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PubMed1984

Adsorption of tumorigenic Agrobacterium tumefaciens cells to susceptible potato tuber tissues.

Cells of tumorigenic Agrobacterium tumefaciens strain B6 were labeled with [35S]methionine and used to estimate bacterial adsorption to potato tuber discs. After 10 min at pH 7.2, about 5 X 10(5) bacteria adsorb to each 9.0-mm disc. Lengthening the incubation period to 90 min increases adsorption to about 11 X 10(5) bacteria per disc. Bacterial adsorption is reduced under both alkaline and acid pH conditions and increases 2.3-fold if the number of bacterial cells in the inoculum is doubled. Adsorption is increased if citrus pectin, polygalacturonic acid, or demethylated pectin is included in the inoculum; methylated polygalacturonic acid is inactive. The activity of citrus pectin is abolished, however, if the compound is applied to the discs as a pretreatment and then removed prior to inoculation. Lipopolysaccharide preparations from five of six A. tumefaciens strains have no effect on bacterial adsorption. The sixth preparation, from nontumorigenic strain NT-1, reduces adsorption by about 20%.

Adsorption↗
PubMed1983

Influence of dietary fiber on exocrine pancreatic function in the rat.

Dietary fiber inhibits pancreatic enzyme activity--i.e., trypsin, lipase and amylase--in buffer solutions and in human duodenal juice in vitro. It is well established that oral administration of trypsin inhibitor stimulates the secretion and growth of the rat pancreas. In the present study, trypsin inhibitor (Trasylol) as well as dietary fiber such as pectin of low (37%) methoxylic esterification and wheat bran were found to stimulate pancreatic enzyme secretion in acute experiments in conscious rats with bile-pancreatic fistulae. Feeding for 10 days with wheat bran resulted in increased pancreatic weight and in increased protein and trypsinogen content. Administration of pectin of high (73%) methylic esterification caused increased pancreatic protein content and that of low methylic esterification increased pancreatic trypsinogen activity/milligram tissue. The results suggest that pectin and wheat bran may interfere with the feedback regulation of pancreatic enzyme secretion exerted by intraluminal trypsin, and, like trypsin inhibitor, have a secretagogue and trophic effect on the pancreas.

Amylases↗
PubMedDate not supplied

Dietary fiber and lipoprotein metabolism in the genetically obese Zucker rat.

The present investigation was designed to examine the influence of dietary fibers with differing soluble fiber compositions upon the metabolism of lipids in a hyperlipemic animal model, the Zucker fatty rat. The response to fiber was examined using a diet supplemented with cellulose, oat bran, or pectin which have a soluble/insoluble fiber ratio of 0:100, 33:66, and 100:0, respectively. These fibers provided 10% of the total diet weight; the control diet contained no fiber. A rapid increase in plasma triglyceride concentration was observed in all animals given fiber-supplemented diets in correlation with the increased carbohydrate content of the defined diets relative to the prestudy diets. This increase in plasma triglyceride was due to increased production of triglycerides with no change in the rates of clearance. The plasma total cholesterol levels were relatively constant on all diets. However, after 7 weeks on the pectin-supplemented diet, rats showed a 39% elevation in HDL and a 44% reduction in LDL concentration. This diet also resulted in reduced weight gain, in spite of a caloric intake equivalent to the control diets. Our data suggest that the ability of dietary fiber to alter plasma lipoproteins might be predictable from the soluble fiber composition or the pectin content of a given dietary fiber in this model of genetic endogenous hyperlipemia.

Animals↗
PubMedDate not supplied

Physiological and anti-inflammatory roles of dietary fiber and butyrate in intestinal functions.

BACKGROUND: We investigated the effects of pectin, a soluble dietary fiber, on the morphological parameters of the small intestine. In addition, we tested the effects of butyrate enemas on dextran sulfate sodium (DSS)-induced experimental colitis. METHODS: Male Wistar rats were fed an elemental diet containing 2.5% pectin for 14 days, and several parameters were then determined. DSS-induced colitis was evoked by the oral administration of water containing 3% DSS for 10 days. The butyrate enema (3 mL of 100 mmol/L butyrate per day) was begun 7 days before the DSS treatment. Interleukin (IL)-8 secretion in the human intestinal epithelial cell line HT-29 was determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Pectin feeding induced a significant increase in the villus height and crypt depth in the small intestine. These effects correlated with a significant increase in plasma enteroglucagon levels. Pretreatment with a butyrate enema significantly blocked the development of DSS-induced experimental colitis. In the in vitro experiment, sodium butyrate dose-dependently inhibited tumor necrosis factor (TNF)-alpha-induced IL-8 secretion in HT-29 cells. CONCLUSIONS: A trophic effect due to dietary fiber was directly observed. The generation of short-chain fatty acids and the induction of enteroglucagon release might play an important role in this process. Butyrate, one of the major metabolites of dietary fiber, exerted a potent anti-inflammatory effect both in vivo and in vitro. Dietary fiber may therefore play important roles in the regulation of normal and pathological conditions in the intestine.

Adenocarcinoma↗
PubMed2004

Functional analysis of CLPT1, a Rab/GTPase required for protein secretion and pathogenesis in the plant fungal pathogen Colletotrichum lindemuthianum.

In eukaryotic cells, Rab/GTPases are major regulators of vesicular trafficking and are involved in essential processes including exocytosis, endocytosis and cellular differentiation. To investigate the role of these proteins in fungal pathogenicity, a dominant-negative mutant allele of CLPT1, a Rab/GTPase of the bean pathogen Colletotrichum lindemuthianum, was expressed in transgenic strains. This mutated gene encodes the amino-acid substitution N123I analogous to the N133I substitution in a known trans-dominant inhibitor of the Sec4 Rab/GTPase from Saccharomyces cerevisiae. A pectinase gene promoter was used to drive the CLPT1(N123I) allele in C. lindemuthianum, allowing the expression of the foreign gene on pectin medium and during pathogenesis, but not on glucose. The same strategy was used to overexpress the wild-type CLPT1 allele. During growth on pectin medium, production of extracellular pectinases was strongly impaired only in CLPT1(N123I)-expressing strains. Cytological analysis revealed that CLPT1(N123I) strains accumulated intracellular aggregates only on pectin, resulting from the fusion of vesicles containing polysaccharides or glycoproteins. Moreover, these strains showed a severe reduction of pathogenesis and were unable to penetrate the host cells. These results indicated that the Rab/GTPase CLPT1 is essential for fungal pathogenesis by regulating the intracellular transport of secretory vesicles involved in the delivery of proteins to the extracellular medium and differentiation of infectious structures.

Alleles↗
PubMed2003

Effects of adding some dietary fibers to a cystine diet on the activities of liver antioxidant enzymes and serum enzymes in rats.

This study investigates whether some dietary fibers can the toxicity due to cystine added to the diet. Wistar rats were investigated for the effects of adding pectin, sugar beet fiber or konjac mannan to a cystine diet on the growth rate and on the activities of liver antioxidant enzymes and serum enzymes. The addition of pectin, sugar beet fiber or konjac mannan to the cystine diet resulted in a significant increase in both the food intake and body weight gain. Feeding the cystine diet caused lower activities of total and Cu,Zn-superoxide dismutase, and of catalase in the liver. The addition of pectin to the cystine diet counteracted the activities of the total and Cu,Zn-superoxide dismutase, and of catalase in liver. Of the dietary fibers tested, konjac mannan prevented the elevation of the two enzyme activities in the serum induced by feeding the cystine diet, indicating that this fiber might have the ability to alleviate hepatic damage due to dietary cystine.

Alanine Transaminase↗
PubMed1997

Viscosity of gums in vitro and their ability to reduce postprandial hyperglycemia in normal subjects.

Experiments were carried out in vitro with three viscous polysaccharides (guar gum, pectin, and carboxymethylcellulose (CMC) of similar initial viscosity submitted to conditions that mimic events occurring in the stomach and duodenum, and their viscosity in these situations was compared to their actions on postprandial hyperglycemia in normal human subjects. Guar gum showed greater viscosity than the other gums during acidification and/or alkalinization and also showed larger effects on plasma glucose levels (35% reduction in maximum rise in plasma glucose) and on the total area under the curve of plasma glucose (control: 20,314 +/- 1007 mg dl-1 180 min-1 vs guar gum: 18,277 +/- 699 mg dl-1 180 min-1, P < 0.01). Pectin, which showed a marked reduction in viscosity at 37 degrees C and after events mimicking those that occur in the stomach and duodenum, did not have a significant effect on postprandial hyperglycemia. The performance of viscosity and the glycemia response to CMC were at an intermediate level between guar gum and pectin. In conclusion, these data suggest that temperature, the process of acidification, alkalinization and exposure to intestinal ions induce different viscosity changes in gums having similar initial viscosity, establishing a direct relationship between a minor decrease of gum viscosity in vitro and a reduction of postprandial hyperglycemia.

Adult↗
PubMed1996

Luminal peptide YY-releasing factors in the isolated vascularly perfused rat colon.

Peptide YY (PYY) is produced in endocrine L cells primarily localized in the distal bowel. These open-type L cells make contact with the intestinal chyme which may thus affect their secretory activity. The aim of the present study was to examine a large variety of luminal compounds found in colonic contents for their potential as PYY-releasing factors, using the isolated vascularly perfused rat colon. The release of PYY into the portal effluent was measured by a specific RIA. Luminal administration of 5 mM glucose or 0.5% (w/v) starch for 30 min did not induce significant release of PYY. Oleic acid (10 and 100 mM) also did not significantly increase PYY secretion. A pharmacological concentration of glucose (250 mM) and a mixture of amino acids (total concentration 250 mM) both induced PYY secretion (200% of basal). Pectin, a poly-galacturonic acid, evoked dose-dependent secretion of PYY-like immunoreactivity over the range 0.1-0.5% (w/v). The maximal response was observed after infusion of 0.5% pectin which induced a prompt and sustained release of PYY (300% of basal). Galacturonic acid itself (5%) produced marked PYY secretion. Gum arabic (0.5%) induced a gradual increase in portal PYY concentration (maximal response 250% of the basal value) whereas cellulose (0.5%) did not elicit PYY secretion. Luminal n-butyrate over the range 0.5-5 mM produced a dose-dependent release of PYY (maximal response 300% of the basal value with 5 mM n-butyrate). Increasing the concentration of n-butyrate to 100 mM provoked a gradual decrease in PYY secretion. Propionate was a less potent stimulant than n-butyrate, and acetate did not increase PYY secretion above the basal value. At a concentration of 2 or 20 mM, taurocholate, cholate and deoxycholate brought about PYY secretion while hyodeoxycholate was without effect. In conclusion, glucose and amino acids may mediate PYY release but only when they are present at high supraphysiological concentrations in the colon while oleic acid does not produce any PYY secretion. Physiological concentrations of fibers (pectin, gum arabic), short-chain fatty acids (n-butyrate, propionate) and bile salts (taurocholate, cholate, deoxycholate) are all potent stimulants of PYY release. Whether the release of PYY by luminal factors is coupled to water and electrolyte transfer via a local/paracrine pathway remains an open question which requires additional work with the isolated vascularly perfused colon preparation.

Amino Acids↗
PubMed1983

Effects of dietary fiber on pancreatic enzyme activities of ileostomy evacuates and on excretion of fat and nitrogen in the rat.

Ileostomized rats were fed diets with different fiber content. The addition of 5% pectin to the diet caused an increase in the wet weight, fat content, amylase activity per gram, and lipase output of the ileostomy evacuates. Twenty percent wheat bran in the diet increased weight, fat and nitrogen content, and trypsin output of the evacuates. In normal rats pectin added to a meal containing 3H-labeled triolein increased the isotope activity of the feces, indicating an impaired fat absorption. In rats operated on with occlusion of the pancreatic ducts with a tissue glue, the fat absorption was, however, not significantly affected by pectin. The results of the study show that fiber can cause a change in the intestinal enzymatic milieu of ileostomized rats and can cause steatorrhea, which can be explained, at least partly, by malabsorption.

Amylases↗
PubMed1996

Availability of calcium for absorption in the small intestine and colon from diets containing available and unavailable carbohydrates: an in vitro assessment.

An in vitro method simulating conditions in the small intestine and colon was used to study the effects of various carbohydrates on Ca release from basal diet (BD) containing dairy products. During enzymatic digestion of BD, 28.5 +/- 0.3% of the Ca was released. This was reduced by 3, 22 and 27% by adding bread, psyllium or pectin to BD, respectively (P < 0.05). After enzymatic digestion, the residue from BD was fermented releasing 11.9 +/- 1.2% of the Ca, a value which was significantly less than with pectin (13.7 +/- 0.9%) and greater than with psyllium (4.4 +/- 0.2%) addition. The total Ca release ranged from 26.5 +/- 0.8 to 42.2 +/- 1.0% with bread>BD>pectin>psyllium. Lactulose did not differ significantly from BD. These results suggest that carbohydrates may bind Ca and reduce its availability for absorption in the small intestine. However, if the carbohydrate is fermented, bound Ca may be released for potential absorption in the colon, whereas less fermented carbohydrates may continue to bind Ca in the colon. The in vitro method described may be useful for estimating total Ca availability. However, studies in humans are required to validate these results.

Biological Availability↗
PubMed1999

Studies of pectic enzymes produced by Talaromyces flavus in submerged and solid substrate cultures.

Tons of peel and rag are generated each year by industries of citrus fruit juices. These by-products are used either for the elaboration of pectin or as substrate for enzyme production. Talaromyces flavus produces extracellular pectinesterase and polygalacturonase after 24 h in submerged culture supplemented with 0.5-0.8% citrus pectin preceded by preculture for 24 h in 2% (w/v) sucrose or in solid substrate culture on passion fruit peel, lemon or orange pulp pellets after 3-6 days of incubation. Chromatographic profiles in a CM-Sepharose column of liquid and solid cultures were very similar, consisting of one endopoligalacturonase (endo-PG I) and one pectinolytic complex constituted by an endopoligalacturonase (endo-PG II) and pectinesterase. Pectin and pectate lyases were undetectable in both media. In Talaromyces flavus the synthesis of pectinases was repressed by glucose and finally controlled by the concentration of products from pectic enzymes degradation.

Ascomycota↗
PubMed2002

Effect of prickly pear (Opuntia robusta) on glucose- and lipid-metabolism in non-diabetics with hyperlipidemia--a pilot study.

BACKGROUND: Besides others pectin, a soluble fibre, has been reported to be effective in lowering cholesterol levels in both animals and man with hyperlipidemia as well as being able to slow carbohydrate absorption and hence reduce the postprandial rise in blood glucose and serum insulin in patients with type-II diabetes. Aim of this pilot study was to assess the effect of prickly pear consumption on glucose- and lipid metabolism. DESIGN: In 24 non-diabetic, non-obese males (aged 37-55 years) suffering from primary isolated hypercholesterolemia (n = 12; group A) or combined hyperlipidemia (n = 12; group B) respectively, the influence of prickly pear pectin (Opuntia robusta)-intake on glucose- and lipid metabolism was examined. After an 8 week pre-running phase with a 7506 KJ step-I diet (phase I), 625 KJ were replaced by prickly pear edible pulp (250 g/day) for 8 further weeks (phase II). RESULTS: Prickly pear leads to a decrease of total cholesterol (12%), low-density lipoprotein-cholesterol (15%), apolipoprotein B (9%), triglycerides (12%), fibrinogen (11%), blood glucose (11%), insulin (11%) and uric acid (10%), while body weight, high-density lipoprotein-cholesterol, apolipoprotein A-I, and lipoprotein(a) remained unchanged. CONCLUSION: The hypocholesterolemic action of prickly pear may be partly explained by the fibre (pectin) content, but the hypoglycaemic actions (improvement of insulin sensitivity) in the non-obese, non-diabetic need further investigation to get more insights on the potential advantage of treating the metabolic syndrome.

Adult↗
PubMed1976

Determination of carbocyanine dye-binding polyanions in malignant and nonmalignant disease states.

Cancer-related changes in the serum seromucoid fraction are well known. Last year Woodman published an interesting carbocyanine dye binding method for determination of serum carbohydrate polyanions in sera of normal, traumatized, and tumor-bearing mice. The usefulness of this method for clinical practice has been investigated in this study. Carbocyanine dye-binding polyanion (CPA) and the sialidase-sensitive fraction of this polyanion (SPA) have been determined in sera of 705 human subjects including healthy normal individuals and patients suffering from a broad spectrum of malignant and nonmalignant disease states. Overall, in malignant diseases the CPA and SPA values, in mg pectin equivalents per liter (mean +/-2 S.D.) (292 +/- 111 and 135 +/- 68, respectively) were significantly higher than in the serum from normal controls (166 +/- 33; 74 +/- 18) and patients hospitalized with a variety of nonmalignant disease (195 +/- 56; 92 +/- 36). The highest CPA and SPA values were found in gynecological (331 +/- 117; 149 +/- 69), bronchial (294 +/- 72; 137 +/- 51), and gastrointestinal cancers (316 +/- 111; 154 +/- 69). Elevated CPA values were found in 59.9% and elevated SPA values in 52.8% of patients suffering from malignant diseases. Successfully, radically treated cancer patients with no detectable residues or metastases for at least 1 year had values (186 +/- 39; 76 +/-24) almost within the normal ranges (93 to 250 mg pectin equivalents per liter for CPA and 35 to 120 mg pectin equivalents per liter for SPA).

Anions↗
PubMed2003

[Preparation of fiber complexes and its role in lipid peroxidation].

This study was designed to prepare the artificial fiber complexes and examine its role in lipid peroxidation in comparison with other fibers. Sixty-four healthy, female Wistar rats (50-80 g) were randomly divided into eight groups based on body weight. All seven kinds of DF (cellulose--group B, pectin--group C, sodium alginate--group D, cellulose-pectin complex--group E, cellulose-sodium alginate complex--group F, cellulose-pectin mixture--group G, cellulose-sodium alginate mixture--group H) were given at a level of 10% in the diet fed on a lipid-rich diet. The control group (group A) was fed on a lipid-rich diet alone without DF. After eight weeks, the effect on growth and development, lipid metabolism and lipid peroxidation in rats were studied. The results showed that: 1. Seven kinds of DF did not affect the growth and development of the experimental rats. 2. Seven kinds of DF all can increase serum superoxide dismutase (SOD) and glutathione peroxidase (GsH-Px) activities and reduce malondiadehyde (MDA) content (except group B and D). Erythrocyte membrane fluidity was significantly increased in DF groups, and fiber complex groups were most effective. 3. The fecal weight and fat contents in all DF groups were significantly higher than that in control group, especially for fiber mixture and complex groups. It is concluded that all these kinds of DF have the effect of reducing lipid peroxidation to some extent in rats, and fiber complexes might be the most effective.

Alginates↗
PubMed1991

Modulation of postprandial glycaemia and insulinaemia by dietary fat.

The present study was designed to examine the effect of corn oil (Co) on postprandial glycaemia and insulinaemia when ingested with glucose (G), casein (Cs), cellulose (Cl) and pectin (P) in various combinations. The study was conducted on six healthy male volunteers, on each of whom six meal tolerance tests were performed. The meals were isocaloric and consisted of G; G and Co; G, Co and Cs; G, Co and P; G, Co, Cs and P; and G, Co, Cs and Cl. The meals were administered after an overnight fast. In addition to a fasting blood sample, blood was collected 0.5, 1.0, 1.5 and 2.0 h after ingestion for measurement of serum glucose and insulin levels. The glycaemic response to GCo was comparable to that to G, but the insulinaemic response was significantly lower. The glycaemic response to GCoCs was significantly lower than that to G but the insulinaemic response to both was comparable. The cellulose containing meal GCoCsCl showed a further reduction in the glycaemic response but not in the insulinaemic response. The pectin containing meals GCoP and GCoCsP gave the lowest glycaemic and insulinaemic responses, the responses to the latter being lower. Corn oil by itself has only a modest effect on the postprandial metabolic response to glucose. Addition of protein and fibre, specially pectin, leads to significant attenuation of glycaemic and insulinaemic responses.

Adult↗
PubMed2006

[Changes in glycosidases and cellulase activities, and cell wall composition in strawberry fruits during development and ripening].

Experiments were carried out with two strawberry (Fragaria x nanassa Duch.) cultivars Fengxiang and Hongfeng, with different softening characteristics during growth, ripening and postharvest storage. The fruits were harvested at different stages of growth and ripening, as assessed by size and the coloration of the surface of the fruits. We selected the following stages: small and green (S1), large and green (S2), white (S3), reddish (S4), and fully red (S5). The main results were as follows. Both alpha- and beta-galactosidase activities were changed with ripening of strawberry fruits (Fig.1A, B). Of the strawberry cultivars tested, no correlation was found between glucosidase activity and fruit ripening (Fig.1C, D). Alpha-mannosidase is an enzyme being ionically bound with cell wall and its activities is correlated with the softening of strawberry fruits (Fig.1E, F). No beta-mannosidase has been detected in strawberry. The activities of cellulase increased as the strawberry fruits developed from stage of small and green to stage of overripe (Fig.2A). The activities of PME increased during the development of strawberry fruits (Fig.2B). Endo-PG was not detected in strawberry, and exo-PG was not related to fruit ripening (Fig.2C). Changes in cell wall component contents were clearly related to the changes in the firmness of strawberry fruits. The increase in soluble pectin, together with reduction of ionically bound pectin content, covalently bound pectin content (Fig.3A, B) and cellulose (Fig.3A, B) resulted in softening of strawberry fruits.

Cell Wall↗
PubMed1985

The influence of dietary fiber on gastric transit time.

Little is known about the effect of dietary fiber on gastric emptying. At present, we do not know whether any therapeutic effects result from delayed gastric transit time. Functional scintigraphy was used to determine the effect of wheat bran, guar and pectin on the transit time of 200 ml fruit juice and 200 or 400 ml of a liquid test meal in normal healthy subjects. The transit time of fruit juice was significantly delayed by the addition of 4 g guar (viscosity 7079 mPA X s). Neither wheat bran, pectin nor guar resulted in a delay of the test meal transit time despite maximal increases in viscosity of up to 21,500 mPa X s. We therefore conclude that dietary fiber does not significantly delay the gastric transit time of test meals regardless of the increase in viscosity. The reduction in postprandial glucose levels after ingestion of guar or pectin is, therefore, probably not due to delayed gastric emptying.

Beverages↗
PubMedDate not supplied

[Dietary fiber content of diets of the Don Basin population].

It has been demonstrated that the total content of food fibers in the daily diet of the Donbas population diets amounts to 24.0-26.3 g (cellulose 5.9-6.7 g, pectin 2.0-2.7 g, hemicellulose 16.1-16.9 g). Baked goods account for the major part of hemicellulose (about 85%) and 1/3 of cellulose. Potato and vegetables (fruit) account for half of pectin and 1/3 of cellulose. The daily requirement of cellulose and pectin was satisfied by about 1/3, which is accounted for by a high relative significance of refined products (about 60% of the diet caloric value).

Adult↗