[Indication for artificial nutrition: enteral and parenteral nutrition]. / Indikation zur künstlichen Ernährung : Enterale und parenterale Ernährung.

Inadequate oral food intake and impending or manifest malnutrition are an indication for artificial nutrition. Regarding the course of the disease and quality of life this can improve the prognosis and also prolong the life span. The indication for nutritional therapy should be based on the guidelines for enteral/parenteral nutrition, however, the individual life situation of the patient should also be considered and the patient's volition should be respected. Prerequisites for any nutritional concept are careful evaluation of the nutritional status and specification of the nutritional concept adapted to any disease-specific changes in digestive capacity and metabolism. Enteral nutrition, if possible as volitional nutritional support, should be preferred to parenteral nutrition.

Cloning and sequencing of the maltohexaose-producing amylase gene of Klebsiella pneumoniae.

The molecular characterization of the maltohexaose-producing amylase gene of Klebsiella pneumoniae revealed an open reading frame in which 2,031 base pairs encode a protein of 677 amino acids with a calculated molecular weight of 75,921. The amylase gene had high similarities of 73.6% in DNA sequence and 79.3% in deduced amino acid sequence with the periplasmic alpha-amylase MalS gene of Escherichia coli.

Crystal structure of a catalytic-site mutant alpha-amylase from Bacillus subtilis complexed with maltopentaose.

The X-ray crystal structure of a catalytic-site mutant EQ208 [Glu208-->Gln] of alpha-amylase from Bacillus subtilis cocrystallized with maltopentaose (G5) and acarbose has been determined by multiple isomorphous replacement at 2.5 A resolution. Restrained crystallographic refinement has resulted in an R-factor of 19.8% in the 7.0 to 2.5 A resolution range. EQ208 consists of three domains containing a (beta/alpha)8-barrel as observed in other alpha-amylases. Clear connected density corresponding to a pentasaccharide was observed, which was considered as the G5 molecule based on the high affinity of EQ208 for G5 that could replace pre-bound acarbose or a possible transglycosylation product of acarbose. The conformation around the third alpha-(1,4)-glucosidic bond makes a sharp turn, allowing the substrate to fit into the L-shaped cleft. Aromatic residues build the walls of the substrate binding cleft and leucine residues form the inner curvature of the cleft. The amide nitrogen of Gln208 forms a hydrogen bond with the glucosidic oxygen in the scissile bond between Glc3 and Glc4 (Glc1 is the non-reducing end glucose residue of the substrate). This hydrogen-bonding manner may correspond to that of the protonated state of Glu208 in the initial kinetic complex between wild-type enzyme and substrate. The amide oxygen of Gln208 is anchored by two hydrogen bonds with Ala177 and a water molecule, assisting to make the amide proton point precisely to the place of the catalytic attack. The carboxyl oxygen atoms of the other catalytic-site residues Asp176 and Asp269 form hydrogen bonds with the oxygen atoms of Glc3. The carboxyl group of Asp176 has non-bonded contacts to the anomeric carbon atom and to the endocyclic oxygen atom of Glc3. These results suggest that Glu208 acts as a general acid and Asp176 as a general base. Glc3 forms seven hydrogen bonds with the surrounding protein groups and a stacking interaction with Tyr62, which is consistent with the fact that Glc3 has the lowest mean thermal factor of 13.2 A2 among the five sugar residues. Three calcium ions are found, one of which is positioned near the substrate binding site as found in other alpha-amylases and could contribute to stabilization of the structure of the active site.

Purification and characterization of the acid soluble 26-kDa polypeptide from soybean seeds.

Whey proteins from soybean seeds of Japanese varieties were analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Among 11 varieties of soybean, three green and one black soybeans lacked a 26-kDa band that was found in all yellow soybeans. In this paper, the 26-kDa protein was named AS26k (acid soluble 26-kDa protein) temporarily. The AS26k protein was purified from Glycine max cv. Nattosyoryu, which is yellow soybean, through four purification steps: 30-35% saturated ammonium sulfate fractionation, ion exchange chromatography on S Sepharose Fast Flow, gel filtration on Sephadex G-100, and hydrophobic chromatography on phenyl Sepharose CL-4B. Purified AS26k was cleaved with V8 proteinase from Staphylococcus aureus or CNBr. The cleaved polypeptide contained two typical dehydrin motif sequences: DEYGNPV and (M)DKIKEKLPG, and a 19 amino acids sequence similar to a pea dehydrin. Native AS26k had a molecular mass of 32 kDa on gel filtration and a pl of 7.2 on two-dimensional PAGE. Similarly to other dehydrins and late embryogenesis abundant (LEA) proteins, AS26k was rich in hydrophilic amino acids, and highly heat stable. These results showed that AS26k was a dehydrin, a group II LEA protein in soybean seeds.

Thioredoxin-linked mitigation of allergic responses to wheat.

Thioredoxin, a ubiquitous 12-kDa regulatory disulfide protein, was found to reduce disulfide bonds of allergens (convert S-S to 2 SH) and thereby mitigate the allergenicity of commercial wheat preparations. Allergenic strength was determined by skin tests with a canine model for food allergy. Statistically significant mitigation was observed with 15 of 16 wheat-sensitive animals. The allergenicity of the protein fractions extracted from wheat flour with the indicated solvent was also assessed: the gliadins (ethanol) were the strongest allergens, followed by glutenins (acetic acid), albumins (water), and globulins (salt water). Of the gliadins, the alpha and beta fractions were most potent, followed by the gamma and omega types. Thioredoxin mitigated the allergenicity associated with the major protein fractions-i.e, the gliadins (including the alpha, beta, and gamma types) and the glutenins-but gave less consistent results with the minor fractions, the albumins and globulins. In all cases, mitigation was specific to thioredoxin that had been reduced either enzymically by NADPH and NADP-thioredoxin reductase or chemically by dithiothreitol; reduced glutathione was without significant effect. As in previous studies, thioredoxin was particularly effective in the reduction of intramolecular (intrachain) disulfide bonds. The present results demonstrate that the reduction of these disulfide bonds is accompanied by a statistically significant decrease in allergenicity of the active proteins. This decrease occurs alongside the changes identified previously-i.e., increased susceptibility to proteolysis and heat, and altered biochemical activity. The findings open the door to the testing of the thioredoxin system in the production of hypoallergenic, more-digestible foods.

Deliberate buffy-coat transfusions and the risk of antibody formation.

Antibody formation was monitored after buffy-coat transfusions were given at weekly intervals for 9 weeks or a single injection of buffy-coat pooled from ten different donors was given. Among patients with no prior transfusion history, 7 patients given repeated transfusions did not develop warm B or T cytotoxins. Among 25 patients receiving pooled buffy-coat, only 1 patient (who had 3 prior pregnancies) developed warm B and T cytotoxins. In contrast, approximately one fourth of patients who had prior blood transfusions developed warm B and T cytotoxins with either repeated or pooled buffy-coat transfusions. We conclude that buffy-coat from 10 donors given weekly or as a single pooled injection does not produce warm B and T cytotoxins in nontransfused patients, but does function as a secondary stimulus in primed patients.