New Measurements of the Beam-Normal Single Spin Asymmetry in Elastic Electron Scattering over a Range of Spin-0 Nuclei.

We report precision determinations of the beam-normal single spin asymmetries (A_{n}) in the elastic scattering of 0.95 and 2.18 GeV electrons off ^{12}C, ^{40}Ca, ^{48}Ca, and ^{208}Pb at very forward angles where the most detailed theoretical calculations have been performed. The first measurements of A_{n} for ^{40}Ca and ^{48}Ca are found to be similar to that of ^{12}C, consistent with expectations and thus demonstrating the validity of theoretical calculations for nuclei with Z≤20. We also report A_{n} for ^{208}Pb at two new momentum transfers (Q^{2}) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the Z≤20 nuclei. These data confirm our basic understanding of the underlying dynamics that govern A_{n} for nuclei containing ≲50 nucleons, but point to the need for further investigation to understand the unusual A_{n} behavior discovered for scattering off ^{208}Pb.

Accurate Determination of the Neutron Skin Thickness of

We report a precision measurement of the parity-violating asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A_{PV}=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(Q^{2}=0.00616 GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R_{n}-R_{p}=0.283±0.071 fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ_{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo) fm^{-3} leading to the interior baryon density ρ_{b}^{0}=0.1480±0.0036(exp)±0.0013(theo) fm^{-3}. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.

Dot blot chemiluminescence assay for studying food protein binding to small intestinal brush border membranes in vitro.

Interactions of food proteins with the apical membrane of small intestinal epithelial cells can influence enterocytic antigen handling. For studying these interactions in vitro, isolated brush border membrane vesicles are a widely accepted model. In order to improve measurement of food protein binding, we developed a sensitive dot blot chemiluminescence assay. This assay comprises immobilization of membrane vesicles on nitrocellulose, detection of bound biotinylated food proteins by a peroxidase-catalyzed chemiluminescence reaction, and densitometric quantitation of signal intensities. By using this assay, saturation of brush border membrane binding of food proteins (gliadin peptides, alpha-casein, beta-lactoglobulin, ovalbumin) was demonstrated. Inhibition studies indicated components of specific membrane binding of gliadin peptides, alpha-casein and beta-lactoglobulin, whereas aggregation tendency of ovalbumin interfered with inhibition experiments. Maximal binding intensities of gliadin peptides (22.2 +/- 1.2 densitometric units (d.u.)/microgram membrane protein), alpha-casein (27.9 +/- 1.7 d.u./microgram) and ovalbumin (21.3 +/- 1.6 d.u./microgram) were comparable to sugar-specific lectin binding (range from 23.4 to 35.1 d.u./microgram), in contrast to significantly less binding of beta-lactoglobulin (6.8 +/- 0.6 d.u./microgram). The dot blot chemiluminescence assay is appropriate for characterizing interactions between food proteins and brush border membranes. Its sensitivity makes investigation of pathological membrane alterations possible. Besides, it might be useful for any studies defining ligand-membrane interactions.

[IgA endomysium antibodies. Detection in children with celiac disease]. / IgA-Endomysiumantikörper. Nachweis bei Kindern mit Zöliakie.

BACKGROUND: Epidemiology of coeliac disease gives rise to the search for a non-invasive, reliable screening test. METHODS: We looked for IgA anti-endomysial antibodies (IgA-EmA) in 103 sera of 90 children (age: 2 months-13.9 years) using an indirect immunofluorescence method on monkey oesophagus sections. In 44 patients, the diagnosis of coeliac disease was confirmed fulfilling new criteria of the European Society of Pediatric Gastroenterology and Nutrition. RESULTS: All 24 coeliac disease patients with an initial flat mucosa had IgA-EmA (sensitivity 100%). In 36% of coeliac disease patients adhering to a gluten-free diet we found IgA-EmA. None of 46 patients in whom coeliac disease had been excluded by jejunal biopsy had IgA-EmA (specificity 100%). The sera of 102 blood-donors were used as controls and showed a test specificity of 99%. In coeliac disease patients, the titer of IgA-EmA declined during gluten-free diet by 0.66 steps/month on average, and rose 1.76 steps/month during gluten challenge. CONCLUSIONS: These results confirm the diagnostic significance of IgA-EmA for patients with suspected coeliac disease and their value for monitoring treatment even in young children (below 2 years).

Crypt-villus differentiation reflected by lectin and protein binding to rat small intestinal brush border membranes.

To compare differentiation along the crypt-villus axis in adult rats with changes observed in postnatal maturation with respect to binding capacities for lectins and food proteins, crypts and villi were isolated by in vivo perfusion and in vitro incubation. Brush border membranes were prepared from adults and newborns, and binding of 125I-labeled lectins and food proteins was assessed by airfuge ultracentrifugation. Crypt and villus membrane protein patterns looked almost identical, unlike newborn membranes. Considerable shifts in lectin binding to membranes were observed during postnatal maturation, but not in crypt-villus differentiation. For instance, fucose-specific lectin binding patterns in both preparations resembled the general adult mode. Contrary to differences in food protein binding between newborn and adult membranes, food protein binding did not show a consistent significant difference between membranes of crypt and villus origin in adult animals. In conclusion, membrane differentiation along the crypt-villus axis was found to follow a pattern dissimilar from neonatal maturation as far as protein and carbohydrate composition and food protein binding were concerned.

Postnatal maturation of rat small intestinal brush border membranes correlates with increase in food protein binding capacity.

To investigate maturational changes of membrane food protein binding capacity, we studied binding characteristics of brush border membranes isolated from small intestines of newborn and adult rats. Binding of biotinylated gliadin peptides, cow's milk proteins (alpha-casein, beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin) and lectins was assessed by a sensitive chemiluminescence blot assay. We found specific food protein binding with regard to saturation and inhibition. Maximal binding of most food proteins and several lectins to brush border membranes of newborn and adult rats was comparable, whereas binding of beta-lactoglobulin was substantially less. Common or adjoining binding sites for the different food proteins tested were indicated by corresponding membrane protein binding patterns and by inhibition properties of unrelated proteins. Compared to newborns, adult membrane vesicles as well as isolated membrane proteins showed higher binding capacities. Thus postnatal maturation of small intestinal brush border membranes correlated with increased food protein binding capacity.