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PubMedDate not supplied

Interaction of maize zein with wheat gluten in composite dough and bread as determined by confocal laser scanning microscopy.

Protein body-free maize zein, when mixed at 35 degrees C (above its glass transition temperature range), significantly (p < 0.01) improved the rheological and leavening properties of sorghum-wheat composite flour dough, resulting in improved loaf volume. Confocal laser scanning microscopy was used to observe the structure of zein fibrils and the interaction between zein and gluten proteins in the composite dough and bread systems. Autofluorescence and immunolocalization techniques were used to locate gluten and zein, respectively. Optical sections were collected every 0.4 microm through the samples and digitally processed to produce reconstructed three-dimensional images. Results showed that zein fibrils form an outer layer that intermittently coats the gluten networks, thereby strengthening them. This type of microstructure is able to withstand the pressure exerted by gas cell expansion during yeast fermentation to increase loaf volume.

Bread↗
PubMed1991

Wheat gluten: rheological and gas retaining properties.

Three general properties of the gluten proteins appear to be responsible for gluten's ability to product unique light products. First is the ability to form a cohesive dough. This probably results from the low charge density of the proteins, which allows for strong hydrogen and hydrophobic bonding. The second factor is the ability of the dough to retain gas. This appears to result from the slow diffusion of low molecular weight molecules, including carbon dioxide, through the gluten matrix. The third factor is the transformation of dough to bread. Little is known about this transformation.

Diffusion↗
PubMed1985

IgA anti-endomysial antibody detection in the serum of patients with dermatitis herpetiformis following gluten challenge.

This study reports the appearance of IgA-class anti-endomysial antibodies in the serum of 8 out of 12 patients with dermatitis herpetiformis who were challenged with gluten after a number of years of control of the rash with a strict gluten-free diet. Although there was no evidence for the antibodies having any pathogenic role in the rash of dermatitis herpetiformis, their presence may be related to the deterioration in the gluten-sensitive enteropathy.

Adult↗
PubMed1993

Disulphide bonds in wheat gluten: further cystine peptides from high molecular weight (HMW) and low molecular weight (LMW) subunits of glutenin and from gamma-gliadins.

Glutenin was prepared from gluten of the wheat variety Rektor by extraction of gliadin with aqueous ethanol. It was cleaved successively into soluble peptides by the enzymes trypsin and thermolysin. Separation of the peptide mixtures was performed by gel permeation chromatography (GPC) on Sephadex G25 and reversed phase high performance liquid chromatography (RP-HPLC) on ODS-Hypersil. Cystine peptides were detected by differential chromatography of the samples prior to and after reduction. After isolation by multi-step RP-HPLC, the cystine peptides were reduced. The resulting cysteine peptides were alkylated with 4-vinylpyridine, separated by RP-HPLC and sequenced by means of the Edman degradation. The isolated cystine peptides represented a considerable portion of the total cysteine in glutenin: four out of seven cysteine residues of HMW subunits, and eight out of nine cysteine residues of LMW subunits are documented by at least one cystine peptide. Most of the peptides corresponded to known sequences of gluten protein components. From the structures of some tryptic peptides, inter- and intramolecular disulphide bonds for HMW subunits of glutenin have been proven. Cystine peptides from the thermolytic digest have been assigned to LMW subunits of glutenin and to gamma-gliadins. Other peptides have been closely related to partial sequences of these protein components. The results have allowed several conclusions about the arrangement of intra- and intermolecular disulphide bridges in gluten proteins.

Amino Acid Sequence↗
PubMed1979

The amino acid composition and protein quality of high-protein gluten bread.

Dietetic bread is mainly produced for diabetics. Gluten accounts 80% of the protein of whole wheat flour. Forty per cent wheat gluten are incorporated in the dough to increase the protein content and decrease the starch in the final product. Gluten-rich foods are still of low cost as compared to others such as skim milk, soya and fish flour.

Amino Acids↗
PubMed2004

Calcium absorption and bone mineral density in celiacs after long term treatment with gluten-free diet and adequate calcium intake.

Calcium malabsorption, hypocalcemia and skeletal demineralization are well-recognized features of untreated celiac disease. This study investigates calcium absorption and bone mineral density (BMD) after a prolonged, over 4 years, treatment with a gluten-free diet. Twenty-four adult females with treated celiac disease and twenty age- and sex-matched control subjects were studied. Mean body mass index (MBI), energy intake, serum calcium, and serum 25(OH)D concentrations in treated celiacs did not differ from controls. However, while both dietary calcium and protein intake were significantly higher in celiacs (P<0.012), fractional calcium absorption was lower (mean percentage+/-SD; treated 39.8+/-12 versus controls 52.3+/-10, P<0.001). Thus, after adjusting for calcium intake, the estimated amount of calcium absorbed daily was similar in both groups. Whole body, spine and trochanter BMD were significantly lower in treated celiac patients compared with controls (P<0.05). There were significant inverse correlations between: serum parathyroid hormone (PTH) and femoral neck or total body BMD (P<0.01), PTH and duration of gluten-free diet (P=0.05), and fractional calcium absorption and alkaline phosphatase (P=0.022). Increased calcium intake could potentially compensate for the reduced fractional calcium absorption in treated adult celiac patients, but may not normalize the BMD. In addition, the inverse correlation between PTH and time following treatment is suggestive of a continuing long-term benefit of gluten withdrawal on bone metabolism in celiac patients.

Absorption↗
PubMed1987

Immunoblotting detection of lectins in gluten and white rice flour.

The gluten lectin was isolated by affinity chromatography, separated by sodium dodecyl sulphate-gel electrophoresis together with purified wheat germ agglutinin (WGA) and electrotransferred to nitrocellulose filters. The binding pattern of anti-WGA to the blotted filters confirmed the presence of WGA in gluten. A lectin from rice bran and white rice flour, respectively, was isolated by affinity chromatography. Both lectins reacted with anti-WA in immunoblotting. As patients with coeliac disease are known to tolerate rice flour, the finding of a WGA-like lectin questioned the suggestion that WGA in gluten is involved in the pathogenesis of coeliac disease. A second lectin was also isolated from rice flour which reacted only with antibodies against soybean lectin on immunoblots. This may indicate a contamination of soybean proteins in rice flour.

Antibodies↗
PubMed1976

The binding of a glycopeptide component of wheat gluten to intestinal mucosa of normal and coeliac human subjects.

A carbohydrate-containing component of wheat gluten (glyc-gli) has been prepared which is toxic to coeliac intestinal mucosa. Its amino acid composition is uniquely different from that of the parent gluten and from alpha-gliadin. This glyc-gli material has been shown to bind to membrane components of the coeliac intestinal cell but to bind only poorly to normal intestinal cell membranes. Furthermore this binding can be interfered with by exogenous free carbohydrate suggesting that the toxic moiety of gluten acts in an analagous way to plant lectins. These data suggest that the underlying defect in coeliac disease is related to the composition of the surface membrane of the enterocyte.

Amino Acids↗
PubMed1995

Molecular flexibility in wheat gluten proteins submitted to heating.

Prolamin proteins are responsible for the network that gives wheat dough its viscoelastic properties. Non-prolamin depleted gluten was prepared under conditions that preserve its functionality. Electron Spin Resonance (ESR) was used to provide information about the dynamics of the protein at temperatures between 5 and 90 degrees C by specific spin labelling of its cysteine residues. The spectra were of a composite type, resulting from at least two populations of spin labels largely differing in molecular mobility. The correlation time of the less mobile nitroxide radicals was determined by saturation transfer ESR. Upon heating there was a transfer from the slow to the fast moving population of radicals, and an increase of mobility of this last catagory that followed the Arrhenius law. The effect of temperature on molecular flexibility was reversible. This was not the case for purified, polymerised glutenin subunits extracted from gluten. Urea created similar modifications on gluten as heat.

Electron Spin Resonance Spectroscopy↗
PubMed1989

Studies of intestinal lymphoid tissue. XII. Epithelial lymphocyte and mucosal responses to rectal gluten challenge in celiac sprue.

The immunopathologic, structural, and functional changes within rectal mucosa of known celiac sprue subjects were quantitated during local challenge with a peptic-tryptic digest of gluten. In the celiac sprue patients challenged with 2 g of digest, major effects occurred in lamina propria, submucosa, and local microvasculature. The lamina propria swelling was biphasic, starting 1-2 h after challenge with widespread extravascular deposition of fibrinogen, indicative of increased microvascular permeability, receding by 24 h postchallenge. A rapid fall in mast cells together with granule discharge suggested their involvement in this response. The late-phase swelling (48-72 h) was preceded by a rapid influx of neutrophils and basophils, the latter showing evidence of degranulation beyond 72 h. Reestablishment of vessel lumina, a rise in mast cells, and loss of neutrophils indicated tapering of the inflammatory cellular cascade by 96 h. Lymphocytes, first seen to enter the lamina by 2 h postchallenge, increased progressively, thereby resulting in substantial infiltration between 36 and 96 h. A marked rise in epithelial lymphocytes, maximal at 6-8 h, waned by 24 h. Volumes of surface and crypt epithelium remained constant throughout. In another challenge series with 4 g of gluten digest, electrical potential difference across rectal mucosa decreased significantly 12 h postchallenge, but the associated decreases in net sodium and chloride absorptive fluxes were insignificant. It is concluded that rectal mucosa is sensitized to gluten in celiac sprue disease and thus offers a promising and convenient in vivo substrate for investigative and diagnostic purposes.

Adult↗
PubMed1991

Differential sugar absorption for the assessment of canine intestinal permeability: the cellobiose/mannitol test in gluten-sensitive enteropathy of Irish setters.

Intestinal permeability was assessed in Irish setters with gluten-sensitive enteropathy by oral administration of an isotonic solution of cellobiose and mannitol, and measurement of their urinary excretion ratio. The cellobiose/mannitol ratio was increased in affected Irish setters fed a wheat-containing diet compared both with littermates reared on a cereal-free diet, with no evidence of jejunal damage, and clinically healthy Irish setters. The ratio fell following six weeks on a gluten-free diet to be comparable with control values, and subsequently increased after six weeks gluten challenge. The results indicate that the cellobiose/mannitol test may be useful for the detection of mucosal damage and for monitoring the response to therapy.

Animals↗
PubMed1990

Rectal gluten challenge and diagnosis of coeliac disease.

44 patients referred consecutively for jejunal biopsy underwent rectal gluten challenge with 2 g peptic-tryptic digest (Frazer's fraction III; FF3). Rectal biopsy was done before the challenge and 6 h afterwards. Total intraepithelial lymphocytes (IEL) overlying a 10(4) micron 2 test area of muscularis mucosae were quantified by computerised image analysis. The subjects comprised 21 controls with disorders other than coeliac disease and 23 patients (14 treated, 9 untreated) with coeliac disease diagnosed by strict jejunal biopsy gold standard criteria. There was no difference between the groups in IEL numbers before challenge. Coeliac disease patients but not controls responded to FF3 with a rise in mucosal IEL (median 60.5% rise for treated, 63.0% for untreated). There was no response to challenge with beta-lactoglobulin in coeliac disease or control subjects. When a predefined, post-challenge IEL "predictive index" of more than 10% above baseline was used to indicate a diagnosis of coeliac disease, it gave a sensitivity of 90% and specificity of 91% (95% confidence intervals 78-93%). Rectal gluten challenge is a simple, safe, and reliable test of gluten sensitivity, both as a screening test for untreated coeliac disease and as a confirmatory test in patients with treated coeliac disease.

Celiac Disease↗
PubMed1992

Intestinal gluten sensitivity: snapshots of an unusual autoimmune-like disease.

Gluten-sensitive disease is activated in genetically susceptible individuals by the ingestion of wheat protein (gluten). Breakdown in normal tolerogenic processes to dietary gluten is likely to play a primary pathogenic role. The disease is characterized by several autoimmune-type features and provides a model for studying autoimmune processes. A recent meeting emphasized the need for a clearer picture of the molecular interactions between disease triggering agents, molecules of the immune system and other products of disease susceptibility genes.

Autoimmune Diseases↗
PubMedDate not supplied

Demonstration of high opioid-like activity in isolated peptides from wheat gluten hydrolysates.

Because of a possible relationship between schizophrenia and celiac disease, a condition in some individuals who are sensitive to wheat gluten proteins in the diet, there has been interest in observations that peptides derived from wheat gluten proteins exhibit opioid-like activity in in vitro tests. To determine the origin of the peptides exhibiting opioid activity, wheat proteins were fractionated by size (gel filtration), by charge differences (ion exchange chromatography) and by differences in hydrophobicity (reversed-phase HPLC). These fractions were hydrolyzed by pepsin or pepsin and trypsin and the resulting peptides separated by gel filtration chromatography. The separated peptides were tested for opioid-like activity by competitive binding to opioid receptor sites in rat brain tissue in the presence of tritium-labeled dihydromorphine. The peptides showed considerable differences in activity; while some peptides exhibited no activity, 0.5 mg of the most active peptides were equivalent to 1 nM of morphine in the binding assay. The most active peptides were derived from the gliadin fraction of the gluten complex.

Animals↗
PubMed2006

Effects of cell wall components on the functionality of wheat gluten.

Normal white wheat flours and especially whole meal flour contain solids from the inner endosperm cell walls, from germ, aleurone layer and the outer layers of cereal grains. These solids can prevent either gluten formation or gas cell structure. The addition of small amounts of pericarp layers (1-2%) to wheat flour had a marked detrimental effect on loaf volume. Microstructural studies indicated that in particular the epicarp hairs appeared to disturb the gas cell structure. The detrimental effects of insoluble cell walls can be prevented by using endoxylanases. It has been shown that some oxidative enzymes, naturally present in flour or added to the dough, will oxidise water-extractable arabinoxylans via ferulic acid bridges, and the resulting arabinoxylan gel will hinder gluten formation. The negative effects of water-unextractable arabinoxylans on gluten yield and rheological properties can be compensated by the addition of ferulic acid. Free ferulic acid can probably prevent arabinoxylan cross-linking via ferulic acid.

Cell Wall↗
PubMed2005

Gluten-free diet--what is toxic?

The cornerstone of treatment of coeliac disease is a gluten-free diet devoid of proteins from wheat, rye, barley and related cereals. Oats are tolerated by most patients with coeliac disease but are not totally innocent. There are considerable differences between individual patients with respect to clinical and mucosal responses to gluten challenge. In vitro and in vivo testing has identified synthetic peptides that are toxic to the coeliac small intestinal mucosa. This toxicity overlaps at least partly to the known epitopes that are recognised by small intestinal T-cells. However, the clinical significance of several of these epitopes is unclear, as is the maximum level of gluten intake that can be recommended to be safe for patients with coeliac disease. Future efforts may lead to better understanding of the disease processes as well as possible new therapeutic options.

Celiac Disease↗
PubMed2006

Chemistry of gluten proteins.

Gluten proteins play a key role in determining the unique baking quality of wheat by conferring water absorption capacity, cohesivity, viscosity and elasticity on dough. Gluten proteins can be divided into two main fractions according to their solubility in aqueous alcohols: the soluble gliadins and the insoluble glutenins. Both fractions consist of numerous, partially closely related protein components characterized by high glutamine and proline contents. Gliadins are mainly monomeric proteins with molecular weights (MWs) around 28,000-55,000 and can be classified according to their different primary structures into the alpha/beta-, gamma- and omega-type. Disulphide bonds are either absent or present as intrachain crosslinks. The glutenin fraction comprises aggregated proteins linked by interchain disulphide bonds; they have a varying size ranging from about 500,000 to more than 10 million. After reduction of disulphide bonds, the resulting glutenin subunits show a solubility in aqueous alcohols similar to gliadins. Based on primary structure, glutenin subunits have been divided into the high-molecular-weight (HMW) subunits (MW=67,000-88,000) and low-molecular-weight (LMW) subunits (MW=32,000-35,000). Each gluten protein type consists or two or three different structural domains; one of them contains unique repetitive sequences rich in glutamine and proline. Native glutenins are composed of a backbone formed by HMW subunit polymers and of LMW subunit polymers branched off from HMW subunits. Non-covalent bonds such as hydrogen bonds, ionic bonds and hydrophobic bonds are important for the aggregation of gliadins and glutenins and implicate structure and physical properties of dough.

Amino Acid Sequence↗
PubMed1996

Decreased intestinal CYP3A in celiac disease: reversal after successful gluten-free diet: a potential source of interindividual variability in first-pass drug metabolism.

BACKGROUND: Cytochrome P450 (CYP) 3A is constitutively expressed in human intestinal villi and may account for significant "first-pass" prehepatic metabolism of a number of drugs in the intestine. Celiac disease results in small intestinal atrophy. We hypothesized that this would result in a loss of CYP3A. METHODS: Formalin-fixed jejunal biopsy specimens taken from nine patients with celiac disease at variable times before and after treatment with a gluten-free diet were immunoperoxidase stained after incubation with anti-CYP3A4 rabbit antisera (1:2000 dilution). The amount of immunoreactive CYP3A was determined by two observers who were blinded to the treatment states of the patients. Staining intensity was graded on a numerical scale from 1 to 4+ on the basis of intensity of staining in individual enterocytes, as well as the total number of enterocytes stained. RESULTS: Slides of biopsy specimens from all nine untreated patients with celiac disease were graded 1. Treatment with a gluten-free diet was associated with a significant increase in CYP3A immunoreactive protein in small bowel biopsy specimens (p < 0.05, Wilcoxon signed-rank test). CONCLUSIONS: We conclude that patients with celiac disease have low intestinal CYP3A immunoreactivity and that treatment with a gluten-free diet is associated with an increase in intestinal CYP3A immunoreactive protein. Our findings suggest that intestinal disease and variability in intestinal CYP3A activity might be an unexamined variable that may contribute to interindividual variability in drug disposition.

Adult↗