Effects of undernutrition and diabetes on serum and liver mRNA expression of IGFs and their binding proteins during rat development

The purpose of the present study was to investigate the influence of nutrients and insulin on IGFs and their binding proteins (IGFBPs) during the fetal and neonatal periods of three rat populations: (a) rats undernourished by a 35% reduction in the diet from day 16 of gestation, (b) streptozotocin-induced diabetic rats from the same day, or 4 days after birth, and (c) control rats. Fetuses from the diabetic population showed a decrease in insulinemia at 19 and 21 days, along with an increase in glycemia at all stages. Neither glycemia nor insulinemia changed in the fetuses of undernourished mothers, but body weight was decreased at birth. Serum IGF-II decreased at 18 and 19 days of gestation in fetuses from undernourished mother, and increased at 18, 19 and 21 days in fetuses from diabetic mothers. Serum IGFBPs of low molecular weight (IGFBP-1 and IGFBP-2) increased in the three fetal populations studied, although no changes in serum IGFBPs were found from the effect of undernutrition or diabetes, but fetal liver IGFBP-1 mRNA expression was found to decreased in undernourished and diabetic animals as compared with controls. In neonatal rats, body weight, insulinemia and serum GH decreased in both undernourished and diabetic rats vs controls, while glycemia decreased in the undernourished and increased in the diabetic group. Serum IGF-II decreased only in diabetic rats and serum IGF-I decreased in both groups. The neonatal serum 30 kDa complex (IGFBP-1 and -2) also increased in undernutrition and diabetes parallel to the expression of mRNA. But, taken together, the changes in IGFBP peptide levels and liver mRNA expression strongly suggest that the 30 kDa complex seems to be composed mostly of IGFBP-1 in the diabetic group and of both IGFBP-1 and -2 in the undernourished animals. The studies of liver mRNA expression of IGFs and IGFBPs confirm the different metabolic control mechanism for the availability of IGFs by the IGFBPs, depending on the animal's maturity. The different adaptation shown by the diabetic neonatal population was confirmed by correlation studies between body weight, glycemia, insulinemia, IGF-I and IGFBPs. The different mechanism of adaptation in diabetic vs undernourished rats seems to be probably due to the decisive role played by hyperglycemia in the diabetic population, and also shows the crucial influence of nutritional status on IGFs and IGFBPs.     

An experimental investigation of the effect of coatings and cutting parameters on the dry drilling performance of aluminium alloys

As a result of the need to automate assembly in the aircraft industry, along with economic and ecological reasons, industry and research institutions have been pushed to develop dry drilling for aluminium alloys to eliminate the need for cooling fluids. The main difficulties in dry drilling are accelerated tool wear due to workpiece material adhesion on the tool and the formation of bigger-sized burrs. This paper describes an experimental research study on machinability in the dry drilling of aluminium alloys and on the potential of the new design of tools and coatings. Dry drilling tests were performed using uncoated drills and two different coatings produced by means of an arc evaporation PVD process. Experiments consisted of machining with a 10-mm diameter three-edged drill to produce 25-mm deep holes. Tool wear evolution and burr size were analysed, as well as the impact of the process parameters on torque, power, feed force and tool temperature.     

A dynamical model for the generation of H2 in microhydrated Al clusters

A dynamical model is proposed to describe the generation of H₂ in the Al_n + H₂O reactions in order to deal with the complexity of the potential energy surface. For that purpose electronic structure Density Functional Theory and Transition State Theory computations have been carried out on the Al₁₇⁺·(H₂O) system. The results are compared with the findings of previous flow-tube experiments, in which Al₁₇⁺ is found to be highly reactive with just one water molecule; that makes this system ideal for modelling. The energy ordering in terms of the activation energies of the various processes is: cluster distortions ≈ -OH migrations < -H migrations < O-H bond breaking < H₂ release. The time-dependent results are reasonably consistent with the experiments and suggest that the lowest-lying structures of the oxo type (H₂Al₁₇O⁺ structures) play the most relevant role in the production of H₂. The sensitivity towards energy removal from the reacting system and the impact of tunnelling have been analysed as well as the possible role of a second water molecule as a catalyst of the water-splitting step by a Grotthuss-relay mechanism.     

Effect of calcium on mineral nutrient uptake and growth of tobacco

The aim of this work was to analyse the dynamics of the nutritional state and biomass production in tobacco plants resulting from the application of various calcium levels (Ca1, 1.25 mol m^?3 CaCl₂; Ca2, 2.50 mol m^?3 CaCl₂; Ca3, 5 mol m^?3 CaCl₂) in the culture medium. Tobacco plants were grown under controlled conditions and submitted to regular fertilisation with macro‐ and micronutrients. The concentrations of Ca, organic N, P, K, Na, Mg, Fe, Mn, Zn, Cu, Cl and B were determined in the roots and leaves. As expected, Ca accumulated progressively with increasing concentration of this element in the culture medium. There was a slight rise in the concentration of organic N but hardly any change in the concentrations of K and Na. In contrast, increasing Ca application caused a gradual decline in P and Mg concentrations. In terms of micronutrient concentrations, Fe, Mn, Zn, Cl and B were influenced positively by Ca treatment. A noteworthy synergetic relationship was found between Ca and B. In contrast, the Cu concentration in the roots declined significantly with increasing Ca application. The effect of Ca on biomass production depended on the organ analysed, since the dry matter content diminished in the roots but was augmented slightly in the leaves. © 2001 Society of Chemical Industry