Interactions among iron, calcium, phosphorus and magnesium in the nutritionally iron-deficient rat

We studied the development of nutritional iron deficiency 0, 10, 20, 30 and 40 days after the intake of a semisynthetic diet lacking iron (diet 0) and the possible interactions with calcium, phosphorus and magnesium in both control rats and rats after 40 days of iron deficiency. During this period, iron deficiency was found to produce stress in the rats, as evidenced by high levels of cortisol in the serum. High levels of parathyroid hormone (PTH) were also found. There was a considerable increase in the absorption of calcium, phosphorus and magnesium, but the phosphorus and magnesium balance decreased and that of calcium remained practically unchanged, although there was an increase in calcium urinary elimination. Despite the noticeable degree of bone demineralization, which was evident in the femur, serum levels of calcium, phosphorus and magnesium remained constant. The present study shows that severe nutritional ferropenic anaemia provokes significant alterations in the metabolism of calcium, phosphorus and magnesium. We conclude that these alterations should be taken into account in the treatment of this pathology, given its prevalence and the fact that it may exacerbate other pathologies, particularly those related to the metabolism of calcium and phosphorus.     

The dynamic mechanical behavior of paper during drying

The dynamic mechanical properties of paper during restrained drying are reported in this article. The apparatus used was a servohydraulic material testing system (MTS), connected to a computer unit. It has been found that the ratio of drying stress to elastic modulus at a given dry solids content corresponds to the instantaneous linear contraction of the sheet when the drying stress is relieved. It is therefore deduced that paper behaves as a linear viscoelastic body during restrained drying. The finding of a maximum loss coefficient and the drastic change in elastic modulus during drying of paper are interpreted in terms of a transitional change in the amorphous regions of wood polymers plasticized by water.     

Extensions to “Output prediction under scarce data operation: control applications”

Albertos et al. (Automatica, 35 (1999) 1671–1681), proposed a simple and computationally cheap output estimation algorithm for systems where some output data is missing. In the original paper, a stability analysis of the algorithm is provided for the special case that every Nth sample of the output is observed. We here show how the stability can be analysed for arbitrary periodical missing data patterns.     

A comparative study of heat and high pressure induced gels of whey and egg albumen proteins and their binary mixtures

Large deformation rheological studies of either egg albumen or whey protein isolate (15% protein w/w) gels induced by heating at 90 °C for 30 min were compared to those induced by a range high pressures (400–800 MPa for 20 min). Gels made by heating indicated higher gel strength and Young's modulus values for whey protein from pressures of 400–600 MPa for 20 min but similar values at 650–800 MPa. In contrast, egg albumen showed no gelation below 500 MPa for 20 min, but there was an increase in both gel strength and Young's modulus with increasing pressure, although values remained lower than those of the heat-induced gels. A mixture of 10:5 whey/egg albumen showed the highest gel strength and Young's modulus for both heated and high pressure-treated (400–600 MPa) gels, although, the heated mixture had the highest values. Electron micrographs indicated that high pressure-treated gels had a porous aggregated network for egg albumen while whey proteins showed a continuous fine stranded network. The heated mixtures of whey:egg albumen (7.5:7.5) showed large dense aggregates whereas high pressure-treated mixtures produced smaller aggregates. Raman spectroscopy of both heated and high pressure-treated whey and egg albumen (15% w/w in D₂O pD7) and their binary mixtures (7.5:7.5, protein w/w) indicated changes in β-sheet structures in the Amide 111′ region (980–990 cm⁻¹); however, peak intensity was reduced for high pressure-treated samples. β-Sheet structure (1238–1240 cm⁻¹) present in heated whey was absent in high pressure-treated whey and in egg albumen. Involvement of hydrophobic regions was reflected by changes in the CH (1350 cm⁻¹) and CH₂ (1450 cm⁻¹) bending vibrations. In addition to the Trp residues at 760 cm⁻¹, there were broad peaks at 874–880 cm⁻¹ and tyrosine 1207 cm⁻¹ in the high pressure-treated samples. Disulphide bands (500–540 cm⁻¹) in heated whey and egg albumen proteins showed higher peak intensities compared to high pressure-treated samples. Differences in the experimental and theoretical spectra indicated changes in the hydrophobic regions, tyrosine (1207 cm⁻¹) and tryptophan (880 cm⁻¹) and CH₂ bending in high pressure-treated samples, whereas heated samples indicated marked changes in β-sheet structures (987 and 1238 cm⁻¹) as well as hydrophobic regions CH (1350 cm⁻¹) and CH₂ (1450 cm⁻¹) bending vibrations.     

Goat milk feeding causes an increase in biliary secretion of cholesterol and a decrease in plasma cholesterol levels in rats

The hypocholesterolemic effect of goat milk with respect to cow milk observed in a previous study led us to examine the influence of goat and cow milk in the diet on certain aspects of biliary physiology in normal rats. The fat content in all diets was 10% but the lipid quality was varied: the standard diet was based on virgin olive oil, and the other 2 diets included fat obtained from lyophilized cow milk and goat milk. We characterized the bile secretion, including biliary phospholipid, cholesterol, and bile acid outputs, the interrelation between bile acids and bile lipids, and the lithogenic index. The consumption of goat milk in the diet, compared with that of cow milk, caused an increase in the biliary secretion of cholesterol together with a decrease in plasma cholesterol concentration, whereas values for bile phospholipids, biliary acid concentrations, and the lithogenic index remained normal. Moreover, consumption of this type of milk decreased plasma triglyceride concentration and therefore had a positive effect, similar to that of olive oil (standard diet), on the lipid metabolism; hence, it may be recommended for consumption by the general population.     

A quantitative method for the determination of amphiphilic drug release kinetics from nanoparticles using a Langmuir balance

Amiodarone is a drug that is widely used in the treatment of heart disease. To circumvent side effects, colloidal drug carriers have been designed to deliver the drug specifically to the site of action. For the purposes of in vitro characterization of such particles, difficult test systems are employed that usually require the quantitative separation of the drug carrier from the release medium before analysis. In this work, a Langmuir balance was used to characterize amiodarone release. Drug-loaded nanoparticles were prepared from a biodegradable polyester and assayed for their drug release kinetics. Simultaneously, nanoparticles were analyzed for their drug release by a standard procedure based on dialysis tubes combined with high-performance, liquid chromatography. The results obtained by the Langmuir balance experiments were compared with those obtained from high-performance liquid chromatography and were found to correlate well. The interexperimental variation was 4.4% for the Langmuir method (n = 4), and the interexperimental variation for HPLC was 2.9% (n = 3). The major advantage of this new method is the possibility diminishing significantly the required sample amount for the experiment, allowing drug detection in the lower nanomolar range. Moreover, the avoidance of prior nanoparticle separation from the release medium provides important progress of this technique. The Langmuir balance has proven its adaptability as a new sensitive tool for the characterization of amphiphilic drug release kinetics.     

Optimization and simulation of traffic flows in the case of evacuating urban areas

In cases where urban areas need to be evacuated, a large number of vehicles must be routed through narrow street networks effectively. This paper combines two aspects of this problem. On the one hand, the traffic flows must be routed through the road network in such a way that e.g. the time required to get all out is as small as possible. Hence, we have to solve an optimization problem to find out which roads shall be used in what direction. On the other hand, even if routes are defined, traffic flows are dynamic in nature and phenomena related to the traffic jam are to be examined by simulation. By defining an optimization-based simulation procedure, we get a heuristic for the overall problem. As an example we compute and simulate an evacuation plan for a neighborhood in the city of Duisburg, Germany, to demonstrate the applicability of our approach to real-world sized problems.