A structural comparison of casein micelles in cow, goat and sheep milk using X-ray scattering.

The casein micelle is a flexible construct, with its key structural components being casein proteins and colloidal calcium phosphate nanoclusters. According to literature, milk from different species exhibits differences in composition and physicochemical properties. X-ray scattering techniques were used to investigate and compare the nanoscale structure of casein micelles present in cow, goat and sheep milk. Although there were differences in the size and density of larger scale protein structures, at an atomic level the protein structures were similar. There were also strong similarities in the structure of the calcium-containing nanoclusters, namely that they had similar sizes and separations within the casein micelle for all three species.

Oxidative stability of iron fortified goat and cow milk and their peptide isolates.

The oxidation potential of iron fortified goat and cow milks and casein phosphopeptides obtained from each species of milk was determined using malondialdehyde as an oxidation product marker. There was a reduction in oxidation when iron was 'bound' to milk or peptides compared to free ferrous sulphate in solution. However, goat milk produced significantly lower amounts of malondialdehyde of 0.46±0.04µgMDA/ml after 3days at 30°C compared to the blank of 1.25±0.16µgMDA/ml. The goat peptides produced non-significantly different levels of malondialdehyde compared to the blank containing no ferrous sulphate.

Assessing the iron chelation capacity of goat casein digest isolates.

We isolated goat phosphopeptides via calcium and ethanol precipitation from a caseinate digest and investigated their feasibility as an iron-fortification ingredient in nutritional foods. Goat tryptic-digested phosphopeptides could bind 54.37 ± 0.50 mg of Fe/g of protein compared with goat milk, which could bind 3.83 ± 0.01 mg of Fe/g of protein, indicating that isolation did increase iron binding. However, the >13-fold increase in iron binding was only partly explained by the increased concentration of phosphoserine-rich residues in the isolated fraction: we observed a 77% increase in serine residue content and a 5.9-fold increase in phosphorus in the goat peptide isolate compared with the starting caseinate material. We investigated the effect of potential industrial processing conditions (including heating, cooling, holding time, and processing order) on iron binding by the tryptic-digested phosphopeptides. In addition, we tested the effect of ionic strength and the addition of peptides to a milk system to understand how food formulations could affect iron binding.

Revisiting the interpretation of casein micelle SAXS data.

An in-depth, critical review of model-dependent fitting of small-angle X-ray scattering (SAXS) data of bovine skim milk has led us to develop a new mathematical model for interpreting these data. Calcium-edge resonant soft X-ray scattering data provides unequivocal evidence as to the shape and location of the scattering due to colloidal calcium phosphate, which is manifested as a correlation peak centred at q = 0.035 Å(-1). In SAXS data this feature is seldom seen, although most literature studies attribute another feature centred at q = 0.08-0.1 Å(-1) to CCP. This work shows that the major SAXS features are due to protein arrangements: the casein micelle itself; internal regions approximately 20 nm in size, separated by water channels; and protein structures which are inhomogeneous on a 1-3 nm length scale. The assignment of these features is consistent with their behaviour under various conditions, including hydration time after reconstitution, addition of EDTA (a Ca-chelating agent), addition of urea, and reduction of pH.

Solving the mystery of the internal structure of casein micelles.

The interpretation of milk X-ray and neutron scattering data in relation to the internal structure of the casein micelle is an ongoing debate. We performed resonant X-ray scattering measurements on liquid milk and conclusively identified key scattering features, namely those corresponding to the size of and the distance between colloidal calcium phosphate particles. An X-ray scattering feature commonly assigned to the particle size is instead due to protein inhomogeneities.

[Antiestrogens in the treatment of advanced breast cancer]. / Antyestrogeny w leczeniu zaawansowanego raka gruczolu piersiowego.

Fifty nine female patients with an advanced, recurrent breast cancer were treated with tamoxifen (TAM) in the daily dose of 40-60 mg. The drug was administered to 44 patients following ineffective chemotherapy and/or hormonotherapy with stilbestrol. Ineffective therapy was related with the deterioration of the general status. TAM was administered to the remaining 15 patients from the beginning due to the serious condition. Twenty four patients with the advanced breast cancer treated according to FAC regimen served as the control group. TAM produced significant improvement in health status of the majority of the treated patients and partial remission of cancer in 30% of them. Incidence of remissions, duration and survival period in patients treated with TAM for the advanced breast cancer did not differ significantly from the results obtained in the control group.