The cholesterol-lowering effect of guar gum in rats is not accompanied by an interruption of bile acid cycling

A viscous hydrocolloid (guar gum, GG; 2.5% of the diet) or a steroid sequestrant (cholestyramine; 0.5% of the diet) was included in semipurified diets containing 0.2% cholesterol to compare the cholesterol-lowering effects of each agent in rats. In the present model, GG significantly lowered plasma cholesterol (−25%), especially in the density <1.040 kg/L fraction, whereas cholestyramine was less potent. Bile acid fecal excretion significantly increased only in rats fed cholestyramine, similar to the cecal bile acid pool; the biliary bile acid secretion was accelerated by GG, but not their fecal excretion, whereas GG effectively enhanced neutral sterol excretion. As a result, the total steroid balance (+13 μmol/d in the control) was shifted toward negative values in rats fed the GG or cholestyramine diets (−27 or −50 μmol/d, respectively). Both agents induced liver 3-hydroxy-3-methylglutaryl-CoA reductase, but cholestyramine was more potent than GG in this respect. The present data suggest that, at a relative low dose in the diet, GG may be more effective than cholestyramine in lowering plasma cholesterol by impairing cholesterol absorption and by accelerating the small intestine/liver cycling of bile acids, which is interestingly, accompanied by reduction of bile acid concentration in the large intestine.     

Psyllium, not pectin or guar gum, alters lipoprotein and biliary bile acid composition and fecal sterol excretion in the hamster

Different soluble dietary fibers known to alter cholesterol metabolism were fed to golden Syrian hamsters, and their specific impact on lipoproteins, biliary bile acid profile, and fecal sterol excretion was evaluated. Semipurified diets containing 20% fat; 0.12% cholesterol; and 8% of psyllium (PSY); high (hePE) and low (lePE) esterified pectin; or high (hvGG) and low (lvGG) viscous guar gum were fed for 5 wk. Compared to control, PSY caused a significant reduction in plasma cholesterol (2.9±0.5 vs. 5.5±0.5 mmol/L), whereas hePE, lePE, hvGG, or lvGG had no apparent effect on plasma lipids. Hepatic total and esterified cholesterol were substantially decreased with PSY, pectin and guar gum, whereby PSY produced the most pronounced effect. Distinctive changes existed in the bile acid profile related to the different fibers. In contrast to pectin and guar gum, PSY caused a significant increase in the cholate:chenodeoxycholate and the glycine:taurine conjugation ratio. Pectin and guar gum did not alter daily fecal neutral sterol excretion while PSY caused a 90% increase due to a higher fecal output. Daily fecal bile acid excretion and total fecal bile acid concentration were significantly increased by PSY, whereas hePE, lePE, hvGG, and lvGG revealed no or only minor effects. Taken together, the disparate hypocholesterolemic effects of PSY, pectin, and guar gum on cholesterol and bile acid metabolism in the hamster are possibly related to different physicochemical properties, e.g., viscosity and susceptibility to fermentation, affecting the fiber-mediated action in the intestine.     

Effectiveness of resistant starch,compared to guar gum,in depressing plasma cholesterol and enhancing fecal steroid excretion

Amylase-resistant starch (RS) represents a substrate that can be administered in substantial amounts in the diet, in contrast to gel-forming polysaccharides, such as guar gum (GG). The aim of this work was thus to compare the effects of GG and RS on cholesterol metabolism in rats adapted to 0.4% cholesterol diets, using dietary GG or RS levels (8 or 20%, respectively) that led to a similar development of fermentations, as assessed by the degree of enlargement of the cecum. The RS diet elicited a marked rise in the cecal pool of short-chain fatty acids, especially acetic and butyric acid, whereas the GG diet favored high-propionic acid fermentations. Both polysaccharides markedly altered the cholesterol excretion, from 50% of ingested cholesterol in controls, up to about 70% in rats adapted to the RS or GG diets. With these diets, the fecal excretion of bile acids was enhanced (67 and 144% with the RS and GG diets, respectively). RS and GG diets were effective in lowering plasma cholesterol (about −40%) and triglycerides (−36%). There was practically no effect of the diets on cholesterol in d>1.040 lipoproteins (high density lipoproteins), whereas RS (and to a larger extent, GG) were very effective to depress cholesterol in d<1.040 lipoproteins (especially in triglyceride-rich lipoproteins). Fermentable polysaccharides counteracted the accumulation of cholesterol in the liver, especially cholesterol esters. In parallel, liver acyl CoA:cholesterol acyltransferase was depressed in rats fed the RS or GG diets, whereas only the GG diet counteracted the downregulation of 3-hydroxy-3-methylglutaryl-CoA by cholesterol. These data suggest that RS may be practically as effective as a gel-forming gum, such as GG, on steroid excretion and on cholesterol metabolism.     

一种新型有机硼交联剂与硼砂交联剂的对比

从瓜胶压裂液的粘度、交联时间、粘时性、滤失性和破胶性五方面,评价了有机硼ALP-3和硼砂交联剂对压裂液冻胶性能的影响。结果表明,两种交联剂均能满足现场施工要求,但新型有机硼交联剂更适用于温度较高、井深较大的油气井。     

The effects of polyoxyethylated cholesterol on fecal bile acids and nitrogen and on cholesterol balance in rats

Polyoxyethalated cholesterol (POEC) is a water soluble derivative of cholesterol which decreases cholesterol absorption in rats without affecting body weight, fatty acid excretion, or intestinal histology. In the present study rat feces were analyzed for cholic, deoxycholic, chenodeoxycholic, muricholic and lithocholic acid following 3 months of feeding a standard or a 2% enriched cholesterol diet with or without 1.5% POEC. In rats maintained on the cholesterol free diet, POEC increased total bile acids (mg/day) by 50% from 14±3 to 21±3 (mean ±SEM) but only the increase in chenodeoxycholic acid was significant (P<0.05). The corresponding POEC effect in the 2% cholesterol diet was 31% (70±8 to 93±3, P<0.01). Fecal nitrogen and serum cholesterol did not vary among groups. Comparing these data with neutral steroid excretion previously determined showed that POEC in the cholesterolfree diet increased the negative cholesterol balance more than three-fold (34±7vs 118±13 P<0.01). In rats fed 2% cholesterol, POEC caused a negative cholesterol balance of 222±8 compared to the control of 27±52 (P<0.01). The data indicate that POEC exerts complex effects in the intestinal tract which increase both bile acid and cholesterol excretion.     

The effect of neurotensin on the concentration of cholesterol and bile acids in the guinea pig

In guinea pigs, total plasma cholesterol concentrations increased above the control values after single intravenous injections and after 3 days of continuous subcutaneous administration of neurotensin (NT). A high dose of NT (125 pmol/100 g body weight) induced tachycardia and severe respiratory distress; the lowest dose (1.25 pmol/100 g body weight) had the greatest hypercholesterolemic effect 15 min after the injections. The bulk of the total plasma cholesterol was in low density lipoprotein fractions. Cholesterol increased in the same fractions after intravenous administrations of NT. NT induced a decrease in the cholesterol content in the ileum but did not affect significantly the cholesterol content in the liver, kidneys or adrenals. In 48-hr fasted controls, plasma cholesterol concentration and cholesterol content in the liver, kidneys, adrenals and terminal ileum increased; after intravenous injections of NT, plasma cholesterol concentration further increased but cholesterol content of the liver, kidneys and ileum decreased. In fed animals, the concentration of the biliary taurochenodeoxycholic acid increased above the control values 5 and 35 min after the intravenous injections of NT. In fasted controls, the total concentration of bile acids was higher than in fed controls, but only the concentration of taurochenodeoxycholic acid further increased after the injections of NT. Proportionately more taurochenodeoxycholic acid than cholesterol was present in bile after the intravenous injections of NT. These data are consistent with the hypothesis that NT has a regulatory role in intestinal cholesterol transport.     

Measurement of the viscosity of guar gum solutions to 50,000 s−1 using a parallel plate rheometer

It is frequently necessary to measure the viscosity of polymer solutions at high shear rates to obtain data under the conditions encountered in industrial processes. Such measurements are most often made on a capillary viscometer. This paper presents a method of determining solution viscosities at shear rates up to 50,000 s^?1 in a rotational rheometer using a parallel plate geometry. The two keys to performing these measurements are very small gaps between the parallel plates (on the order of 50 microns) to eliminate inertial secondary flows, and the ability to increase and decrease the shear rate quickly to minimize viscous heating. A technique for setting and measuring small gaps is presented. Possible sources of error including inertia, axial compliance, and viscous heating are analyzed. A comparison Is made between the viscosity of a 0.7 percent hydroxypropyl guar (HPG) solution measured on the parallel plate rheometer and the viscosity measured in a capillary viscometer. Viscosities of HPG solutions having concentrations of 0.25, 0.50, 1.00, and 1.45 percent are presented over the shear rate range 100 to 50,000 s^?1.     

Influence of additives on the fabric stiffness and colour depth of viscose printed with a guar gum thickener and a reactive dye

The effect of additives in a printing paste containing guar gum thickener and bireactive dye for cellulose printing was studied. The efficiency of the additives with respect to their chemical structure and concentration and the efficiency in combination with thickeners of different types (nonsubstituted, different degrees of carboxymethylation) and different concentrations (solid content) was investigated by assessing the fabric stiffness, colour depth, dye penetration, the viscosity and viscoelasticity of the printing paste and the printing paste add-on. Some additives caused a decrease in the fabric stiffness to an acceptable degree with little effect on the colour depth. Dye penetration was found to be exclusively additive-dependent. Spectroscopic and rheological investigations confirmed the reduction of dye/guar gum interactions due to the occurrence of additive/guar gum and additive/dye interactions. The best quality prints were obtained using a printing past containing a nonionic surfactant and a highly carboxymethylated guar gum thickener.     

Hydrogenation of a fatty acids is not influenced by the position it occupies on a triglyceride molecule

Randomly rearranged soybean oil (Iodine Value 128) was hydrogenated with samples being taken at decrements of 10 I.V. units. The composition of the fatty acids occupying the various positions of the triglyceride molecules of these fats was determined. The results demonstrate that the position an unsaturated fatty acid occupies on a triglyceride molecule does not influence its rate of hydrogenation.     

Boric acid incorporated on the surface of reactive nanosilica providing a nano‐crosslinker with potential in guar gum fracturing fluid

Small molecule borate crosslinker widely used in hydraulic fracturing treatment has a low crosslinking efficiency of less than 1%. Thus boric acid was introduced onto the surface of reactive nanosilica (denoted as nano‐SiO₂; size: about 20 nm) containing ? NH₂ group to obtain a nanosilica‐based crosslinker (denoted as nano‐crosslinker) with increased crosslinking efficiency, thereby broadening the application of nano‐SiO₂ in guar gum fracturing fluid. Moreover, the influence of the as‐prepared nano‐crosslinker on the rheological behavior of guar gum gel was investigated with borate crosslinker as a reference. Results show that boric acid chemically reacts with the amino group of the reactive nano‐SiO₂ to form N? B bond, which is beneficial to the formation of the network structure of guar gum gel. The guar gum gel crosslinked with the 57 ppm of borate based on the carrier of nano‐SiO₂ exhibits better temperature tolerance and shear resistance as well as breaking behavior than the counterpart crosslinked with 200 ppm of borate. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45037.     

The effects of boron derivatives on lipid absorption from the intestine and on bile lipids and bile acids of sprague dawley rats

N,N-dimethyl-n-octadecylamine borane 1 at 8 mg/kg/day, tetrakis-u-(trimethylamine boranecarboxylato)-bis(trimethyl-carboxyborane)-dicopper(II) 2 at 2.5 mg/kg/day and trimethylamine-carboxyborane 3 at 8 mg/kg/day were evaluated for their effects on bile lipids, bile acids, small intestinal absorption of cholesterol and cholic acid and liver and small intestinal enzyme activities involved in lipid metabolism. The agent administered orally elevated rat bile excretion of lipids, e.g. cholesterol and phospholipids, and compounds 2 and 3 increased the bile flow rate. These agents altered the composition of the bile acids, but there was no significant increase in lithocholic acid which is most lithogenic agent in rats. The three agents did decrease cholesterol absorption from isolated in situ intestinal duodenum loops in the presence of drug. Hepatic and small intestinal mucosa enzyme activities, e.g. ATP-dependent citrate lyase, acyl CoA cholesterol acyl transferase, cholsterol-7-alpha -hydroxylase, sn glycerol-3-phosphate acyl transferase, phosphatidylate phosphohydrolase, and lipoprotein lipase, were reduced. However, the boron derivatives 1 and 3 decreased hepatic HMG-CoA reductase activity, the regulatory enzyme for cholesterol synthesis, but the compounds had no effects on small intestinal mucosa HMG-CoA reductase activity. There was no evidence of hepatic cell damage afforded by the drugs based on clinical chemistry values which would induce alterations in bile acid concentrations after treatment of the rat.     

Synthesis and characterization of a new guar gum 4‐hydroxybenzoic acid resin and its use for the separation of heavy metal ions in industrial effluents

Hydroxybenzoic acid group has been incorporated onto guar gum by modified Porath's method of functionalization of polysaccharides. The newly synthesized guar gum 4‐hydroxybenzoic acid (GHBA) resin was characterized by Fourier‐transform infrared spectroscopy, elemental analysis, ion‐exchange capacity, column reusability, and physicochemical properties. The distribution coefficient (K_d) values and effect of pH on chelation of these metal ions using batch method were studied. The separations of mixture of Fe²⁺, Zn²⁺, Cu²⁺, Cd²⁺, and Pb²⁺ metal ions on GHBA resin on the basis of their distribution coefficient at various pH were also achieved using column chromatography. The effect of experimental parameters such as pH, treatment time, agitation speed, temperature, adsorbent dose, initial metal ion concentration, and flow rate on the removal of metal ions has been also studied. GHBA resin is effective adsorbents for the removal of different toxic metal ions from aqueous solutions and follows the order: Fe²⁺ > Zn²⁺ > Cu²⁺ > Cd²⁺ > Pb²⁺. POLYM. ENG. SCI. 2013. © 2012 Society of Plastics Engineers     

The effect of mono-enoic fatty acid esters on the growth and fecal lipides of rats

Summary The growth rates of rats fed a purified diet containing 5% corn oil or the methyl esters of oleic, eicosenoic, orerucic acid have been compared. At this level none of the esters significantly depressed the growth of male rats, but all three reduced the growth of females below that of those fed corn oil. Food efficiency and food consumption were not significantly reduced by any of the esters. Symptoms of essential fatty acid deficiency occurred only among rats fed the fatty acid esters and not among rats fed the fat-free diet. Methyl erucate increased the excretion of true fatty acids, acidic material not soluble in hexane and unsaponifiable matter, as compared to methyl oleate. The true fatty acid excreted was largely erucic. Methyl eicosenoate gave results not appreciably different from methyl oleate except for a slight increase in the excretion of mono-unsaturated fatty acid from rats fed eicosenoate. Both corn oil and methyl erucate increased the excretion of unsaponi-fiable matter. The coefficient of digestibility of methyl eicosenoate and erucate were 96% and 90%, respectively, which are higher values than have been previously reported.     

The effect of difunctional acids on the performance properties of polyurethane coatings

Hydroxyl-terminated polyesters are the most common polyols that are crosslinked through an isocyanate group. In this study, the polyester polyol resins were synthesized by using 1,4-cyclohexanedimethanol (1,4-CHDM) with the mixture of different diacids as 1,3-cyclohexanedicarboxylicacid (1,3-CHDA), 1,4-cyclohexanedicarboxylicacid (1,4-CHDA), isophthalic acid (IPA), adipic acid (AA), and azelaic acid (AZA). The solubility and viscosity of these polyester polyol resins were determined by using suitable solvent. All the polyester polyols were crosslinked with HDI isocyanurate and IPDI trimer to form polyurethane coating films. These films were evaluated for their mechanical, thermal, and chemical resistance properties. The studies on film characteristics reveal that the cycloaliphatic diacids afforded polyurethane with greater performance properties than that of aromatic and linear aliphatic diacids.     

The effect of water on the solidification points of fatty acids. Solubility of water in fatty acids

Summary The effect of water on the solidification points of the normal saturated fatty acids from caproic to stearic, inclusive, has been investigated, and the depressions caused by given amounts of water in each of these acids has been presented. The solubility of water in six of the acids above their solidification points has been determined, and these data have been reported, together with rough approximations of the solubility of water in the other acids of this series.     

The effect of weak acids upon the transport of carbon dioxide in alkaline solutions

The transport of carbon dioxide through stationary alkaline liquid films is investigated both theoretically and experimentally. Attention is focused on the effect of catalysis of the hydrolysis reaction and on the role of weak acids which may be present. As a result of their ionic character and their buffering capabilities, weak acids can substantially increase the rate of transport. The experimental magnitude of this effect, which has apparently not been generally recognized, is in good quantitative agreement with theoretical prediction.     

The effect of positional and geometrical isomerism on the dilatometric properties of some octadecenoic acids

Summary Four isomeric octadecenoic acids, oleic, elaidic, petroselinic, and petroselaidic, were prepared and their expansibility determined. The melting dilation of each acid was calculated and found to increase in the order oleic, petroselinic, petroselaidic, and elaidic. In each instance the melting dilation of the trans acid was greater than that of its cis isomer. Of the two cis acids studied, the melting dilation was less for the acid with the double bond farther from the carboxyl end of the carbon chain. The trans acids did not follow this pattern. At temperatures above 52°C., at which all acids were liquid, the absolute specific volumes of the acids were very nearly equal whereas at temperatures below −7°C, at which all were in the solid state, the specific volumes of petroselinic and elaidic acids were at variance with the specific volumes of oleic and petroselaidic acids. This variance must be attributed to differences in crystal packing. Oleic acid clearly showed the two polymorphic forms previously recognized and, in addition, apparently reversibly transformed at about −5°C., indicating the possible existence of a third polymorphic form. These transformations of oleic acid occurred regardless of tempering, and without visual melting. The other three acids did not exhibit polymorphism under the conditions employed in the dilatometric measurements. Presented at the 44th Annual Meeting of the American Oil Chemists' Society New Orleans, La., May 4–6, 1953. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

The hypercholesterolemic effect of dietary coconut fatversus corn oil in hypo- or hyperresponsive rabbits is not exerted through influencing cholesterol absorption

In two inbred strains of rabbits with high or low response of plasma cholesterol to dietary saturatedversus polyunsaturated fatty acids, the efficiency of intestinal cholesterol absorption was measured. The feeding of a cholesterol-free purified diet containing saturated fatty acids in the form of coconut fat, when compared with a diet containing corn oil as polyunsaturated fatty acids, did not influence the efficiency of cholesterol absorption in the two rabbit strains. Irrespective of the dietary fat source, the hyperresponsive rabbits absorbed cholesterol more efficiently. It is concluded that the hypercholesterolemic effect of dietary coconut fatversus corn oil is not exerted by influencing cholesterol absorption.