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At least 1,351 records · Page 75Linked to original sources
PubMed1993

[The effect of starch sources barley, corn and potatoes and their ration proportions on nutrient digestibility and energy utilization in ruminants. 2. Fractions of ruminally and postruminally digested nutrients in cattle].

The investigations of this paper are part of a complex research project to develop energetic feed evaluation within the Net Energy Fat System. The aim was to obtain new results to estimate the relation between place as well as kind of nutrient digestion and energetic utilization of rations in cattle. The ruminal nutrient digestibility was measured in adult oxen on feeding level 1.7 by means of duodenal reentrant cannula for 9 rations including the starch sources barley, maize and potatoes and with their energy parts of 50, 25 and 10%. The intake of starch ranged from 484 to 2573 g/animal.d and the amounts of ruminal and postruminal digested starch from 444 to 2336 as well as 10 to 284 g/animal.d. For the organic matter, starch, water soluble carbohydrates and N free residual substances high relative parts of ruminal digested from apparent digested nutrients were measured with values between 78 and 88, 83 and 98, 93 and 97 as well as 88 and 100% respectively.

Animal Feed↗
PubMed1993

[The effect of starch sources barley, maize and potatoes and their ration portions on the nutrient digestibility and energy utilization in ruminants. 4. Nitrogen metabolism in the rumen].

In 9 experimental periods on four adult bulls (LW 550 kg) fitted with re-entrant cannulae in the proximal duodenum isoenergetic rations were used on feeding level 1.7 with ground barley, ground maize or fresh potatoes as starch sources. The net energy parts of these concentrates in the ration amounted to 50, 25 and 10%. 50 to 80% of the ration DM consisted of dried grass and about 10% of sugar beet pulp. The dried grass supplied on an average 87, 79 and 62% of the feed crude protein. The intake of DM was 7.74 +/- 0.42 (mean +/- SD) kg/d. The energetic efficiency of microbial N synthesis in the rumen (g N/kg organic matter true fermented in the rumen, TFOM) was averaged 16.4 with a range of 10.6 to 21.4. The microbial efficiency achieved a maximum when the ratio of nitrogen-free extract to crude fibre in the diet was 1.7 and 2.1 with barley, 1.8 with potatoes and 2.1 and 3.3 with corn as starch source. Changes in the microbial efficiency were positively correlated with the rate of passage of non-microbial organic matter from the rumen (g/d) and with the duodenal flow rate (kg digesta/kg DM intake). The relation to the rate of carbohydrate fermentation in the rumen (in %) and to the amount of TFOM (g/d) was negative. The duodenal flow of microbial N and non-ammonia N (g/d) correlated negatively with the organic matter apparently fermented in the rumen (AFOM) and positively with the non AFOM. The amino acid (AA) profile of the duodenal protein was affected by the starch source. It was concluded that the metabolism of nitrogen in the forestomachs of cattle is affected by the source of starch and the ratio of forage to concentrate. There exists a relationship between both factors. The net synthesis of microbial protein in the rumen is not only the result of substrate fermentation. The passage of non-AFOM from the rumen significantly affects the energetic efficiency of microbial nitrogen synthesis and the duodenal supply of AA.

Amino Acids↗
PubMed2001

Study on tablet binding and disintegrating properties of alternative starches prepared from taro and sweet potato tubers.

To demonstrate the potential alternative sources of starch used in tablet formulations, starches from taro (TS) and sweet potato (SPS) tubers were prepared with obtained yields of 11.0 and 9.6%, respectively. Both TS and SPS met USP22-NF17 identification and specifications. Their equilibrium moisture contents and gelatinization temperatures were comparable with those of commercial starch, whereas amylose contents of TS and SPS were 21.38% w/w and 41.76% w/w, respectively. Both were found to possess similar flow characteristics. To evaluate TS and SPS as granulating agents and disintegrants, tablets with controlled compression loads were prepared by incorporating a starch candidate with dibasic calcium phosphate in paste and powders forms, respectively. Tablets were then evaluated based on compressibility, friability, and disintegration. It was found that the binding and disintegrating performance of both TS and SPS was similar to that of commercial cornstarch.

Chemistry, Pharmaceutical↗
PubMed2002

Acetylation enhances the tabletting properties of starch.

The aim of this study was the evaluation of starch acetate (SA) powders used as tablet excipients. Deformation during powder volume reduction, strain-rate sensitivity, intrinsic elasticity of the materials, and tensile strength of the tablets were examined. Results showed that SA with the lowest degree of substitution (ds) still possessed characteristics of native starch granules. Due to dissolution in synthesis, the properties of higher ds SAs depended on precipitation and drying processes. The acetate moiety, perhaps in combination with existing hydroxyl groups, was a very effective bond-forming substituent. The formation of strong molecular bonds increased, leading to a very firm and intact tablet structure. Small changes existed in compression-induced deformation due to acetylation. Some fragmentation was induced due to the slightly harder and more irregular shape of high-substituted SA particles. The plastic flow under compression was enhanced. Acetylated material was slightly less sensitive to fast elastic recovery in-die, but somewhat more elastic out-of-die. In spite of their superior bonding, SAs under compression behaved similarly to native starches. It was concluded that deformation properties were more the consequence of the molecular chain structure properties of the starch polymer than the effect of the acetate moiety itself. In contrast, the opposite seemed to be the case with the extensive improvement in bond-forming properties.

Acetylation↗
PubMed1962

The influence of environment on the shell structure of starch granules.

It is well known from light microscope studies of potato starch that the granules formed in a constant environment (of light and temperature) have a ring formation indistinguishable from that of granules formed under field conditions. Electron microscope studies have confirmed that normal potato starch granules have a fine shell structure not usually resolved by the light microscope, and also that shells do not develop in barley granules grown in a constant environment. The paper presented here reports a further study of the dependence of shell formation on environment. Potatoes were grown in a constant environment and starch granules from the newly formed tubers were examined in the light microscope, and in the electron microscope after corrosion by acid. No difference between these granules and normal granules was observed; both wide (light microscope) rings and fine lamellae developed in both granules. Parallel studies were made on wheat starch granules. In this case, shells were not differentiated in granules that developed in a constant environment, but they could be produced at will by imposing a dark period. Thus, shell formation in potato granules must be controlled by an endogenous rhythm, whereas in wheat granules it must be controlled by external environment.

Electrons↗
PubMed1979

Insulin and glucose responses in rats fed sucrose or starch.

Rats fed 54% sucrose for 11 to 13 weeks ad libitum or 5 weeks ad libitum followed by 6 to 8 weeks of meal feeding had significantly higher serum insulin, glucose, and triglyceride levels than rats fed comparable amounts of starch after 12 to 14 hr without food. The serum insulin response measured before, 1/2, and 4 hr after a meal showed insulin levels of sucrose-fed rats to be higher than comparable levels of rats fed starch at all three times. An intraperitoneal glucose tolerance test measuring serum glucose before, 1/2, 2, and 2 hr after a glucose injection revealed glucose levels of rats fed sucrose to be higher than levels of rats fed starch. When insulin was added to the injection medium, serum glucose of rats fed sucrose remained higher than comparable levels of rats fed starch indicating insulin insensitivity. Meal feeding generally resulted in higher insulin and triglyceride levels than in rats fed ad libitum but had little effect on glucose levels. These results are clear evidence that sucrose feeding has undesirable effects on glucose tolerance.

Adipose Tissue↗
PubMed1983

The rate of starch hydrolysis in vitro does not predict the metabolic responses to legumes in vivo.

The aim of this study was to determine whether legumes in a physical form which is rapidly digested in vitro give rise to proportionately greater metabolic responses in vivo than legumes which are slowly digested in vitro. Samples of cooked whole and ground lentils were incubated in vitro with pancreatic amylase for 30 min and the percentage starch hydrolysis determined. Grinding the lentils before cooking resulted in a 5-fold increase in the rate of starch hydrolysis (whole lentils 12.1%, ground lentils 60.9%). For the in vivo studies six healthy, young, lean subjects consumed two test meals containing 50 g starch: whole lentils and lentils that had been ground finely before cooking. Postprandial glucose and insulin responses were measured over 4 h. Peak glucose and insulin responses occurred 60 min postprandially for the whole lentils and 30 min postprandially for ground lentils. Although the increase in plasma glucose after ground lentils (1.6 mM) was significantly higher (p less than 0.025) than that after whole lentils (0.9 mM), there was no difference in the magnitude of the insulin responses. These results indicate that, unlike for cereals, the rate of intestinal starch hydrolysis is not the major factor determining the metabolic responses to legumes. By virtue of their low postprandial glucose and insulin responses, irrespective of their physical form and digestibility, legumes would appear to be ideal for inclusion in the diet of diabetics.

Adult↗
PubMed1985

Indices of copper status in humans consuming a typical American diet containing either fructose or starch.

Twenty-four male subjects originally participated in a study to determine the effects of feeding diets comparatively low in copper (1.03 mg/day/2850 kcal) and containing either 20% fructose or starch on indices of copper status. During the course of feeding the diets for 11 wk, four of the subjects exhibited heart-related abnormalities and were removed from the study. Fructose ingestion had no effect on serum ceruloplasmin activity or serum copper concentration but did significantly reduce cuprozinc superoxide dismutase (SOD) activity of erythrocytes as compared to starch. Repletion of the subjects with 3 mg copper/day for 3 wk significantly increased SOD levels in subjects previously fed fructose but not starch. Apparent copper balance was significantly greater when the subjects consumed the fructose as compared to the starch diet. These results suggest that the type of dietary carbohydrate fed can differentially affect indices of copper status in humans.

Adult↗
PubMed1991

Rice varieties with similar amylose content differ in starch digestibility and glycemic response in humans.

Three high-amylose rice varieties, IR42, IR36, and IR62, with similar chemical composition including amylose content (26.7-27.0%), were cooked under the same conditions and tested for in vitro digestibility as well as blood glucose and insulin responses in healthy human volunteers. The starch-digestion rate and the glycemic and insulin responses were the highest in IR42, followed by IR36 and, then IR62. The differences were not due to unabsorbed carbohydrate but were related to their physicochemical properties, such as gelatinization temperature, minimum cooking time, amylograph consistency, and volume expansion upon cooking. When the three varieties were cooked for their minimum cooking time, they had the same degree of gelatinization and their starch-digestion rates and glycemic responses were similar. We conclude that amylose content alone is not a good predictor of starch-digestion rate or glycemic response. Rice varieties with similar high-amylose contents can differ in physicochemical (gelatinization) properties and this, in turn, can influence starch digestibility and blood glucose response.

Adult↗
PubMed1993

Validation of an in vitro assay for predicting the amount of starch that escapes digestion in the small intestine of humans.

The aim of the present study was to validate an in vitro assay for quantifying resistant starch (RS) in foods against an in vivo model. The amount of starch escaping digestion in the small intestine of ileostomates was compared with that observed by using the in vitro assay. Subjects with ileostomies were fed five foods containing different types and amounts of RS (baked beans, pearl barley, cornflakes, and whole and ground rice). The total amount of starch escaping digestion and recovered in the effluent (ranging from 5.7% in baked beans to 0.7% in ground rice) was compared with results obtained by using the in vitro assay with an incubation time of 6 h. The assay was found to be a good qualitative predictor (r = 0.90, P < 0.05), but a poor quantitative predictor of RS amounts. Increasing the duration of incubation with alpha-amylase and amyloglucosidase to 15 h resulted in a very close agreement between results from the in vitro technique and the in vivo model. These data indicate that for a variety of foods the in vitro assay produced an excellent estimate of starch escaping digestion in the small intestine of humans.

Adult↗
PubMed1994

Resistant starch: the effect on postprandial glycemia, hormonal response, and satiety.

The effect of resistant starch (RS) on postprandial plasma concentrations of glucose, lipids, and hormones, and on subjective satiety and palatability ratings was investigated in 10 healthy, normal-weight, young males. The test meals consisted of 50 g pregelatinized starch (0% RS) (S) or 50 g raw potato starch (54% RS) (R) together with 500 g artificially sweetened syrup. After the R meal postprandial plasma concentrations of glucose, lactate, insulin, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1, and epinephrine were significantly lower compared with after the S meal. Moreover, subjective scores for satiety and fullness were significantly lower after the R meal than after the S meal. Differences in GIP, texture, and palatability may have been involved in these findings. In conclusion, the replacement of digestible starch with RS resulted in significant reductions in postprandial glycemia and insulinemia, and in the subjective sensations of satiety.

Adult↗
PubMed1999

Euglycemic hyperinsulinemic clamp to assess posthepatic glucose appearance after carbohydrate loading. 2. Evaluation of corn and mung bean starches in healthy men.

BACKGROUND: The rate of absorption of glucose from carbohydrates is important in several aspects of health. We recently validated a noninvasive technique in pigs, euglycemic hyperinsulinemic clamp plus oral carbohydrate loading (OC-Clamp), to quantify the rate of net posthepatic appearance of glucose after ingestion of carbohydrates. OBJECTIVE: The OC-Clamp procedure was performed in 8 healthy men to compare the net posthepatic appearance of glucose after ingestion of 1 of 3 carbohydrates. DESIGN: Human volunteers underwent the OC-Clamp procedure at an insulin infusion rate of 1.5 mU x kg(-1) x min(-1) (n = 5). The oral carbohydrate load (1 g/kg) consisted of glucose, cornstarch, or mung bean starch. During the OC-Clamp procedure, the glucose infusion rate decreased during absorption to maintain plasma glucose steady state and the decrease reflected the net posthepatic appearance of glucose. In addition, carbohydrates were loaded without insulin infusion (n = 6) and glycemic indexes were calculated (with glucose as the reference). RESULTS: The mean (+/-SEM) glycemic index of cornstarch was higher (95 +/- 18) than that of mung bean starch (51 +/- 13). In the OC-Clamp experiments, the posthepatic appearance of glucose and cornstarch did not differ significantly and represented 79.4 +/- 5.0% and 72.6 +/- 4.0%, respectively, of the load after complete absorption (within 3 h). In contrast, the net posthepatic appearance of glucose from mung bean starch was significantly lower (35.6 +/- 4.6% of the load, P < 0.001) than that from glucose and cornstarch, even 4.5 h postprandially. CONCLUSIONS: The OC-Clamp technique allows a continuous assessment of net posthepatic appearance of glucose after ingestion of carbohydrates and significant discrimination between corn and mung bean starches.

Analysis of Variance↗
PubMed1988

Contamination of perfused donor kidneys by starch from surgical gloves.

Starch induces a variety of inflammatory reactions in humans and may contaminate surgical procedures from surgical gloves. Using polarized microscopy and electron microscopy, the authors observed starch particles in renal perfusate and in glomeruli of perfused donor kidneys. Group 1 consisted of 10 unusable kidneys handled with standard concern of glove sterility. Eight other kidneys (Group 2) were perfused with particular attention toward avoidance of starch contamination. The gloves were rinsed five times, and the cuffs were not dipped into the perfusate. Two kidneys (Group 3), deemed unsuitable for transplantation, were perfused for 24 hours with perfusate swished with unwashed sterile gloves. Group 4 consisted of five transplant biopsies performed within one week after transplantation. Perfusates alone were also circulated through the Waters Perfusion Machine continuously for 24, 72, and 188 hours with and without the use of gloves. The number of birefringent crosses were counted in each of 25 glomeruli per specimen. Group 1 displayed a mean of 1.8 birefringent crosses per glomerulus; Group 2, 0; Group 3, 5.3; and Group 4, 4.4. Groups 1 and 3 also exhibited birefringent crosses in peripheral renal vessels. Perfusate alone, handled without gloves, showed no birefringent crosses; by contrast, perfusate handled with gloves showed numerous birefringent crosses. The authors conclude that starch from surgical gloves can enter the perfusate and lodge in glomeruli and other sites of donor kidneys. Rinsing gloves five times and avoiding contact of the perfusate with the glove cuff effectively eliminates the contamination.

Birefringence↗
PubMed2005

Phenology of flowering and starch accumulation in grape (Vitis vinifera L.) cuttings and vines.

BACKGROUND AND AIMS: A reliable protocol for flowering and fruiting in cuttings was developed with the aim of (a) studying inflorescence and flower development in grapevine cuttings and field plants, and (b) assisting haploid plant production. METHODS: Inflorescence and flower development was studied in 'Gewurztraminer' (GW) and 'Pinot Noir' (PN) grape vines and cuttings grown in a glasshouse, along with variations in starch in the flowers. As there is a strong relationship between flower development and starch, the starch content of reproductive structures was estimated. KEY RESULTS: Inflorescence and flower development were similar in the vines and cuttings with consistent differences between the two cultivars. Indeed, the ontogenesis of male and female organs is not synchronous in GW and PN, with both female and male meiosis occurring earlier in PN than in GW. Moreover, changes of starch reserves were similar in the two plant types. CONCLUSIONS: Cuttings have a similar reproductive physiology to vines, and can be used to study grape physiology and to develop haploid plants.

Botany↗
PubMed2002

A motif of a microbial starch-binding domain found in human genethonin.

The sequence of the starch-binding domain present in 10% of amylolytic enzymes of microbial origin and classified as the carbohydrate-binding module family 20, was identified in the equivalent part of sequence of human genethonin, a skeletal muscle protein of unknown function. The sequence identity between the starch-binding domain from Bacillus sp. strain 1011 cyclodextrin glucanotransferase and the corresponding segment of human genethonin was higher than 28%. The amino acid residues known to be involved in the raw starch binding were found to be conserved in the genethonin sequence. The three-dimensional structure of the genethonin 'starch-binding domain' was modelled and its eventual function briefly discussed.

Amino Acid Motifs↗
PubMed2006

Hydroxyethyl starch is superior to lactated Ringer as a replacement fluid in a pig model of acute normovolaemic haemodilution.

BACKGROUND: Tissue tolerance to oxygen privation during acute normovolaemic haemodilution with different fluids remains unclear. We tested the hypothesis that hydroxyethyl starch (HES) is superior to lactated Ringer's solution in pigs for preserving tissue perfusion during acute normovolaemic haemodilution. METHODS: Twenty-four animals were randomized into control, lactated Ringer's solution and HES groups. All groups, except the control, underwent acute normovolaemic haemodilution. Haemodynamics, oxygen parameter indices, global anaerobic metabolic markers, echocardiographic parameters, gastric tonometry and serum osmolarity were monitored at baseline, immediately after (0 min) and 60 and 120 min after the end of haemodilution. Myocardial, liver, stomach and intestine samples were collected for further evaluation. RESULTS: Cardiac and oxygen parameter index responses to acute normovolaemic haemodilution were comparable. However, the increment in cardiac index, stroke volume index, and left ventricular stroke work index were more sustained in the starch group. In the lactated Ringer's group, gastric pH decreased significantly and was accompanied by a significant increase in lactate. Myocardial ultrastructure was better preserved in the starch group. The other tissue samples presented no change. CONCLUSIONS: In this model of ANH, the starch group had a superior haemodynamic response. Minor loss of myocardial cellular integrity and preserved gastric pHi reinforce these findings.

Animals↗
PubMed2006

Dietary resistant starch type 3 prevents tumor induction by 1,2-dimethylhydrazine and alters proliferation, apoptosis and dedifferentiation in rat colon.

Some epidemiological and experimental studies suggest that consumption of resistant starch is preventive against colon cancer. Resistant starch leads to a fermentation-mediated increase in the formation of short-chain fatty acids, with a particularly high butyrate fraction in large bowel. Butyrate is considered to be protective against colon cancer because it causes growth arrest and apoptosis and regulates expression of proteins involved in cellular dedifferentiation in various tumor cell lines in culture. We sought to investigate these processes under conditions of a carcinogenicity experiment in vivo. In the present study, 1,2-dimethylhydrazine-treated Sprague-Dawley rats were fed standard diet (n=12) or diet with 10% hydrothermally modified Novelose 330, a resistant starch type 3 (RS3), replacing digestible starch (n=8). After 20 weeks tumor number, epithelial proliferation, apoptosis, immunoreactivity of carcinogenesis-related proteins [protein kinase C-delta (PKC-delta), heat shock protein 25 (HSP25) and gastrointestinal glutathione peroxidase (GI-GPx)], as well as mucin properties were evaluated in proximal and distal colon in situ. No tumors developed under RS3 diet, compared to a tumor incidence of 0.6+/-0.6 (P<0.05) under the standard diet. RS3 decreased the number of proliferating cells, the length of the proliferation zone and the total length of the crypt in the distal colon, but not proximal colon, and enhanced apoptosis in both colonic segments. It induced PKC-delta and HSP25 expression, but inhibited GI-GPx expression in the epithelium of distal colon. RS3 increased the number of predominantly acidic mucin containing goblet cells in the distal colon, but had no effect on the goblet cell count. We conclude that hydrothermally treated RS3 prevented colon carcinogenesis, and that this effect was mediated by enhanced apoptosis of damaged cells accompanied by changes in parameters of dedifferentiation in colonic mucosa.

1,2-Dimethylhydrazine↗
PubMed2004

Two additional carbohydrate-binding sites of beta-amylase from Bacillus cereus var. mycoides are involved in hydrolysis and raw starch-binding.

In the previous X-ray crystallographic study, it was found that beta-amylase from Bacillus cereus var. mycoides has three carbohydrate-binding sites aside from the active site: two (Site2 and Site3) in domain B and one (Site1) in domain C. To investigate the roles of these sites in the catalytic reaction and raw starch-binding, Site1 and Site2 were mutated. From analyses of the raw starch-binding of wild-type and mutant enzymes, it was found that Site1 contributes to the binding affinity to raw-starch more than Site2, and that the binding capacity is maintained when either Site1 or Site2 exists. The raw starch-digesting ability of this enzyme was poor. From inhibition studies by maltitol, GGX and alpha-CD for hydrolyses of maltopentaose (G5) and amylose ( (n) = 16) catalyzed by wild-type and mutant enzymes, it was found that alpha-CD is a competitive inhibitor, while, maltitol behaves as a mixed-type or competitive inhibitor depending on the chain length of the substrate and the mutant enzyme. From the analysis of the inhibition mechanism, we conclude that the bindings of maltitol and GGX to Site2 in domain B form an abortive ESI complex when amylose ( (n) = 16) is used as a substrate.

Bacillus cereus↗