of depolymerization kinetics of amylose, amylopectin, and soluble starch by Aspergillus oryzae alpha-amylase using a fluorimetric 2-p-toluidinylnaphthalene-6-sulfonate/flow-injection analysis system.

This study reports on the determination of the depolymerization kinetics of amylose, amylopectin, and soluble starch by Aspergillus oryzae alpha-amylase using flow-injection analysis with fluorescence detection and 2-p-toluidinylnaphthalene-6-sulfonate as the fluorescent probe. The experimental data points, corresponding to the evolution of the concentration of "detectable" substrate with depolymerization time, were fit to a single exponential decay curve in the case of amylose and to a double exponential decay curve in the cases of amylopectin and soluble starch. For all the assayed substrates, the determined depolymerization rates at time zero correlated well with the initial enzyme and substrate concentrations through the usual Michaelis-Menten hyperbola. Therefore, this methodology allows the determination of alpha-amylase activity using any of these substrates. For amylopectin and soluble starch, the value of the total depolymerization rate at any depolymerization time was the result of the additive contribution of two partial depolymerization rates. In contrast, the total depolymerization rate for amylose was always a single value. These results, in conjunction with the relative time evolution of the two partial depolymerization rates (for amylopectin and soluble starch), are in good agreement with a linear molecular structure for amylose, a "grape-like" cluster molecular structure for amylopectin, and an extensively degraded grape-like cluster structure for soluble starch.

Amylopectin↗

PubMed2000

Effects of xanthan and galactomannan on the freeze/thaw properties of starch gels.

Three starches (maize, rice and wheat), and the two non-starch polysaccharides xanthan and locust bean gum galactomannan (LBG) were examined in gel and dough systems for texture and stability properties during freezing and low temperature storage. Xanthan and LBG were found to confer increased resistance to freeze/thaw cycling on rice starch gels but the non-starch polysaccharides had little effect on the performance of maize and wheat starch gels or on wheat dough.

Bread↗

PubMed2002

Effect of annealing and heat moisture conditioning on the physicochemical characteristics of Bambarra groundnut (Voandzeia subterranea) starch.

Isolated starch of Bambarra groundnut (Voandzeia subterranean) was subjected to hydrothermal modifications through annealing and heat moisture conditioning. Both annealing and heat moisture conditioning reduced the swelling power and solubility of the starch. Water binding capacity reduced after annealing heat moisture conditioning at 18% moisture level (HMB18) and heat moisture conditioning at 21% moisture level (HMB21). Both heat moisture conditioning at 24% moisture level (HMB24) and heat moisture conditioning at 27% moisture level (HMB27) increased the water binding capacity. Hydrothermal modifications reduced the oil absorption capacity of the raw starch. Annealing and heat moisture conditioning reduced the peak viscosity (Pv), viscosity at 95 degrees C (Hv) and viscosity at 95 degrees C after 30 min holding (Hv30). However, viscosity increased on cooling down to 50 degrees C after annealing. Annealing and heat moisture treatments as revealed by scanning electron micrograph and light micrograph did not alter the shape and size of the raw starch. The results indicate a rearrangement within the starch granule following hydrothermal treatments.

Fabaceae↗

PubMed2002

Effect of sodium chloride on the gelatinization of starch: a multimeasurement study.

The effect of sodium chloride on the gelatinization and rheological properties of wheat and potato starches has been studied using differential scanning calorimetry, dynamic mechanical thermal analysis, and electron spin resonance techniques. All samples contained 60% water (w/w wet starch basis) and the salt content ranged from 0 to 16% (g/100 g starch-water). The presence of salt affected the onset (T(o)), peak (T(p)), and end (T(e)) temperatures of gelatinization, gelatinization enthalpy (DeltaH), storage modulus (G'), and rotational mobility coefficient (D(rot)), and the effect differed by salt concentration. 1H-NMR was used in parallel in order to elucidate how salts affect the properties of water in starch suspensions and in aqueous salt solutions according to their position on the Hofmeister series classification. The obtained results suggest that the mechanism of starch gelatinization in salt solutions can be attributed to the effect of solute on water properties and direct polymer-solute interactions. These two effects conflict with one another and result in complex effect patterns depending on the concentration of the salts.

Biopolymers↗

PubMed2002

Hydrolysis of wheat starch and its effect on the falling number procedure: mathematical model.

A population balance model was developed for wheat starch hydrolysis to simulate the performance parameters of a viscosity-based device, known as the Falling Number instrument. The instrument is widely used as an indirect means to gauge the level of preharvest sprout activity in cereal grains such as wheat and barley. The model consists of three competing kinetics: starch gelatinization, enzymatic hydrolysis, and enzyme thermal deactivation. Using established principles of starch rheology and fluid mechanics, the model simulates the velocity profiles of the falling stirrer, starch gel viscosity, and the Falling Number readings at various levels of alpha-amylase. Model predictions for the velocity of the stirrer at any time during the downward fall, as well as the prediction of the total time needed for the fall, defined as the Falling Number, were in fair agreement with experimental measurements. There was better agreement between the modeled viscosity and the final viscosity of the starch gel as measured by a precision rheometer than there was with the measured Falling Number.

Computer Simulation↗

PubMed2003

Starch fermentation by recombinant saccharomyces cerevisiae strains expressing the alpha-amylase and glucoamylase genes from lipomyces kononenkoae and saccharomycopsis fibuligera.

Lipomyces kononenkoae and Saccharomycopsis fibuligera possess highly efficient alpha-amylase and/or glucoamylase activities that enable both of these yeasts to utilize raw starch as a carbon source. Eight constructs containing the L. kononenkoae alpha-amylase genes (LKA1 and LKA2), and the S. fibuligera alpha-amylase (SFA1) and glucoamylase (SFG1) genes were prepared. The first set of constructs comprised four single gene cassettes each containing one of the individual amylase coding sequences (LKA1, LKA2, SFA1 or SFG1) under the control of the phosphoglycerate kinase gene (PGK1) promoter and terminator, while the second set comprised two single cassettes containing SFA1 and SFG1 linked to their respective native promoters and terminators. The third set of constructs consisted of two double-gene cassettes, one containing LKA1 plus LKA2 under the control of the PGK1 promoter and terminator, and the other SFA1 plus SFG1 controlled by their respective native promoters and terminators. These constructs were transformed into a laboratory strain Saccharomyces cerevisiae (Sigma1278b). Southern-blot analysis confirmed the stable integration of the different gene constructs into the S. cerevisiae genome and plate assays revealed amylolytic activity. The strain expressing LKA1 and LKA2 resulted in the highest levels of alpha-amylase activity in liquid media. This strain was also the most efficient at starch utilization in batch fermentations, utilizing 80% of the available starch and producing 0.61g/100 mL of ethanol after 6 days of fermentation. The strain expressing SFG1 under the control of the PGK1 expression cassette gave the highest levels of glucoamylase activity. It was shown that the co-expression of these heterologous alpha-amylase and glucoamylase genes enhance starch degradation additively in S. cerevisiae. This study has resulted in progress towards laying the foundation for the possible development of efficient starch-degrading S. cerevisiae strains that could eventually be used in consolidated bioprocessing, and in the brewing, whisky, and biofuel industries.

Coenzymes↗

PubMed1997

Italian buckwheat (Fagopyrum esculentum) starch: physico-chemical and functional characterization and in vitro digestibility.

A study on the physico-chemical properties and structure together with the evaluation of starch digestibility was carried out on starch isolated from buckwheat (Fagopyrum esculentum) cultivated in different Italian areas. Results showed that buckwheat samples analysed were different among them and from wheat starch used as reference. Buckwheat granules were polygonal in shape and had a smaller diameter than the wheat starch granule. The starch obtained from buckwheat had a higher swelling power than the wheat one, probably as a consequence of the wheaker but more extensive bonding forces in the granule. During cooling, buckwheat samples showed a good paste stability.

Amylases↗

PubMed2003

Gelatinization and pasting properties of rice starch modified with 2-octen-1-ylsuccinic anhydride.

Rice starch was modified with various levels of 2-octen-1-ylsuccinic anhydride (OSA). Treatments with OSA at 3, 5, and 10% resulted in starch derivatives with 0.016, 0.033, and 0.070 degrees of substitution (DS), respectively. Thermovisco properties of the derivatives were investigated by differential scanning calorimetry (DSC) and rapid visco analysis (RVA). Water content in the sample was found to have a significant effect on the characteristics of the DSC endotherm. Pasting properties of the OSA-starch and the effect of pH and salt on the RVA profiles were also studied. In general, with increased OSA-modification, the starch derivatives swelled and gelatinized at lower temperatures to achieve higher viscosities. Specifically, based on DSC analysis at 80% water, the peak temperature of gelatinization decreased from 68.5 to 63.2 degrees C as the OSA modification increased in DS from 0 (intact starch) to 0.070. On the other hand, RVA results indicate that, for samples undergoing similar increase in OSA modification, the pasting temperature decreased from 88.7 to 51.5 degrees C and the peak viscosity increased from 668 to 6822 cP.

Calorimetry, Differential Scanning↗

PubMed2003

Phosphorylation of starch and dextrin by dry-heating in the presence of phosphate, and their calcium phosphate-solubilizing ability.

Starch and dextrin were phosphorylated by dry-heating in the presence of phosphate, and their properties were examined. The phosphorylation of starch was accelerated with decreasing moisture, rising incubation temperature and prolongation of the incubation period. However, a rise in incubation temperature, and lengthened incubation period caused increased browning and degradation. A decrease in the pH from 5.5 to 3.0 resulted in a modest increase of phosphorylation, but also marked browning and degradation. When potato starch was phosphorylated at 140 degrees C and pH 5.5 for 24 h, its phosphorus content was increased up to 3.47%, with fewer side reactions. Phosphorlylated starch and dextrin had calcium phosphate-solubilizing abitity. Phosphorylated dextrin with 2.42% phosphorus had about half the calcium phosphate-solubilizing ability of casein phosphopeptide (CPP). The possibility of substituting of phosphorylated starch and dextrin for CPP as a calcium phosphate-absorption enhancing material is discussed herein.

Calcium Phosphates↗

PubMed2005

A randomized unblinded pilot study comparing albumin versus hydroxyethyl starch in spontaneous bacterial peritonitis.

The administration of albumin improves circulatory function, prevents hepatorenal syndrome, and reduces hospital mortality in patients with cirrhosis and spontaneous bacterial peritonitis. This randomized unblinded pilot study compared the effect of albumin (10 patients) and the synthetic plasma expander hydroxyethyl starch 200/0.5 (10 patients) on the systemic hemodynamics of patients with spontaneous bacterial peritonitis. Baseline measurements were performed within 12 hours after diagnosis of infection. Patients then received 2 doses of the volume expander (1.5 g/kg body weight after baseline measurements and 1 g/kg body weight on day 3). Measurements were repeated after infection resolution. Treatment with albumin was associated with a significant increase in arterial pressure and a suppression of plasma renin activity, indicating an improvement in circulatory function. This occurred in the setting of a significant expansion of central blood volume (increase in cardiopulmonary pressures and atrial natriuretic factor) and an increase in systolic volume and systemic vascular resistance. In contrast, no significant changes were observed in these parameters in patients treated with hydroxyethyl starch. Von Willebrand-related antigen plasma levels significantly decreased in patients treated with albumin but not in those treated with hydroxyethyl starch. Serum nitrates and nitrites increased in patients treated with hydroxyethyl starch but not in those treated with albumin. These data suggest an effect of albumin on endothelial function. In conclusion, albumin but not hydroxyethyl starch improves systemic hemodynamics in patients with spontaneous bacterial peritonitis. This effect is due not only to volume expansion but also to an action on the peripheral arterial circulation.

Anti-Bacterial Agents↗

PubMed1979

Grafting of proteins onto polymer surfaces with the use of oxidized starch.

A study has been carried out on the coupling of proteins onto crosslinked poly(vinyl alcohol) hydrogel membranes and ethylene-vinyl alcohol copolymer(EVA) films previously grafted with oxidized starches having many pendant aldehyde groups. The coupling reaction of proteins is based on the Schiff's base formation between the amino groups of proteins and the aldehyde groups of the oxidized starches which have been grafted onto the substrate membrane or film through acetalization of the aldehyde of starch with hydroxyl groups of the substrate polymers. The grafting of oxidized starches onto the EVA films seems to be restricted to the film surface, since no detectable change is observed in the weight and the attenuated total reflection infrared spectrum of the grafted films. The amount of grafted protein, determined by the ninhydrin method, reveals that, at least, plasma proteins such as serum albumin and fibrinogen are grafted to the film surface in a monomolecular layer without undergoing a marked denaturation. The alpha-amylase grafted onto the EVA film showed a distinct enzymatic activity in hydrolysis of amylose and starch, but the activity was very low compared with that of the ungrafted, soluble alpha-amylase.

Adsorption↗

PubMed1984

Characterization of polyacryl starch microparticles as carriers for proteins and drugs.

Biodegradable microparticles of cross-linked starch (maltodextrin) have been designed as carriers of proteins and low molecular weight drugs in vivo. Methods are presented for the synthesis of acryloyl starch and its polymerization to microparticles. Macromolecules were immobilized in the microparticles in high yields, i.e., up to 40% of the dry weight consisted of the immobilized protein. The optimal conditions of immobilization were investigated by varying the concentration of starch (D), the concentration of acryloyl groups (T), and the amount of additional cross-linking agent (C). Exclusion of the cross-linking agent gave maximal immobilization of the macromolecules. Enzyme kinetics, release profiles, surface localization, and heat stability of the immobilized macromolecules are also presented. Micro-particles based on starch with small amounts of acryloyl groups were completely degraded after incubation with amyloglucosidase. The degradation of microparticles in serum and in the target organelle, the lysosome, was investigated in vitro. The polyacrylic starch microspheres (mean diameter, 0.5 micron) constitute an attractive alternative to other drug and enzyme carriers.

Biotransformation↗