Human Tumor Cell Proliferation Evaluated Using Manganese-Enhanced MRI

Tumor cell proliferation can depend on calcium entry across the cell membrane. As a first step toward the development of a non-invasive test of the extent of tumor cell proliferation in vivo, we tested the hypothesis that tumor cell uptake of a calcium surrogate, Mn(2+) [measured with manganese-enhanced MRI (MEMRI)], is linked to proliferation rate in vitro.Proliferation rates were determined in vitro in three different human tumor cell lines: C918 and OCM-1 human uveal melanomas and PC-3 prostate carcinoma. Cells growing at different average proliferation rates were exposed to 1 mM MnCl(2) for one hour and then thoroughly washed. MEMRI R(1) values (longitudinal relaxation rates), which have a positive linear relationship with Mn(2+) concentration, were then determined from cell pellets. Cell cycle distributions were determined using propidium iodide staining and flow cytometry. All three lines showed Mn(2+)-induced increases in R(1) compared to cells not exposed to Mn(2+). C918 and PC-3 cells each showed a significant, positive correlation between MEMRI R(1) values and proliferation rate (p≤0.005), while OCM-1 cells showed no significant correlation. Preliminary, general modeling of these positive relationships suggested that pellet R(1) for the PC-3 cells, but not for the C918 cells, could be adequately described by simply accounting for changes in the distribution of the cell cycle-dependent subpopulations in the pellet.These data clearly demonstrate the tumor-cell dependent nature of the relationship between proliferation and calcium influx, and underscore the usefulness of MEMRI as a non-invasive method for investigating this link. MEMRI is applicable to study tumors in vivo, and the present results raise the possibility of evaluating proliferation parameters of some tumor types in vivo using MEMRI

Reconstitution properties of micellar casein powder: Effects of composition and storage

A problem associated with micellar casein (MC) powders is their poor reconstitution properties. In this study, we prepared MCs with different salt and protein compositions and having different reconstitutabilities directly after production. Reconstitutability further decreased during storage at 30 degrees C. Differential scanning calorimetry, infrared spectroscopy, and small angle X-ray scattering showed that the powders were very similar on a molecular or sub-micellar level, indicating that the loss of reconstitutability is probably controlled by higher order structural changes, such as cross-linking between casein micelles, possibly involving intermolecular beta-sheet formation. The reconstitutability of MC could be improved by adding sodium caseinate to the concentrated milk before spray drying. This novel approach to improve reconstitutability can easily be incorporated into the existing processing protocol. We propose two possible mechanisms for the protecting effect of the non-micellar caseins.(C) 2011 Elsevier Ltd. All rights reserved

Purification and Characterization of Novel α-Amylase from Bacillus subtilis KIBGE HAS

Purification of extracellular α-amylase from Bacillus subtilis KIBGE HAS was carried out by ultrafiltration, ammonium sulfate precipitation and gel filtration chromatography. The enzyme was purified to homogeneity with 96.3-fold purification with specific activity of 13011 U/mg. The molecular weight of purified α-amylase was found to be 56,000 Da by SDS-PAGE. Characteristics of extracellular α-amylase showed that the enzyme had a Km and Vmax value of 2.68 mg/ml and 1773 U/ml, respectively. The optimum activity was observed at pH 7.5 in 0.1 M phosphate buffer at 50°C. The amino acid composition of the enzyme showed that the enzyme is rich in neutral/non polar amino acids and less in acidic/polar and basic amino acids. The N-terminal protein sequence of 10 residues was found to be as Ser-Ser-Asn-Lys-Leu-Thr-Thr-Ser-Trp-Gly (S-S-N-K-L-T-T-S-W-G). Furthermore, the protein was not N-terminally blocked. The sequence of α-amylase from B. subtilis KIBGE HAS was a novel sequence and showed no homology to other reported α-amylases from Bacillus strain

Combined Drying Technologies for High-Quality Kiwifruit Powder Production

Freeze-drying is a dehydration technique which, from a sensory, nutritional and functional point of view, provides high-quality powder products. Nevertheless, both long processing times and high economic costs are required. In this study, pre-drying the samples using hot air or microwave has been considered in order to reduce the initial product's water content thereby shortening the freeze-drying time so as to obtain high value products at a reduced cost. The effect of dehydration pre-treatments on the kinetics, antioxidant activity and solubility of freeze-dried kiwifruit products was evaluated. Nine different thin-layer semi-theoretical models were used to fit the drying data. According to the obtained results, the pre-treated samples exhibited higher drying rates than the fresh sample. 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