Soluble Β-glucan Research Articles

Performance of grower/finisher pigs fed barley and wheat -based diets containing different levels of a β-glucanase and xylanase enzyme combination

Exogenous enzymes have been used in pig feed to reduce the antinutritional factors in the cereal components of the diets and, as a consequence, improve energy and protein digestibility. The predominant fibre components in barley are soluble β-glucans and insoluble arabinoxylans, both of which are known to have anti-nutritional effects in the pig but through different mechanisms. In wheat both soluble and insoluble arabinoxylans are relevant, for the same reasons (Partridge, 2001). Consequently a product with a combination of β-glucanase and xylanase may be necessary to elicit a performance improvement in pigs fed diets containing both barley and wheat. Furthermore, much work in grower/finisher pigs has been undertaken at single inclusion levels of enzyme product. The object of the current study was to compare the response of growing and finishing pigs fed diets containing barley and wheat supplemented with a β-glucanase and xylanase product included at different levels in the diet.

Determination of β-glucan content of cereals with an amperometric glucose electrode

A rapid method for determination of the soluble and total amount of β-glucan was investigated. β-Glucan was extracted from the samples with the modified extraction method and then incubated with lichenase and β-glucosidase. The optimum incubation parameters were determined by using pure β-glucan solutions as follows: lichenase concentration, 0.04 international units (IU) ml–1; β-glucosidase concentration, 0.125 IU ml–1; reaction time, 20 min; reaction temperature, 50 °C; reaction acidity, pH 6. After enzymatic incubation, free D-glucose produced by the action of enzymes on soluble and total β-glucans was measured with an amperometric glucose electrode. The linearity of the β-glucan assay was determined as 8.0% (w/w) under the considered enzymatic reaction condition. In the last part of the study, soluble and total β-glucan contents of certain samples were determined by both the improved method and the AOAC Official Method. A high correlation (R2: 0.992) between the results of these two methods was observed.

Soluble carbohydrates in the nutrition of house longhorn beetle larvae, Hylotrupes bajulus (L.) (Col., Cerambycidae): from living sapwood to faeces

: Water-soluble carbohydrates from (a) living sapwood of Scots pine (Pinus sylvestris L); (b) dry sapwood blocks from Scots pine (EUROPEAN STANDARD EN 46, 1988); and (c) faeces from Hylotrupes bajulus (L) larvae feeding from these blocks were analysed. Living sapwood contains high amounts of sucrose, glucose, fructose and starch. These carbohydrates seem to be hydrolysed and metabolized during the production of the sapwood blocks. The faeces contain carbohydrates which are not present either in living sapwood or in the sapwood blocks: xylose and an oligosaccharide of uncertain composition. This oligosaccharide is the dominant water-soluble carbohydrate in the faeces. In contrast to living sapwood and sapwood blocks, the faeces contain considerable amounts of soluble β-glucans. The results show that the composition and the amounts of carbohydrates differ significantly from that in the sapwood blocks (fodder for the larvae). The α-glucans (starch) present in the wood are not significantly utilized by the larvae. Regarding soluble carbohydrates, diet wood has only little in common with the living wood of the standing tree.

The effect of soluble β-1,3-glucan and lipopolysaccharide on cytokine production and coagulation activation in whole blood

Soluble β-1,3-glucan has been demonstrated to protect against infection and shock in rats and mice, and clinical studies suggest that administration of soluble glucans to trauma/surgical patients decreases septic complications and improves survival. However, little is known about the precise mechanisms by which glucans influence the state of activation of blood cells, which are responsible for the fulminant cytokine production and the activation of the coagulation system observed in serious gram-negative infection. We studied therefore the effect of an underivatized, soluble yeast β-1,3-glucan and lipopolysaccharide (LPS), either alone or in combination, on tumor necrosis factor-α (TNFα), interleukin-6 (IL-6), IL-8 and IL-10 secretion and monocyte tissue factor (TF) expression in human whole blood. As expected, LPS induced the secretion of substantial amounts of all measured parameters, whereas only minor amounts of TNFα, IL-6, and IL-10 were induced by β-glucan itself. However, β-glucan itself induced the production of significant amounts of IL-8 and TF. Soluble β-1,3-glucan had a strong synergistic effect on the LPS-induced secretion of IL-8, IL-10, and on monocyte TF activity, but not on TNFα and IL-6 production. On the other hand, soluble β-glucan strongly primed LPS stimulation of all parameters, including TNFα and IL-6. β-Glucan also induced detectable neutrophil degranulation within 15 min, whereas a response to LPS was first detected after 90 min. In conclusion, soluble β-1,3-glucan upregulated leukocyte activity, both on its own and in concert with LPS.

Relationships Between Barley Hordeins and Malting Quality in a Mutant of cv. Triumph. II. Genetic and Environmental Effects on Water Uptake

The spring malting barley mutant TL43 and its parent cultivar, Triumph, were grown in field trials at Dundee, Scotland and Lleida, Spain in 1997 and 1999, to study water uptake and distribution after steeping and the grain properties that influence them. In 1997, TL43 absorbed more water than Triumph at both sites despite having higher protein and hordein contents. However, it had a lower proportion of B hordein. In 1999 a different steeping regime was employed, incorporating longer air rests, and water uptake of both TL43 and Triumph from Spain was extremely high. At Dundee, Triumph showed greater water uptake than TL43, but poorer distribution of water through the endosperm. This was attributed to the high B-hordein content in the sub-aleurone region of Triumph, which created an effective barrier to initial hydration of the endosperm. Subsequent hydration was, as demonstrated by the Spanish-grown samples, more effective in Triumph compared to TL43, due to the less compacted structure of the inner endosperm. NMR imaging suggested that hydration in TL43 spread throughout the sub-aleurone layer before moving to the inner endosperm, but, in Triumph, proceeded on a broader front from the scutellum towards the distal parts of the grain. A general conclusion was that water uptake in malting, although influenced both by genotype and environment, was more dependent, here, on the latter. B-hordein quantity and distribution were significant factors, but soluble β-glucan content, previously implicated in water uptake differences between Spain and Scotland, appeared to have little effect on the germplasm in this study.

Improvement of malting quality of barley by complementing the malt enzyme spectrum

The processing quality of cereals can be modified by altering the structural grain constituents or the enzyme activities that mobilize storage reserves of the seeds. In order to complement the malt enzyme spectrum, a gene encoding for a thermotolerant fungal endo-(1,4)-β-glucanase was introduced into two barley cultivars, Kymppi and Golden Promise. The gene was expressed in the seeds during germination, thus providing a thermotolerant enzyme that is active under mashing conditions. The amount of thermotolerant β-glucanase produced by the seeds (ca. 0.025% soluble seed protein) has been shown to be sufficient to reduce wort viscosity by decreasing the soluble β-glucan content. For the safe commercial cultivation of transgenic plants risk assessment of their cultivation is needed. In our study experimental estimates of the transgene flow from transgenic barley by pollen dispersal were produced. Field trials were conducted during the summers of 1996 and 1997. A transgenic barley line homozygous for the gene encoding for neomycin phosphotransferase was used as a source of pollen and male-sterile barley lines as recipients. In order to be able to transform the cross-fertilization frequencies to corresponding values of normal male-fertile barley, plots of normal barley were also included in the experimental plan. On the basis of our study, cross-fertilization in male-sterile recipient barley is possible with very low frequency up to 50 meters from the donor area. However, the frequency dramatically decreases with distance and due to self-pollination the possibility of cross-fertilization remains very low in normal cultivated barley.

Regulation of CR3 (CD11b/CD18)-dependent natural killer (NK) cell cytotoxicity by tumour target cell MHC class I molecules.

Phagocyte and NK cell CR3 functions as both an adhesion molecule and an iC3b receptor mediating cytotoxic responses to microorganisms. Cytotoxic activation of iC3b receptor function requires ligation of both a CD11b I-domain site for iC3b and a lectin site located in the C-terminus of CD11b. Because tumours lack the CR3-binding polysaccharides of bacteria and fungi, iC3b-opsonized tumours do not stimulate CR3-dependent cytotoxicity. Previous studies showed that NK cells could be induced to kill iC3b-opsonized tumours with small soluble beta-glucans that bound with high affinity to CR3, bypassing the absence of similar polysaccharides on tumour membranes. Because CR3 signalling requires several tyrosine phosphorylation events, it appeared possible that CR3-dependent killing of autologous tumour cells might be suppressed by NK cell inhibitory receptors for MHC class I (KIR and CD94/NKG2) whose action involves recruitment of SHP-1 and SHP-2 tyrosine phosphatases. In the current study, Epstein-Barr virus (EBV)-transformed B cells were used as targets following opsonization with iC3b. Soluble beta-glucan primed CR3 for killing of iC3b-coated B cells, but autologous class I-bearing targets were 84% more resistant than class I-deficient Daudi cells. Blockade of target cell class I with a MoAb specific for a domain recognized by both KIR and CD94/NKG2 resulted in comparable killing of class I+ B cells. By contrast, another MoAb to class II had no effect on cytotoxicity. These data suggest that NK cell recognition of class I suppresses CR3/tyrosine kinase-dependent cytotoxicity in the same way as it suppresses cytotoxicity mediated by other tyrosine kinase-linked receptors such as FcgammaRIIIA (CD16).

Lactic acid fermentation of wheat and barley whole meal flours improves digestibility of nutrients and energy in Atlantic salmon ( Salmo salar L.) diets

The effects of lactic acid fermentation of wheat and barley whole meal flours (WMF) on digestibility parameters in Atlantic salmon were studied. The WMFs were inoculated with a specific Lactobacillus strain and fermented for 16 h at 30 °C prior to mixing with other feed ingredients and processing by extrusion. Fermentation of the WMFs significantly decreased total starch ( P<0.01) and total mixed-linked (1–3)(1–4)-β-glucan ( P<0.001) contents in both cereals. Soluble β-glucans decreased ( P<0.001) from 25.2 to 12.0 g kg −1 dry matter in barley WMF during fermentation. In Experiment 1, where diets with 24% untreated wheat or barley WMF and 12%, 24%, or 36% fermented WMFs were fed to Atlantic salmon (0.5 kg) for 25 days, there were indications of improved starch and fat digestibility by fermentation. Experiment 2 comprised diets containing 24% untreated or fermented wheat or barley WMFs fed to each of triplicate groups of Atlantic salmon (0.5 kg) during a 17-day experimental period. This experiment showed that protein ( P<0.001), fat ( P<0.05) and energy ( P<0.001) were more efficiently digested in diets with wheat than in diets with barley. Apparent digestibility of starch was greatly improved by fermentation ( P<0.001), more in barley diets (from 47.5% to 67.0%) than in wheat diets (from 51.7% to 65.4%). Improvements in digestibility of fat ( P<0.05) and energy ( P<0.001) were obtained by fermenting the cereals. The absorption of Na was higher for salmon fed wheat than barley diets ( P<0.05). Fermentation resulted in improved Na absorption ( P<0.01); from 68.8% to 73.2% for wheat diets and from 60.3% to 71.7% for barley diets. Fermentation caused a significant ( P<0.05) improvement in Zn absorption from 32.7% to 40.5% for wheat diets and from 33.2% to 43.5% for barley diets. This may be related to the significant reduction in phytic acid levels seen in both fermented cereals ( P<0.001). In conclusion, the potential of wheat and especially barley as ingredients in salmon diets is greatly improved by fermentation.

Effect of Barley and Barley Components on Rheological Properties of Wheat Dough

The effects of addition of whole barley and barley components (starch, β-glucans and arabinoxylans) on rheological properties of dough prepared from wheat flours with variable gluten quality (cv. Glenlea, extra-strong; cv. Katepwa, very strong; cv. AC Karma, strong; and cv. AC Reed, weak) were investigated in these studies using Mixograph and dynamic rheological measurements. Whole barley meal, starch and non-starch polysaccharides from hulless barley with variable starch characteristics (normal, high amylose, waxy, and zero amylose waxy) were tested. Upon addition of either β-glucans or arabinoxylans, significant increases in peak dough resistance, mixing stability, and work input were recorded in all flours. The addition of starch to various wheat flours reduced the strength of the respective flour-water doughs. The improvement of dough strength upon addition of waxy or zero amylose waxy barley meal was associated with the high content of total and soluble β-glucans present in barley samples. The addition of arabinoxylans or β-glucans increased the G′ of wheat doughs; arabinoxylans had a greater effect than β-glucans. Starch substantially decreased the elastic modulus of dough prepared from cv. Glenlea but waxy and high amylose starches increased the G′ of dough prepared from cv. AC Karma. A combination of the high amounts of non-starch polysaccharides and unusual starch characteristics in barley seems to balance the negative effects associated with gluten dilution brought about by addition of barley into wheat flour.

Carbon flux distribution and kinetics of cellulose fermentation in steady-state continuous cultures of Clostridium cellulolyticum on a chemically defined medium.

The metabolic characteristics of Clostridium cellulolyticum, a mesophilic cellulolytic nonruminal bacterium, were investigated and characterized kinetically for the fermentation of cellulose by using chemostat culture analysis. Since with C. cellulolyticum (i) the ATP/ADP ratio is lower than 1, (ii) the production of lactate at low specific growth rate (mu) is low, and (iii) there is a decrease of the NADH/NAD(+) ratio and q(NADH produced)/ q(NADH used) ratio as the dilution rate (D) increases in carbon-limited conditions, the chemostats used were cellulose-limited continuously fed cultures. Under all conditions, ethanol and acetate were the main end products of catabolism. There was no shift from an acetate-ethanol fermentation to a lactate-ethanol fermentation as previously observed on cellobiose as mu increased (E. Guedon, S. Payot, M. Desvaux, and H. Petitdemange, J. Bacteriol. 181:3262-3269, 1999). The acetate/ethanol ratio was always higher than 1 but decreased with D. On cellulose, glucose 6-phosphate and glucose 1-phosphate are important branch points since the longer the soluble beta-glucan uptake is, the more glucose 1-phosphate will be generated. The proportion of carbon flowing toward phosphoglucomutase remained constant (around 59.0%), while the carbon surplus was dissipated through exopolysaccharide and glycogen synthesis. The percentage of carbon metabolized via pyruvate-ferredoxin oxidoreductase decreased with D. Acetyl coenzyme A was mainly directed toward the acetate formation pathway, which represented a minimum of 27.1% of the carbon substrate. Yet the proportion of carbon directed through biosynthesis (i.e., biomass, extracellular proteins, and free amino acids) and ethanol increased with D, reaching 27.3 and 16.8%, respectively, at 0.083 h(-1). Lactate and extracellular pyruvate remained low, representing up to 1.5 and 0.2%, respectively, of the original carbon uptake. The true growth yield obtained on cellulose was higher, [50.5 g of cells (mol of hexose eq)(-1)] than on cellobiose, a soluble cellodextrin [36.2 g of cells (mol of hexose eq)(-1)]. The rate of cellulose utilization depended on the solid retention time and was first order, with a rate constant of 0.05 h(-1). Compared to cellobiose, substrate hydrolysis by cellulosome when bacteria are grown on cellulose fibers introduces an extra means for regulation of the entering carbon flow. This led to a lower mu, and so metabolism was not as distorted as previously observed with a soluble substrate. From these results, C. cellulolyticum appeared well adapted and even restricted to a cellulolytic lifestyle.

Variation in total and soluble beta-glucan content in hulless barley: effects of thermal, physical, and enzymic treatments.

Total and soluble beta-glucan content and effects of various treatments of barley grain on extractability and molecular characteristics of soluble beta-glucan were studied. Four types of hulless barley (normal, high amylose, waxy, and zero amylose waxy) from 29 registered and experimental genotypes were analyzed. For each, moisture, protein, amylose, 100 kernel weight, starch, beta-glucan (total and soluble), beta-glucanase activity, and slurry viscosity were determined. Significant differences in total beta-glucan were observed among the groups, with average values of 7. 49%, 6.86%, 6.30%, and 4.38% for high amylose, waxy, zero amylose waxy, and normal barley, respectively. The extractability of beta-glucan in high amylose barley was relatively low (20.6-29.7%) compared to that in normal (29.8-44.3%), zero amylose waxy (34.0-52. 5%), and waxy (36.7-52.7%) barley genotypes. Viscosity of barley flour slurries was affected by the content of soluble beta-glucans, beta-glucanase activity, and molecular weight of beta-glucans. Hydrothermal treatments (autoclaving and steaming) of barley had no effect on extractability of beta-glucans, but prevented enzymic hydrolysis of beta-glucans, and thereby substantially improved their molecular weight. The addition of enzymes (protease and esterase) during extraction and/or physical treatments (sonication) increased extractability of beta-glucans from barley.

Effect of Dietary Barley β-Glucan on Cholesterol and Lipoprotein Fractions in Rat

The flours of three barley cultivars, namely Dolma (hull-less), DL-88 (hull-less) and BH-331 (hulled), containing 6·23, 4·60, 2·18% total β-glucan and 5·39, 2·06, 1·08% soluble β-glucan contents, respectively, were used in the diets of rats to compare their hypocholesterolaemic effects. Comparison was also made with a standard casein diet. After 40 days of feeding trial, feed intake and weight gain were found to be the highest for the casein diet and differed significantly from those of the barley diets. Dolma (hull-less) based diet, fed to rats caused significant (p<0·05) reductions in the levels of total cholesterol (39%), LDL-cholesterol (61%) and triglyceride (21%), and significant elevation in the level of HDL-cholesterol (34%) in serum compared with the casein diet. Similar changes were observed in liver also. There was a significant increase in the HDLc/TC ratio and decrease in the LDLc/HDLc ratio in the serum and livers of Dolma diet-fed rats. The casein group had the highest total serum protein and liver protein compared with other test groups. Among the test diets, DL-88 had an intermediate and BH-331 the lowest cholesterol-lowering effect. Total and soluble β-glucan appeared to be strong predictors of the cholesterol-lowering in serum and liver of rats. The viscous property of soluble β-glucan may result in reduced absorption, or reabsorption of lipids.

Structural characterization of water soluble β-glucan of oat bran

β-glucan was isolated from oat bran in a highly purified form. The bran was characterized for its contents of dietary fiber, β-glucan, fat and protein. The isolated β-glucan was free of protein and contained only glucose in GC sugar analysis. Two types of β-glucan were obtained with different solubilities. Their molar masses were 1.6 million for the less soluble and 1.1 million for the more readily soluble type. No structural differences were found. The two-dimensional correlation NMR spectrum of the isolated β-glucan showed that the glucose units are joined with 1,3- and 1,4-linkages only. The oligosaccharides produced by the action of a specific enzyme, lichenase, were analyzed by HPLC and capillary zone electrophoresis. The major products are 3 2-β- d-glucosyl cellobiose (trisaccharide) and 3 3-β- d-glucosyl cellotriose (tetrasaccharide), which account for 95% of the whole. Also, 3 4-β- d-glucosyl cellotetraose (pentasaccharide) and other oligosaccharides with degree of polymerization (DP) higher than 5 were detected as minor components.

Critical role of Kupffer cell CR3 (CD11b/CD18) in the clearance of IgM-opsonized erythrocytes or soluble β-glucan

Liver macrophages (Kupffer cells) play a major role in blood clearance of both C3-opsonized immune complexes and therapeutic β-glucan polysaccharides. Human Kupffer cells express three types of C3-receptors: CR1 (C3b-receptor; CD35), CR3 (iC3b- and β-glucan-receptor), and CR4 (iC3b-receptor; CD11c/CD18). Studies of isolated macrophages have suggested that CR3 is the major receptor mediating capture of either C3-opsonized erythrocytes (E) or β-glucans. In this investigation, the organ distribution and function of CR3 in the clearance of IgM-opsonized E and soluble CR3-binding polysaccharides were explored in normal vs. CR3-knockout (CR3-KO) mice. Analysis of intravenously (i.v.) injected 125I-anti-CR3 showed that the major vascular reservoir of CR3 was the liver, followed by spleen and lungs. By contrast, clearance of 125I-anti-CR1 appeared to be mediated predominantly by splenic B lymphocytes, as only subsets of splenic macrophages or Kupffer cells were found to express CR1. Clearance of IgM-opsonized 51Cr-E occurred rapidly to the livers of normal mice but was nearly absent in CR3-KO mice. Soluble 125I-β-glucan exhibited rapid clearance to the liver in normal mice, whereas clearance in CR3-KO mice was significantly reduced. In conclusion, Kupffer cell CR3 plays a crucial role in the clearance of both IgM-opsonized E and β-glucans.

Mechanism of substrate hydrolysis by a thermophilic endoglucanase from Thermotoga maritima

A cellulase from the thermophile, Thermotoga maritima, hydrolyzed oligosaccharide substrates by an exoglucanase mode of action but acted as an endoglucanase to rapidly reduce the viscosity of the soluble polysaccharides carboxymethylcellulose and barley β-glucan. The Vmax for hydrolysis of the substrate, p-nitrophenyl β-d-cellobioside, was 42 μmol min−1 (mg protein)−1, while that for barley β-glucan was 637. The enzyme had little activity on crystalline cellulose.

β-Glucan, a “Specific” Biologic Response Modifier That Uses Antibodies to Target Tumors for Cytotoxic Recognition by Leukocyte Complement Receptor Type 3 (CD11b/CD18)

Abstractβ-Glucans were identified 36 years ago as a biologic response modifier that stimulated tumor rejection. In vitro studies have shown that β-glucans bind to a lectin domain within complement receptor type 3 (CR3; known also as Mac-1, CD11b/CD18, or αMβ2-integrin, that functions as an adhesion molecule and a receptor for factor I-cleaved C3b, i.e., iC3b) resulting in the priming of this iC3b receptor for cytotoxicity of iC3b-opsonized target cells. This investigation explored mechanisms of tumor therapy with soluble β-glucan in mice. Normal mouse sera were shown to contain low levels of Abs reactive with syngeneic or allogeneic tumor lines that activated complement, depositing C3 onto tumors. Implanted tumors became coated with IgM, IgG, and C3, and the absent C3 deposition on tumors in SCID mice was reconstituted with IgM or IgG isolated from normal sera. Therapy of mice with glucan- or mannan-rich soluble polysaccharides exhibiting high affinity for CR3 caused a 57–90% reduction in tumor weight. In young mice with lower levels of tumor-reactive Abs, the effectiveness of β-glucan was enhanced by administration of a tumor-specific mAb, and in SCID mice, an absent response to β-glucan was reconstituted with normal IgM or IgG. The requirement for C3 on tumors and CR3 on leukocytes was highlighted by therapy failures in C3- or CR3-deficient mice. Thus, the tumoricidal function of CR3-binding polysaccharides such as β-glucan in vivo is defined by natural and elicited Abs that direct iC3b deposition onto neoplastic cells, making them targets for circulating leukocytes bearing polysaccharide-primed CR3. Therapy fails when tumors lack iC3b, but can be restored by tumor-specific Abs that deposit iC3b onto the tumors.

Promotion of Neutrophil Chemotaxis Through Differential Regulation of β1 and β2 Integrins

Abstract Migration of neutrophils requires sequential adhesive and deadhesive interactions between β1 and β2 integrins and components of the extracellular matrix. Prompted by reports that describe interaction of soluble β-glucan with the β2 integrin Mac-1, a role for β-glucan in regulation of integrin-mediated migration was investigated. Neutrophil migration in response to fMLP was assessed using an agarose overlay method with slides precoated with fibronectin (Fn) ± β-glucan. On Fn, random migration in excess of directed migration was observed. In contrast, migration on Fn + β-glucan was directional, with marked diminution of random migration. This conversion of random to directed migration was seen neither when Fn was supplemented with alternative polysaccharides nor when β-glucan was applied to other components of the extracellular matrix. This effect of β-glucan was shown to be cation dependent and to be effected by Arg-Gly-Asp-containing peptides consistent with an integrin-mediated event. mAb inhibition studies demonstrate that β-glucan effects this shift toward directed migration through suppression of migration mediated by Mac-1 and very late Ag 5 and enhancement of very late Ag 3-mediated migration. Adhesion assays suggest that the prochemotactic influence of β-glucan is due, in part but not entirely, to modulation of PMN adhesion to Fn. In summary, these data support a novel role for β-glucan in regulation of β1- and β2-mediated neutrophil migration on Fn.

Antigen-specific response of murine immune system toward a yeast β-glucan preparation, zymosan

Zymosan, a particulate β-glucan preparation from Saccharomyces cerevisiae, shows various biological activities, including anti-tumor activity. We have previously shown that soluble β-glucan initiated anti-tumor activity was long-lived and was effective even by prophylactic treatment at 1 month prior to tumor challenge. However, the activity by zymosan was relatively short-lived. Antigen-specific responses of mice to zymosan might be a causative mechanism. In this paper, mice were immunized with zymosan and antibody production and antigen-specific responses of lymphocytes to zymosan were analyzed. Sera of zymosan immune mice contained zymosan-specific IgG assessed by enzyme-linked immunosorbent assay and FACS. Spleen and bone marrow cells of zymosan-immune mice showed higher cytokine production in response to zymosan. Specificity of zymosan-specific responses were also analyzed using various derivatives prepared from zymosan. These facts strongly suggested that mice recognize zymosan as antigen in addition to non-specific immune stimulant.

Nutritional influence of broiler chicken diets based on covered normal, waxy and high amylose barleys with or without enzyme supplementation

A total of 384 day-old broiler chickens were fed unpelleted diets based on covered barley cultivars (696 g/kg) with normal (Golf) high amylose (HAG) and high amylopectin (waxy) starch for a total of 18 days. Diets were fed ad libitum without or with supplementation of a commercial enzyme preparation containing β-glucanase activity. Normal diets were found to contain approximately 30 g/kg total β-glucan while the HAG and waxy diets contained approximately 40 g/kg total β-glucan. Soluble β-glucan was found to account for approximately 48%, 36% and 49% of the total β-glucan content of the normal, HAG and waxy diets, respectively. Generally birds fed the normal diets weighed more, consumed more feed and had lower feed conversion ratios than animals fed the HAG and waxy diets, respectively, at 13 days of age. Enzyme supplementation of diets generally increased chicken body weights and feed intakes, improved feed conversion ratios (g feed/g weight gain) and increased total (16% increase on average) and (HDL-cholesterol) concentrations in comparison to birds provided diets without enzyme. The ileal digesta dry matter content was increased by enzyme supplementation. Ileal digestibility of nutrients was generally improved among chickens given enzyme supplemented diets when compared to animals fed diets without enzyme, the greatest increase in ileal fat digestibility (19% increase) and ileal starch digestibility (9% increase) being observed among animals given the enzyme supplemented waxy diet in comparison to the unsupplemented waxy diet. The ileal digestibility of total β-glucan was also improved by enzyme supplementation and it was concluded that the β-glucanase used in this study may have reduced β-glucan-enhanced intestinal viscosity or nutrient encapsulation due to the presence of intact cell walls and thus, facilitated nutrient uptake. The ileal digestibility of starch was significantly lower among chickens fed the waxy diet without enzyme in comparison to animals fed the normal diet without enzyme but the difference was small. This difference was attributed to the effect of β-glucan when comparisons of starch digestibility between animals fed the waxy and normal diets with enzyme supplementation were made, no significant differences were observed.

Modulation of endotoxin- and enterotoxin-induced cytokine release by in vivo treatment with beta-(1,6)-branched beta-(1,3)-glucan.

Leukocytes activated by endotoxin or enterotoxins release proinflammatory cytokines, thereby contributing to the cascade of events leading to septic shock. In the present studies, we analyzed the effects of in vivo administration of a soluble immunomodulator, beta-(1,6)-branched beta-(1,3)-glucan (soluble beta-glucan), on toxin-stimulated cytokine production in monocytes and lymphocytes isolated from treated mice. In vitro stimulation of lymphocytes isolated from soluble beta-glucan-treated mice with lipopolysaccharide (LPS) resulted in enhanced production of interleukin-6 (IL-6) and suppressed production of tumor necrosis factor alpha (TNF-alpha), while stimulation of these cells with staphylococcal enterotoxin B (SEB) or toxic shock syndrome toxin 1 (TSST-1) resulted in enhanced production of gamma interferon (IFN-gamma) and suppressed production of IL-2 and TNF-alpha compared to that in cells isolated from untreated mice. In vitro stimulation of monocytes isolated from soluble beta-glucan-treated mice with LPS also resulted in suppressed TNF-alpha production, while stimulation of these cells with SEB or TSST-1 resulted in suppressed IL-6 and TNF-alpha production compared to that in cells isolated from untreated mice. Thus, the overall cytokine pattern of leukocytes from soluble beta-glucan-treated mice reflects suppressed production of proinflammatory cytokines, especially TNF-alpha. Taken together, our results suggest that treatment with soluble beta-glucan can modulate the induction cytokines during sepsis, resulting in an overall decrease in host mortality.