Elevated CD8 T cell responses in type 1 diabetes patients to a 13 amino acid coeliac-active peptide from α-gliadin.

Some type 1 diabetes (T1D) patients have been reported to exhibit T cell reactivity to wheat gluten. We tested the hypothesis that this T cell reactivity could be abolished by using prolyl-endopeptidase (PEP), an enzyme that cleaves peptide bonds after proline. Peripheral blood mononuclear cells (PBMCs) were isolated from T1D patients and healthy controls. PBMCs were stimulated with a peptic-tryptic digest of wheat gluten; a peptic-tryptic-PEP digest of wheat gluten; and a 13 amino acid peptide from wheat gluten. Fluorescent-labelled antibodies to CD3, CD4 and CD8 cell marker proteins were utilized to determine proliferative responses of CD3, CD4 and CD8 T cells. There were no significant differences in proliferative responses of CD3 or CD4 T cells to the wheat gluten antigens. A significantly higher proportion of CD8(+) T cells from T1D patients proliferated in the presence of the 13 amino acid peptide than when challenged with the peptic-tryptic or the peptic-tryptic-PEP digests of wheat gluten. PEP treatment had no significant effect on CD8 T cell reactivity to the peptic-trytic digest of wheat gluten. Our results suggest that wheat gluten-derived peptides, containing ≤ 13 amino acids, may evoke T cell responses in T1D patients.

PSE-like turkey breast enhancement through adjunct incorporation in a chunked and formed deli roll.

A randomized complete block design with five treatments (100% pale, soft, and exudative-like (PSE-like), 100% PSE-like+1.5% collagen, 100% PSE-like+0.30% κ-/ι-carrageenan, 100% PSE-like+1.5% soy protein concentrate, and 100% Normal) and six replications was utilized to test the effects of meat raw material, turkey collagen (TC), soy protein concentrate (SPC), and carrageenan (CG) on protein functionality in the formulation of chunked and formed turkey breast. Addition of 1.5% SPC and 1.5% TC both decreased (P<0.05) cooking loss and increased (P<0.005) the protein bind of treatments formulated with 100% PSE-like raw material. Purge loss decreased (P<0.05) in PSE-like raw material when 1.5% TC, 1.5% SPC, or 0.30% CG were utilized, and no differences (P>0.05) existed in consumer acceptability among treatments. This research demonstrates the potential to increase the water holding capacity and improve the texture of deli rolls from PSE-like raw material through the incorporation of collagen, soy protein, or carrageenan.

Is celiac disease due to molecular mimicry between gliadin peptide-HLA class II molecule-T cell interactions and those of some unidentified superantigen?

This paper presents a new hypothesis for the etiology and pathogenesis of celiac disease (CD). It is our contention that CD is triggered by the binding of one or more gliadin peptides to CD-associated HLA class II molecules. Furthermore, we propose that these putative CD peptides bind to oligosaccharide residues on HLA class II molecules distal to the peptide-binding groove invoking recognition and binding by specialized subsets of gamma delta T cell receptor-bearing lymphocytes. The binding of these gamma delta T cells serves as a signal for abrogation of oral tolerance to ingested proteins setting in motion a series of immune responses directed against the small intestinal epithelium of CD patients. CD patients are victimized by this self-distructed immune response because of inheritance of certain combinations of HLA-DQ and DR haplotypes. Dimers encoded by HLA-DR haplotypes may be the primary restriction elements for lectin-like, gliadin peptides while the degree of immune suppression (or lack thereof) to ingested gliadins is governed by inherited HLA-DQ haplotypes. Finally, we speculate that molecular mimicry between one or more gliadin peptides and some, as yet unidentified, bacterial or viral superantigen plays a role in disease pathogenesis.

Interactions between dietary proteins and the human system: implications for oral tolerance and food-related diseases.

Mounting evidence suggests that there are a number of important, but poorly understand, interactions between dietary proteins and the human immune system. The usual response of the human immune system to dietary proteins seems to be that of oral tolerance, a phenomenon involving up-regulation of protective gut localized immune mechanisms and down-regulation of potentially harmful systemic immunity to the protein in question. Abrogation of oral tolerance may play an important role in the development of food allergies and food enteropathies. Immune mechanisms underlying oral tolerance are therefore discussed in light of current understanding of such food-related diseases as IgE mediated food allergies and gluten sensitive enteropathy. Possible development of oral vaccines to immune-related diseases like multiple sclerosis and rheumatoid arthritis is also discussed.

Protein, calcium, and iron content of wild and cultivated species of Echinochloa.

Two species of Echinochloa millets and their direct wild ancestor species were analyzed for proximate composition, and amino acid, calcium, and iron content. Additionally, lactate polyacrylamide gel electrophoresis (PAGE) was performed to separate and resolve prolamin polypeptide present in the wild and domesticated species. The protein, calcium, and iron content of the four species were comparable to or greater than in other major cereals. Calcium was higher in each of the wild species than their domesticated counterpart. Essential amino acid values for the three species analyzed were generally higher than the FAO/WHO standards, except for lysine. Densitometric analysis of lactate PAGE gels revealed that the domesticated species contained prolamin, polypeptides that were either absent or present in smaller amounts in the wild species. The results indicate a wide variation in the content of examined nutrients and suggest that there is opportunity for improvement in the nutritional value of the Echinochloa millets via selective crossbreeding of wild and domesticated species.

Electrophoretic analysis of ruminal degradability of corn proteins.

Albumin, globulin, and prolamin fractions were extracted from corn meal in water, .5 M NaCl, and 50% (vol/vol) 1-propanol and examined by SDS-PAGE and densitometric scanning to investigate fractional degradation rates of corn proteins. Several protein fractions were identified for globulins, zein prolamins, and glutelins. Ruminal degradability of individual subfractions was evaluated by suspension of corn and corn gluten meal samples in the rumen of lactating dairy cows from 0 to 72 h. Electrophoretic and densitometric analysis of protein residues revealed that the prolamin fraction zein for corn and corn gluten meal was more resistant to ruminal degradation than albumins, globulins, and glutelins. Relative rates of degradation of zein and the fraction containing albumins, globulins, and glutelins were .060, .026, and .018, .015/h for corn and corn gluten meal, respectively. Total degradabilities of corn and corn gluten meal, measured by summation of degradability of subfractional components, were 52.2 and 18.6%. Quantitative measurement of ruminally degradable subfractions and estimation of their degradation rates by electrophoretic and densitometric scanning are useful in understanding ruminal degradability of corn proteins.

Protein, calcium, iron, and amino acid content of selected wild and domesticated cultivars of finger millet.

Two wild and eight domesticated cultivars of finger millet were analyzed to determine their proximate composition and calcium, iron, and amino acid content. Wide variations were observed in the protein (mean values ranged from 7.5 to 11.7%), calcium (376 to 515 mg/100 g), and iron (3.7 to 6.8 mg/100 g) content of the wild and domesticated cultivars. A wild progenitor of finger millet, E coracana subsp. africana was significantly higher in protein than four of the six domesticated accessions analyzed. The calcium and iron content of the wild progenitor was also significantly greater than that of two domesticated cultivars. The wild species was also found to be higher in lysine and five other essential amino acids. These results indicate that the nutritional value of finger millet may be significantly improved by selective crossbreeding of the cereal's wild and domesticated cultivars.

Changes in the nutritive value of soy protein concentrate during autoclaving.

Soy protein concentrate (Promosoy R Plus) was mixed with water to form a thick paste and autoclaved at 121 degrees C for 10 min, 30 min, 2 h, or 4 h. Unautoclaved SPC served as a control. Nitrogen solubility measurements and SDS-PAGE analysis indicated that autoclaving resulted in the formation of soy protein aggregates, with a MW of approximately 1 million daltons, held together by non-covalent and disulfide bonds. The 10 min, 30 min, 2 h, and 4 h SPC samples contained 6, 20, 27 and 39% less cysteine, respectively, than the SPC control. No significant differences were found in the PERs, 2.6-2-7, of a casein control, unautoclaved SPC control and 10 min and 30 min autoclaved samples. PERs of the 2 h and 4 h autoclaved samples, 2.0 and 1.9 respectively, were significantly lower than the other four diets. No significant differences were found in the apparent digestibility of the 10 min, 30 min, and 2 h autoclaved samples; the 4 h autoclaved sample however was significantly less digestible. Decreased PERs of autoclaved SPC samples were likely due to (1) crysteine destruction, (2) decreased protein digestibility, and (3) decreased food intake.

In vivo rat assay for true protein digestibility: collaborative study.

Eight laboratories participated in a collaborative study to estimate precision of a standardized rat assay for determining true protein digestibility in selected animal, fish, and cereal products. Each of 7 test protein sources (casein, tuna fish, macaroni/cheese, pea protein concentrate, rolled oats, pinto beans, and nonfat dried milk) was fed as the sole source of protein at a 10% protein level in mixed diets. Each diet was fed to 2 replicate groups of 4 rats each for a 4-day acclimation period and a 5-day balance period. Mean digestibilities ranged from 98.6% for casein to 72.6% for pinto beans. Repeatability standard deviations ranged from 0.5 to 2.0%; the mean relative standard deviation for repeatability was 0.9% (range 0.5-2.8%). Reproducibility standard deviations ranged from 1.2 to 3.2%, and the mean relative standard deviation for reproducibility was 2.4% (range 1.3-4.4%). The method has been approved interim official first action for determining true protein digestibility in foods and ingredients.

Nutritional evaluation of experimental weaning foods prepared from green leaves, peanut oil, and legume flour.

Experimental weaning foods were prepared from alfalfa leaves, peanut oil, and mung bean, chickpea or soy flour. The weaning foods were analyzed to determine their yield, proximate composition and amino acid content. Yields from starting materials ranged from 29 to 99%. Highest yields were obtained when 20% legume or oilseed flour was incorporated into leaf protein-peanut oil gels. The moisture content of the weaning foods ranged from 42 to 65%, protein from 3.4 to 6.5%, fat from 23 to 48%, and carbohydrate from 3 to 13%. Proteins in the experimental weaning foods were found to be deficient in the sulfur amino acids. Amino acid scores for weaning foods containing 20% legume or oilseed flour ranged from 50 for mung bean to 62 for soy. It was estimated that a four-ounce daily serving of one of the soy weaning foods would supply 40% of the energy and 35% of the protein needs of a one-year-old infant.

The effect of Candida albicans on the isolation of N. gonorrhoeae.

Recently, several studies have reported that strains of Candida albicans and perhaps other noraml bacterial flora are capable of inhibiting the growth of Neisseria gonorrhoeae in vitro, and it is possible that this may occur in vivo as well. This possible antagonism between N. gonorrhoeae and normal flora microorganisms poses many questions regarding the reliable laboratory diagnosis of gonorrhea. Mixed cultures of C. albicans and N. gonorrhoeae were grown together on GC base agar plates with varying concentrations of nystatin. Recovery of N. gonorrhoeae was improved as nystatin concentration was increased to 25 IU/ml, while growth of C. albicans was effectively inhibited. At concentrations of 50 and 100 IU/ml nystatin also began to inhibit N. gonorrhoeae. There was a noticeable decrease of nystatin bioactivity against C. albicans when the GC plates were stored at 4 C, thus making it more difficult to isolate N. gonorrhoeae. Growth curves of C. albicans and N. gonorrhoeae grown together in liquid medium did not significantly differ from growth curves of the individual organisms. Statistical analysis of our findings does not support the theory that strains of C. albicans produce a soluble diffusible factor that is inhibitory to N. gonorrhoeae.