Effect of protein fortification on heat damage and occurrence of ß-casomorphins in (un)digested donor human milk intended for nutrition of preterm infants.

Pasteurized donor human milk (PDHM) for preterm infant nutrition is fortified with hydrolyzates of cow's milk proteins, which have been poorly investigated in relation to heat-damage and occurrence of the bioactive peptides ß-casomorphins (BCMs). Therefore, thermal protein modifications of three commercial fortifiers were assessed by measuring well-recognized indexes of heat load. The fortifiers did not contain pyrraline, whereas furosine and lysinoalanine levels roughly overlapped the lowest values reported for liquid formulas addressed to term infant nutrition. Bovine BCMs 3 to 7 and human BCMs 3 to 9 were searched. Bovine BCMs 3, 4, 6 and 7 were found in the undigested fortifiers. Following in vitro digestion simulating the digestive conditions of premature infant, bovine BCMs still occurred in fortified PDHM; the human BCMs 3, 7, 8 and 9 formed. Overall, these results better address the nutritional features of protein fortifiers and fortified PDHM intended for nutrition of preterm infants.

Determination of hepatotoxic indospicine in Australian camel meat by ultra-performance liquid chromatography-tandem mass spectrometry.

Indospicine is a hepatotoxic amino acid found in Indigofera plant spp. and is unusual in that it is not incorporated into protein but accumulates as the free amino acid in the tissues (including muscle) of animals consuming these plants. Dogs are particularly sensitive to indospicine, and secondary poisoning of dogs has occurred from the ingestion of indospicine-contaminated horse meat and more recently camel meat. In central Australia, feral camels are known to consume native Indigofera species, but the prevalence of indospicine residues in their tissues has not previously been investigated. In this study, a method was developed and validated with the use of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to determine the level of indospicine in camel meat samples using isotopically labeled indospicine as an internal standard. UPLC-MS/MS analysis showed that the method is reproducible, with high recovery efficiency and a quantitation limit of 0.1 mg/kg. Camel meat samples from the Simpson Desert were largely contaminated (≈50%) by indospicine with levels up to 3.73 mg/kg (fresh weight) determined. However, the majority of samples (95%) contained less than 1 mg/kg indospicine.

Influence of casein and soy flour proteins on aminoacid content in the liver of experimental animals.

We have observed a significantly increased content of fats and decreased content of proteins in the liver of experimental rats fed a diet supplemented with 25% casein proteins in comparison with the application of de-fatted soy flour. Casein proteins have a higher content of methionine in relation to cystine than baked soy flour. But the soy diet in contrast to the casein diet has a high content of free aminoacids which are not present in casein at all: aspartic acid, asparagine, alpha-aminoadipic acid, methionine, norleucine, lysine, phenylalanine, beta-alanine, ethanolamine, histidine, proline, gamma-aminobutyric acid, taurine. Differences in free valine, alanine, arginine, glycine, ornithine and cysteic acid are also significant. The content of free aminoacids in the liver of experimental animals fed a soy diet is high in the content of cystine, cystathionine, ornithine, beta-aminoisobutyric acid, beta-alanine, gamma-aminobutyric acid, leucine. We have also found accumulation of methionine, glycine, alpha-aminobutyric acid, taurine and citrulline in free aminoacids from the liver of animals fed a casein diet. Citrulline and glycine in free aminoacids from the liver of animals fed a soy protein supplement were not recorded. Our investigations have shown that the application of a soy diet enriched with cystine acts protectively on methionine and that methionine is preferentially utilized for protein synthesis. The catabolic pathway of methionine prevails in animals on a casein diet.

The composition of the insoluble collagenous matrix of bovine predentine.

Predentine obtained from bovine teeth by microdissection was extracted with EDTA and tris-NaCl solutions. The insoluble residue consisted mainly of collagen and resembled dentine collagen in overall amino acid composition. The residue differed in containing no detectable phosphoprotein, a much larger amount of collagen hexose and more non-collagenous glycoprotein, the neutral sugar composition of which was determined. Differences were also observed in the contents of reducible collagen cross-links. Half of the total phosphorus found in the predentine could not be accounted for solely by hydroxyapatite. The remainder was partly soluble and dialysable.